Publications by authors named "Namrita Lall"

68 Publications

Structural elucidation of an immunological arabinan from the rhizomes of Ligusticum chuanxiong, a traditional Chinese medicine.

Int J Biol Macromol 2021 Feb 11;170:42-52. Epub 2020 Dec 11.

State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy, Tianjin Key Laboratory of Molecular Drug Research, and Drug Discovery Center for Infectious Disease, Nankai University, Tianjin 300350, People's Republic of China. Electronic address:

In the present study, an immunological arabinan, LCP70-2A, was isolated from Ligusticum chuanxiong for the first time. The absolute molecular weight of LCP70-2A was determined to be 6.46 × 10 g/mol using the HPSEC-MALLS-RID method. The absolute configuration of arabinose in LCP70-2A was determined to be L-configuration. Physicochemical characterization revealed that LCP70-2A was a homogeneous polysaccharide and had a backbone of (1 → 5)-linked α-L-Araf with terminal α-L-arabinose residues at position O-2 and O-3. Molecular conformation analysis showed that LCP70-2A was a branching polysaccharide with a compact coil chain conformation in 0.1 M NaCl solution. In addition, in vitro cell assays showed that LCP70-2A can activate macrophages by enhancing the phagocytosis and potentiating the secretion of immunoregulatory factors including NO, TNF-α, IL-6, and IL-1β. Furthermore, LCP70-2A was proved to promote the production of ROS and NO using the zebrafish model, suggesting that LCP70-2A can be further developed as a candidate supplement for immunological enhancement.
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http://dx.doi.org/10.1016/j.ijbiomac.2020.12.069DOI Listing
February 2021

Traditional usage and biological activity of Plectranthus madagascariensis and its varieties: A review.

J Ethnopharmacol 2021 Apr 3;269:113663. Epub 2020 Dec 3.

Department of Plant and Soil Sciences, University of Pretoria, Pretoria, South Africa; School of Natural Resources, University of Missouri, Columbia, MO, United States; College of Pharmacy, JSS Academy of Higher Education and Research, India. Electronic address:

Ethnopharmacological Relevance: Plectranthus madagascariensis (Pers.) Benth. is an indigenous aromatic South African plant species that are traditionally used to treat various dermatological and respiratory ailments.

Aim Of The Study: Three varieties of P. madagascariensis exist in South Africa, namely, Plectranthus aliciae (Codd) van Jaarsv. & T.J. Edwards, Plectranthus ramosior (Benth.) Van Jaarsv. and Plectranthus madagascariensis (Pers.) Benth var. madagascariensis. This article summarizes the documented ethnobotanical uses and research which has been conducted to date on the chemical constituents and biological effects of P. madagascariensis and its varieties. This review aimed to investigate and highlight the lack scientific reports of the potential activity of these varieties based on their traditional usage and to emphasise the need for further investigation of the benefits of P. madagascariensis and its varieties.

Materials And Methods: Extensive database retrieval using platforms not limited to but including Google Scholar, ScienceDirect and PubMed, was performed by using keywords such as "Plectranthus madagascariensis" "Plectranthus madagascariensis var. aliciae", "Plectranthus aliciae", "Plectranthus ramosior", "Plectranthus madagascariensis var. ramosior" and "Plectranthus hirtus" In addition, relevant books and digital documentation were consulted to collect all available scientific literature to provide a comprehensive review.

Results: Several studies have reported the traditional usage of P. madagascariensis for the treatment of diseases related to the respiratory system such as coughs, colds and asthma as well as dermatological disorders associated with wounds and inflammation. Whilst there are no reports on the traditional usage of P. madagascariensis varieties to treat other maladies, several other species within the genus are used in other traditional practices. Plectranthus ramosior is used as a toxin for fishing. In literature, seven major phytochemical compounds have been identified from P. madagascariensis. Its extract and essential oil contain polyphenols, abietane diterpenes and abietane diterpenes with a quinone moiety. The extracts and major chemical constituents of P. madagascariensis and its major phytochemicals have reported activity against several biological targets. Reports relating to the antibacterial activity of P. madagascariensis against microbes associated with tuberculosis and wound infections has been consistent and correlates with the documented traditional usage of the plant. Literature reported on the antibacterial activity of P. aliciae targeting bacteria associated with wound infections and lung cancer cells. No further literature reports of the biological activity of the other P. madagascariensis varieties have been found. Other noteworthy biological activities reported in the literature of P. madagascariensis and its compounds include their activities against targets of Alzheimer's disease and breast cancer, in particular. This activity is not related to the traditional usage of the plant.

Conclusion: Plectranthus madagascariensis and its compounds have been proven to be effective in treating a range of maladies. Based on the extensive literature on this plant, it can be concluded that numerous in vitro pharmacological activities of P. madagascariensis have been reported. However, there is a lack of information available for this species with regards to its in vivo data including both pre-clinical and clinical studies. Since the extract of P. madagascariensis and its isolated compounds have displayed noteworthy anticancer potential, we recommend further investigation of pharmacokinetic studies to be included in future research.
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http://dx.doi.org/10.1016/j.jep.2020.113663DOI Listing
April 2021

Anti-SARS-CoV Natural Products With the Potential to Inhibit SARS-CoV-2 (COVID-19).

Front Pharmacol 2020 25;11:561334. Epub 2020 Sep 25.

Department of Plant and Soil Sciences, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), known to cause the disease COVID-19, was declared a pandemic in early 2020. The objective of this review was to collate information regarding the potential of plants and natural products to inhibit coronavirus and targets associated with infection in humans and to highlight known drugs, which may have potential activity against SARS-CoV-2. Due to the similarity in the RNA genome, main proteases, and primary host receptor between SARS-CoV and SARS-CoV-2, a review was conducted on plants and secondary metabolites, which have shown activity against SARS-CoV. Numerous scientific reports on the potential of plants and secondary metabolites against SARS-CoV infection were found, providing important information on their possible activity against SARS-CoV-2. Based on current literature, 83 compounds have been identified with the potential to inhibit COVID-19. The most prominent selectivity was found for the alkaloid, lycorine, the lignan, savinin, and the abietane terpenoid, 8-beta-hydroxyabieta-9(11),13-dien-12-one with selectivity index values greater than 945, 667, and 510, respectively. Plants and their secondary metabolites, with activity against targets associated with the SARS-CoV infection, could provide valuable leads for the development into drugs for the novel SARS-CoV-2. The prospects of using computational methods to screen secondary metabolites against SARS-CoV targets are briefly discussed, and the drawbacks have been highlighted. Finally, we discuss plants traditionally used in Southern Africa for symptoms associated with respiratory viral infections and influenza, such as coughs, fever, and colds. However, only a few of these plants have been screened against SARS-CoV. Natural products hold a prominent role in discovering novel therapeutics to mitigate the current COVID-19 pandemic; however, further investigations regarding , , pre-clinical, and clinical phases are still required.
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http://dx.doi.org/10.3389/fphar.2020.561334DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7546787PMC
September 2020

Profiling Anticancer and Antioxidant Activities of Phenolic Compounds Present in Black Walnuts () Using a High-Throughput Screening Approach.

