Potensi limbah kulit buah Nyirih Xylocarpus granatum sebagai inhibitor tirosinase

The aim of the present study was to analyse the peel waste of Xylocarpus granatum fruits as potential source of tyrosinase inhibitors. Dried peel samples were ground to yield a powder (simplicia). Subsequently, they were extracted with organic solvents of distinct polarity levels, namely n-hexane (non-polar), chloroform (semi-polar) and methanol (polar) by use of the single-maceration method. Inhibitory effects on tyrosinase activity (monophenolase) and DOPA auto-oxidation (diphenolase) were determined in bioassays. Assays with the methanol extract revealed IC50 values of 784.87 μg mL-1 (monophenolase) and of 1176.66 μg mL-1 (diphenolase), respectively. In contrast, n-hexane and chloroform extracts showed no activity. These results indicate that the methanolic fruit peel extract contained tyrosinase-inhibiting compounds, such as flavonoids, tannins and saponins, whereas the n-hexane and chloroform extracts yielded alkaloids, steroids and triterpenoids without tyrosinase-inhibiting activity. The phenolic compounds had a strong effect on the tyrosinase enzymes, inhibiting monophenolases by 97% and diphenolases by 96%, with a positive correlation between the total phenolic content and the inhibition rate in both activities