Publications by authors named "Cassandra L Quave"

67 Publications

Ethnobotany of the Aegadian Islands: safeguarding biocultural refugia in the Mediterranean.

J Ethnobiol Ethnomed 2021 Jul 28;17(1):47. Epub 2021 Jul 28.

Center for the Study of Human Health, Emory University, 1557 Dickey Dr, Anthropology 306, Atlanta, GA, 30322, USA.

Background: The Aegadian Islands are located west of Trapani, Sicily. Once the site of bountiful tuna fisheries and fruit orchards (plums, peaches, apricots), grapevines, prickly pears, and grains, the local economy is now based on tourism, and many traditional agricultural and maritime practices have been abandoned. In this study, we aimed to evaluate the state of traditional ecological knowledge (TEK) concerning the use of wild and cultivated plants and fungi for human health, food, maritime, and agricultural purposes on the islands of Levanzo, Favignana, and Marettimo and compare present-day practices with those documented in the past.

Methods: In-depth semi-structured interviews were conducted in Italian with 48 participants with prior informed consent from May 2016 to July 2017 and October 2018. Herbarium voucher specimens of wild species were collected for herbarium deposit. A rigorous literature review of scientific and other local reports on TEK of wild flora and their application in food, health, and household applications was undertaken for the purpose of comparing findings from this field study with prior reports.

Results: A total of 122 plant and five fungal taxa representing 54 families were cited for 355 uses. Among the most pervasive species in the landscape, Agave americana and A. sisalana had diverse applications in the past, which ranged from cordage for agricultural and maritime applications to tools for sewing, eating land snails, and constructing furniture. Fields of Ferula communis also dominate the landscape, and the dry stems were used extensively in furniture making; this species also serves as an environmental indicator for the location of the most preferred edible mushrooms, Pleurotus eryngii var. ferulae. Other important flora included topical medicinal applications of Glaucium flavum for hematomas and Artemisia arborescens for ritual bathing of newborns.

Conclusion: While many plant-based traditions have disappeared from daily practice, especially those related to traditional fishing and health practices, they remain in the memories of the eldest subset of the population. Documenting this knowledge before it disappears from oral history is a key factor in reducing loss of TEK and biocultural diversity, safeguarding the role of the Aegadian Islands as biocultural refugia.
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http://dx.doi.org/10.1186/s13002-021-00470-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8320050PMC
July 2021

Castaneroxy A From the Leaves of Inhibits Virulence in .

Front Pharmacol 2021 28;12:640179. Epub 2021 Jun 28.

Center for the Study of Human Health, Emory University, Atlanta, GA, United States.

Methicillin-resistant (MRSA) represents one of the most serious infectious disease concerns worldwide, with the CDC labeling it a "serious threat" in 2019. The current arsenal of antibiotics works by targeting bacterial growth and survival, which exerts great selective pressure for the development of resistance. The development of novel anti-infectives that inhibit quorum sensing and thus virulence in MRSA has been recurrently proposed as a promising therapeutic approach. In a follow-up of a study examining the MRSA quorum sensing inhibitory activity of extracts of Italian plants used in local traditional medicine, 224C-F2 was reported as a bioactive fraction of a (European chestnut) leaf extract. The fraction demonstrated high activity and effective attenuation of MRSA pathogenicity in a mouse model of skin infection. Through further bioassay-guided fractionation using reverse-phase high performance liquid chromatography, a novel hydroperoxy cycloartane triterpenoid, castaneroxy A (), was isolated. Its structure was established by nuclear magnetic resonance, mass spectrometry and X-ray diffraction analyses. Isomers of were also detected in an adjacent fraction. In a series of assays assessing inhibition of markers of MRSA virulence, exerted activities in the low micromolar range. It inhibited ::P3 activation (IC = 31.72 µM), δ-toxin production (IC = 31.72 µM in NRS385), supernatant cytotoxicity to HaCaT human keratinocytes (IC = 7.93 µM in NRS385), and rabbit erythrocyte hemolytic activity (IC = 7.93 µM in LAC). Compound did not inhibit biofilm production, and at high concentrations it exerted cytotoxicity against human keratinocytes greater than that of 224C-F2. Finally, reduced dermonecrosis in a murine model of MRSA infection. The results establish as a promising antivirulence candidate for development against MRSA.
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http://dx.doi.org/10.3389/fphar.2021.640179DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8274328PMC
June 2021

Cruciferous vegetables () confer cytoprotective effects in intestines.

Gut Microbes 2021 Jan-Dec;13(1):1-6

Center for the Study of Human Health, Emory University College of Arts and Sciences, Atlanta, Georgia.

Varieties and cultivars of the cruciferous vegetable are widely presumed to elicit positive influences on mammalian health and disease, particularly related to their indole and sulforaphane content. However, there is a considerable gap in knowledge regarding the mechanisms whereby these plant-derived molecules elicit their beneficial effects on the host. In this study, we examined the chemical variation between varieties and evaluated their capacity to both activate Nrf2 in the intestine and elicit cytoprotection. Ten types of edible were purchased and was wild collected. Fresh material was dried, extracted by double maceration and green kale was also subjected to anaerobic fermentation before processing. Untargeted metabolomics was used to perform Principal Component Analysis. Targeted mass spectral analysis determined the presence of six indole species and quantified indole. Extracts were tested for their capacity to activate Nrf2 in the intestine in third instar larvae. Cytoprotective effects were evaluated using a paraquat-induced oxidative stress gut injury model. A "Smurf" assay was used to determine protective capacity against a chemically induced leaky gut. Extracts of Brussels sprouts and broccoli activated Nrf2 and protected against paraquat-induced damage and leaky gut. Lacto-fermented kale showed a cytoprotective effect, increasing survival by 20% over the non-fermented extract, but did not protect against leaky gut. The protective effects observed do not directly correlate with indole content, suggesting involvement of multiple compounds and a synergistic mechanism.
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http://dx.doi.org/10.1080/19490976.2021.1921926DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8115444PMC
May 2021

An ethnopharmacological survey and comparative analysis of plants from the Sudhnoti District, Azad Jammu and Kashmir, Pakistan.

