Phytochemicals and anti-aging potentials of the extracts from Lagerstroemia speciosa and Lagerstroemia floribunda

Skin aging is caused by oxidative stress and the enhanced activation of proteolytic enzymes. Inhibition of these mechanisms by natural plants might be a promising approach to prevent skin aging. The flowers of Lagerstroemia speciosa and Lagerstroemia floribunda are unused parts of agricultural products. They have been reported to possess antioxidant activity and inhibitory properties against matrix metalloproteinase enzymes. In the present study, the ethanolic flowers extracts of L. speciosa and L. floribunda were studied for their total phenolic, flavonoid, and anthocyanin contents, and antioxidant properties. Additionally, the active compounds were identified using high performance liquid chromatography (HPLC). The extracts were also evaluated for their inhibitory effects against hyaluronidase, elastase and tyrosinase. Finally, the extracts were investigated for their protective effects on hydrogen peroxide-induced oxidative stress in human keratinocytes. Results showed that antioxidant activities of the flowers extracts of L. speciosa and L. floribunda were equal to that of ascorbic acid. Both plants also inhibited hyaluronidase, elastase and tyrosinase activity. In addition, these flower extracts showed remarkable inhibitory potential against hyaluronidase, which was higher than that of the standard oleanolic acid. Furthermore, these extracts were found to inhibit hydrogen peroxide-induced cell death in human keratinocytes. L. speciosa extract exhibited higher antioxidant properties, enzymatic inhibitory activities and cytoprotective effects compared with that of L. floribunda. HPLC analysis had revealed that ellagic acid, epicatechin gallate, and quercetin were the major compounds in both extracts, but with higher contents in L. speciosa than in L. floribunda. Taken together, the results suggest that these flower extracts can be considered as new natural sources to be potentially used as anti-aging ingredients in skin care formulations.