Molecules 2020 Oct 2;25(19). Epub 2020 Oct 2.

Center for Agroforestry, School of Natural Resources, University of Missouri, Columbia, MI 65211, USA.

Our recent studies have demonstrated multiple health-promoting benefits from black walnut kernels. These biological functions of black walnuts are likely associated with their bioactive constituents. Characterization of phenolic compounds found in black walnut could point out underexplored bioactive activities of black walnut extracts and promote the development of novel applications of black walnut and its by-products. In the present study, we assessed bioactivity profiles of phenolic compounds identified in the kernels of black walnuts using a high-throughput screening (HTS) approach. Black walnut phenolic compounds were evaluated in terms of their total antioxidant capacity, antioxidant response element (ARE) induction, and anticancer activities. The anticancer activities were identified by evaluating the effects of the phenolic compounds on the growth of the tumorigenic alveolar epithelial cells (A549) and non-tumorigenic lung fibroblast cells (MRC-5). Out of 16 phenolic compounds tested, several compounds (penta--galloyl--d-glucose, epicatechin gallate, quercetin, (-)-epicatechin, rutin, quercetin 3--d-glucoside, gallic acid, (+)-catechin, ferulic acid, syringic acid) exerted antioxidant activities that were significantly higher compared to Trolox, which was used as a control. Two phenolic compounds, penta--galloyl--d-glucose and quercetin 3--d-glucoside, exhibited antiproliferative activities against both the tumorigenic alveolar epithelial cells (A549) and non-tumorigenic lung fibroblast cells (MRC-5). The antioxidant activity of black walnut is likely driven not only by penta--galloyl--d-glucose but also by a combination of multiple phenolic compounds. Our findings suggested that black walnut extracts possibly possess anticancer activities and supported that penta--galloyl--d-glucose could be a potential bioactive agent for the cosmetic and pharmaceutical industries.
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http://dx.doi.org/10.3390/molecules25194516DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7583942PMC
October 2020

Anti-Inflammatory -Kaurane Diterpenoids from .

J Nat Prod 2020 10 29;83(10):2844-2853. Epub 2020 Sep 29.

State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy, and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin 300350, People's Republic of China.

Ten new -kaurane diterpenoids, including two pairs of epimers / and / and a 6,7---kauranoid , were obtained from the aerial parts of . The structures of the new compounds were confirmed by extensive spectroscopic methods and electronic circular dichroism (ECD) data analysis. An anti-inflammatory assay was applied to evaluate their nitric oxide (NO) inhibitory activities by using LPS-stimulated BV-2 cells. Compounds and exhibited notable NO production inhibition with IC values of 15.6 and 7.3 μM, respectively. Moreover, the interactions of some bioactive diterpenoids with inducible nitric oxide synthase (iNOS) were explored by employing molecular docking studies.
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http://dx.doi.org/10.1021/acs.jnatprod.9b01281DOI Listing
October 2020

Editorial: Cosmeceuticals From Medicinal Plants.

Front Pharmacol 2020 29;11:1149. Epub 2020 Jul 29.

Department of Plant and Soil Sciences, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa.

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http://dx.doi.org/10.3389/fphar.2020.01149DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7403217PMC
July 2020

Antioxidant and Anti-Inflammatory Activities of (Lam.) Benth.

Evid Based Complement Alternat Med 2020 17;2020:4352084. Epub 2020 Jun 17.

Phytomedicine Programme, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.

is used to manage inflammation among indigenous communities. We hypothesized that extracts contain phytoconstituents with good antioxidant and anti-inflammatory activities. The methanolic extract of fruits and leaves (SPK04), aqueous fruit extract (KFM02), and acetone fruit extract (KFM05) were subjected to antioxidant and anti-inflammatory assays. Antioxidant activity was evaluated using the ABTS radical scavenging assay, and the MTT cell viability assay was used for cytotoxicity. The extracts were preincubated with enzymes and assayed for 15-LOX and COX-2 enzyme activity using an ELISA method. Nitric oxide (NO) inhibitory effect of the extracts was evaluated and measurement of proinflammatory cytokines (IL-1, TNF-, and IL-6) and the anti-inflammatory cytokine (IL-10) was done using ELISA kits. SPK04 had the highest antioxidant activity with a mean inhibition of 99.37 ± 0.56% and an IC of 4.28 g/mL. SPK04 and KFM05 did not inhibit 15-LOX as their IC values were >1000 g/mL. All extracts were safe on Vero cells at the highest concentration (200 g/mL) tested. KFM02 was the best inhibitor of NO production and had the highest cell viability at both the lowest (50 g/mL) and highest concentrations (200 g/mL). SPK04 was the best COX-2 inhibitor while KFM05 expressed the strongest suppression effect for IL- and IL-6. KFM02 did not inhibit IL-6 at the highest concentration (200 g/mL). The order of suppression of TNF- by the extracts differed across concentrations, KFM05 > SPK04 > KFM02 at 200 g/mL, KFM02 > SPK04 > KFM05 at 100 g/mL, and SPK04 > KFM02 > KFM05 at 50 g/mL. All the tested extracts had no inhibitory effect against IL-10. SPK04, KFM05, and KFM02 had good antioxidant and anti-inflammatory activity and this supports their use as potential anti-inflammatory therapies. This study presents for the first time the antioxidant and anti-inflammatory activity of and polyherbal extract. It is also among the very few studies that have reported the inhibitory effect of cytokines IL-1, TNF-, IL-6, and IL-10 by .
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http://dx.doi.org/10.1155/2020/4352084DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7317318PMC
June 2020

A review on traditionally used South African medicinal plants, their secondary metabolites and their potential development into anticancer agents.

J Ethnopharmacol 2020 Oct 17;261:113101. Epub 2020 Jun 17.

Department of Plant and Soil Sciences, University of Pretoria, Pretoria, 0002, South Africa; School of Natural Resources, University of Missouri, Columbia, MO, 65211, United States; College of Pharmacy, JSS Academy of Higher Education and Research, Mysuru, Karnataka, 570015, India. Electronic address:

Ethnopharmacological Relevance: Approximately 70% of anticancer drugs were developed or derived from natural products or plants. Southern Africa boasts an enormous floral diversity with approximately 22,755 plant species with an estimated 3000 used as traditional medicines. In South Africa more than 27 million individuals rely on traditional medicine for healthcare. The use of South African plants for the treatment of cancer is poorly documented, however there is potential to develop anticancer agents from these plants. Limited ethnobotanical studies report the use of plants for cancer treatment in traditional medicine. Plants growing in tropical or subtropical regions, such as in South Africa, produce important secondary metabolites as a protective mechanism, which could be used to target various factors that play a key role in carcinogenesis.

Aims: The aim was to collate information from primary ethnobotanical studies on South African plants traditionally used for the treatment of cancer. Evaluation of literature focused on traditionally used plants that have been tested for their in vitro activity against cancer cells. Secondary metabolites, previously identified within these plant species, were also included for discussion regarding their activity against cancer. The toxicity was evaluated to ascertain the therapeutic potential in further studies. Additionally, the aim was to highlight where a lack of reports were found regarding plant species with potential activity and to substantiate the need for further testing.