J Ethnobiol Ethnomed 2021 Mar 20;17(1):14. Epub 2021 Mar 20.

Center for the Study of Human Health, Emory University, 550 Asbury Circle, Atlanta, GA, 30322, USA.

Background: This is the first comprehensive report on the traditional and novel uses of medicinal plants practiced by the indigenous communities of the Sudhnoti district of Azad Jammu and Kashmir (AJK), Pakistan. The area is rich in folklore and indigenous medicinal knowledge due to a unique tribal composition and socioeconomic conditions. This study aimed to document traditional knowledge of native plant use by the local communities, particularly those used for therapeutic purposes.

Methods: Field surveys were conducted from September 2015 to March 2017. Interviews with 125 local inhabitants of different tribes, age groups, genders, and occupations were conducted using structured and semi-structured questions along with group discussions. Data gathered on plant uses, local names, and modes of application of each plant species were organized in tables. Ethnobotanical indices such as use value (UV) and cultural significance index (CSI) were used to produce quantitative information on the plant use category, frequency, and cultural preference of species. Reports on therapeutic uses of medicinal plants were compared with previous studies.

Results: In all, 88 plant species from 45 families were reported, out of which 67 (77%) were used in ethnomedical applications. Asteraceae, Rosaceae, Fabaceae, and Lamiaceae were the dominant families. Berberis lycium was the most valued plant species, followed by Zanthoxylum armatum and Taraxacum officinale. Mentha arvensis had the highest cultural significance, followed by Mentha longifolia, Punica granatum, and Zanthoxylum armatum. Leaves were the most preferred plant parts in the preparation of medicine exclusively or mixed with other parts. The most frequently used process of crude preparation of medicinal plants was cooking. Oral intake was the predominant route of administration.

Conclusions: Our comparative analysis confirmed that most of the plants documented have uses that match those previously reported for the region and other parts of the world, with the exception of novel medicinal uses for 11 plant species, including Verbascum thapsus for earache, Elaeagnus umbellata for hepatitis, Achillea millefolium for oral care, Dicliptera roxburghiana to prevent sunstroke in cattle, Rumex hastatus for allergy antidote, Pyrus pashia for hepatitis, and Nerium oleander for diabetes.
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http://dx.doi.org/10.1186/s13002-021-00435-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7980561PMC
March 2021

A Systematic Review of Plants With Antibacterial Activities: A Taxonomic and Phylogenetic Perspective.

Front Pharmacol 2020 8;11:586548. Epub 2021 Jan 8.

Center for the Study of Human Health, Emory University, Atlanta, GA, United States.

Antimicrobial resistance represents a serious threat to human health across the globe. The cost of bringing a new antibiotic from discovery to market is high and return on investment is low. Furthermore, the development of new antibiotics has slowed dramatically since the 1950s' golden age of discovery. Plants produce a variety of bioactive secondary metabolites that could be used to fuel the future discovery pipeline. While many studies have focused on specific aspects of plants and plant natural products with antibacterial properties, a comprehensive review of the antibacterial potential of plants has never before been attempted. This systematic review aims to evaluate reports on plants with significant antibacterial activities. Following the PRISMA model, we searched three electronic databases: Web of Science, PubMed and SciFinder by using specific keywords: "plant," "antibacterial," "inhibitory concentration." We identified a total of 6,083 articles published between 1946 and 2019 and then reviewed 66% of these (4,024) focusing on articles published between 2012 and 2019. A rigorous selection process was implemented using clear inclusion and exclusion criteria, yielding data on 958 plant species derived from 483 scientific articles. Antibacterial activity is found in 51 of 79 vascular plant orders throughout the phylogenetic tree. Most are reported within eudicots, with the bulk of species being asterids. Antibacterial activity is not prominent in monocotyledons. Phylogenetic distribution strongly supports the concept of chemical evolution across plant clades, especially in more derived eudicot families. The Lamiaceae, Fabaceae and Asteraceae were the most represented plant families, while , and were the most studied species. South Africa was the most represented site of plant collection. Crude extraction in methanol was the most represented type of extraction and leaves were the main plant tissue investigated. Finally, was the most targeted pathogenic bacteria in these studies. We closely examine 70 prominent medicinal plant species from the 15 families most studied in the literature. This review depicts the current state of knowledge regarding antibacterials from plants and provides powerful recommendations for future research directions.
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http://dx.doi.org/10.3389/fphar.2020.586548DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7821031PMC
January 2021

Staphylococcal Hemolytic Potential Is Correlated with Increased Severity of Atopic Dermatitis in Children and Young Adults.

J Invest Dermatol 2021 Jun 25;141(6):1588-1591. Epub 2020 Dec 25.

Department of Dermatology, Emory University School of Medicine, Atlanta, Georgia, USA. Electronic address:

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http://dx.doi.org/10.1016/j.jid.2020.11.023DOI Listing
June 2021

Ethnobotany and the Role of Plant Natural Products in Antibiotic Drug Discovery.

Chem Rev 2021 03 9;121(6):3495-3560. Epub 2020 Nov 9.

Center for the Study of Human Health, Emory University, 1557 Dickey Drive, Atlanta, Georgia 30322, United States.

The crisis of antibiotic resistance necessitates creative and innovative approaches, from chemical identification and analysis to the assessment of bioactivity. Plant natural products (NPs) represent a promising source of antibacterial lead compounds that could help fill the drug discovery pipeline in response to the growing antibiotic resistance crisis. The major strength of plant NPs lies in their rich and unique chemodiversity, their worldwide distribution and ease of access, their various antibacterial modes of action, and the proven clinical effectiveness of plant extracts from which they are isolated. While many studies have tried to summarize NPs with antibacterial activities, a comprehensive review with rigorous selection criteria has never been performed. In this work, the literature from 2012 to 2019 was systematically reviewed to highlight plant-derived compounds with antibacterial activity by focusing on their growth inhibitory activity. A total of 459 compounds are included in this Review, of which 50.8% are phenolic derivatives, 26.6% are terpenoids, 5.7% are alkaloids, and 17% are classified as other metabolites. A selection of 183 compounds is further discussed regarding their antibacterial activity, biosynthesis, structure-activity relationship, mechanism of action, and potential as antibiotics. Emerging trends in the field of antibacterial drug discovery from plants are also discussed. This Review brings to the forefront key findings on the antibacterial potential of plant NPs for consideration in future antibiotic discovery and development efforts.
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http://dx.doi.org/10.1021/acs.chemrev.0c00922DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8183567PMC
March 2021

Antibacterial activity of plant species used for oral health against Porphyromonas gingivalis.

