Publications by authors named "Graeme Bradley"

19 Publications

  • Page 1 of 1

GC-MS Profiling and Antineoplastic Activity of Pelargonium Inquinans Ait Leaves on Acute Leukaemia Cell Lines U937 and Jurkat.

Nutr Cancer 2021 Sep 3:1-23. Epub 2021 Sep 3.

Department of Biochemistry, Faculty of Science & Agriculture, University of Fort Hare, Alice, South Africa.

We investigated the antineoplastic activities of extracts of leaves, a plant native to South Africa on acute leukemia cell lines, U937 and Jurkat and the inflammatory effect (nitric oxide and cyclo-oxygenase-2) on RAW 264.7 cells. The extracts of have significant cytotoxicity especially on U937 cells and pro-inflammatory release of nitric oxide on RAW 264.7 macrophages. The GC-MS study of the essential oil showed it had more than a hundred compounds. This study showed that have antineoplastic and anti-inflammatory activities which can be further explored in In Vivo studies.
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http://dx.doi.org/10.1080/01635581.2021.1969417DOI Listing
September 2021

evaluation of the anti-diabetic potential of Hilliard & B.L. Burtt using HepG2 (C3A) and L6 cell lines.

F1000Res 2020 15;9:1240. Epub 2020 Oct 15.

Medicinal Plant and Economic Development (MPED) Research Centre, University of Fort Hare, Alice, Eastern Cape, 5700, South Africa.

Hilliard & B.L. Burtt has been listed in a survey of plants used in traditional medicine for the treatment of type 2 diabetes in the Eastern Cape of South Africa. In this study, the antidiabetic potentials of ethanol, cold aqueous (CAQ) and boiled aqueous (BAQ) extracts of were investigated. The cytotoxic and glucose utilization effects of the extracts were evaluated using L6 myocytes and HepG2 (C3A) hepatocytes. α-amylase, α-glucosidase and lipase inhibition assays were also carried out. The ethanol extract showed significant cytotoxic effects in the treated cells. Both BAQ and CAQ extracts significantly increased glucose uptake in L6 and C3A cell lines. The CAQ extract enhanced glucose uptake more in the L6 myocytes than in the C3A cell-lines hepatocytes. The BAQ extract showed higher levels of inhibition on α-amylase and α-glucosidase than CAQ. The activities were not significantly different from acarbose. However, BAQ showed lower lipase inhibition than acarbose (p<0.05). The BAQ and CAQ extracts of may, therefore, contain pharmacologically active and relatively non-toxic hypoglycaemic chemicals, which may be effective substitutes in the treatment of diabetes mellitus.
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http://dx.doi.org/10.12688/f1000research.26855.2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8080987PMC
May 2021

Effect of Sex and Breed on HSPA1A, Blood Stress Indicators and Meat Quality of Lambs.

Animals (Basel) 2020 Aug 27;10(9). Epub 2020 Aug 27.

Department of Biochemistry and Microbiology, Faculty of Science and Agriculture, University of Fort Hare, Alice 5700, South Africa.

The objective of this study was to examine sex and breed effects on heat shock protein 70 (HSPA1A), blood stress indicators and meat quality attributes of lambs. A hundred male and female lambs from the Dorper (n = 50) and Merino (n = 50) breeds were used in this study. Breed and sex had a significant ( < 0.05) effect on the levels of plasma HSPA1A and lactate; where the Merino lambs had higher levels than Dorper. The female lambs had higher levels of plasma HSPA1A than male lambs. Significant sex and breed interactions ( < 0.05) on the levels of plasma HSPA1A were seen. Females had higher ( < 0.05) pHu than males. Dorper lambs had higher ( < 0.05) pH, meat lightness, thawing loss and tougher meat the Merino breed. Significant correlations were found amongst plasma stress indicators and meat quality attributes. The results indicate that female lambs were more stressed by the pre-slaughter period than males, while the Merino had a higher physiological stress response compared to the Dorper. However, the Dorper breed produced tougher meat.
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http://dx.doi.org/10.3390/ani10091514DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7552312PMC
August 2020

Inhibition of HIV-1 Protease by (L.).

Evid Based Complement Alternat Med 2020 7;2020:9648056. Epub 2020 Jun 7.

Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa.