Materials And Methods: A review of ethnobotanical surveys conducted in South Africa for plants used in the treatment of cancer was performed. Databases such as Science Direct, PubMed and Google Scholar, university repositories of master's dissertations and PhD theses, patents and books were used. Plant species showing significant to moderate activity were discussed regarding their toxicity. Compounds identified within these species were discussed for their activity against cancer cells and toxicity. Traditionally used plants which have not been scientifically validated for their activity against cancer were excluded.

Results: Twenty plants were documented in ethnobotanical surveys as cancer treatments. Numerous scientific reports on the potential in vitro activity against cancer of these plants and the identification of secondary metabolites were found. Many of the secondary metabolites have not been tested for their activity against cancer cells or mode of action and should be considered for future studies. Lead candidates, such as the sutherlandiosides, sutherlandins, hypoxoside and pittoviridoside, were identified and should be further assessed. Toxicity studies should be included when testing plant extracts and/or secondary metabolites for their potential against cancer cells to give an indication of whether further analysis should be conducted.

Conclusion: There is a need to document plants used traditionally in South Africa for the treatment of cancer and to assess their safety and efficacy. Traditionally used plants have shown promising activity highlighting the importance of ethnobotanical studies and traditional knowledge. There are many opportunities to further assess these plants and secondary metabolites for their activity against cancer and their toxic effects. Pharmacokinetic studies are also not well documented within these plant extracts and should be included in studies when a lead candidate is identified.
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http://dx.doi.org/10.1016/j.jep.2020.113101DOI Listing
October 2020

Ethnobotany, Phytochemistry and Pharmacological Activity of (Lam.) Benth. (Bignoniaceae).

Plants (Basel) 2020 Jun 15;9(6). Epub 2020 Jun 15.

Phytomedicine Programme, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.

has been used in the management of human ailments since time immemorial. Ethnobotanists have documented the traditional uses of , which include treatment of skin disorders, cancer and gynecological complaints, among others. This has interested scientists, who have examined plant parts for their bioactivity. This review provides an insightful understanding on the ethnobotany, phytochemistry and pharmacology of . Web search engines Google and Google Scholar, as well as the databases of PubMed, Scopus, JSTOR, HINARI, SID, AJOL and Springer Link, were exhaustively searched using key words and phrases. Institutional reports and conference papers were also consulted. A total of 125 relevant international literature sources meeting the inclusion criteria were included. has biologically active phytochemicals, many of which have been isolated. Whilst the fruits are most often cited in pharmacological studies, other plant parts are also used in herbal preparations. Commercially available products have been formulated from though many have not been fully standardized. Despite many efforts by researchers to scientifically validate traditional uses of , many remain merely claims, thus the need to conduct more research, scientifically validate other traditional uses, isolate new bioactive phytochemicals and standardize products.
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http://dx.doi.org/10.3390/plants9060753DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7356732PMC
June 2020

Anti-inflammatory -Clerodane Diterpenoids from .

J Nat Prod 2020 04 27;83(4):894-904. Epub 2020 Mar 27.

State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy, and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin 300350, People's Republic of China.

Eight new -clerodane diterpenoids (-) were acquired from the aerial parts of . Spectroscopic data analysis permitted the definition of their structures, and experimental and calculated electronic circular dichroism data were used to define their absolute configurations. Compounds and - were found to have NO inhibitory effects with IC values of 20.2, 45.5, 34.0, 27.0, 45.0, and 25.8 μM, respectively. The more potent compounds , , and were analyzed to establish their anti-inflammatory mechanism, including regulation of the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins as well as their binding interactions with the two proteins.
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http://dx.doi.org/10.1021/acs.jnatprod.9b00629DOI Listing
April 2020

Caseahomopene A, a ring-expanded homotriterpenoid from Casearia kurzii showing anti-inflammatory activities in vitro and in vivo.

Bioorg Chem 2020 05 13;98:103758. Epub 2020 Mar 13.

State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy, and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin 300350, People's Republic of China. Electronic address:

Caseahomopene A (1), a rare natural product with a ring-expanded homotriterpenoid skeleton, was isolated from the leaves of Casearia kurzii. The structure including the absolute configuration was determined by spectroscopic data and X-ray crystallography analysis. Compound 1 showed anti-inflammatory effects in vitro and in vivo using LPS-stimulated cell and zebrafish model. As a potential anti-inflammatory agent, the anti-inflammatory mechanism of 1 was also investigated.
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http://dx.doi.org/10.1016/j.bioorg.2020.103758DOI Listing
May 2020

Diterpenoids from the leaves of Casearia kurzii showing cytotoxic activities.

Bioorg Chem 2020 05 9;98:103741. Epub 2020 Mar 9.

State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy, and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin 300350, People's Republic of China. Electronic address:

A phytochemical investigation to obtain bioactive substances as lead compounds or agents for cancer led to the obtainment of six new and two known clerodane diterpenoids from the leaves of Casearia kurzii. Their structures were elucidated using NMR techniques and electronic circular dichroism (ECD) calculations. The subsequent biological cytotoxicity evaluation of these isolates toward human lung cancer A549, human cervical cancer HeLa, human chronic myeloid leukemia K562, and human hepatocellular carcinoma HepG2 was carried out. The most active compound 4 with an IC value of 9.7 μM against HepG2 cells was selected to examine the cytotoxic mechanism, which induced the apoptosis and arrested the HepG2 cell cycle at S stage. The in vivo zebrafish experiments revealed that compound 4 had the property of inhibiting tumor proliferation and migration.
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http://dx.doi.org/10.1016/j.bioorg.2020.103741DOI Listing
May 2020

H-NMR Metabolomics and LC-MS Analysis to Determine Seasonal Variation in a Cosmeceutical Plant .

Front Pharmacol 2020 5;11:219. Epub 2020 Mar 5.

Department of Agriculture and Animal Health, University of South Africa, Johannesburg, South Africa.

is an evergreen shrub belonging to the Rosaceae family with previous studies that indicated that extracts exhibited strong anti-bacterial properties against , showing potential as a cosmeceutical. The plant is traditionally used as a vermifuge, as an astringent and to treat conjunctivitis. Commercial production is, however, not possible as no information is available on cultivation and the effect of external environmental factors such as seasonal variation on the medicinal properties of the plant. Seasonal variation was investigated and it was found that significant differences were observed between the anti-acne () activity of plant material collected in different seasons. The best activity was found in winter with a mean minimum inhibitory concentration (MIC) of 5.20 μg mL compared to spring at 26.04 μg mL. A H NMR-based untargeted metabolomic analysis was used to determine the differences in the chemical profiles of plant samples collected in different seasons. Principal component analysis (PCA) showed clear separation of the seasons and a supervised orthogonal partial least square discriminant analysis (OPLS-DA) was used to determine the compounds that differentiated the spring from the winter samples. The contribution plot indicated a strong positive association with the NMR regions from δ 1.2-1.6, 3.3-4.1, and 6.8-8.0 ppm indicative of a compound with an aromatic ring. Different LC-MS analyses were used in conjunction with a compound database, MAGMa and CSIFingerID, which led to the identification of the compound 2-(4-ethoxyphenyl)-5,6,7,8-tetramethoxy-4H-1-benzopyran-4-one and also confirmed the presence of tangeritin, rutin, quercetin glucoside, and kaempferol glucosides as well as several other compounds previously identified from the plant. This compound similar in structure to the anti-microbial flavonoid tangeritin, was only present in the winter samples. It is therefore recommended that seasonal variation be closely monitored during cultivation and commercial harvesting, and that winter is the preferred harvesting season to obtain the best anti-acne activity.
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http://dx.doi.org/10.3389/fphar.2020.00219DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7066304PMC
March 2020

Exploring the Anti-Acne Potential of Impepho [ (L.) Sweet] to Combat Virulence.

