Antimycobacterial and cytotoxic activity of selected medicinal plant extracts

AbstractEthnopharmacological relevanceTuberculosis (TB) caused by Mycobacterium tuberculosis remains an ongoing threat to human health. Several medicinal plants are used traditionally to treat tuberculosis in Ghana. The current study was designed to investigate the antimycobacterial activity and cytotoxicity of crude extracts from five selected medicinal plants.Material and methodsThe microplate alamar blue assay (MABA) was used for antimycobacterial studies while the CellTiter 96® AQueous Assay, which is composed of solutions of a novel tetrazolium compound [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt; MTS] and an electron coupling reagent (phenazine methosulfate) PMS, was used for cytotoxic studies. Correlation coefficients were used to compare the activity of crude extracts against nonpathogenic strains and the pathogenic Mycobacterium tuberculosis subsp.tuberculosis.ResultsResults of the MIC determinations indicated that all the crude extracts were active on all the three tested mycobacterial strains. Minimum inhibitory concentration values as low as 156.3µg/mL against M. tuberculosis; Strain H37Ra (ATCC® 25,177™) were recorded from the leaves of Solanum torvum Sw. (Solanaceae). Cytotoxicity of the extracts varied, and the leaves from S. torvum had the most promising selectivity index. Activity against M. tuberculosis; Strain H37Ra was the best predictor of activity against pathogenic Mycobacterium tuberculosis subsp.tuberculosis (correlation coefficient=0.8).ConclusionThe overall results of the present study provide supportive data on the use of some medicinal plants for tuberculosis treatment. The leaves of Solanum torvum are a potential source of anti-TB natural products and deserve further investigations to develop novel anti-TB agents against sensitive and drug resistant strains of M. tuberculosis

In vitro antimycobacterial activity and toxicity of eight medicinal plants against pathogenic and nonpathogenic mycobacterial strains

Tuberculosis (TB) caused by Mycobacterium tuberculosis remains a serious public health challenge towards which new hits are urgently needed. Medicinal plants remains a major source of new ligands against global infectious illnesses. In our laboratories, we are currently investigating locally used ethnobotanicals for novel compounds against zoonotic tuberculosis. The microplate alamar blue assay (MABA) was used to study the anti-TB activity while the CellTiter 96® AQueous Assay, which is composed of solutions of a novel tetrazolium compound [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt; MTS] and an electron coupling reagent (phenazine methosulfate) PMS, was used for cytotoxic studies. Correlation coefficients (R2) were used to compare the relationship between antimycobacterial activity of the eight crude extracts against nonpathogenic strains and the pathogenic Mycobacterium bovis. Minimum inhibitory concentration (MICs) values indicated that all the eight tested medicinal plant species had activity against all the three tested mycobacterial strains. Minimum inhibitory concentration value as low as 19.5 μg/mL was observed against non-pathogenic strains M. bovis. Activity of the crude extracts against M. aurum was the best predictor of natural product activity against the pathogenic Mycobacterium bovis strain, with a correlation coefficient value (R2) of 0.1371. Results obtained from the current study validate, in part, the traditional utilization of the tested medicinal plants against tuberculosis. The unripe fruits from Solanum torvum are a potential source of safe and efficacious anti-TB crude drugs as well as a source for natural compounds that act as new anti-infection agents, and thus deserve further investigation towards development of a new class of molecules with activity against sensitive and drug resistant strains of M. bovis

In vitro antimycobacterial and cytotoxic data on medicinal plants used to treat tuberculosis

This article contains data on in vitro antimycobacterial activity and cytotoxicity of hydroethanolic crude extracts from five selected medicinal plant species traditionally used to treat tuberculosis in Ghanaian ethnomedicine, see “Medicinal plants used to treat TB in Ghana” [1]. The interpretation and discussion of these data and further extensive insights into drug discovery against tuberculosis from natural products of plant biodiversity can be found in “Antimycobacterial and cytotoxic activity of selected medicinal plant extracts” [2]

Antimycobacterial ingredients from plants used in traditional medicine to treat Buruli ulcer

