Evaluation of flavonoids from Dorstenia barteri for their antimycobacterial, antigonorrheal and anti-reverse transcriptase activities

The aim of this study was to evaluate the antimycobacterial, antigonorrheal and reverse transcriptase activities of five flavonoids: isobachalcone (IBC); kanzanol C (KAN); 4-hydroxylonchocarpin (4-LCP); stipulin (SPL) and amentoflavone (AMF) from Dortenia barteri, together with the crude extract from this plant. The Agar disc diffusion, broth microdilution, microplate alamar blue assay (MABA), radiometric respiratory technique using BACTEC 460 system and the reverse transcriptase (RT) assay were used for the investigations. The results of the antimycobacterial assay showed that the crude extract and compounds were able to prevent the growth of Mycobacteria with MIC < 10 μg/ml being recorded with IBC on M. tuberculosis. Results of the killing rate experiment revealed that total inhibition effect on M. tuberculosis H37Rv strain was noted with IBC and SPL at day 9 when tested at 4× MIC. The results of the antigonorrheal assay indicated that MIC values below 10 μg/ml were also recorded with IBC on all the tested N. gonorrhoeae strains, meanwhile good activities (MIC < 10 μg/ml) were also noted with the extract, KAN, 4-LCP and SPL on some of these strains. The anti-reverse transcriptase activities of extract and compounds also demonstrated that all samples were able to inhibit at various extents the reverse transcriptase activity, with IBC and 4-LCP showing the best effects. The overall results of this work provided evidence that the crude extract as well as some flavonoids from D. barteri could be potential sources of new antimicrobial drug against tuberculosis (TB), gonorrhea and probably the acquired immunodeficiency syndrome.