Front Pharmacol 2019 30;10:1559. Epub 2020 Jan 30.

Department of Plant and Soil Sciences, University of Pretoria, Pretoria, South Africa.

The Gram-positive bacterium (previously ), plays an important role in the pathogenesis and progression of the dermatological skin disorder acne vulgaris. The methanolic extract of (L.) Sweet (HO-MeOH) was investigated for its ability to target bacterial growth and pathogenic virulence factors associated with acne progression. The gas chromatography-mass spectrometry (GC-MS) analysis of HO-MeOH identified -humulene (3.94%), -curcumene (3.74%), and caryophyllene (8.12%) as major constituents, which correlated with previous reports of other species. The HO-MeOH extract exhibited potent antimicrobial activity against (ATCC 6919) with a minimum inhibitory concentration (MIC) of 7.81 µg/ml. It enhanced the antimicrobial activity of benzoyl peroxide (BPO). The extract showed high specificity against . cell aggregation at sub-inhibitory concentrations, preventing biofilm formation. Mature . biofilms were disrupted at a sub-inhibitory concentration of 3.91 µg/ml. At 100 µg/ml, HO-MeOH reduced interleukin-1α (IL-1α) cytokine levels in . -induced human keratinocytes (HaCaT) by 11.08%, highlighting its potential as a comedolytic agent for the treatment of comedonal acne. The extract exhibited a 50% inhibitory concentration (IC) of 157.50 µg/ml against lipase enzyme activity, an enzyme responsible for sebum degradation, ultimately causing inflammation. The extract's anti-inflammatory activity was tested against various targets associated with inflammatory activation by the bacterium. The extract inhibited pro-inflammatory cytokine levels of IL-8 by 48.31% when compared to . -induced HaCaT cells at 7.81 µg/ml. It exhibited cyclooxygenase-II (COX-II) enzyme inhibition with an IC of 22.87 µg/ml. Intracellular nitric oxide (NO) was inhibited by 40.39% at 7.81 µg/ml when compared with NO production in lipopolysaccharide (LPS)-induced RAW264.7 cells. The intracellular NO inhibition was potentially due to the 2.14 fold reduction of inducible nitric oxide synthase (iNOS) gene expression. The HO-MeOH extract exhibited an IC of 145.45 µg/ml against virulent hyaluronidase enzyme activity, which is responsible for hyaluronan degradation and scar formation. This study provides scientific validation for the traditional use of as an ointment for pimples, not only due to its ability to control . proliferation but also due to its inhibitory activity on various targets associated with bacterial virulence leading to acne progression.
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http://dx.doi.org/10.3389/fphar.2019.01559DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7002546PMC
January 2020

Antioxidant, Anti-Inflammatory and Skin Permeation of and Its Isolated Compound Myrsinoside B.

Front Pharmacol 2019 8;10:1410. Epub 2020 Jan 8.

Department of Plant and Soil Sciences, University of Pretoria, Pretoria, South Africa.

Dermal aging is characterized by states of oxidative stress, chronic inflammation, and abnormal proteolytic degradation due to the action of hydrogen peroxide, superoxide, 5-lipoxygenase, and elastase, respectively. Noteworthy elastase inhibition has previously been reported, and so this study aimed to investigate the ability of and myrsinoside B to reduce the activity of hydrogen peroxide, superoxide, and 5-lipoxygenase as supplementary mechanisms of action by which may reduce the appearance of wrinkles. The use of maltose microneedles were also investigated as a means to enhance the delivery of myrsinoside B into the skin as this is a crucial aspect to investigate when characterizing the efficacy of an active ingredient. has traditionally been used for skin allergies, boils, and to purify blood (as an astringent) and was selected for this study based on it use in skincare. The crude extract exhibited IC's of 56.08 ± 2.88 and 132.74 ± 1.64 µg/ml against the hydrogen peroxide and superoxide radicals, while myrsinoside B exhibited IC's of 52.19 ± 4.16 and 192.14 ± 3.52 µg/ml, respectively. The IC of the extract and compound against 5-lipoxygenase was 29.65 ± 2.92 and 29.33 ± 3.08 µg/ml, respectively. No toxicity was observed at the highest concentration tested. Microneedle treatment increased the permeation of the active through the skin after 24 h to 12.46 ± 5.14 µg/cm compared to the passive group (1.30± 0.85 µg/cm). The amount of active retained in the epidermis and dermis was 8.97 ± 0.90 and 6.98 ± 0.73 µg/cm respectively, greater than the retention observed in the passive group (3.24 ± 1.41 and 3.27 ± 1.47 µg/cm, respectively). and myrsinoside B showed promising antioxidant and anti-inflammatory activity thus supporting the potential of and myrsinoside B as anti-wrinkle agents. Further, treatment of dermatomed human skin with maltose microneedles facilitated topical delivery of myrsinoside B and provided an effective means for compound delivery to ensure maximum effect.
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http://dx.doi.org/10.3389/fphar.2019.01410DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6960167PMC
January 2020

Predictive Binding Affinity of Plant-Derived Natural Products Towards the Protein Kinase G Enzyme of (PknG).

Plants (Basel) 2019 Nov 6;8(11). Epub 2019 Nov 6.

Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE , UK.

Tuberculosis (TB), caused by , is a growing public health concern worldwide, especially with the emerging challenge of drug resistance to the current drugs. Efforts to discover and develop novel, more effective, and safer anti-TB drugs are urgently needed. Products from natural sources, such as medicinal plants, have played an important role in traditional medicine and continue to provide some inspiring templates for the design of new drugs. Protein kinase G, produced by (PKnG), is a serine/threonine kinase, that has been reported to prevent phagosome-lysosome fusion and help prolong survival within the host's macrophages. Here, we used an in silico, target-based approach (docking) to predict the interactions between PknG and 84 chemical constituents from two medicinal plants ( and ) that have a well-documented historical use as natural remedies for TB. Docking scores for ligands towards the target protein were calculated using AutoDock Vina as the predicted binding free energies. Ten flavonoids present in the aerial parts of and/or showed docking scores ranging from -11.1 to -13.2 kcal/mol. Upon calculation of all ligand efficiency indices, we observed that the (-G/MW) ligand efficiency index for flavonoids (), () and () was similar to the one obtained for the AX20017 control. When taking all compounds into account, we observed that the best (-G/MW) efficiency index was obtained for coumaric acid, coumaraldehyde, -hydroxyphenyl acetic acid and -hydroxybenzyl alcohol. We found that methyl gallate and myricetin had ligand efficiency indices superior and equal to the AX20017 control efficiency, respectively. It remains to be seen if any of the compounds screened in this study exert an effect in -infected macrophages.
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http://dx.doi.org/10.3390/plants8110477DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6918344PMC
November 2019

(Subsp. ) Nutritive Value and Its Potential Medicinal Properties.

