Antimycobacterial, antibacterial and antifungal activities of Terminalia superba (Combretaceae)

The methanol extract from the stem bark of Terminalia superba (TSB), fractions (TSB1-7) and two compounds isolated following bio-assay guided fractionation namely 3,4′-di-O-methylellagic acid 3′-O-β-d-xylopyranoside (1) and 4′-O-galloy-3,3′-di-O-methylellagic acid 4-O-β-d-xylopyranoside (2) were evaluated for their antimycobacterial, antibacterial and antifungal activities. The broth microdilution, the microplate Alamar Blue assay (MABA) and the agar disc diffusion methods were used for the investigations. The results of the antimycobacterial assays showed that the crude extract, fractions TSB5-7 and compound 1 were able to prevent the growth of all the studied mycobacteria. The lowest minimal inhibitory concentration (MIC) value of 39.06 µg/ml for this extract was recorded on both M. smegmatis and M. tuberculosis MTCS2. The corresponding values were 19.53 µg/ml and 4.88 µg/ml for fractions and compounds respectively. The MIC determination results on other organisms indicated values ranging from 19.53 to 78.12 µg/ml for TSB and compound 2 on 90.9% of the tested organisms, meanwhile compound 1 as well as fractions TSB 6 and 7 exhibited detectable MIC values on all studied microorganisms. The overall results provide promising baseline information for the potential use of the crude extract from T. superba, fractions 6-7 and the tested compounds in the treatment of tuberculosis, bacterial and fungal infections.