The aim of this study was to test the inhibitory effect of fruit extracts from Washingtonia filifera on skin aging-related enzymes. The pulp extracts did not exert a significant enzyme inhibition while seed extracts from W. filifera exhibit anti-elastase, anti-collagenase, and anti-tyrosinase activities. Tyrosinase was mildly inhibited while a stronger effect was observed with respect to elastase and collagenase inhibition. Alcoholic extracts provided better results than aqueous extracts. Among them, methanol extracts showed the prominent enzyme inhibitory activities being IC50 value for elastase and collagenase comparable and even better than the reference compound. The inhibition mode of the most active extracts was investigated by Lineweaver-Burk plot analysis. Seed extracts from W. filifera were also investigated for their photo-protective effect by Mansur equation and the antioxidant activity of W. filifera extract was evaluated in oxidative-stressed cells. To evaluate the safety of the extract, the effect on cell viability of human keratinocytes cells was analyzed. Methanol extract presented the best photo-protective effect and exerted an antioxidant activity in a cellular system with no cytotoxic effect. The overall results demonstrate that W. filifera extracts are promising sources of bioactive compounds that could be used in cosmetic and pharmaceutical preparation.
Keywords: Washingtonia filifera; collagenase; elastase; enzyme inhibition; plant extracts; seeds; skin aging; tyrosinase.