(L.) is a plant commonly found in the Eastern Cape Province of South Africa and is used for the general treatment of infections relating to the human immunodeficiency virus (HIV). HIV-1 protease plays an important role during HIV replication and maturation to its infectious form, and therefore inhibition of the enzyme is one of the main focus areas in drug development. The inhibitory effect of a water extract of leaves against HIV-1 protease activity was determined using the SensoLyte® 520 HIV-1 protease assay fluorimetric kit and employing a HiLyte Fluor™488/QXL™520 fluorescence resonance energy transfer (FRET) peptide. Cytotoxicity of the extract towards HeLa Chang cell lines was determined using an MTT assay, and the phytochemical profile of the extract was determined with FT-IR and LC-MS. HIV-1 protease activity was inhibited 83.06% (IC 1.6 mg/ml) ( < 0.0001) by the pepstatin A inhibitor control. Treatment with all extract concentrations (16, 1.6, 0.16, and 0.016 mg/ml) inhibited HIV-1 protease activity significantly ( < 0.0001) in a typical dose response manner. With regards to cytotoxicity, the negative controls containing untreated HeLa Chang cells exhibited high formazan formation rates in contrast with the positive controls, containing curcumin, which reduced formazan formation significantly ( < 0.001), exhibiting cytotoxicity towards the cells. There was no significant ( > 0.05) difference in the formazan formation rates between the negative controls and 1, 0.5, 0.125, 0.065, 0.031, and 0.015 mg/ml plant extract, confirming no toxicity of extracts towards HeLa Chang cells. Major functional phytochemical compounds identified included alcohols, phenols, alkanes, amines, carboxylic acids, and esters. LC-ESI-TOF/MS analysis revealed the putative identities of main compounds present in the aqueous leaves extract, including some that contribute to its anti-HIV-1 protease action.
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http://dx.doi.org/10.1155/2020/9648056DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7298281PMC
June 2020

In Vitro Investigation of Potential Anti-Diabetic Activity of the Corm Extract of Hypoxis Argentea Harv. Ex Baker.

Acta Pharm 2018 Dec;68(4):389-407

Plant stress response group Department of Biochemistry and Microbiology, University of Fort Hare Alice, 5700, Alice, South Africa.

The corms of Hypoxis argentea are widely used as a traditional remedy for diabetes mellitus in South Africa. In this study, we investigated the effects of non-toxic concentrations (12.5-100 μg mL-1) of the aqueous extract of H. argentea (HAA) corms on glucose uptake, pancreatic beta cell proliferation, and adipocyte differentiation. HAA stimulated glucose uptake in HepG2 cells up to 19.6 % and 17.0 % in L6 myotubes. Live-cell imaging microscopy revealed significant increases (p < 0.001) in total INS-1 cell numbers exposed to HAA, although no effect was observed on adipogenesis in 3T3-L1 pre-adipocytes. HAA produced weak to moderate inhibition of porcine pancreatic α-amylase, α-glucosidase, porcine pancreatic lipase, dipeptidyl peptidase IV (DPP IV) activities, as well as protein glycation. Our results suggest that the acclaimed anti-diabetic effects of H. argentea could be mediated by its promotion of glucose utilization and preservation of pancreatic beta cell populations while preventing fat accumulation in adipocytes.
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http://dx.doi.org/10.2478/acph-2018-0023DOI Listing
December 2018

Chemical composition, antioxidant, anti-inflammatory, and cytotoxic activities of Opuntia stricta cladodes.

PLoS One 2019 29;14(1):e0209682. Epub 2019 Jan 29.

Department of Biochemistry, Faculty of Science & Agriculture, University of Fort Hare, Alice, South Africa.

Background: The Opuntia spp. have been used in traditional medicine for many centuries. It is used in the management of diseases that involves oxidative stress, especially diabetes, obesity and cancer. Opuntia stricta (Haw) is one of the relatively unknown species in South Africa where it is regarded more as a weed. Because of this, not much is known about its chemical composition.

Aim: To determine the chemical composition, antioxidant, anti-inflammatory, and cytotoxic activities of Opuntia stricta cladodes.

Methods: The phytochemical composition of acetone, aqueous and ethanol extract of cladodes of Opuntia stricta (Haw), as well as the vitamins A, C and E of its dried weight cladodes and the antioxidant activities, were evaluated using standard in vitro methods. The anti-inflammatory and cytotoxic activities were evaluated using cell-based assays. The phytochemical composition and vitamins were determined spectrophotometrically, while the antioxidant activities were determined by DPPH, nitric oxide, hydrogen peroxide scavenging activity and phosphomolybdenum (total) antioxidant activity. Anti-inflammatory activity was determined using RAW 264.7 cells, while cytotoxicity was determined using U937 cells.

