6 research outputs found
Noxious to ecosystems, but relevant to pharmacology : four South African alien invasive plants with pharmacological potential
Alien invasive plants pose a huge threat to natural and semi-natural ecosystems in their introduced ranges thereby compromising ecosystem integrity. However, anecdotal and empirical evidence suggests that some invasive alien plants are used in traditional medicine due to their pharmacological activities. Here, we evaluated the antimicrobial activity of 70% ethanol, dichloromethane, acetone and hot water extracts of four invasive alien plants in South Africa viz. Dolichandra unguis-cati, Cardiospermum grandiflorum, Chromolaena odorata and Gomphrena celosioides against pathogenic and non-pathogenic microbes. The test organisms included Staphylococcus aureus, Salmonella enterica serovar Typhimurium (S. Typhimurium), Salmonella Dublin, Klebsiella pneumoniae, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Mycobacterium aurum, M. fortuitum, M. smegmatis, Candida albicans, Aspergillus fumigatus and Cryptococcus neoformans. Phytochemicals that may be responsible for antimicrobial activity were determined using standard phytochemical methods. A further objective was to investigate the safety of these plants by conducting cytotoxicity and genotoxicity tests. All solvent extracts of plants investigated exhibited a broad spectrum of antibacterial activity with minimum inhibitory concentration (MIC) values ranging from 0.039 to 2.5 mg/ml, with the acetone and dichloromethane extracts showing better activity against E. coli, K. pneumoniae and E. faecalis (MIC between 0.039 and 0.078 mg/ml). Of all extracts tested, only the ethanol extracts of C. grandiflorum showed good antimycobacterial activity with MIC of 0.078 mg/ml against M. smegmatis. In contrast, C. grandiflorum only showed moderate antifungal activity, while dichloromethane and acetone extracts of the other three plants were very effective against C. neoformans and A. fumigatus with MIC values ranging from 0.019 to 0.078 mg/ml. All four plants moderately inhibited C. albicans at MIC of 0.156 mg/ml. The plant species were rich in phenolics, flavonoids and tannins in varying amounts and had relatively low levels of cytotoxicity and none was mutagenic. Promising selectivity index values (between 10 and 50) highlight the potential of these plant species as sources of antimicrobial remedies. Despite the ecological noxiousness of these alien invasive plants, our findings suggest that they possess some antimicrobial properties that are too pharmacologically relevant to ignore.AGO is grateful to the National Research Foundation-The World Academy of Science (NRF-TWAS) for the provision of a PhD grant. The NRF is also acknowledged for providing research funding to LJM (Grant No 105993).http://www.elsevier.com/locate/sajb2019-07-01hj2019Paraclinical Science
Pharmacological evaluation of hydro-ethanol and hot water leaf extracts of Bauhinia galpinii (Fabaceae) : a South African ethnomedicinal plant
Please read abstract in the article.The University of Pretoria for the Postdoctoral Fellowship, the National Research Foundation (grant numbers 105993 and 111945) and the University of Benin, Nigeria.http://www.elsevier.com/locate/sajb2021-01-01hj2020Paraclinical Science
Flavonoids isolated from the South African weed Chromolaena odorata (Asteraceae) have pharmacological activity against uropathogens
BACKGROUND: Urinary tract infections (UTIs) caused by opportunistic pathogens are among the leading health
challenges globally. Most available treatment options are failing as a result of antibiotic resistance and adverse
effects. Natural sources such as plants may serve as promising alternatives.
METHODS: Compounds were isolated from the South African weed Chromolaena odorata through column
chromatography. Purified compounds were tested for antimicrobial activity using the p-iodonitrotetrazolium
chloride (INT) colorimetric method, against uropathogenic Escherichia coli, Staphylococcus aureus, Klebsiella
pneumoniae, Aspergillus fumigatus and Cryptococcus neoformans. Anti-biofilm, anti-adhesion and metabolic inhibition
activities were investigated against selected strains. Safety of the compounds was determined against Vero monkey
kidney, C3A human liver and colon (Caco2) cells.