PLoS One 2020 8;15(10):e0239316. Epub 2020 Oct 8.

Center for the Study of Human Health, Emory University College of Arts and Sciences, Atlanta, GA, United States of America.

Porphyromonas gingivalis is the keystone pathogen of periodontitis, a chronic inflammatory disease which causes tooth loss and deterioration of gingiva. Medicinal plants have been traditionally used for oral hygiene and health and might play a role as antibacterial agents against oral pathogens. In this work, we aimed to evaluate the antibacterial activity of plants used for oral hygiene or symptoms of periodontitis against P. gingivalis. We first reviewed the literature to identify plant species used for oral hygiene or symptoms of periodontitis. Then, we cross-checked this species list with our in-house library of plant extracts to select extracts for testing. Antibacterial activity tests were then performed for each plant extract against P. gingivalis, and their cytotoxicity was assessed on HaCaT cells. The selectivity index (SI) was then calculated. A total of 416 plant species belonging to 110 families and 305 genera were documented through our literature search, and 158 plant species were noted as being used by North American Native peoples Once cross-checked with the extracts contained in our library of natural products, 30 matches were identified and 21 were defined as high priority. Of the 109 extracts from 21 plant species selected and tested, 21 extracts from 11 plants had higher than 90% inhibition on P. gingivalis at 64 μg/mL and were further selected for MIC (Minimum Inhibitory Concentration) assays. Out of 21 plant extracts, 13 extracts (7 plant species) had a SI > 10. Pistacia lentiscus fruits showed the best MIC with value of 8 μg/mL, followed by Zanthoxylum armatum fruits/seeds with a MIC of 16 μg/mL. P. lentiscus fruits also showed the highest SI of 256. Most of the extracts tested present promising antibacterial activity and low cytotoxicity. Further testing for biofilm eradication and examination of activity against other dental pathogens and oral commensals should be performed to confirm the potential of these extracts as antibacterial agents. Future work will focus on application of a bioassay-guided fractionation approach to isolating and identifying the most active natural products in the top performing extracts. This study can serve as a basis for their future development as ingredients for oral hygiene products.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0239316PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7544490PMC
November 2020

Pentagalloyl glucose from Schinus terebinthifolia inhibits growth of carbapenem-resistant Acinetobacter baumannii.

Sci Rep 2020 09 18;10(1):15340. Epub 2020 Sep 18.

Department of Dermatology, Emory University School of Medicine, Atlanta, GA, USA.

The rise of antibiotic resistance has necessitated a search for new antimicrobials with potent activity against multidrug-resistant gram-negative pathogens, such as carbapenem-resistant Acinetobacter baumannii (CRAB). In this study, a library of botanical extracts generated from plants used to treat infections in traditional medicine was screened for growth inhibition of CRAB. A crude extract of Schinus terebinthifolia leaves exhibited 80% inhibition at 256 µg/mL and underwent bioassay-guided fractionation, leading to the isolation of pentagalloyl glucose (PGG), a bioactive gallotannin. PGG inhibited growth of both CRAB and susceptible A. baumannii (MIC 64-256 µg/mL), and also exhibited activity against Pseudomonas aeruginosa (MIC 16 µg/mL) and Staphylococcus aureus (MIC 64 µg/mL). A mammalian cytotoxicity assay with human keratinocytes (HaCaTs) yielded an IC for PGG of 256 µg/mL. Mechanistic experiments revealed iron chelation as a possible mode of action for PGG's activity against CRAB. Passaging assays for resistance did not produce any resistant mutants over a period of 21 days. In conclusion, PGG exhibits antimicrobial activity against CRAB, but due to known pharmacological restrictions in delivery, translation as a therapeutic may be limited to topical applications such as wound rinses and dressings.
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http://dx.doi.org/10.1038/s41598-020-72331-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7501240PMC
September 2020

Quantifying synergy in the bioassay-guided fractionation of natural product extracts.

PLoS One 2020 14;15(8):e0235723. Epub 2020 Aug 14.

Department of Dermatology, Emory University School of Medicine, Atlanta, Georgia, United States of America.

Mixtures of drugs often have greater therapeutic value than any of their constituent drugs alone, and such combination therapies are widely used to treat diseases such as cancer, malaria, and viral infections. However, developing useful drug mixtures is challenging due to complex interactions between drugs. Natural substances can be fruitful sources of useful drug mixtures because secondary metabolites produced by living organisms do not often act in isolation in vivo. In order to facilitate the study of interactions within natural substances, a new analytical method to quantify interactions using data generated in the process of bioassay-guided fractionation is presented here: the extract fractional inhibitory concentration index (EFICI). The EFICI method uses the framework of Loewe additivity to calculate fractional inhibitory concentration values by which interactions can be determined for any combination of fractions that make up a parent extract. The EFICI method was applied to data on the bioassay-guided fractionation of Lechea mucronata and Schinus terebinthifolia for growth inhibition of the pathogenic bacterium Acinetobacter baumannii. The L. mucronata extract contained synergistic interactions (EFICI = 0.4181) and the S. terebinthifolia extract was non-interactive overall (EFICI = 0.9129). Quantifying interactions in the bioassay-guided fractionation of natural substances does not require additional experiments and can be useful to guide the experimental process and to support the development of standardized extracts as botanical drugs.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0235723PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7428089PMC
September 2020

Targeting ESKAPE pathogens with anti-infective medicinal plants from the Greater Mpigi region in Uganda.

