y Tyrosinase Inhibitory and Antioxidant Activity of Paederia foetida L.

Paederia foetida L. is a tropical Asian plant containing bioactive compounds and often used as functional food. The aim of this study was to determine the antioxidant capacity and inhibitory activity of P. foetida leaves extract on tyrosinase activity. In addition, the total phenolic content (TPC) and total flavonoid content (TFC) were determined. TPC and TFC were evaluated by the Folin-Ciocalteu and the aluminum chloride (AlCl3) colorimetric method, respectively. The 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and cupric reducing antioxidant capacity (CUPRAC) methods were used to determine antioxidant capacity. Trolox equivalent antioxidant capacity (TEAC) and ascorbic acid equivalent capacity (AEC) were used to express antioxidant capacity (AAEC). The tyrosinase inhibitory activity was conducted by enzyme-linked immunosorbent assay (ELISA) using L-tyrosine as a substrate and measured at 490 nm by ELISA reader. TPC in the crude extract, fraction A, and fraction B was 173.18 +/- 3.99, 553.95 +/- 5.70 and 405.37 +/- 33.90, respectively. TFC in the crude extract, fraction A, and fraction B was 12.79 +/- 0,25, 143.16 +/- 9.27, 143.50 +/- 6.90, respectively. The best antioxidant capacity of the extract was shown in the DPPH method (15.71 +/- 1.6 mg TEAC/g and 100.77 +/- 8.5 mg AAEC/g). Meanwhile, fraction B showed the best antioxidant capacity by the FRAP (11.48 +/- 1.5 TEAC/g and 8.39 +/- 1.2 mg AAEC/g) and CUPRAC (116.34 +/- 1.9 mg TEAC/g and 66.11 +/- 1.3 mg AAEC/g) methods. Tyrosinase inhibitory activity exhibited that the IC50 of fractions A (13.67 mu g/mL) and B (13.37 mu g/mL) were not significantly different with the IC50 of arbutin. Our molecular docking study showed that the arbutin could suppress the function of the tyrosinase enzyme. Therefore, we assumed that the tyrosinase inhibitor effect of both fractions was most likely due to the arbutin content.

Automated summary

Paederia foetida L. leaves extract showed strong antioxidant capacity and inhibitory activity on tyrosinase activity, indicating its potential as a functional food ingredient.