Total methanol extract and n-hexane, ethyl acetate and water fractions of P. palatiferum (Nees) Radlk. leaves were investigated for their antioxidant, antimicrobial and tyrosinase inhibitory activities in correlation with their phytochemical constituents. Of the extracts, the ethyl acetate fraction had the highest level of phenolics (327.00 +/- 56.30 mg gallic acid equivalents/g of extract), more than half of which were flavonoids (182.77 +/- 14.37 mg quercetin equivalents/g of extract), confirming the result of thin layer chromatography analysis. Ethyl acetate and water fractions had antioxidant activity by dose-dependent 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging action (IC50 = 90.01 +/- 4.12 and 82.36 +/- 2.38 ug/mL, respectively), which closely correlated with the total phenolic content (R2 = 0.936). P. palatiferum leaf extracts showed stronger antibacterial activity against Escherichia coli and Bacillus subtilis than Staphylococcus au reus . Only the n-hexane fraction showed inhibitory activity on Pseudomonas sp. and Candida sp. The methanol extract of P. palatiferum (Nees) Radlk. leaves exhibited a moderate inhibitory effect on the 1-3,4-dihydroxyphenylalanine (L-DOPA) oxidase activity of tyrosinase in the melanin biosynthesis pathway. Further study may lead to new bioactive compounds from ethyl acetate and n-hexane fractions.
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