Phenolic Constituents with Antioxidative, Tyrosinase Inhibitory and Anti-aging Activities from Dendrobium loddigesii Rolfe

Abstract

Abstract Aqueous ethanol extracts of powdered stems of Dendrobium loddigesii afforded three new phenolics including threo- 7- O- ethyl - 9- O- (4-hydroxyphenyl)propionyl-guaiacylglycerol ( 1 ), ( R )-4,5,4ʹ-trihydroxy-3,3ʹ,α-trimethoxybibenzyl ( 2 ) and ( S )-5,5′,7-trihydroxy-3′,4′-dimethoxyflavanone ( 3 ), together with eleven known analogues. Their structures were determined by extensive spectroscopic analysis. To identify natural antioxidants, whitening, and anti-aging agents, the abilities of these phenolics were assessed to scavenge the 1,2-diphenyl-2-picrylhydrazyl (DPPH) radical, their abilities to inhibit tyrosinase production, and their abilities to stimulate collagen production by human dermal fibroblasts-adult (HDFa) assay. It was found that compounds 1 , 4 – 8 , 13 and 14 exhibited significant DPPH radical scavenging activities, compound 10 exhibited tyrosinase inhibitory activity (IC 50 37.904 μg/mL), and compound 9 showed significant collagen production with an EC 50 value of 3.182 μg/mL. These results suggest that phenolic constituents from D. loddigesii may be candidate antioxidants, skin-whitening and/or anti-aging agents. Graphic Abstract