Tyrosinase inhibition, 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, and phytochemical screening of fractions and ethanol extract from leaves and stem bark of matoa (Pometia pinnata)

Objective: This study aims to investigate the potency of matoa as a tyrosinase inhibitor and antioxidant and also to identify the chemical compounds in the most active fraction and an ethanol extract from the leaves and stem bark of matoa. Methods: The extracts were tested for their tyrosinase inhibitory activity by evaluating the formation of L-dopachrome at 490 nm. Antioxidant activity was tested using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. The most active extract from liquid-liquid partition analysis was fractionated, and then, the assays were performed. Results: The ethanol extract of leaves and stem bark of matoa showed weak anti-tyrosinase activity (percent inhibition was 24.54±0.22% and 21.93±0.57%, respectively, final concentration 200 μg/mL), but they showed strong DPPH radical scavenging activity (IC₅₀ values were 6.11 μg/mL and 5.47 μg/mL, respectively). The ethyl acetate fraction was the most active fraction with an IC₅₀ value of 5.38 μg/mL. Ethanol extract from the leaves and stem bark of matoa and the ethyl acetate fraction contains flavonoids, tannins, saponins, triterpenoids, and glycosides. Conclusion: Matoa does not have potency as a tyrosinase inhibitor, but it has good antioxidant activity, although still lower than that of quercetin.