Cytotoxicity and anti-mycobacterial activities of sclerocarya birrea and Dodonae viscosa anguistifolia against MTB strain

Abstract

Background: Tuberculosis is a major public health concern with over 2 billion people currently infected, 8.6 million cases per year and more than 1.3 million deaths annually. Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis (MTB) which mainly affects the lungs causing pulmonary TB. In South Africa, the use of the Directly Observed Treatment Short Course (DOTS) strategy is applied where patients have to travel to primary Health care facilities (DOTS clinics) to get their medication. The rising prevalence of multidrug resistant and extensive drug resistant TB throughout the world highlights the critical need for novel anti-tuberculosis compounds/drugs. Objective: The aim of this study was to determine the cytotoxicity and antimycobacterial activities of Sand Olive and Marula. Methodology: The leaves (L) and barks (B) of Dodonaea Viscosa Anguistifolia (DVA or D) and S. birrea (S) plants were collected in the Vhembe district, Limpopo. Separate macerations in methanol (C) and distilled water (H) were done to obtain a total of 8 crude extracts (SBC, SBH, SLC. SLH, DBC, DBH, DLC, DLH). Phytochemical analysis was conducted on all extracts using thin layer chromatography (TLC), the profiling of metabolites was achieved with liquid chromatography-Mass spectrometry (LCMS) method. The antimycobacterial activity against M. smegmatis was determined using the microbroth dilution assay. The cytotoxicity of the plant extracts was assessed using the MTT assay. Results: The percentage yield ranged from 21.07% (DBC) to 4.4% (DBH). The phytochemical screening showed the presence of saponins, cardiac glycosides, steroids, terpenoids and tannins. The BEA solvent system revealed more bands than the CEF solvent system while the EMW solvent system was the least efficient. LCMS method showed sufficient revolving power to separate isomeric forms of several compounds. From the extracts of DVA and S. birrea, 508 chemicals were present in all the chromatograms assessed, but only 40 compounds were putatively identified and comprised of flavonoids, phenolics, terpenoids, and saponins. Of the 8 plant extracts that were tested 5 (DLH (50μg/ml (83.5%), (100μg/ml (85.9%)), DBH (50μg/ml (70.9%), (100μg/ml (60.3%)), DBC (50μg/ml (76.6%), 100μg/ml (83.9%) SLH (50μg/ml (66.8%), (100μg/ml (66.1%) and SLC (50μg/ml (79.9%), (100μg/ml (77.1%)) were found to have moderate cytotoxic effects on Vero cells at both treatment concentration while 3 (DLC (50μg/ml (91.5%), (100μg/ml (105%), SBH (50μg/ml (98.7%), (100μg/ml (106.8%) and SBC (50μg/ml (105.3%), (100μg/ml (118.2)) did increase viability of Vero cells. Amongst all the samples screened for antimycobacterial activity, only 3 plant extracts (SBC, DBC and DBH) inhibited the growth of M. smegmatis. Conclusion: The results of the study demonstrate the potential use of DVA and S. birrea as alternative treatment for tuberculosis. The bark of the plants may contain active compounds with anti-TB activities needing further investigation.