Results: The phytochemical composition showed a significant difference in the various extracts. The total phenolics were higher than other phytochemicals in all the extracts used. All the extracts displayed antioxidant activity, while most of the extracts showed anti-inflammatory activity. Only one extract showed cytotoxicity, and it was mild.

Conclusion: The results show that the Opuntia stricta is rich in polyphenolic compounds and has good antioxidant activity as well as anti-inflammatory activities.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0209682PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350967PMC
November 2019

Medicinal Plants Used for the Traditional Management of Diabetes in the Eastern Cape, South Africa: Pharmacology and Toxicology.

Molecules 2018 Oct 25;23(11). Epub 2018 Oct 25.

Department of Biochemistry and Microbiology, University of Fort Hare, Alice 5700, South Africa.

The use of medicinal plants for the management of diabetes mellitus is on the rise in the developing countries, including South Africa. There is increasing scientific evidence that supports the claims by the traditional healers. In this review, we compare the families of previously reported anti-diabetic plants in the Eastern Cape by rating the anti-diabetic activity, mode of action and also highlight their therapeutic potentials based on the available evidence on their pharmacology and toxicity. Forty-five plants mentioned in ethnobotanical surveys were subjected to a comprehensive literature search in the available electronic databases such as PubMed, ScienceDirect, Google Scholar and Elsevier, by using "plant name" and "family" as the keywords for the primary searches to determine the plants that have been scientifically investigated for anti-diabetic activity. The search returned 25 families with Asteraceae highly reported, followed by Asphodelaceae and Alliaceae. Most of the plants have been studied for their anti-diabetic potentials in vivo and/or in vitro, with most of the plants having a higher percentage of insulin release and inhibition against carbohydrate digesting enzymes as compared with insulin mimetic and peripheral glucose uptake. Almost all the investigated plants also inhibit oxidative stress as part of their hypoglycemic activity with less toxicity. However, the isolation of their bioactive molecules is still lacking. This review provides a resource to enable thorough assessments of the therapeutic profiles of available medicinal plants used for the management of diabetes in the Eastern Cape, South Africa. Further studies such as the identification of the active ingredients of potent plants still need to be carried out; this may lead to new molecules in drug discovery and development.
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http://dx.doi.org/10.3390/molecules23112759DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278280PMC
October 2018

Antidiabetic Activity and Mechanism of Action of (Thunb.) DC.

Evid Based Complement Alternat Med 2018 4;2018:4170372. Epub 2018 Jul 4.

Plant Stress Group, Department of Biochemistry and Microbiology, University of Fort Hare, P.O. Box X1314, Alice, South Africa.

In South Africa, the number of people suffering from diabetes is believed to be rising steadily and the current antidiabetic therapies are frequently reported to have adverse side effects. Ethnomedicinal plant use has shown promise for the development of cheaper, cost-effective antidiabetic agents with fewer side effects. The aim of this study was to investigate the antidiabetic activity and mechanism of action of aqueous leaf extract prepared from . The potential of the extract for cytotoxicity was evaluated using MTT assay in HepG2 cells. The effects of the plant extract on glucose utilization in HepG2 cells and L6 myotubes, triglyceride accumulation in 3T3-L1, INS-1 proliferation, glucose metabolism in INS-1 cells, and NO production in RAW macrophages were also investigated using cell culture procedures. The inhibitory effects of the extract on the activities of different enzymes including alpha-amylase, alpha-glucosidase, pancreatic lipase, dipeptidyl peptidase IV (DPP-IV), collagenase, and CYP3A4 enzymes were evaluated. The extract also tested against protein glycation using standard published procedure. The plant extract displayed low level of toxicity, where both concentrations tested did not induce 50% cell death. The extract caused a significant increase in glucose uptake in HepG2 liver cells, with efficacy significantly higher than the positive control, berberine. The crude extract also displayed no significant effect on muscle glucose uptake, triglyceride accumulation in 3T3-L1, glucose metabolism in INS-1 cells, alpha-amylase, alpha-glucosidase, DPP-IV, lipase, protein glycation, and collagenase compared to the respective positive controls. The extract displayed a proliferative effect on INS-1 cells at 25 g/ml when compared to the negative control. The plant also produced a concentration-dependent reduction in NO production in RAW macrophages and also demonstrated weak significant inhibition on CYP3A4 activity. The findings provide evidence that possess antidiabetic activity and appear to exact its hypoglycemic effect independent of insulin.
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http://dx.doi.org/10.1155/2018/4170372DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6077518PMC
July 2018

Phytochemical Composition and Antioxidant Activities of Hooper and Hypoxis Argentea Harv Ex Baker: Plants Used for the Management of Diabetes Mellitus in Eastern Cape, South Africa.

