In vitro antioxidant and anti-HIV-1 protease (PR) activities of two Clusiaceae plants endemic to Tanzania

Abstract

In this study, the ethanol extracts from Allanblackia ulugurensis Engl. and Mammea usambarensis Verdc. were evaluated for their antioxidant and anti-HIV PR activities. Among the tested extracts, the stem bark extract of M. usambarensis showed the highest DPPH activity value of 6,165 ± 152 ìmol TE/g, which is more than twice as higher as that of the standard (Chlorogenic acid, 3,056 ± 157 ìmol TE/g). Furthermore, in the Oxygen Radical Absorbance Capacity (ORAC) assay, the crude extracts of the stem bark of M. usambarensis and root bark of A. ulugurensis showed significant activity at 12,282 ± 413 and 10,342 ± 562 ìmol TE/g respectively with standard compound (Chlorogenic acid) showing ORAC activity at 11,077 ± 236 ìmol TE/g. For anti-HIV-1 PR assay from the same extracts, the root bark and stem bark of A. ulugurensis showed strong inhibitory activities against HIV-1 protease with IC50 values of 4.1 and 5.6 ìg/ml, respectively while that of the standard, Acetyl pepstatin, was at 2.2 ìg/ml. This study has shown the potential of the Clusiaceae extracts as the source of possible lead compounds for antioxidants and anti-HIV drugs. Phytochemical screening indicated the presence of phenolic compounds while isolation of active principles from active fractions is inevitable.