RESULTS: Four compounds identified as pectolinaringenin (1), (±)-4′,5,7-trimethoxy flavanone (2), 5-hydroxy-3,7,4′-
trimethoxyflavone (3) and 3,5,7-trihydroxy-4′-methoxyflavone) (4) were isolated. Minimum inhibitory concentration
(MIC) varied between 0.016 and 0.25 mg/mL. Compounds 2 and 3 showed promising antimicrobial activity against
E. coli, S. aureus, K. pneumoniae, A. fumigatus and C. neoformans with MIC between 0.016 and 0.125 mg/mL,
comparable to gentamicin, ciprofloxacin and amphotericin B used as positive controls. Compounds 2 and 3
showed good anti-biofilm and metabolic inhibition activities against E. coli and S. aureus but weak anti-adhesion
activity against the organisms. Low toxicity with selectivity indexes between 1 and 12.625 were recorded with the
compounds, indicating that the compounds were rather toxic to the microbial strains and not to the human and
animal cells.
CONCLUSION: Pharmacological activities displayed by compounds 2 and 3 isolated from C. odorata and low toxicity
recorded credits it as a potential lead for the development of useful prophylactic treatments and anti-infective
drugs against UTIs. Although known compounds, this is the first time these compounds have been isolated from
the South African weed C. odorata and tested for antimicrobial, anti-biofilm, metabolic inhibition and anti-adhesion
activities.The National Research Foundation, South Africahttps://bmccomplementmedtherapies.biomedcentral.compm2020Paraclinical Science
Synergistic activity of extracts of three South African alien invasive weeds combined with conventional antibiotics against selected opportunistic pathogens
Plants are known to play a major role in the treatment of microbial infections, as they contain important bioactive components that may act in synergism with conventional antibiotics, which are presently under threat of microbial resistance. Synergistic activity between dichloromethane, acetone, 70% ethanol, 50% methanol and hot water extracts of three southern African alien invasive plant species, namely Chromolaena odorata, Gomphrena celosioides and Tithonia rotundifolia and gentamicin, streptomycin, rifampicin and amphotericin B was studied using the checkerboard method. Antioxidant activity of the extracts was determined using the quantitative 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) decolourisation methods. The anti-inflammatory activity was determined with the 15-lipoxygenase enzyme assay. Synergistic to additive effects were observed among all tested extracts in combination with the conventional antibiotics against most of the tested strains. This was evident when the extracts were combined with gentamicin or amphotericin B against Klebsiella pneumoniae, Enterococcus faecalis, Salmonella Typhimurium, Cryptococcus neoformans and Candida albicans. The extracts of C. odorata had the best antioxidant activity in the ABTS assay with the 70% ethanol extract showing a minimum inhibitory concentration (IC50) of 1.960 μg/mL, better than that of vitamin C (IC50 = 2.027 μg/mL). The dichloromethane extract of T. rotundifolia displayed promising radical scavenging activity in the DPPH assay with an IC50 of 16.231 μg/mL. Most of the extracts of C. odorata (except the acetone extract) had anti-inflammatory activity better than that of the positive control quercetin (IC50 = 24.601 μg/mL). Results from this study indicate that extracts of these weedy plant species contain bioactive compounds that may act in synergy with conventional antibiotics in the fight against resistant microbial strains. Additionally they may reduce oxidative stress and inflammation.The National Research Foundationhttp://www.elsevier.com/locate/sajb2020-08-01hj2020Paraclinical Science
Invasive alien plants and weeds in South Africa : a review of their applications in traditional medicine and potential pharmaceutical properties
ETHNOPHARMACOLOGICAL RELEVANCE : Traditional pharmacopoeias are constantly evolving and adapting, hence the assimilation of alien plants and weeds into traditional systems of healing. Invasive plants are detrimental to the ecosystem, however they are also potential sources of secondary metabolites with useful biological activities.