Sci Rep 2020 07 20;10(1):11935. Epub 2020 Jul 20.

Department of Dermatology, Emory University School of Medicine, 615 Michael St., Atlanta, GA, 30322, USA.

Antibiotic resistance poses one of the greatest threats to global health today; conventional drug therapies are becoming increasingly inefficacious and limited. We identified 16 medicinal plant species used by traditional healers for the treatment of infectious and inflammatory diseases in the Greater Mpigi region of Uganda. Extracts were evaluated for their ability to inhibit growth of clinical isolates of multidrug-resistant ESKAPE pathogens. Extracts were also screened for quorum quenching activity against S. aureus, including direct protein output assessment (δ-toxin), and cytotoxicity against human keratinocytes (HaCaT). Putative matches of compounds were elucidated via LC-FTMS for the best-performing extracts. These were extracts of Zanthoxylum chalybeum (Staphylococcus aureus: MIC: 16 μg/mL; Enterococcus faecium: MIC: 32 μg/mL) and Harungana madagascariensis (S. aureus: MIC: 32 μg/mL; E. faecium: MIC: 32 μg/mL) stem bark. Extracts of Solanum aculeastrum root bark and Sesamum calycinum subsp. angustifolium leaves exhibited strong quorum sensing inhibition activity against all S. aureus accessory gene regulator (agr) alleles in absence of growth inhibition (IC values: 1-64 μg/mL). The study provided scientific evidence for the potential therapeutic efficacy of these medicinal plants in the Greater Mpigi region used for infections and wounds, with 13 out of 16 species tested being validated with in vitro studies.
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http://dx.doi.org/10.1038/s41598-020-67572-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7371678PMC
July 2020

A Clerodane Diterpene from Resensitizes Methicillin-Resistant to β-Lactam Antibiotics.

ACS Infect Dis 2020 07 29;6(7):1667-1673. Epub 2020 Jun 29.

Emory University, Department of Dermatology, 615 Michael Street, Whitehead 105L, Atlanta, Georgia 30322, United States.

The rise of antibiotic resistance presents a significant healthcare challenge and precludes the use of many otherwise valuable antibiotics. One potential solution to this problem is the use of antibiotics in combination with resistance-modifying agents, compounds that act synergistically with existing antibiotics to resensitize previously resistant bacteria. In this study, 12(),16ξ-dihydroxycleroda-3,13-dien-15,16-olide, a clerodane diterpene isolated from the medicinal plant , was found to synergize with oxacillin against methicillin-resistant s. This synergy was confirmed by checkerboard (fractional inhibitory concentration index (FICI) = 0.125) and time-kill assays, with a subinhibitory dose of 12(),16ξ-dihydroxycleroda-3,13-dien-15,16-olide causing the effective concentration of oxacillin to fall below the susceptibility breakpoint for , a >32-fold decrease in both cases.
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http://dx.doi.org/10.1021/acsinfecdis.0c00307DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8183163PMC
July 2020

Triterpenoid acids isolated from Schinus terebinthifolia fruits reduce Staphylococcus aureus virulence and abate dermonecrosis.

Sci Rep 2020 05 15;10(1):8046. Epub 2020 May 15.

Center for the Study of Human Health, Emory University College of Arts and Sciences, 30322, Atlanta, Georgia, USA.

Staphylococcus aureus relies on quorum sensing to exert virulence to establish and maintain infection. Prior research demonstrated the potent quorum sensing inhibition effects of "430D-F5", a refined extract derived from the fruits of Schinus terebinthifolia, a medicinal plant used for the traditional treatment of skin and soft tissue infections. We report the isolation and identification of three compounds from 430D-F5 that reduce virulence and abate dermonecrosis: 3-oxo-olean-12-en-28-oic acid (1), 3-oxotirucalla-7,24Z-dien-26-oic acid (2) and 3α-hydroxytirucalla-7,24 Z-dien-27-oic acid (3). Each compound inhibits all S. aureus accessory gene regulator (agr) alleles (IC 2-70 μM). Dose-dependent responses were also observed in agr-regulated reporters for leucocidin A (lukA, IC 0.4-25 μM) and glycerol ester hydrolase or lipase (gehB, IC 1.5-25 μM). Surprisingly, dose-dependent activity against the nuclease reporter (nuc), which is under the control of the sae two-component system, was also observed (IC 0.4-12.5 μM). Compounds 1-3 exhibited little to no effect on the agr-independent mgrA P2 reporter (a constitutive promoter from the mgrA two-component system) and the esxA reporter (under control of mgrA). Compounds 1-3 inhibited δ-toxin production in vitro and reduced dermonecrosis in a murine in vivo model. This is the first report of triterpenoid acids with potent anti-virulence effects against S. aureus.
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http://dx.doi.org/10.1038/s41598-020-65080-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7229044PMC
May 2020

Prevalence and Therapeutic Challenges of Fungal Drug Resistance: Role for Plants in Drug Discovery.

Antibiotics (Basel) 2020 Mar 31;9(4). Epub 2020 Mar 31.

Department of Dermatology and Center for the Study of Human Health, Emory University, Atlanta, GA 30322, USA.

Antimicrobial resistance is a global issue that threatens the effective practice of modern medicine and global health. The emergence of multidrug-resistant (MDR) fungal strains of and azole-resistant were highlighted in the Centers for Disease Control and Prevention's (CDC) 2019 report, . Conventional antifungals used to treat fungal infections are no longer as effective, leading to increased mortality. Compounding this issue, there are very few new antifungals currently in development. Plants from traditional medicine represent one possible research path to addressing the issue of MDR fungal pathogens. In this commentary piece, we discuss how medical ethnobotany-the study of how people use plants in medicine-can be used as a guide to identify plant species for the discovery and development of novel antifungal therapies.
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http://dx.doi.org/10.3390/antibiotics9040150DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7235788PMC
March 2020

Genomic analysis of variability in Delta-toxin levels between strains.

