Chemical compounds, anti-aging and antibacterial properties of Rosa rugosa Purple branch

Rosa rugosa Purple branch is a rare continuously flowering variety of R. rugosa and also is one of main cultivar varieties of R. rugosa in China. Although R. rugosa has been successfully used in the field of cosmetics, there are also many reports on its chemical components. The chemical composition and application value in cosmetics of R. rugosa Purple branch are still limited. The purpose of this study was to investigate the chemical components in the petals of R. rugosa Purple branch as well as evaluate their skincare and antibacterial potentials through DPPH radical scavenging, tyrosinase inhibition, elastase inhibition and antibacterial bioassays. Two new compounds, isorhamnetin-3-O-(2"-O-galloyl)-β-D-glucopyranoside (1), kaempferol-3-O-β-D-glucopyranosyl-(1→2)-(6''-O-trans-p-coumaroyl)-β-D-glucopyranoside (2) and thirteen known compounds (3-15) were isolated and identified from the petals by bioassay-guided fractionation. All the compounds were isolated and reported from R. rugosa Purple branch for the first time, in which twelve of them are discovered from R. rugosa for the first time. The tyrosinase inhibitory activities of 1, 2, rosarugoside B (3), kaempfero-3-O-β-D-glucopyranosyl(1→2)-β-D-glucopyranoside (4), astragalin-2'',6''-di-O-gallate (8), quercetin-3-O-β-D-glucopyranosyl(1→2)-β-D-glucopyranoside (10), 2-phenylethyl-β-D-glucopyranoside (13), 2-phenylethyl-6-O-α-L-arabinofuranosyl-β-D-glucopyranoside (14), and 2-phenylethyl-D-rutinoside (15) were firstly reported here, in which 8 showed strong tyrosinase inhibitory activity with IC50 of 187.32 ± 0.18 μg/mL. There were eight compounds (1, 6-12) showed strong antioxidant activity, with the scavenging rates of DPPH radical ranging from 88.59% to 94.30% and the IC50 ranging from 4.22 to 13.85 μg/mL, among them, 1 and quercetin-3-O-(6''-O-Z-p-coumaroyl)-β-D-glucopyranoside (11) exhibited antioxidant activity for the first time. 3 exhibited moderate elastase inhibitory activity with IC50 of 148.67 ± 0.11 μg/mL. In addition, seven compounds (2, 5-8, 10-11) showed varying degrees of antibacterial activity. These results indicated that R. rugosa Purple branch had anti-aging, whitening and antibacterial activities, which can be further applied to the development of functional cosmetics.