Antioxidants (Basel) 2019 Oct 30;8(11). Epub 2019 Oct 30.

Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, 3036 Lemesos, Cyprus.

L. subsp. is an endemic species of the Eastern Mediterranean region with several uses in traditional medicine. The present study aims to explore the unknown properties of investigating the nutritional content as well as the antioxidant, anticancer, antituberculosis, antiwrinkle, anti-acne, hyper/hypo-pigmentation and antibacterial activities. Mineral content, nutritional value, the composition and antioxidant properties of the essential oil, the antityrosinase, the antibacterial activity and anti-elastase potential of the extract, were evaluated. The antiproliferative activity of against cervical cancer (HeLa), human melanoma (UCT-Mel-1), human hepatocellular carcinoma (HepG2) and human epidermoid carcinoma (A431) was investigated. Cytotoxic effects on normal human keratinocyte (HaCat) and kidney epithelial (Vero) cell lines were also determined. exhibited high nutritional value of proteins and minerals (K, P, Mg, Fe, Zn, Cu). The most abundant components of the essential oil were found to be α-pinene, β-phelladrene, valeranone, β-pinene and sabinene. The ethanolic extract of displayed moderate antioxidant potential and antibacterial activity against Noteworthy elastase and moderate anticancer potential against the human liver cancer cell line (HepG2) was observed with IC values of 57.18 ± 3.22 μg/mL and 64.27 ± 2.04 μg/mL respectively. The noteworthy activity of could be due to the presence of flavonoids and phenols in the leaves, having high nutritional value. could potentially be useful to reduce the appearance of wrinkles and for the treatment of liver cancer. The moderate antibacterial, antioxidant and elastase activity of the plant can be linked to the traditional use of for the treatment of wounds and inflammation.
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http://dx.doi.org/10.3390/antiox8110521DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6912803PMC
October 2019

In Vitro Human Metabolism and Inhibition Potency of Verbascoside for CYP Enzymes.

Molecules 2019 Jun 11;24(11). Epub 2019 Jun 11.

Department of Plant and Soil Sciences, University of Pretoria, Pretoria 0002, South Africa.

Verbascoside is found in many medicinal plant families such as Verbenaceae. Important biological activities have been ascribed to verbascoside. Investigated in this study is the potential of verbascoside as an adjuvant during tuberculosis treatment. The present study reports on the in vitro metabolism in human hepatic microsomes and cytosol incubations as well as the presence and quantity of verbascoside within . Additionally, studied are the inhibitory properties on human hepatic CYP enzymes together with antioxidant and cytotoxic properties. The results yielded no metabolites in the hydrolysis or cytochrome P450 (CYP) oxidation incubations. However, five different methylated conjugates of verbascoside could be found in S-adenosylmethionine incubation, three different sulphate conjugates with 3'-phosphoadenosine 5'-phosphosulfate (PAPS) incubation with human liver samples, and very low levels of glucuronide metabolites after incubation with recombinant human uridine 5'-diphospho-glucuronosyltransferase (UGT) 1A7, UGT1A8, and UGT1A10. Additionally, verbascoside showed weak inhibitory potency against CYP1A2 and CYP1B1 with IC values of 83 µM and 86 µM, respectively. Potent antioxidant and low cytotoxic potential were observed. Based on these data, verbascoside does not possess any clinically relevant CYP-mediated interaction potential, but it has effective biological activity. Therefore, verbascoside could be considered as a lead compound for further drug development and as an adjuvant during tuberculosis treatment.
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http://dx.doi.org/10.3390/molecules24112191DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6600574PMC
June 2019

Comparison of structures and cytotoxicity of mupirocin and batumin against melanoma and several other cancer cell lines.

Future Med Chem 2019 04 5;11(7):677-691. Epub 2019 Apr 5.

Department of  Plant & Soil Sciences, Medicinal Plant Science Section, University of Pretoria, Pretoria 0002, South Africa.

To determine the computer-predicted anticancer activity of mupirocin and to compare its activities with those determined for another polyene antibiotic, batumin. Molecular docking, cytotoxicity assays, cell microscopy and cell cycle progression were studied in cancer and nontumorigenic cell lines. Cytotoxicity of mupirocin against several cancerous cell lines was detected with the highest one (IC = 5.4 μg/ml) against melanoma cell line. The profile of cytotoxicity of mupirocin was similar to that reported for batumin. Nevertheless, the morphology of cells treated with these antibiotics and alterations in cell cycle progression suggested possible dissimilarity in their mechanisms of action. Selective cytotoxicity of mupirocin against melanoma cells potentiates further studies to discover nontoxic drugs for melanoma prevention.
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http://dx.doi.org/10.4155/fmc-2018-0333DOI Listing
April 2019

Promising anticancer activity of batumin: a natural polyene antibiotic produced by Pseudomonas batumici.

Future Med Chem 2018 Sep 7;10(18):2187-2199. Epub 2018 Aug 7.

Department of Biochemistry, Genetics & Microbiology, Centre for Bioinformatics & Computational Biology, University of Pretoria, Pretoria 0002, South Africa.

Aim: To determine the computer-predicted anticancer activity of antibiotic batumin.

Materials & Methods: Cytotoxicity assays, cell morphology microscopy and cell cycle progression were studied in cancer and nontumorigenic cell lines. An in vivo experiment on Lewis lung carcinoma (3LL)-transplanted mice was conducted to evaluate potential antimetastatic.

Results & Conclusion: Cytotoxicity against melanoma and lung carcinoma cells (IC ≈ 5 μg/ml) was detected. Hypercondensed chromatin and apoptotic body formation in batumin-treated cells suggested the induction of apoptosis supported also by an observed increase in the quantity of cells occupying the sub-G1 cell cycle phase. Twofold reduction in the number and volume of lung metastases in Lewis lung carcinoma (3LL)-bearing batumin-treated mice was demonstrated. Highly specific cytotoxicity of batumin against cancer cell lines potentiates further studies.
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http://dx.doi.org/10.4155/fmc-2018-0062DOI Listing
September 2018

An integrated computational approach of molecular dynamics simulations, receptor binding studies and pharmacophore mapping analysis in search of potent inhibitors against tuberculosis.

J Mol Graph Model 2018 08 3;83:17-32. Epub 2018 May 3.

