Inhibitory effects of shell of Camellia oleifera Abel extract on mushroom tyrosinase and human skin melanin.

Abstract

As an oil production byproducts, the shell of Camellia oleifera Abel (SC) is usually discarded in the dump. However, previous investigations suggested that the SC could provide valuable bioactive materials. The objectives of this study were to examine the ability of SC extract to inhibit in vitro tyrosinase activity and the melanin inhibition effects of cosmetic formulations containing SC 1,3-butanediol extract in human volunteers. The cell viability was determined using a WTT assay. A mushroom tyrosinase was used to evaluate the anti-tyrosinase activity of the SC extract. The placebo (no extract) or test (SC 1,3-butanediol extract) or positive control (kojic acid) cosmetic cream was applied on face of volunteers(30 female subjects) three times a day for 8weeks. The active compounds in SC extract were screened using liquid chromatography-high-resolution mass spectrometry (UHPLC-QTOF). The result showed that the cytotoxicity of SC extract is insignificant when the concentration of SC extract is below 160µg/mL. In addition, SC extract dose dependently inhibited tyrosinase activity and SC 1,3-butanediol extract possessed a stronger inhibitory activity than methanol extract and water extract. Clinical evaluations revealed that facial melanin levels of the volunteers receiving cosmetic formulations (containing SC 1,3-butanediol extract) were decreased 59% from baseline in 6th weeks, whereas the placebo group showed no effect. SC 1,3-butanediol extract was detected to contain 12 kaempferol compounds, significantly, kaempferol 3-O-[α-rhamnopyranosyl-(1→6)-β-glucopyranoside] and kaempferol-3,7-O-α-L-dirhamnoside are the major compounds. These results indicate that SC extract can be used as a natural skin-whitening agent in cosmetic products.