Pharmacogn Mag 2018 Apr-Jun;14(54):195-202. Epub 2018 Apr 10.

Department of Biochemistry and Microbiology, University of Fort Hare, Alice 5700, Eastern Cape, South Africa.

Background: Inhabitants of the Eastern Cape Province of South Africa use the roots of and corms of to treat diabetes mellitus and other ailments.

Objective: The objective of this study was to analyze the phytochemical composition and antioxidant activities of the aqueous and ethanol extracts of the roots and corms of two plants.

Materials And Methods: Total phenolics, flavonoids, flavonols, proanthocyanidins, tannins, and alkaloids were determined by standard methods. The scavenging activities of the extracts against 1,1 diphenyl-2-picrylhydrazyl (DPPH), 2'-azino-bis (3-ethylbenthiazoline-6-sulfonic acid (ABTS), nitric oxide (NO), hydrogen peroxide (HO), and their ferric-reducing antioxidant potentials (FRAPs) were measured.

Results: The ethanol extract of had the highest content of phenolics (66.71 ± 2.71 mg gallic acid equivalent/g) and tannins (1.18 ± 0.07 mg TAE/g), while the ethanol extract of gave higher contents of flavonoids and proanthocyanidins (62.21 ± 1.75 mg Qe/g and 432.62 ± 2.43 mg Ca/g, respectively). Flavonols were the most predominant in the aqueous extract of (25.51 ± 1.92 mg Qe/g). We observed a concentration-dependent response in the ABTS- and HO-scavenging activities and FRAP values of the extracts and standards (Vitamin C, butylated hydroxytoluene, and rutin). The ethanol extracts of both plants generally demonstrated better antioxidant activities against HO, NO, and ABTS while also possessing better reducing power than the aqueous extracts. The aqueous extract of , however, showed the best DPPH scavenging activity.

Conclusion: The higher content of phytochemicals and antioxidant capacity obtained for the ethanol extracts of and may prove to be valuable information in selecting suitable extraction solvents for the medicinal applications of both plants.

Summary: Ethanol extracts of had the highest levels of phenolics and tanninsEthanol extracts of had the highest levels of flavonoids and proanthocyanidinsEthanol extracts of both plants possess better antioxidant activityagainst hydrogen peroxide, nitric oxide, and ABTS as well as higher reducingpower than the aqueous extractsAqueous extract of had the highest free radical scavenging activity as measured with DPPH. ABTS: 2'-azino-bis (3-ethylbenthiazoline-6-sulfonic acid); BHT: Butylated hydroxytoluene; DPPH: 1,1 diphenyl-2-picrylhydrazyl; DTA: aqueous extract (16.6%); DTE: ethanol extract (2.4%); Fe-TPTZ: Ferric tripyridyltriazine; FRAP: Ferric-reducing antioxidant potentials; GAE: Gallic acid equivalent; HAA: aqueous extract (3.2%); HAE: ethanol extract (1.8%); Qe: Quercetin equivalence; ROS: Reactive oxygen species; TBA: Thiobarbituric acid;TCA: Trichloroacetic acid.
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http://dx.doi.org/10.4103/pm.pm_157_17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5909315PMC
April 2018

Chemical composition profiling and antifungal activity of the essential oil and plant extracts of Mesembryanthemum edule (L.) bolus leaves.

Afr J Tradit Complement Altern Med 2014 4;11(4):19-30. Epub 2014 Jun 4.

Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa.

Background: Essential oil from Mesembryanthemum edule leaves have been used by the Eastern Cape traditional healers for the treatment of respiratory tract infections, tuberculosis, dysentery, diabetic mellitus, laryngitis and vaginal infections. The investigation of bioactive compounds in the essential oil of this plant could help to verify the efficacy of the plant in the management or treatment of these illnesses.

