Aging effect of Aloe vera on the tyrosinase inhibition and antioxidant activities

Abstract

Aloe vera extract is an essential ingredient in a wide variety of cosmetic products. This research compares the antioxidant effects and tyrosinase inhibitors of the A. vera extracted from leaves at different stages. The results could be applied in arranging the A. vera leaf into grades for the cosmetic field. In this study, three stages of A. vera leaf: A1 (4-6 months), A2 (7-9 months), and A3 (10-12 months) were divided. The results showed that the water content of the A. vera leaf at A1, A2, and A3 were 98.00 ± 0.02, 97.10 ± 0.02, and 96.00 ±0.04, respectively. In the extraction processes, the A. vera leaf samples were peeled and rinsed with deionized water. After the A. vera gel was blended thoroughly and freeze-dried, A. vera powder was obtained. The A. vera powder was extracted with 80% v/v methanol and dried volatilized by pressure reduction technique. The extract yields of all three stages (A1-A3) was 24.97 ± 0.28, 35.27 ± 0.70, and 32.20 ± 0.29, respectively. The methanol crude extracts examined the antioxidant activity using DPPH and ABTS techniques with Trolox as the standard. The samples (A1-A3) and standard Trolox showed the antioxidant activity against the DPPH radical in terms of percent inhibition at 41.76 ± 0.57%, 40.72 ±2.31%, 37.01 ± 2.22%, and 49.90 ± 1.74%, respectively. The samples (A1-A3) and standard Trolox showed the antioxidant activity against the ABTS•+ radical in term of percent inhibition at 13.65 ± 3.44%, 53.02 ± 1.16%, 13.85 ± 1.08%, and 74.88 ±2.15%, respectively. Among three A. vera extracts, the A2 stage showed the highest antioxidant activity derived from the ABTS technique. Tyrosinase inhibition of A. veraextracts (A1-A3) was investigated and compared with standardized kojic acid at the concentration of 50 ug/mL. It was found that the A. vera extracted at the A2 stage showed the highest tyrosinase inhibition at 18.68 ± 0.99%, while the A. vera A1, A2 stages and the kojic acid showed tyrosinase inhibition at 17.93 ± 0.80%, 15.74 ± 1.17%, and 13.03 ± 0.96%, respectively. The results showed that 7-9 months growth periods of A. vera were an antioxidant activity and tyrosinase inhibition of the gel-extracts suitable for cosmetic application.