Antioxidant, anti-collagenase and anti-tyrosinase activities of extracts of Phyllanthus emblica (AMLA) locally grown in Thailand for use in cosmetic products

Abstract

Ma-kham-pom (Phyllanthus emblica Linn., family Euphorbiaceae) has been used for thousands of years m food and medicine in Asian countries. The obj ective of this study was to evaluate different solvent extracts of p. emblica fruits, locally grown in Thailand for their antioxidant, anti- collagenase and anti-tyrosinase activities. Spray-dried powder of p. emblica was directly and separately extracted with three solvents of different polarities, i.e. ethyl acetate, acetone and ethanol using a Soxhlet extractor. After ethyl acetate extraction, the remaining spray-dried powder was also successively extracted with acetone and then ethanol to yield acetone (successive) and ethanol (successive) extracts, respectively. The five extracts plus the spray-dried and commercial p. emblica were evaluated for their H-donating and hydroxyl radical scavenging activities. All the p. emblica extracts showed H-donating activity on l,l-diphenyl-2-picrylhydrazine (DPPH) radical. The DPPH- scavenging activity of acetone (direct), ethanol (direct), ethanol (successive), acetone (successive) extracts and spray-dried p. emblica (IC50 = 4.43, 4.62, 4.63, 5.00 and 6.29 /Xg/mL, respectively), although lower than EGCG, 1-ascorbic acid and Trolox®, was still greater than the commercial p. emblica extract (6.87 /Xg/mL). Ethyl acetate extract exhibited the lowest H-donating activity with the highest IC50 of 7.74 /Xg/mL. Regarding the hydroxyl radical scavenging activity, the acetone (successive) extract (IC50 0.88 mg/mL) exhibited the highest potency comparable to Trolox® (IC50 0.92 mg/mL), whereas spray-dried p. emblica (IC50 1.12 mg/mL) and EGCG (IC50 1.19 mg/mL) had an activity slightly less than the first two components but greater than the commercial p. emblica extract (IC50 1.62 mg/mL) and the acetone (direct) extract (IC50 1.67 mg/mL). At lower concentrations, prooxidant activity was observed for all p. emblica extracts based on deoxyribose degradation. However, their pro-oxidant effect decreased at higher concentrations. The acetone (successive) extract was completely free from pro-oxidant activity at concentration above 1 mg/mL, whereas other p. emblica extracts and EGCG still showed some pro-oxidant activity. Both the ethanol (successive, direct) and acetone (successive, direct) extracts possessed more potent anti-collagenase activity than other p. emblica extracts, whereas the commercial p. emblica extract exhibited the lowest anti-collagenase activity. Anti-tyrosinase activity of p. emblica was also evaluated for its protective effect on melanogenesis. The ethyl acetate extract was found to give the highest tyrosinase inhibitory activity and, thus, both the direct acetone and ethanol extracts provided more potent anti-tyrosinase activity than the successive extracts. Moreover, all of the extracts exhibited good long-term stability with respect to the DPPH-scavenging activity during 9-month storage at ambient temperature. These results thus suggested that p. emblica locally grown in Thailand was capable of helping protect the skin from damaging effects caused by free radicals, as well as from the collagenase and tyrosinase enzymes. Therefore, the multifunctional effects of p. emblica extracts may have a strong potential for uses in cosmetic and other health-related industries.