Materials And Methods: Various concentrations of the hydro-distilled essential oil, ranging from 0.005-5 mg/ml, were tested against some fungal strains, using the micro-dilution method. Minimum inhibitory activity was compared with four other different crude extracts of hexane, acetone, ethanol and aqueous samples from the same plant. The chemical composition of the essential oil, hexane, acetone and ethanol extracts was determined using GC-MS.

Results: GC/MS analysis of the essential oil resulted in the identification of 28 compounds, representing 99.99% of the total oil. Phytoconstituents of hexane, acetone and ethanol extracts yielded a total peak chromatogram of fifty nine compounds. A total amount of 10.6% and 36.61% of the constituents were obtained as monoterpenes and oxygenated monoterpenes. Sesquiterpene hydrocarbons (3.58%) were relatively low compared to the oxygenated sesquiterpenes (9.28%), while the major concentrated diterpenes and oxygenated diterpenes were 1.43% and 19.24 %, respectively and phytol 12.41%. Total amount of fatty acids and their methyl esters content, present in the oil extract, were found to be 19.25 %. Antifungal activity of the oil extract and four solvent extracts were tested against five pathogenic fungal strains. The oil extract showed antifungal activity against Candida albican, Candida krusei, Candida rugosa, Candida glabrata and Cryptococcus neoformans with MIC ranges of 0.02 0.31 mg/ml. Hexane extract was active against the five fungal strains with MICs ranging between 0.02-1.25 mg/ml. Acetone extracts were active against C. krusei only at 0.04mg/ml. No appreciable antifungal activity was found in either ethanol or water extracts when compared with commercial antibiotics.

Conclusion: The profile of chemical constituents found in M. edule essential oil and its antifungal properties support the use of M. edule by traditional healers as well as in the pharmaceutical and food industries as a natural antibiotic and food preservative.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4202392PMC
http://dx.doi.org/10.4314/ajtcam.v11i4.4DOI Listing
June 2015

The inhibitory effect of Mesembryanthemum edule (L.) bolus essential oil on some pathogenic fungal isolates.

BMC Complement Altern Med 2014 May 23;14:168. Epub 2014 May 23.

Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa.

Background: Mesembryanthemum edule is a medicinal plant which has been indicated by Xhosa traditional healers in the treatment HIV associated diseases such as tuberculosis, dysentery, diabetic mellitus, laryngitis, mouth infections, ringworm eczema and vaginal infections. The investigation of the essential oil of this plant could help to verify the rationale behind the use of the plant as a cure for these illnesses.

Methods: The essential oil from M. edule was analysed by GC/MS. Concentration ranging from 0.005-5 mg/ml of the hydro-distilled essential oil was tested against some fungal strains, using micro-dilution method. The plant minimum inhibitory activity on the fungal strains was determined.

Result: GC/MS analysis of the essential oil resulted in the identification of 28 compounds representing 99.99% of the total essential oil. A total amount of 10.6 and 36.61% constituents were obtained as monoterpenes and oxygenated monoterpenes. The amount of sesquiterpene hydrocarbons (3.58%) was low compared to the oxygenated sesquiterpenes with pick area of 9.28%. Total oil content of diterpenes and oxygenated diterpenes detected from the essential oil were 1.43% and 19.24%. The fatty acids and their methyl esters content present in the essential oil extract were found to be 19.25%. Antifungal activity of the essential oil extract tested against the pathogenic fungal, inhibited C. albican, C. krusei, C. rugosa, C. glabrata and C. neoformans with MICs range of 0.02-0.31 mg/ml. the activity of the essential oil was found competing with nystatin and amphotericin B used as control.

Conclusion: Having accounted the profile chemical constituent found in M. edule oil and its important antifungal properties, we consider that its essential oil might be useful in pharmaceutical and food industry as natural antibiotic and food preservative.
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http://dx.doi.org/10.1186/1472-6882-14-168DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4057826PMC
May 2014

Protective effect of Tulbaghia violacea Harv. on aortic pathology, tissue antioxidant enzymes and liver damage in diet-induced atherosclerotic rats.

Int J Mol Sci 2012 Oct 8;13(10):12747-60. Epub 2012 Oct 8.

Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa.