AIM OF THE REVIEW : The aim of this review was to investigate published reports of traditional use and biological activity of declared invasive alien plants and other weeds in South Africa.
MATERIALS AND METHODS : Information was retrieved from scientific databases including Scopus, Web of Science, ScienceDirect, Google Scholar, PubMed, Chemical Abstracts Services and books, theses, dissertations and technical reports. Keywords used for the search engines were “South Africa” or “southern Africa” in conjunction with “(native weeds OR alien invasive)” AND “medicinal”. Separate searches were conducted on the individual invasive plant species recorded as having been used in ethnobotanical surveys to determine their known biological activities and chemical components.
RESULTS : A total of 89 plant species regarded as invasive species or weeds in South Africa were identified as being used in traditional medicine. The most commonly mentioned plant family was the Asteraceae with a total of 15 species followed by the Fabaceae and Solanaceae with 6 species each. Of the 89 species recorded, 68% were reported to have traditional usage with both phytochemical and biological data available. A history of traditional usage coupled with biological data was available for 12% of species. Records of traditional usage alone were linked to 11% of species. Invasive alien species comprised 61% of recorded species, while native and non-invasive alien weeds formed the remaining 39%.
CONCLUSIONS : The exploration of alternative uses for weeds and particularly invasive plants, whether native or alien, as medicines for possible commercialisation may lead to innovative mechanisms for putting such species to good use.The National Research Foundation (NRF) South Africa AND the University of KwaZulu-Natal.http://www.elsevier.com/locate/jethpharm2022-08-24hj2021Paraclinical Science
Flavonoids of Chromolaena odorata (L.) R.M.King & H.Rob. as potential leads for treatment against tuberculosis
Tuberculosis (TB) is currently rated as the 13th leading cause of mortality and the second leading cause of death after COVID-19, and above AIDS. Existing challenges relating to the development of multidrug-resistant strains and dangerous side effects of currently used drugs add impetus to the search for additional TB treatments. Hence, interest has grown in the use of medicinal plants as a source of bioactive preparations with efficacy against TB-causing organisms, and also with the ability to ameliorate the negative effects of TB drugs. This study aimed to evaluate the antimycobacterial and hepatoprotective potentials of extracts and isolated flavonoid compounds from invasive Chromolaena odorata. Test organisms used were pathogenic Mycobacterium bovis and M. tuberculosis H37RV, and the fast-growing M. aurum, M. fortuitum and M. smegmatis. The selectivity index (SI) values of the test substances were determined through cytotoxicity assays to promote these extracts and compounds as leads for the development of effective and safe anti-tubercular drugs. The antimycobacterial activity was evaluated using a serial microdilution method, and the SI was calculated from the 50% lethal concentrations calculated from cytotoxicity tests. Hepatoprotective activity was determined using HepG2 liver cells treated with rifampicin as a toxin. The extracts and compounds had a range of antimycobacterial activity with minimum inhibitory concentration (MIC) values ranging from 0.031 to 2.5 mg/mL. Two flavonoid compounds, 5,7,4′-trimethoxy flavanone and 5‑hydroxy-3,7,4′-trimethoxyflavone showed promising antimycobacterial potential, and minimal toxicity was observed, as most SI values were higher than 1. The flavonoid compound 5,7,4′-trimethoxy flavanone had the highest SI (6.452), which was against M. tuberculosis H37RV. The HepG2 cells were reduced to 65% due to toxicity by rifampicin, however, the flavonoid compounds were able to improve cell viability to between 81 and 89% at different concentrations tested. Results obtained indicate that C. odorata may serve as a lead for the development of safe and effective antimycobacterial and hepatoprotective drugs.The National Research Foundation-The World Academy of Science (NRF-TWAS).http://www.elsevier.com/locate/sajb2024-05-13hj2023Paraclinical Science