Anti-aging and tyrosinase inhibition effects of Cassia fistula flower butanolic extract

BACKGROUND Natural products made from plant sources have been used in a variety of cosmetic applications as a source of nutrition and as a whitening agent. The flowers of Cassia fistula L, family Fabaceae, have been used as a traditional medicine for skin diseases and wound healing and have been reported to possess anti-oxidant properties. The anti-aging effect of C. fistula flower extract on human skin fibroblast was investigated. METHODS The butanolic extraction of C. fistula flowers was completed and the active compounds were classified. The cytotoxicity of fibroblasts was evaluated by SRB assay for the purposes of selecting non-toxic doses for further experiments. The collagen and hyaluronic acid (HA) synthesis was then measured using the collagen kit and ELISA, respectively. Moreover, the enzyme activity, including collagenase, matrixmelloproteinase-2 (MMP-2) and tyrosinase, were also evaluated. RESULTS It was found that the flower extract did not affect skin fibroblast cell growth (IC50 > 200 μg/mL). The results did show that the flower extract significantly increased collagen and HA synthesis in a dose dependent manner. The flower extract (50-200 μg/mL) also significantly inhibited collagenase and MMP-2 activity. Furthermore, this flower extract could inhibit the tyrosinase activity that causes hyperpigmentation, which induces skin aging. CONCLUSIONS The C. fistula flower extract displayed a preventive effect when used for anti-aging purposes in human skin fibroblasts and may be an appropriate choice for cosmetic products that aim to provide whitening effects, and which are designated as anti-aging facial skin care products.