The protective effect Tulbaghia violacea rhizomes (TVR) against derangements in serum lipid profile, tissue antioxidant enzyme depletion, endothelium dysfunction and histopathological changes in the aorta and liver of rats fed with an atherosclerogenic (Ath) diet (4% cholesterol, 1% cholic acid and 0.5% thiouracil) was investigated in this study. Co-treatment with the TVR extracts (250 and 500 mg/kg body weight for two weeks significantly (p < 0.05) protected against elevated serum triglyceride (TG), total cholesterol (TC), LDL-cholesterol, VLDL-cholesterol and decreased HDL-cholesterol in a dose-dependent manner when compared with the atherogenic control. The extracts also reduced (p < 0.05) elevated thiobabutric reacting substance (TBARS) and reversed endothelial dysfunction parameters (fibrinogen and total NO levels) and tissue antioxidant enzyme activities to near normal. The protective ability of the extract was confirmed by the significant (p < 0.05) reduction in the activities of serum markers of liver (LDH, AST, ALT, ALP, bilirubin) and kidney damage (creatinine and bilirubin) in extract-treated groups compared with the atherogenic control group. Also, histopathology evaluations of aorta sections revealed that the extracts protected against the development of fatty streak plaques (aorta) and fatty changes in hepatocytes. The observed activities of the extracts compared favorably with standard drug atorvastatin. Our study thus showed that the methanolic extract of TVR could protect against the early onset of atherosclerosis.
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http://dx.doi.org/10.3390/ijms131012747DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3497297PMC
October 2012

Antioxidant and phytochemical properties of Carpobrotus edulis (L.) bolus leaf used for the management of common infections in HIV/AIDS patients in Eastern Cape Province.

BMC Complement Altern Med 2012 Nov 9;12:215. Epub 2012 Nov 9.

Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa.

Background: Carpobrotus edulis (Mesembryanthemaceae), also known as igcukuma in Xhosa language is a medicinal plant used by the traditional healers to treat common infections in HIV/AIDS patients. Based on this information, we researched on the plant phytoconstituents, as well as its inhibitory effect using aqueous and three different organic solvent extracts in order to justify its therapeutic usage.

Methods: Antioxidant activity of the extracts were investigated spectrophotometrically against 1,1- diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) diammonium salt, hydrogen peroxide (H2O2), nitric oxide (NO), and ferric reducing power, Total phenols, flavonoids, flavonols, proanthocyanidins, tannins, alkaloids and saponins were also determined using the standard methods.

Results: Quantitative phytochemical analysis of the four solvent extracts revealed a high percentage of phenolics (55.7 ± 0.404%) in the acetone extract, with appreciable amount of proanthocyanidins (86.9 ± 0.005%) and alkaloids (4.5 ± 0.057%) in the aqueous extract, while tannin (48.9 ± 0.28%) and saponin (4.5 ± 0.262%) were major constituents of the ethanol extract. Flavonoids (0.12 ± 0.05%) and flavonols (0.12 ± 0.05%) were found at higher level in the hexane extract in comparison with the other extracts. The leaf extracts demonstrated strong hydrogen peroxide scavenging activity, with the exception of water and ethanol extracts. IC50 values of the aqueous and ethanolic extract against DPPH, ABTS, and NO were 0.018 and 0.016; 0.020 and 0.022; 0.05 and 0.023 mg/ml, respectively. The reducing power of the extract was found to be concentration dependent.

Conclusion: The inhibitory effect of the extracts on free radicals may justify the traditional use of this plant in the management of common diseases in HIV/AIDs patients in Eastern Cape Province. Overall, both aqueous and ethanol were found to be the best solvents for antioxidant activity in C. edulis leaves.
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http://dx.doi.org/10.1186/1472-6882-12-215DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3528461PMC
November 2012

Protective effect of T. violacea rhizome extract against hypercholesterolemia-induced oxidative stress in Wistar rats.

Molecules 2012 May 21;17(5):6033-45. Epub 2012 May 21.

Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa.

The present study examines the effect of methanolic extract of T. violacea rhizomes on high cholesterol (2%) diet fed rats (HCD). At the end of 4 weeks, serum total protein, albumin, reduced glutathione (GSH), and markers of oxidative stress viz., catalase (CAT), superoxide dismutase (SOD), thiobarbituric acid reactive substances (TBARS--a marker of lipid peroxidation), glutathione-S-transferase (GST) and glutathione peroxidase (GPx) in the serum, aorta, liver and heart of HCD and normal rats were assessed and compared. A significant (p < 0.05) elevation in TBARS, and a reduction (p < 0.05) in serum total protein, albumin, GSH and antioxidant enzyme activities was observed in tissues of HCD fed rats compared with the normal group. Co-administration of crude extracts of T. violacea rhizomes protected the liver, heart, serum and aorta against HCD-induced lipid peroxidation in a dose dependant manner. The activities of the extract (500 mg/kg) compared favorably with gemfibrozil. The extracts also protected against HCD-induced reduction in serum total protein, GSH and restored the activities of antioxidant tissues (liver, heart and aorta) enzymes to near normal values. This result suggested that consumption of T. violacea rhizome may help to protect against hypercholesterolemia- induced oxidative stress diseases in the heart and liver.
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http://dx.doi.org/10.3390/molecules17056033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6268349PMC
May 2012