Aim and objectives: Buruli ulcer (BU) is a neglected tropical disease caused by a mycobacteria, Mycobacterium ulcerans. The WHO recommended Rifampicin-Streptomycin combination side effects and poor compliance, leaves rural populations with no choice than to patronise indigenous remedies. This study is aimed at validating medicinal plants used in traditional medicine to treat BU by investigating the in vitro efficacy and safety as well as their composition in active molecules. Methods: A short report-based survey was used to identify medicinal plants used traditionally for BU treatment. Maceration of collected plant samples in methanol, hydroethanolic, ethanol, dichloromethane, and hexane, resulted in a total of 67 extracts assessed for antimycobacteria activity against Mycobacterium smegmatis and Mycobacterium ulcerans using the Resazurin Microtiter Assay. The cytotoxicity effect of promising extracts was assessed on normal human liver cells using the MTT assay. The bio-guided fractionation of the promising extracts led to the isolation of active compounds. Results: Majority of plants prepared as infusion, decoction, poultice, and macerate were administered topically. Significant antimycobacterial activity with MIC values ranging from 16 to 250 μg/mL was recorded against M. smegmatis (25 extracts) and M. ulcerans (17 extracts).1 Most of antimycobacterial extracts showed no significant cytotoxicity against normal human hepatocytes. 1The isolation guided by the biological activity revealed nine compounds with significant in vitro anti-M. ulcerans activity (MIC = 16–128 μg/mL). Conclusions: The results completed support the use these plants in the indigenous knowledge against BU. Further analyses of active principles might lead to new drug toe fight against BU

In Vitro Activity of Selected West African Medicinal Plants against Mycobacterium ulcerans Disease

Buruli ulcer (BU) is the third most prevalent mycobacteriosis, after tuberculosis and leprosy. The currently recommended combination of rifampicin-streptomycin suffers from side effects and poor compliance, which leads to reliance on local herbal remedies. The objective of this study was to investigate the antimycobacterial properties and toxicity of selected medicinal plants. Sixty-five extracts from 27 plant species were screened against Mycobacterium ulcerans and Mycobacterium smegmatis, using the Resazurin Microtiter Assay (REMA). The cytotoxicity of promising extracts was assayed on normal Chang liver cells by an MTT assay. Twenty five extracts showed activity with minimal inhibitory concentration (MIC) values ranging from 16 µg/mL to 250 µg/mL against M. smegmatis, while 17 showed activity against M. ulcerans with MIC values ranging from 125 µg/mL to 250 µg/mL. In most of the cases, plant extracts with antimycobacterial activity showed no cytotoxicity on normal human liver cells. Exception were Carica papaya, Cleistopholis patens, and Polyalthia suaveolens with 50% cell cytotoxic concentrations (CC50) ranging from 3.8 to 223 µg/mL. These preliminary results support the use of some West African plants in the treatment of Buruli ulcer. Meanwhile, further studies are required to isolate and characterize the active ingredients in the extracts

Antimycobacterial potency and cytotoxicity study of three medicinal plants

Objective/Background: Mycobacterial infections including tuberculosis, leprosy, and buruli ulcer are among the most prevalent, debilitating, and deadly tropical diseases, especially in Sub-Saharan Africa. The development of drug resistance to the currently available drugs and the poor compliance emphasize the need for new chemotherapeutic agents. This study was designed to evaluate the in vitro activity of Cleistopholis patens, Annona reticulata, and Greenwayodendron suaveolens against Mycobacterium smegmatis. The safety on normal liver cells was also assessed. Methods: The crude extracts, fractions, and subfractions were tested against M. smegmatis and for cell cytotoxicity on WRL-68, normal human hepatocyte using microdilution resazurin-based assays. The phytochemical screening was performed using standard methods. Results: Most of the extracts, fractions, and subfractions inhibited the growth of M. smegmatis with minimum inhibitory concentration (MIC) values ranging from 6.25 μg/mL to 125 μg/mL. The subfractions P12 and P29 from G. suaveolens twig were more potent with MIC values of 6.25 μg/mL and 25 μg/mL, respectively. Fruit crude extract and root CH2Cl2 fraction from A. reticulata also showed activity with MIC values of 50 μg/mL and 25 μg/mL, respectively. Crude extracts from the twig and stem bark of C. patens displayed inhibition at MIC values of 125 μg/mL and 100 μg/mL, respectively. Majority of active extracts showed no cell cytotoxicity, except the extract from C. patens with IC50 ranging from 41.40 μg/mL to 93.78 μg/mL. The chemical investigation of the promising extracts revealed the presence of phenols, alkaloids, glycosides, triterpenes, and acetogenins. Conclusion: The results achieved from this preliminary antimycobacterial drug discovery study supported the traditional claims of C. patens, A. reticulata, and G. suaveolens in the treatment of mycobacterial infections. Meanwhile, further fractionation is required to characterize the active ingredients