PeerJ 2020 24;8:e8717. Epub 2020 Mar 24.

Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Atlanta, GA, United States of America.

Background: The delta-toxin (δ-toxin) of is the only hemolysin shown to cause mast cell degranulation and is linked to atopic dermatitis, a chronic inflammatory skin disease. We sought to characterize variation in δ-toxin production across strains and identify genetic loci potentially associated with differences between strains.

Methods: A set of 124 strains was genome-sequenced and δ-toxin levels in stationary phase supernatants determined by high performance liquid chromatography (HPLC). SNPs and kmers were associated with differences in toxin production using four genome-wide association study (GWAS) methods. Transposon mutations in candidate genes were tested for their δ-toxin levels. We constructed XGBoost models to predict toxin production based on genetic loci discovered to be potentially associated with the phenotype.

Results: The strain set encompassed 40 sequence types (STs) in 23 clonal complexes (CCs). δ-toxin production ranged from barely detectable levels to >90,000 units, with a median of >8,000 units. CC30 had significantly lower levels of toxin production than average while CC45 and CC121 were higher. MSSA (methicillin sensitive) strains had higher δ-toxin production than MRSA (methicillin resistant) strains. Through multiple GWAS approaches, 45 genes were found to be potentially associated with toxicity. Machine learning models using loci discovered through GWAS as features were able to predict δ-toxin production (as a high/low binary phenotype) with a precision of .875 and specificity of .990 but recall of .333. We discovered that mutants in the gene, encoding the small chain of carbamoyl phosphate synthase, completely abolished toxin production and toxicity in .

Conclusions: The amount of stationary phase production of the toxin is a strain-specific phenotype likely affected by a complex interaction of number of genes with different levels of effect. We discovered new candidate genes that potentially play a role in modulating production. We report for the first time that the product of the gene is necessary for δ-toxin production in USA300. This work lays a foundation for future work on understanding toxin regulation in and prediction of phenotypes from genomic sequences.
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http://dx.doi.org/10.7717/peerj.8717DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7100594PMC
March 2020

Phytochemical Study of Eight Medicinal Plants of the Lamiaceae Family Traditionally Used as Tea in the Sharri Mountains Region of the Balkans.

ScientificWorldJournal 2020 19;2020:4182064. Epub 2020 Feb 19.

Department of Pharmaceutical Chemistry, Faculty of Medicine, University of Prishtina "Hasan Prishtina", Bulevardi I Dëshmorëve, p.n. 10 000 Prishtina, Kosovo.

In the present study, eight plant species belonging to Lamiaceae family were identified as ingredients for herbal teas in the region of Sharri Mountains: , , , , , , and respectively. Chemical composition of essential oils obtained from these species was analyzed using GC-MS and GC-FID with the aim of examining their volatile compound profiles, responsible for their respective flavors and fragrance. Principal Component Analysis (PCA) was performed with the aim of grouping plant species under study on the basis of their chemical composition. Experimental data revealed the typical volatile constituent pattern for the Lamiaceae family. Monoterpenes and sesquiterpenes, responsible for flavor and medicinal use of these plants, were the most abundant groups of the volatile constituents. PCA data analysis resulted in the grouping of these analyzed species in four principal clusters.
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http://dx.doi.org/10.1155/2020/4182064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7049868PMC
October 2020

LEGO MINDSTORMS Fraction Collector: A Low-Cost Tool for a Preparative High-Performance Liquid Chromatography System.

Anal Chem 2020 01 3;92(2):1687-1690. Epub 2020 Jan 3.

Center for the Study of Human Health , Emory University , Atlanta , Georgia 30322 , United States.

Preparative high-performance liquid chromatographic (prep-HPLC) systems are used in many research schemes including purifying products from reaction mixtures, fractionating natural product extracts, and isolating compounds. Manual fraction collection from a prep-HPLC is a common method; however, it often lacks the reproducibility of automated fraction collectors due to human error. Automated fraction collectors for prep-HPLC systems can add thousands of dollars to the cost of prep-HPLC and are thus not always available to budgetary constrained research programs. Nevertheless, an automated fraction collector is a tremendous resource for any lab that employs prep-HPLC methods. Using LEGO MINDSTORMS pieces and easily obtained lumber and a steel C-channel, we were able to deploy an automated fraction collector for only a fraction of the cost of a commercial instrument. The programming software allows for a simple interface to create fraction collection programs tailored to individual HPLC methods. This fraction collector can be connected to any LC system and tailored to collect fractions in nearly any size or shaped container. This fraction collector was designed to provide maximum versatility and will make automated fraction collection more accessible to all researchers. The simple interface allows for quickly adapting the fraction collector method to any liquid chromatographic separation, no matter how complex.
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http://dx.doi.org/10.1021/acs.analchem.9b04299DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8178934PMC
January 2020

Growth Inhibitory Activity of Leaf Extracts Against .

Front Pharmacol 2019 15;10:1206. Epub 2019 Oct 15.

Center for the Study of Human Health, Emory College of Arts and Sciences, Atlanta, GA, United States.

Acne vulgaris is a common skin disease affecting adolescents and young adults of all ethnic groups, negatively impacting self-esteem, self-confidence, and social life. The Gram-positive bacteria colonizes the sebum-rich follicle and contributes to inflammation of the pilosebaceous gland. Long-term antibiotic therapies targeting lead to the development of antimicrobial resistance, and novel acne vulgaris therapies are needed. This study investigated the inhibitory activity of leaves, a native Southeastern United States shrub historically used by Native Americans to treat fever, stomachache, and pruritis. Flash chromatography fractions of the ethyl acetate-soluble ethanol leaf extract (649C-F9 and 649C-F13) exhibited MICs ranging from 16 to 32 µg ml and IC range of 4-32 μg ml against a panel of 10 distinct isolates. Cytotoxicity against an immortalized human keratinocyte cell line (HaCaTs) skin was detected at more than eight times the dose required for growth inhibitory activity (IC of 256 μg ml for 649C-F9 and IC of >512 μg ml for 649C-F13). This work highlights the potential of leaf extracts as a cosmeceutical ingredient for the management of acne vulgaris. Further research is necessary to assess its mechanism of action and efficacy.
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http://dx.doi.org/10.3389/fphar.2019.01206DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6803531PMC
October 2019

Peyssonnosides A-B, Unusual Diterpene Glycosides with a Sterically Encumbered Cyclopropane Motif: Structure Elucidation Using an Integrated Spectroscopic and Computational Workflow.