Antidiabetic Activities of Aqueous Stem Bark Extract of Strychnoshenningsii Gilg in Streptozotocin-nicotinamide Type 2 Diabetic Rats.

Iran J Pharm Res 2012 ;11(1):221-8

School of Biological Sciences, University of Fort Hare, Alice 5700, South Africa.

Strychnos henningsii Gilg is recommended among other remedies for the treatment of diabetes in traditional medicine of Southern Africa. The antidiabetic effect of oral administration of aqueous bark extract of the plant at 125, 250 and 500 mg/Kg body weight was investigated in diabetic rats induced with streptozotocin-nicotinamide for 15 days. The extract decreased the blood glucose level, feed and water intake as well as triacylglycerol at the three doses investigated while the best result was obtained at 250 mg/Kg. Similarly, the extract was able to lower the cholesterol level appreciably at 500 mg/Kg while the remaining doses did not have any significant effect as compared with diabetic untreated groups. In addition, the weight loss of diabetic-treated rats was markedly normalized at all doses. The glucose tolerance level of diabetic animals was effectively reduced to near normal level after 90 min of extract administration especially at the dose of 250 and 500 mg/Kg. The phytochemical screening of S. henningsii revealed the presence of flavonoids, tannins and saponins which have been reported to increase the insulin secretion. The results obtained from this study demonstrated that the aqueous extract of S. henningsii possess antihyperglycemic and antilipidemic properties and thus could prevent various complications of diabetes. Generally, this study has validated the traditional use of this plant for the treatment of diabetes mellitus.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3813109PMC
November 2013

In silico analysis of cis-acting regulatory elements in 5' regulatory regions of sucrose transporter gene families in rice (Oryza sativa Japonica) and Arabidopsis thaliana.

Comput Biol Chem 2010 Dec 30;34(5-6):268-83. Epub 2010 Oct 30.

Plant Stress Response Group, Department of Biochemistry & Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa.

The regulation of gene expression involves a multifarious regulatory system. Each gene contains a unique combination of cis-acting regulatory sequence elements in the 5' regulatory region that determines its temporal and spatial expression. Cis-acting regulatory elements are essential transcriptional gene regulatory units; they control many biological processes and stress responses. Thus a full understanding of the transcriptional gene regulation system will depend on successful functional analyses of cis-acting elements. Cis-acting regulatory elements present within the 5' regulatory region of the sucrose transporter gene families in rice (Oryza sativa Japonica cultivar-group) and Arabidopsis thaliana, were identified using a bioinformatics approach. The possible cis-acting regulatory elements were predicted by scanning 1.5kbp of 5' regulatory regions of the sucrose transporter genes translational start sites, using Plant CARE, PLACE and Genomatix Matinspector professional databases. Several cis-acting regulatory elements that are associated with plant development, plant hormonal regulation and stress response were identified, and were present in varying frequencies within the 1.5kbp of 5' regulatory region, among which are; A-box, RY, CAT, Pyrimidine-box, Sucrose-box, ABRE, ARF, ERE, GARE, Me-JA, ARE, DRE, GA-motif, GATA, GT-1, MYC, MYB, W-box, and I-box. This result reveals the probable cis-acting regulatory elements that possibly are involved in the expression and regulation of sucrose transporter gene families in rice and Arabidopsis thaliana during cellular development or environmental stress conditions.
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http://dx.doi.org/10.1016/j.compbiolchem.2010.09.003DOI Listing
December 2010

Stronger induction of callose deposition in barley by Russian wheat aphid than bird cherry-oat aphid is not associated with differences in callose synthase or beta-1,3-glucanase transcript abundance.

Physiol Plant 2009 Feb 26;135(2):150-61. Epub 2008 Nov 26.

Department of Botany, Rhodes University, Grahamstown 6140, South Africa.