Department of Pharmaceutical Sciences, Dr. Harisingh Gour University (A Central University), Sagar, MP, India. Electronic address:

Tuberculosis is an infectious chronic disease caused by obligate pathogen Mycobacterium tuberculosis that affects millions of people worldwide. Although many first and second line drugs are available for its treatment, but their irrational use has adversely lead to the emerging cases of multiple drug resistant and extensively drug-resistant tuberculosis. Therefore, there is an intense need to develop novel potent analogues for its treatment. This has prompted us to develop potent analogues against TB. The Mycobacterium tuberculosis genome provides us with number of validated targets to combat against TB. Study of Mtb genome disclosed six epoxide hydrolases (A to F) which convert harmful epoxide into diols and act as a potential drug target for rational drug design. Our current strategy is to develop such analogues which inhibits epoxide hydrolase enzyme present in Mtb genome. To achieve this, we adopted an integrated computational approach involving QSAR, pharmacophore mapping, molecular docking and molecular dynamics simulation studies. The approach envisaged vital information about the role of molecular descriptors, essential pharmacophoric features and binding energy for compounds to bind into the active site of epoxide hydrolase. Molecular docking analysis revealed that analogues exhibited significant binding to Mtb epoxide hydrolase. Further, three docked complexes 2s, 37s and 15s with high, moderate and low docking scores respectively were selected for molecular dynamics simulation studies. RMSD analysis revealed that all complexes are stable with average RMSD below 2 Å throughout the 10 ns simulations. The B-factor analysis showed that the active site residues of epoxide hydrolase are flexible enough to interact with inhibitor. Moreover, to confirm the binding of these urea derivatives, MM-GBSA binding energy analysis were performed. The calculations showed that 37s has more binding affinity (ΔGtotal = -52.24 kcal/mol) towards epoxide hydrolase compared to 2s (ΔGtotal = -51.70 kcal/mol) and 15s (ΔGtotal = -49.97 kcal/mol). The structural features inferred in our study may provide the future directions to the scientists towards the discovery of new chemical entity exhibiting anti-TB property.
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http://dx.doi.org/10.1016/j.jmgm.2018.04.019DOI Listing
August 2018

Biological Activities of Against Micro-Organisms Involved in Oral Infections.

Front Pharmacol 2018 10;9:291. Epub 2018 Apr 10.

Department of Plant and Soil Science, University of Pretoria, Pretoria, South Africa.

The use of complementary and alternative medicine from plants in South Africa, as in the rest of the world, continues to increase. , known as the Lavender tree, is indigenous to South Africa and is traditionally used for oral care. The ethanolic extract, of the leaves and twigs, of was investigated for antimicrobial activity against selected oral microorganisms. was found to be the most sensitive oral microorganism to the extract, with a minimum inhibitory concentration (MIC) of 0.88 mg/ml and an MIC of 2.6 mg/ml against . Five known compounds were identified from the ethanolic extract of . The compounds were identified as aurentiacin A (1), cardamomin (2), 5-hydroxy-7-methoxy-6-methylflavanone (3), quercetin (4) and 3,5,7-trihydroxyflavan (5). The MICs of the compounds 1 and 4 were found to be 0.06 mg/ml and 1 mg/ml, respectively, against . The cytotoxicity, acute and sub-acute toxicity in pre-clinical studies were also determined for The extract showed moderate cytotoxicity (35.56 ± 0.16 μg/ml) on human monocyte cells. The acute and sub-acute toxicity analysis of indicated the NOEL (no-observed-effect level) at 200 mg/kg. Interleukin-8 (IL-8) is a chemokine that stimulates the recruitment of leukocytes. A significant reduction of IL-8 production by macrophage cells was observed when exposed to the extract of . It is possible that can prevent excessive tissue damage in periodontal diseases through its reduction of inflammation. Enzymatic bioanalysis of lactic and acetic acid production from and was done. A reduction in the acid production from each bacterium was observed on exposure to the extract of . Consequently, this increased the pH, which could possibly reduce the demineralization of enamel which may help prevent the formation of dental caries. In addition the extract may be considered for preventing periodontal diseases.
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http://dx.doi.org/10.3389/fphar.2018.00291DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5903190PMC
April 2018

Antibacterial Activity of , , , and and their mechanism of action against .

Pharmacogn Mag 2018 Jan-Mar;14(53):76-80. Epub 2018 Feb 20.

Department of Integrated Plant and Soil Sciences (Medicinal Plant Sciences), Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa.

Background: Curative plants have reportedly been used to make chewing sticks/toothbrushes intended for the treatment of oral diseases.

Objective: The antibacterial activities of , , , and were evaluated against , along with the cytotoxicity and antioxidant and synergistic potentials. The effect of on the expression of crucial virulence genes and of S. mutans was determined.

Materials And Methods: The antibacterial activity was determined using a modified microdilution method. The antioxidant potential was evaluated using diphenyl picrylhydrazyl (DPPH), Griess reagent, and nitroblue tetrazolium calorimetric assays. The synergistic activity was investigated using a modified checkerboard method, while the cytotoxicity was determined according to a cell proliferation 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide salt assay. Reverse transcription was the chosen method for determining the difference in expression of the and genes after treatment with the plant sample.

Results: and had the highest antibacterial activity at concentrations of 0.3 mg/ml and 6.25 mg/ml, respectively. had the best free radical scavenging of DPPH, exhibiting 50% inhibition at 28.72 μg/ml; while showed better superoxide scavenging potential than the positive control quercetin. Both and had adequate activity against the nitric oxide-free radical (12.87 and 18.89 μg/ml, respectively). selectively reduced the expression of the gene, indicating a mechanism involving Glucotranferases, specifically targeting bacterial attachment.

Summary: and had very good antibacterial activity against and moderate toxicity against Vero cells had the best antioxidant capacity overall reduced the expression of gene at 0.5 mg/ml. : AA: Ascorbic acid; BHI: Brain-heart infusion; CHX: Chlorhexidine; DPPH: Diphenyl picrylhydrazyl; DMSO: Dimethlysulfoxide; NBT: Nitroblue tetrazolium; NO: Nitric oxide.
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http://dx.doi.org/10.4103/pm.pm_102_17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5858246PMC
February 2018

Selected essential oils inhibit key physiological enzymes and possess intracellular and extracellular antimelanogenic properties in vitro.

J Food Drug Anal 2018 01 20;26(1):232-243. Epub 2017 Apr 20.

