Background: It is a practice to use traditional medicine for curing various illnesses in West Africa. Acacia hebecladoides, Acacia albida and Gmelina arborea were selected based on their traditional belief for treating various ailments such as: hallucinations, inflammation and tuberculosis. The study sought to validate the antitubercular activity, antioxidant properties and phytochemical components of extracts and fractions of the leaves of selected plants.
Method: The antitubercular activities of the plants were evaluated against Mycobacterium tuberculosis (MTB), multidrug-resistant Mycobacterium tuberculosis (MDR-TB) and non-mycobacterium tuberculosis (NTM) using the Lowenstein Jensen (LJ) proportion method. Gas chromatography mass spectrometer (GCMS) assay and the antioxidant assays (1,1- diphenyl -2-picryhydrazyl (DPPH) radical assay, total phenolic content (TPC), β-carotene bleaching activity and nitric oxide scavenging activity) were all carried out.
Results: All three plant extracts used in the study inhibited Mycobacterium tuberculosis with G. arborea showing the lowest MIC value of 31.25μg/ml. Also, G. arborea inhibited MDR-TB with an MIC value of 125μg/ml. The most active plant, G. arborea was fractionated into four partitions, three (aqueous, n-hexane and ethyl acetate) fractions showed inhibitory activity against MTB with an MIC value of 62.5μg/ml. Also n-hexane and chloroform fractions of G. arborea showed inhibitory activities against MDR-TB with the lowest MIC value of 31.25μg/ml. The nitric oxide activity of the plant fractions showed that ethyl acetate fraction of G. arborea had high nitric oxide antioxidant activity. The ethanolic extract A. hebecladoides and G. arborea, while fractions of G. arborea (aqueous, ethyl acetate and chloroform) showed DPPH scavenging activity. The ethanolic extract A. hebecladoides and A. albida, while aqueous fraction of G. arborea had high total phenolic content. The ethanolic extract G. arborea and its fractions (aqueous and n hexane) showed β-carotene bleaching inhibition. Twelve compounds were found in the n-hexane fraction of G. arborea as 2,3-dihydro-3,5,-6-methy 4H-Pyran-4-one and 5-hydroxymethylfurfural were abundant with 35.81% and 19.03% respectively, followed by 3,5-dihydroxy-2-methy-4H-Pyran-4-one (9.82%) and n-Hexadecanoic acid (8.45%).
Conclusions: The study carried out showed that ethanolic extract and fractions of G. arborea possess inhibitory activities against MTB and MDR-TB. Also ethyl acetate and aqueous fractions of G. arborea showed high antioxidant activities.