J Org Chem 2019 07 18;84(13):8531-8541. Epub 2019 Jun 18.

Parker H. Petit Institute for Bioengineering and Bioscience , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States.

Two sulfated diterpene glycosides featuring a highly substituted and sterically encumbered cyclopropane ring have been isolated from the marine red alga Peyssonnelia sp. Combination of a wide array of 2D NMR spectroscopic experiments, in a systematic structure elucidation workflow, revealed that peyssonnosides A-B (1-2) represent a new class of diterpene glycosides with a tetracyclo [7.5.0.0.0] tetradecane architecture. A salient feature of this workflow is the unique application of quantitative interproton distances obtained from the rotating frame Overhauser effect spectroscopy (ROESY) NMR experiment, wherein the β-d-glucose moiety of 1 was used as an internal probe to unequivocally determine the absolute configuration, which was also supported by optical rotatory dispersion (ORD). Peyssonnoside A (1) exhibited promising activity against liver stage Plasmodium berghei and moderate antimethicillin-resistant Staphylococcus aureus (MRSA) activity, with no cytotoxicity against human keratinocytes. Additionally, 1 showed strong growth inhibition of the marine fungus Dendryphiella salina indicating an antifungal ecological role in its natural environment. The high natural abundance and novel carbon skeleton of 1 suggests a rare terpene cyclase machinery, exemplifying the chemical diversity in this phylogenetically distinct marine red alga.
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http://dx.doi.org/10.1021/acs.joc.9b00884DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6614789PMC
July 2019

American Civil War plant medicines inhibit growth, biofilm formation, and quorum sensing by multidrug-resistant bacteria.

Sci Rep 2019 05 22;9(1):7692. Epub 2019 May 22.

Center for the Study of Human Health, Emory University, Atlanta, Georgia, USA.

A shortage of conventional medicine during the American Civil War (1861-1865) spurred Confederate physicians to use preparations of native plants as medicines. In 1863, botanist Francis Porcher compiled a book of medicinal plants native to the southern United States, including plants used in Native American traditional medicine. In this study, we consulted Porcher's book and collected samples from three species that were indicated for the formulation of antiseptics: Liriodendron tulipifera, Aralia spinosa, and Quercus alba. Extracts of these species were tested for the ability to inhibit growth in three species of multidrug-resistant pathogenic bacteria associated with wound infections: Staphylococcus aureus, Klebsiella pneumoniae, and Acinetobacter baumannii. Extracts were also tested for biofilm and quorum sensing inhibition against S. aureus. Q. alba extracts inhibited growth in all three species of bacteria (IC 64, 32, and 32 µg/mL, respectively), and inhibited biofilm formation (IC 1 µg/mL) in S. aureus. L. tulipifera extracts inhibited biofilm formation (IC 32 µg/mL) in S. aureus. A. spinosa extracts inhibited biofilm formation (IC 2 µg/mL) and quorum sensing (IC 8 µg/mL) in S. aureus. These results support that this selection of plants exhibited some antiseptic properties in the prevention and management of wound infections during the conflict.
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http://dx.doi.org/10.1038/s41598-019-44242-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6531439PMC
May 2019

Wound healing with botanicals: A review and future perspectives.

Curr Dermatol Rep 2018 Dec 25;7(4):287-295. Epub 2018 Oct 25.

Department of Dermatology, Emory University School of Medicine, Atlanta, GA, United States.

Purpose Of Review: Botanicals have long played a crucial role in the management of chronic and infected wounds, yet the mechanistic basis of these therapies remains largely poorly understood by modern science.

Recent Findings: Studies have begun to unveil the mechanistic bases of botanical therapies for wound healing, but more work is necessary. Most notably, investigation into the growing conditions, postharvest treatment and pharmacological preparation of these botanicals has demonstrated their importance in terms of the chemical makeup and pharmacological activity of the final product used in pre-clinical and clinical studies.

Summary: This work evaluates the potential safety, efficacy and mechanistic basis of some key botanical ingredients used in traditional medicine for wound care: aloe, marigold and St. John's wort. Furthermore, perspectives on the future role that botanical natural products may play in anti-infective and wound care innovations are explored.
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http://dx.doi.org/10.1007/s13671-018-0247-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6519724PMC
December 2018

Validation of a 16th Century Traditional Chinese Medicine Use of as a Topical Antimicrobial.

Front Microbiol 2019 16;10:775. Epub 2019 Apr 16.

Center for the Study of Human Health, Emory University, Atlanta, GA, United States.

In the search for new therapeutic solutions to address an increasing number of multidrug-resistant bacterial pathogens, secondary metabolites from plants have proven to be a rich source of antimicrobial compounds. , a tree native to China, has been spread around the world as an ornamental tree. Its seeds have been used as snacks and medical materials in Traditional Chinese Medicine (TCM), while over the last century its leaf extracts emerged as a source of rising pharmaceutical commerce related to brain health in Western medicine. Besides studies on the neuro-protective effects of Ginkgo, its antibacterial activities have gained more attention from researchers in the past decades, though its leaves were the main focus. We reviewed a 16th-century Chinese text, the by Li Shi-Zhen, to investigate the ancient prescription of Ginkgo seeds for skin infections. We performed antibacterial assays on various Ginkgo seed extracts against pathogens (, , , ) relevant to skin and soft tissue infections (SSTIs). We demonstrate here that Ginkgo seed coats and immature seeds exhibit antibacterial activity against Gram-positive skin pathogens (, and ), and thus validated its use in TCM. We also identified one compound tied to the antibacterial activity observed, ginkgolic acid C15:1, and examine its toxicity to human keratinocytes. These results highlight the relevance of ancient medical texts as leads for the discovery of natural products with antimicrobial activities.
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http://dx.doi.org/10.3389/fmicb.2019.00775DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6478001PMC
April 2019

Antibacterial Oligomeric Polyphenols from the Green Alga Cladophora socialis.

