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 inhibitorsand natural antioxidants, but they are not used as they are considered as waste. Thisresearch evaluated the inhibition test towards tyrosinase enzyme and antioxidant activityof corncob fraction using in-vitro DPPH method and its correlation to phenolic andflavonoids. Corncob fraction was extracted using the maceration method applying 70%ethanol solvent. The ethanol extract of corncob was suspended by water and thenpartitioned with chloroform, ethyl acetate, and aquadest to produce three fractions(chloroform, ethyl acetate, and aquadest fractions). These fractions were analyzed throughthe tyrosinase inhibition test, applying in vitro tyrosinase enzyme inhibition andantioxidant activity using radical scavenging test DPPH (2 2,2-diphenyl-1-picrylhydrazyl).Meanwhile, the total phenolic and flavonoids content tests were determinedspectroscopically. The results showed ethyl acetate fraction had the highest tyrosinaseactivity with IC50 values of 185.76 µg/mL, followed by the aquadest fraction (IC50676.44µg/ml) and the chloroform fraction (IC50 709.26 µg/mL). The antioxidant activityusing DPPH radical scavenging method exhibited that ethyl acetate fraction had thehighest 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 phenoliccontent of the corncob fraction ranged between 1.73 to 7.43% (w/w) gallic acidequivalents (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 corncobfractions correlated with the total phenolic and flavonoid contents.