Department of Health Sciences, Faculty of Science, University of Mauritius, Réduit, Mauritius. Electronic address:

Essential oils (EOs) extracted from six medicinal herbs and food plants [Cinnamomum zeylanicum (CZ), Psiadia arguta (PA), Psiadia terebinthina (PT), Citrus grandis (CGp), Citrus hystrix (CH), and Citrus reticulata (CR)] were studied for any inhibitory potential against key physiological enzymes involved in diabetes (α-glucosidase), skin aging (collagenase and elastase), and neurodegenerative disorders (acetylcholinesterase). Kinetic studies of the active EOs on the aforementioned enzymes were determined using Lineweaver-Burk plots. The intracellular and extracellular antimelanogenic potential of the EOs were evaluated on B16F10 mouse melanocytes. CH and CR were found to significantly inhibit (2.476 ± 0.13 μg/mL and 3.636 ± 0.10 μg/mL, respectively) acetylcholinesterase, compared with galantamine (3.989 ± 0.16 μg/mL). CH inhibited collagenase (50% inhibitory concentration 28.71 ± 0.16 μg/mL) compared with the control (24.45 ± 0.19 μg/mL). The percentage inhibition in the elastase assay of CH was 63.21% compared to the positive control (75.09%). In addition, CH, CR, CGp, CZ, and PT were found to significantly inhibit α-glucosidase (276.70 ± 0.73 μg/mL, 169.90 ± 0.58 μg/mL, 240.60 ± 6.50 μg/mL, 64.52 ± 0.69 μg/mL, and 313.0 ± 5.0 μg/mL, respectively), compared to acarbose (448.80 ± 0.81 μg/mL). Active EOs showed both uncompetitive and competitive types of inhibition. The EOs also inhibited intracellular (50% inhibitory concentration 15.92 ± 1.06 μg/mL, 23.75 ± 4.47 μg/mL, and 28.99 ± 5.70 μg/mL for CH, CR, and CGp, respectively) and extracellular (< 15.625 μg/mL for CH, CR, CGp, and PT) melanin production when tested against B16F10 mouse melanocytes. Results from the present study tend to show that EOs extracted from these medicinal plants can inhibit key enzymes and may be potential candidates for cosmetic and pharmaceutical industries.
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http://dx.doi.org/10.1016/j.jfda.2017.03.002DOI Listing
January 2018

Isolation of Flavonoids and Flavonoid Glycosides from Myrsine africana and Their Inhibitory Activities against Mushroom Tyrosinase.

J Nat Prod 2018 01 4;81(1):49-56. Epub 2018 Jan 4.

Department of Plant and Soil Sciences, University of Pretoria , Pretoria 0002, South Africa.

Bioassay-guided fractionation of the methanol extract of the shoots of Myrsine africana led to the isolation of the new compound myricetin 3-O-(2″,4″-di-O-acetyl)-α-l-rhamnopyranoside (9) and 11 known compounds. The known compounds quercetin 3-O-(3″,4″-di-O-acetyl)-α-l-rhamnopyranoside (8), rutin (10), quercetin 3-O-α-l-rhamnopyranoside (11), and myricetin 3-O-α-l-rhamnopyranoside (12) are reported for the first time from the methanol extract of the shoots of M. africana. Compounds 10 and 12 showed significant inhibition of tyrosinase with 50% inhibition (IC values) of the enzyme at 0.13 ± 0.003 and 0.12 ± 0.002 mM, respectively, which was supported by the docking fitness scores obtained through molecular docking analysis. In addition, compounds 1-12 displayed significant antioxidant activity with IC values ranging 1.90 to 3.90 μM.
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http://dx.doi.org/10.1021/acs.jnatprod.7b00564DOI Listing
January 2018

and Activity of on Elastase Inhibition and Anti-wrinkle Activity.

Pharmacogn Mag 2017 Oct-Dec;13(52):583-589. Epub 2017 Nov 13.

Department of Plant and Soil Sciences, University of Pretoria, Pretoria 0002, South Africa.

Background: (MA) is a plant traditionally used in South Africa to treat various diseases.

Objective: The ethanolic extract of MA, was used for and studies to determine its elastase inhibitory activity.

Materials And Methods: MA and its isolated compound, myrsinoside B, were tested for their elastase inhibitory activity. The MA extract was also evaluated for mutagenicity using two strains of (TA 98 and TA 100), microbial count, metal analysis, and stability. studies included irritancy and wrinkle reduction trials using Visioscan and Visioface.

Results: The leaf extract showed good elastase inhibition with a 50% inhibitory concentration (IC) of 28.04 μg/ml. Myrsinoside B inhibited the elastase enzyme at an IC of 4.68 ± 0.34 μg/ml. No colony growth observed during mutagenicity studies and it was concluded that MA ethanolic extract is a nonmutagen. MA extract was found to be a nonirritant during the patch test clinical trial. MA was found to contain negligible amounts of microorganisms and heavy metals. Gel cream containing MA crude extract was found to be stable for 2 years when kept at temperatures below 30°C. In clinical trials (), it was found that the test product containing 5% ethanolic extract of MA was effective in reducing wrinkles after application 2 times a day for 14 days and 28 days compared to the placebo aqueous cream.

Conclusion: MA is effective in reducing the appearance of wrinkles.

Summary: This is a first time report of the elastase inhibitory potential of and myrsinoside B and the anti-wrinkle potential of ethanolic extract effectively inhibited the elastase enzyme was effective in studies to reduce the appearance of wrinkles after 14 days. 4-NQO: 4-nitroquinoline, D14-BL: Baseline to day fourteen, D28-BL: Baseline to day twenty-eight, CFU: Colony forming units, IC: 50% inhibitory concentration, MA: , MOU: Measurement of uncertainty, NaCl: Sodium chloride, NaH PO.HO: Sodium phosphate monobasic monohydrate, SEM: Standard error of the mean, TA 98: strain 98, TA 100: strain 100, TLC: Thin layer chromatography, TMA: Total microbial activity, XVB salt: Vogel-Bonner medium E.
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http://dx.doi.org/10.4103/pm.pm_145_17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5701395PMC
November 2017

AN ETHNOBOTANICAL STUDY OF MEDICINAL PLANTS USED IN VILLAGES UNDER JONGILANGA TRIBAL COUNCIL, MPUMALANGA, SOUTH AFRICA.

Afr J Tradit Complement Altern Med 2016 29;13(6):83-89. Epub 2016 Sep 29.

Department of Plant and Soil Sciences, University of Pretoria, Pretoria 0002, South Africa.

Background: Medicinal plants remain an integral part of the lives of people in rural areas. The aim of this study was to document information about the medicinal plants used by Shangaan people in villages under Jongilanga tribal council, Bushbuckridge municipality, Mpumalanga Province, South Africa.

Materials And Methods: An ethnobotanical survey of medicinal plants was conducted using a semi-structured questionnaire with 15 traditional healers as informants; one of them also served as a field guide during data collection. Results were analysed by using various quantitative indices of information consensus factor (ICF), use report (UR), frequency citation (FC) and relative frequency citation (RFC).

Results And Methods: The study reported 86 medicinal plants used in villages for the treatment of various ailments, the majority (25 species) of which were used for urino-genital disorders. The Fabaceae family was the most represented family (17 species) of all the medicinal plants recorded in this study. The roots were the most frequently used plant part, accounting for 56% of the plants reported, and decoctions were often used in the preparation of herbal remedies. Respiratory diseases had the highest ICF value recorded among the 8 categories of ailments. The highest use report was reported for (4), while the FC and RFC values (15) were highest in 12 plant species. The study revealed that medicinal plants are still widely used in rural areas and this documentation can serve as an ethno pharmacological basis for selecting plants with potential pharmaceutical properties.
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http://dx.doi.org/10.21010/ajtcam.v13i6.13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5412206PMC
August 2017

Diallyl Polysulfides from Allium sativum as Immunomodulators, Hepatoprotectors, and Antimycobacterial Agents.