J Org Chem 2019 05 3;84(9):5035-5045. Epub 2019 Apr 3.

Aquatic Chemical Ecology Center , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States.

A series of oligomeric phenols including the known natural product 3,4,3',4'-tetrahydroxy-1,1'-biphenyl (3), the previously synthesized 2,3,8,9-tetrahydroxybenzo[ c]chromen-6-one (4), and eight new related natural products, cladophorols B-I (5-12), were isolated from the Fijian green alga Cladophora socialis and identified by a combination of NMR spectroscopy, mass spectrometric analysis, and computational modeling using DFT calculations. J-resolved spectroscopy and line width reduction by picric acid addition aided in resolving the heavily overlapped aromatic signals. A panel of Gram-positive and Gram-negative pathogens used to evaluate pharmacological potential led to the determination that cladophorol C (6) exhibits potent antibiotic activity selective toward methicillin-resistant Staphylococcus aureus (MRSA) with an MIC of 1.4 μg/mL. Cladophorols B (5) and D-H (7-11) had more modest but also selective antibiotic potency. Activities of cladophorols A-I (4-12) were also assessed against the asexual blood stages of Plasmodium falciparum and revealed cladophorols A (4) and B (5) to have modest activity with EC values of 0.7 and 1.9 μg/mL, respectively.
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http://dx.doi.org/10.1021/acs.joc.8b03218DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6503470PMC
May 2019

Antibacterial Activity of and Against ESKAPE Pathogens.

Front Pharmacol 2019 6;10:67. Epub 2019 Feb 6.

Center for the Study of Human Health, Emory College of Arts and Sciences, Atlanta, GA, United States.

Plants in the genus (Family: Crassulaceae) are used in traditional medicine throughout the tropics for treating a variety of conditions. Two species, and , have established ethnobotanical usage but have been neglected in previous research concerning their potential bioactivity. Here, we provide a thorough review of the reported antimicrobial activities of genus and evaluate the antibacterial effects of two previously unexplored species against a panel of multidrug-resistant bacteria, the ESKAPE pathogens (, and ). Plant specimens were collected and voucher specimens deposited in the Emory University Herbarium. Dried plant material was ground into a powder and extracted as ethanolic macerations or as aqueous decoctions. Extracts were tested against the ESKAPE pathogens for growth inhibitory activity. Cytotoxicity to human cells was assessed via a lactate dehydrogenase assay of treated human keratinocytes (HaCaTs). extracts demonstrated growth inhibitory effects against two Gram-negative species, (strain CDC-33) and (AH-71), as well as (UAMS-1). In these cases, growth inhibition greater than 50% (IC) was generally observed at concentrations of 256 μg mL, though one extract (1465, prepared from stems) exhibited an IC against at 128 μg mL. All extracts were well tolerated by HaCaTs (LD ≥ 256 μg mL). Chemical characterization using HPLC and chemical standards established the presence of caffeic acid and quercetin in both plant species, as well as kaempferol in These results reveal to be a plant of medicinal interest, and future research should aim to characterize the bioactivity of this species and its active constituents through bioassay-guide fractionation. Effects on bacterial biofilm formation and quorum-sensing are also research topics of interest for this genus.
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http://dx.doi.org/10.3389/fphar.2019.00067DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6374630PMC
February 2019

Opportunities for plant natural products in infection control.

Curr Opin Microbiol 2018 10 13;45:189-194. Epub 2018 Sep 13.

Center for the Study of Human Health, Emory University College of Arts and Sciences, Atlanta, GA, United States; Department of Dermatology, Emory University School of Medicine, Atlanta, GA, United States; Antibiotic Resistance Center, Emory University, Atlanta, GA, United States; Emory University Herbarium, Atlanta, GA, United States. Electronic address:

The continued spread of antimicrobial resistance represents one of the most serious infectious disease threats to global health. There is consensus that a key component of addressing this threat is to replenish the waning pipeline of antimicrobials, with attention being paid to novel mechanisms of action. This includes the development of new classes of classic bacteriostatic and bactericidal antibiotics as well as antivirulence drugs, and it is especially in these areas where plant natural products demonstrate great potential. To this end, we discuss the unique characteristics of plant natural products, the advantages of plants as a resource for anti-infective drug discovery, and recent technologies that have further enabled this path of inquiry. As a result of emerging realization of their advantages, plant natural products have recently enjoyed increased scrutiny in antimicrobial lead discovery, and they will continue to serve as a source of leads. We conclude that plant natural products represent a promising and largely untapped source of new chemical entities from which novel anti-infectives can be discovered.
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http://dx.doi.org/10.1016/j.mib.2018.08.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6295356PMC
October 2018

Antibacterial Properties of Medicinal Plants From Pakistan Against Multidrug-Resistant ESKAPE Pathogens.

Front Pharmacol 2018 2;9:815. Epub 2018 Aug 2.

Center for the Study of Human Health, Emory University College of Arts and Sciences, Atlanta, GA, United States.

