Potential of corncobs (Zea mays) fraction as tyrosinase inhibitor and natural antioxidant in vitro

Corncobs (Zea mays) are beneficial to human health as they contain tyrosinase inhibitors and natural antioxidants, but they are not used as they are considered as waste. This research evaluated the inhibition test towards tyrosinase enzyme and antioxidant activity of corncob fraction using in-vitro DPPH method and its correlation to phenolic and flavonoids. Corncob fraction was extracted using the maceration method applying 70 ethanol solvent. The ethanol extract of corncob was suspended by water and then partitioned with chloroform, ethyl acetate, and aquadest to produce three fractions (chloroform, ethyl acetate, and aquadest fractions). These fractions were analyzed through the tyrosinase inhibition test, applying in vitro tyrosinase enzyme inhibition and antioxidant activity using radical scavenging test DPPH (2 2,2-diphenyl-1-picrylhydrazyl). Meanwhile, the total phenolic and flavonoids content tests were determined spectroscopically. The results showed ethyl acetate fraction had the highest tyrosinase activity with IC50 values of 185.76 µg/mL, followed by the aquadest fraction (IC50 676.44µg/ml) and the chloroform fraction (IC50 709.26 µg/mL). The antioxidant activity using DPPH radical scavenging method exhibited that ethyl acetate fraction had the highest antioxidant activity with IC50 of 25.79 µg/mL followed by the chloroform fraction (IC50 of 29.15 µg/mL) and the aquadest fraction (IC50 of 32.41 µg/mL). The total phenolic content of the corncob fraction ranged between 1.73 to 7.43 (w/w) gallic acid equivalents (GAE), while the entire flavonoid content ranged between 0.01 to 1.34 (w/w) quercetin equivalent (QE). The tyrosinase activity and antioxidants of the corncob fractions correlated with the total phenolic and flavonoid contents. © 2021 The Authors. Published by Rynnye Lyan Resources.