Eriodictyon angustifolium extract, but not Eriodictyon californicum extract, reduces human hair greying.

Abstract

Yerba Santa (Eriodictyon angustifolium and Eriodictyon californicum) has been used for many years in traditional medicine. However, the effect of Yerba Santa on melanogenesis has not yet been investigated. We aimed to assess the biological effects of Yerba Santa on hair pigmentation. Yerba Santa extracts were assessed for their cytological effects following X-ray irradiation treatment and then tested directly for the prevention of human hair greying. Ultra-performance liquid chromatography (UPLC) was utilized to identify the individual extract components. Eriodictyon angustifolium extract significantly increased melanin synthesis in the melanoma cell line through activation of the WNT/MITF/tyrosinase-signalling pathway. In contrast, E.californicum had no effect on melanin synthesis. E.angustifolium extract also demonstrated a protective effect against the damage induced by X-ray irradiation in human keratinocytes. Application of the extracts to subjects who had grey beards demonstrated a reduced number of grey beard hair per year specifically with the E.angustifolium extract. A significant decrease in grey head hair was also observed after application of E.angustifolium extract. Upregulation of gene expression related to melanin production and WNT signalling was observed after the application of E.angustifolium extract. Sterubin was the most abundant flavonoid detected by UPLC in E.angustifolium extract. In addition, sterubin showed the highest difference in terms of quantity, between E.angustifolium and E.californicum extract. Eriodictyon angustifolium extract, which is abundant in sterubin, may be suitable as a potential cosmetic and medical agent for the prevention and improvement of hair greying.