J Med Food 2017 Jul 14;20(7):685-690. Epub 2017 Apr 14.

1 Department of Plant and Soil Sciences, University of Pretoria , Pretoria, South Africa .

Mycobacterium tuberculosis remains one of the world's deadliest killers, with an annual death rate of ∼1.5 million. The medicinal effects of garlic have been well documented, and natural products have been shown to have antimycobacterial activity. The current study evaluated the efficacy of six Allium sativum L. polysulfide mixtures as antimycobacterial agents together with their cytotoxic, immunomodulatory, and hepatoprotective activities. The microtitre PrestoBlue assay was used to determine the minimum inhibitory concentrations (MIC). Cytotoxicity was evaluated by using peripheral blood mononuclear cells (PBMC). Excreted cytokine levels were determined by utilizing an enzyme-linked immunosorbent assay (ELISA), by exposing isolated PBMCs to varying concentrations of polysulfide mixtures. Human C3A liver cells were utilized in the hepatoprotective study, to assess the protective effect against the toxicity induced by acetaminophen. Samples with higher amounts of diallyl trisulfide (Sample G4) showed the highest antimycobacterial activity, exhibiting an MIC of 2.5 μg/mL against M. tuberculosis H37Rv. Five samples showed moderate toxicity in PBMC, with G1 showing no toxicity. The selective index of G4 was the highest, with a selectivity index close to one. Two samples, G3 and G6 containing higher amounts of diallyl tetrasulfide and lower amounts of diallyl trisulfide, showed >50% hepatoprotection. This is comparable to a hepatoprotective agent, Silymarin, which showed a hepatoprotective effect of 30% at the tested concentration. Diallyl tetrasulfide showed significant antimycobacterial activity. A combination of higher diallyl tetrasulfide and lower diallyl trisulfide was indicative of hepatoprotective activity.
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http://dx.doi.org/10.1089/jmf.2016.0137DOI Listing
July 2017

Insights into tyrosinase inhibition by compounds isolated from Greyia radlkoferi Szyszyl using biological activity, molecular docking and gene expression analysis.

Bioorg Med Chem 2016 11 22;24(22):5953-5959. Epub 2016 Sep 22.

Department of Plant and Soil Sciences, University of Pretoria, Pretoria 0002, South Africa.

Greyia radlkoferi ethanol extract and its five compounds were tested for their inhibitory activity against the mushroom tyrosinase enzyme and melanin production on melanocytes. The crude extract showed significant tyrosinase inhibition with IC of 17.96μg/ml. This is the first report of the isolation of these 5 compounds from Greyia radlkoferi. 2',4',6'-Trihydroxydihydrochalcone showed the highest tyrosinase inhibition at 17.70μg/ml (68.48μM), with low toxicity when compared with crude extract. This compound is therefore, a key component in the crude extract, which is responsible for tyrosinase inhibitory activity. The RT-qPCR indicated that the mechanism of action is most likely post transcriptional. Further, the molecular docking study showed that tyrosinase inhibitory activity depends on interaction of the compound with Cu ions at the active site. This is the first report of the tyrosinase inhibitory activity of the G. radlkoferi extract and molecular insights on interaction of its compounds with Cu ions as the driving factor for tyrosinase inhibition. These results suggest that the extract of G. radlkoferi and the compound 2',4',6'-trihydroxydihydrochalcone have great potential to be further developed as pharmaceutical or cosmetic agents for use against dermatological disorders associated with melanin.
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http://dx.doi.org/10.1016/j.bmc.2016.09.054DOI Listing
November 2016

In vitro and In vivo antimycobacterial, hepatoprotective and immunomodulatory activity of Euclea natalensis and its mode of action.

J Ethnopharmacol 2016 Dec 20;194:740-748. Epub 2016 Oct 20.

Department of Plant and Soil Sciences, University of Pretoria, South Africa. Electronic address:

Ethnopharmacological Relevance: The Natal gwarri or Natal ebony (Euclea natalensis A.DC.) is a deciduous tree found widespread throughout southern Africa, especially in Kwazulu-Natal and the southern cost. It has been widely used by indigenous communities such as the Zulus, Tsongas and Vendas for symptoms related to tuberculosis (TB). The decoctions made from the plant parts are administered for chest diseases to treat complications such as chest pains, bronchitis, pleurisy and asthma. TB is prevalent in immune-compromised patients and it is evident that TB-drugs cause hepatotoxicity. The objective of the present study was therefore to evaluate the antimycobacterial activity of the ethanolic extract of E. natalensis against TB and its hepatoprotective and immunomodulatory activities.

Materials And Methods: The antimycobacterial, antioxidant, hepatoprotective, immunomodulatory activity and cytotoxicity of the ethanolic extract of the shoots of E. natalensis were determined in vitro. The mechanism of action of the antituberculosis activity was determined by investigating the inhibitory effect on mycothiol disulfide reductase enzyme. Furthermore, the acute, sub-acute toxicity (50-2000mg/kg) and antimycobacterial effect (300mg/kg) of E. natalensis shoot extract were investigated in Balb/c mice. Hepatoprotective activity of the extract (50-150mg/kg) was evaluated on isoniazid and rifampicin (50mg/kg; i.p.) induced hepatic damage in a rat model.

Results: The minimum inhibitory concentration of the extract was found to be 125µg/ml against Mycobacterium tuberculosis. The extracts 50% inhibitory concentration (IC) against 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical was found to be 22.55µg/ml. The plant showed a hepatoprotective effect (50% at 12.5µg/ml) and the ability to increase T-helper 1 cell cytokines; Interleukin 12, Interleukin 2 and Interferon α by up to 12 fold and the ability to decrease the T-helper 2 cell cytokine Interleukin 10 4 fold when compared to baseline cytokine production. No cellular toxicity was observed in primary peripheral blood mononuclear cells (PBMC's) and two secondary cell lines; U937 monocytes and Chang liver cells (a derivative of the HepG2 cell line). During mechanistic studies, the extract showed a 50% inhibition of mycothiol reductase activity at 38.62µg/ml. During the acute and sub-acute studies, E. natalensis exhibited no toxic effect and the 50% lethal dose (LD) was established to be above 2000mg/kg. The extract was able to reduce the mycobacterial load (1.5-fold reduction) in infected mice. Isoniazid and rifampicin caused significant hepatic damage in rats, and the extract was able to reduce the toxicity by 15% and 40% at 50 and 150mg/kg respectively.

Conclusion: The present study supports the traditional usage of the plant against tuberculosis symptoms. The study showed the ability of E. natalensis shoot extract to inhibit mycobacterial growth, stimulate an appropriate immune response and have a hepatic protective effect. Due to the extract's significant results for hepatoprotective, immunomodulatory effects and antimycobacterial activity, it may prove to be effective to serve as an adjuvant for TB-patients.
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http://dx.doi.org/10.1016/j.jep.2016.10.060DOI Listing
December 2016