Abstract:
BACKGROUND: Different parts of Podocarpus henkelii have been used in many cultures around the world to treat
ailments such as cholera, stomach diseases, rheumatism, cancer, canine distemper in dogs and gall sickness in
cattle. The aim of this study was to evaluate the biological activity and toxicity of isolated compounds from
Podocarpus henkelii after an earlier study indicated a promising activity in crude extracts against viral pathogens of
veterinary importance.
METHODS: The antibacterial and antifungal activity of two biflavonoids 7, 4’, 7”, 4”’-tetramethoxy amentoflavone
(TMA), isoginkgetin (IGG) and podocarpus flavone–A (PFA) isolated from the leaves of Podocarpus henkelii were
determined using a serial microplate dilution method with tetrazolium violet as growth indicator. The cytotoxicity
of compounds TMA and IGG were determined on different cell types using a tetrazolium-based colorimetric cellular
assay (MTT). The Ames test was used to determine their mutagenic activities.
RESULTS: TMA had reasonable antifungal activity against Aspergillus fumigatus (MIC = 30 μg/ml). IGG had a wide
spectrum of activity against four bacterial and two fungal pathogens with much higher selectivity index values
obtained for A. fumigatus and Cryptococcus neoformans (SI > 30). PFA had a broad spectrum of activity against
Enterococcus faecalis and Pseudomonas aeruginosa (SI > 15) and less activity against the two fungal pathogens. In
both the cytotoxicity assays and Ames mutagenicity test using Salmonella typhimurium strains TA98 and TA100,
TMA and IGG had no deleterious effect on the different cell types and did not induce mutations in the Ames test.
CONCLUSION: Although the antimicrobial activities of the isolated compounds were not that exciting, the
compounds had no cytotoxic activity at the highest concentration (1000 μg/ml) tested against all three cell lines.
IGG was the most active against E. coli, S. aureus, A. fumigatus and C. neoformans, exhibiting both antibacterial and
antifungal activity with good selectivity index values. PFA had a broad spectrum of activity against E. faecalis and
P. aeruginosa. The two compounds isolated had low toxicity and no genotoxic activity in the Ames test.