Local people in the Sudhnoti district of Pakistan share a rich practice of traditional medicine for the treatment of a variety of ailments. We selected nine plants from the Sudhnoti ethnopharmacological tradition used for the treatment of infectious and inflammatory disease. Our aim was to evaluate the anti-infective potential of extracts from these species against multidrug-resistant (MDR) ESKAPE (, and species) pathogens. Plant specimens were collected in the Sudhnoti district of Pakistan and vouchers deposited in Pakistan and the USA. Dried bulk specimens were ground into a fine powder and extracted by aqueous decoction and maceration in ethanol. Extracts were assessed for growth inhibitory activity against ESKAPE pathogens and biofilm and quorum sensing activity was assessed in . Cytotoxicity to human cells was assessed via a lactate dehydrogenase assay of treated human keratinocytes (HaCaTs). Four ethanolic extracts (, and ) inhibited the growth of MDR strains of ESKAPE pathogens (IC: 256 μg mL). All extracts, with the exception of and , exhibited significant quorum quenching in a reporter strain for I. The ethanolic extract of fruits (Extract 1290) inhibited quorum sensing (IC 32-256 μg mL) in reporter strains for I-III. The quorum quenching activity of extract 1290 was validated by detection of δ-toxin in the bacterial supernatant, with concentrations of 64-256 μg mL sufficient to yield a significant drop in δ-toxin production. None of the extracts inhibited biofilm formation at sub-inhibitory concentrations for growth. All extracts were well tolerated by human keratinocytes (LD ≥ 256 μg mL). Chemical analysis of extract 1290 by liquid chromatography-Fourier transform mass spectrometry (LC-FTMS) revealed the presence of 29 compounds, including eight with putative structural matches. In conclusion, five out of the nine selected anti-infective medicinal plants exhibited growth inhibitory activity against at least one MDR ESKAPE pathogen at concentrations not harmful to human keratinocytes. Furthermore, was identified as a source of quorum quenching natural products and further bioassay-guided fractionation of this species is merited.
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http://dx.doi.org/10.3389/fphar.2018.00815DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6082950PMC
August 2018

Targeting Virulence in by Chemical Inhibition of the Accessory Gene Regulator System .

mSphere 2018 Jan-Feb;3(1). Epub 2018 Jan 17.

Center for the Study of Human Health, Emory University, Atlanta, Georgia, USA.

Methicillin-resistant (MRSA) presents one of the most serious health concerns worldwide. The WHO labeled it as a "high-priority" pathogen in 2017, also citing the more recently emerged vancomycin-intermediate and -resistant strains. With the spread of antibiotic resistance due in large part to the selective pressure exerted by conventional antibiotics, the use of antivirulence strategies has been recurrently proposed as a promising therapeutic approach. In MRSA, virulence is chiefly controlled by quorum sensing (QS); inhibitors of QS are called quorum quenchers (QQ). In , the majority of QS components are coded for by the accessory gene regulator (Agr) system. Although much work has been done to develop QQs against MRSA, only a few studies have progressed to models. Those studies include both prophylactic and curative models of infection as well as combination treatments with antibiotic. For most, high efficacy is seen at attenuating MRSA virulence and pathogenicity, with some studies showing effects such as synergy with antibiotics and antibiotic resensitization. This minireview aims to summarize and derive conclusions from the literature on the efficacy of QQ agents in MRSA infection models. data are also summarized to provide sufficient background on the hits discussed. On the whole, the reported effects of the reviewed QQs against MRSA represent positive progress at this early stage in drug development. Follow-up studies that thoroughly examine and activity are needed to propel the field forward and set the stage for lead optimization.
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http://dx.doi.org/10.1128/mSphere.00500-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5770542PMC
January 2018

Identification of Staphylococcal Quorum Sensing Inhibitors by Quantification of õ-Hemolysin with High Performance Liquid Chromatography.

Methods Mol Biol 2018 ;1673:363-370

Department of Immunology and Microbiology, The University of Colorado School of Medicine, Mail Stop 8333, Research Complex 1 North, 12800 E. 19th Ave., Rm. P18-9101, Aurora, CO, 80045, USA.

Quorum sensing plays a major role in regulation of virulence factor production by staphylococci. Chemical inhibitors that block this process and prevent the production of exotoxins and exoenzymes could have medical utility for infection prophylaxis and therapy. Here, we describe a high performance liquid chromatography method amenable to medium throughput screening for staphylococcal quorum sensing inhibitors by quantification of õ-hemolysin, a direct protein output of this system.
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http://dx.doi.org/10.1007/978-1-4939-7309-5_27DOI Listing
June 2018

The Chemical and Antibacterial Evaluation of St. John's Wort Oil Macerates Used in Kosovar Traditional Medicine.

Front Microbiol 2017 8;8:1639. Epub 2017 Sep 8.

Center for the Study of Human Health, Emory UniversityAtlanta, GA, United States.

L. (Hypericaceae), or St. John's Wort, is a well-known medicinal herb often associated with the treatment of anxiety and depression. Additionally, an oil macerate (Oleum Hyperici) of its flowering aerial parts is widely used in traditional medicine across the Balkans as a topical wound and ulcer salve. Other studies have shown that Oleum Hyperici reduces both wound size and healing time. Of its active constituents, the naphthodianthrone hypericin and phloroglucinol hyperforin are effective antibacterial compounds against various Gram-positive bacteria. However, hyperforin is unstable with light and heat, and thus should not be present in the light-aged oil macerate. Additionally, hypericin can cause phototoxic skin reactions if ingested or absorbed into the skin. Therefore, the established chemistry presents a paradox for this oil macerate: the hyperforin responsible for the antibacterial bioactivity should degrade in the sunlight as the traditional oil is prepared; alternately, if hypericin is present in established bioactive levels, then the oil macerate should cause photosensitivity, yet none is reported. In this research, various extracts of were compared to traditional oil macerates with regards to chemical composition and antibacterial activity (inhibition of growth, biofilm formation, and quorum sensing) vs. several strains of in order to better understand this traditional medicine. It was found that four Kosovar-crafted oil macerates were effective at inhibiting biofilm formation (MBIC active range of 0.004-0.016% v/v), exhibited moderate inhibition of quorum sensing (QSIC active range of 0.064-0.512% v/v), and contained detectable amounts of hyperforin, but not hypericin. Overall, levels of hypericin were much higher in the organic extracts, and these also exhibited more potent growth inhibitory activity. In conclusion, these data confirm that oil macerates employed in traditional treatments of skin infection lack the compound credited with phototoxic reactions in use and exhibit anti-biofilm and modest quorum quenching effects, rather than growth inhibitory properties against .
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http://dx.doi.org/10.3389/fmicb.2017.01639DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5596533PMC
September 2017
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