Author(s): Magadula, Joseph Jangu*
The phytochemical isolation of the ethanol extract of the stem bark of Allanblackia ulugurensis led to the isolation and identification of two polycyclic polyprenylated acylphloroglucinols (PPAPs), named guttiferone F (1) and 30-epi-cambogin (2) and a biphenyl compound, 3-hydroxy-5-methoxybiphenyl (3). The ethanolic crude extract of A. ulugurensis exhibited high activity in anti-HIV protease assay with IC50 of 4.1 mg/ml, while the standard drug has IC50 of 2.2 mg/ml. However, compounds 1 and 2 indicated lower activity in anti-HIV protease assay with IC50 values of 11.3 and 22.7 mg/ml respectively. The ethanolic crude extract of the stem bark of Mammea usambarensis indicated potent antioxidant activity in the DPPH assay with a value of 6,165 ± 152 μmol TE/g, which is more than twice as higher as that of the standard (Chlorogenic acid; 3,056 ± 157 μmol TE/g). Two compounds namely mammea B/BB (4) and mammea B/BD (5) were isolated from the stem bark extract of M. usambarensis showing antioxidant activities in DPPH assay at 4,012 ± 117 and 2,176 ± 102 μmol TE/g) respectively. The lower activities of the isolated compounds compared to the crude extracts may be attributed by the synergistic effect. Interestingly, the activities of the isolated compounds were higher than the corresponding standard compounds.