The effects of infestation by the bird cherry-oat aphid (BCA), (Rhopalosiphum padi L) and the Russian wheat aphid (RWA) (Diuraphis noxia Mordvilko) on callose deposition and transcription of genes related to callose accumulation were investigated in barley (Hordeum vulgare L. cv. Clipper). The BCA, which gives no visible symptoms, induced very limited callose deposition, even after 14 days of infestation. In contrast, RWA, which causes chlorosis, white and yellow streaking and leaf rolling, induced callose accumulation already after 24 h in longitudinal leaf veins. The deposition was pronounced after 72 h, progressing during 7 and 14 days of infestation. In RWA-infested source leaves, callose was also induced in longitudinal veins basipetal to the aphid-infested tissue, whereas in sink leaves, more callose deposition was found above the feeding sites. Eight putative callose synthase genes were identified in a database search, of which seven were expressed in the leaves, but with similar transcript accumulation in control and aphid-infested tissue. Five out of 12 examined beta-1,3-glucanases were expressed in the leaves. All five were upregulated in RWA-infested tissue, but only two in BCA-infested tissue, and to a lesser extent than by RWA. The results suggest that callose accumulation may be partly responsible for the symptoms resulting from RWA infestation and that a callose-inducing signal may be transported in the phloem. Furthermore, it is concluded that the absence of callose deposition in BCA-infested leaves is not because of a stronger upregulation of callose-degrading beta-1,3-glucanases in this tissue, as compared to RWA-infested leaves.
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http://dx.doi.org/10.1111/j.1399-3054.2008.01180.xDOI Listing
February 2009

Nuclear translocation of the phosphoprotein Hop (Hsp70/Hsp90 organizing protein) occurs under heat shock, and its proposed nuclear localization signal is involved in Hsp90 binding.

Biochim Biophys Acta 2008 Jun 31;1783(6):1003-14. Epub 2008 Jan 31.

Chaperone Research Laboratory, Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown, South Africa.

The Hsp70-Hsp90 complex is implicated in the folding and regulation of numerous signaling proteins, and Hop, the Hsp70-Hsp90 Organizing Protein, facilitates the association of this multichaperone machinery. Phosphatase treatment of mouse cell extracts reduced the number of Hop isoforms compared to untreated extracts, providing the first direct evidence that Hop was phosphorylated in vivo. Furthermore, surface plasmon resonance (SPR) spectroscopy showed that a cdc2 kinase phosphorylation mimic of Hop had reduced affinity for Hsp90 binding. Hop was predominantly cytoplasmic, but translocated to the nucleus in response to heat shock. A putative bipartite nuclear localization signal (NLS) has been identified within the Hsp90-binding domain of Hop. Although substitution of residues within the major arm of this proposed NLS abolished Hop-Hsp90 interaction as determined by SPR, this was not sufficient to prevent the nuclear accumulation of Hop under leptomycin-B treatment and heat shock conditions. These results showed for the first time that the subcellular localization of Hop was stress regulated and that the major arm of the putative NLS was not directly important for nuclear translocation but was critical for Hop-Hsp90 association in vitro. We propose a model in which the association of Hop with Hsp90 and the phosphorylated status of Hop both play a role in the mechanism of nucleo-cytoplasmic shuttling of Hop.
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http://dx.doi.org/10.1016/j.bbamcr.2008.01.014DOI Listing
June 2008

Arginine deiminases: therapeutic tools in the etiology and pathogenesis of Alzheimer's disease.

J Enzyme Inhib Med Chem 2007 Feb;22(1):121-6

Department of Biochemistry, Microbiology and Biotechnology Rhodes University, Grahamstown, South Africa.

There is, at present, no definitive pre-mortem diagnostic tool for Alzheimer's disease, (AD) which relates to a poor understanding of its etiology. Brains of AD patients contain large amounts of the toxic plaque-forming beta-amyloid1-42 fragment in addition to elevated concentrations of the amino acid L-arginine. This work proposes that lowering levels of arginine in the astrocytes surrounding amyloid plaques may serve as a therapeutic tool in this neurodegenerative disorder. Arginine deiminase (ADI), from Pseudomonas aeruginosa, and peptidylarginine deiminase [PAD II], from bovine brain, are inhibited by amyloid peptides that contain arginine (amyloid1-42) and those that have no arginine (amyloid12-28/22-35). Enhanced activity of PAD II is noted with free L-arginine.
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http://dx.doi.org/10.1080/14756360600990829DOI Listing
February 2007
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