Antioxidation and active constituents analysis of flower residue of Rosa damascena

OBJECTIVE: To make full usage of resource and turn waste into treasure, the chemical constituents and bioactivity were firstly investigated on Damask rose (Rosa damascena) flower residue (DRFR). METHODS: DPPH and ABTS experiments were applied to assess the antioxidant activity of DRFR. Then, column chromatography was used to purify compounds from an antioxidation extract (DRFR-A), and the chemical structure was identified using NMR. The total phenolic acid content was measured by Folin-Ciocalteu colorimetric method, and the content of gallic acid of the indicator ingredient was detected by HPLC. RESULTS: DRFR-A was found to show a high activity both on DPPH (IC(50): 2.760 µg/mL) and ABTS (IC(50): 2.258 µg/mL) compared to positive control V(C). Ten compounds were isolated and identified as quercetin (1), kaempferol (2), gallic acid (3), protocatechuic acid (4), pyrogallic acid (5), 2-phenylethyl 3,4,5-trihydroxybenzoate (6), methyl gallate (7), p-hydroxybenzoic acid (8), p-hydroxyphenethyl alcohol (9) and astragalin (10) from DRFR-A. Among them, pyrogallic acid, 2-phenylethyl-3, 4, 5-trihydroxybenzoate, p-hydroxybenzoic acid and p-hydroxyphenethyl alcohol are obtained from the plant for the first time. The content of total phenolic acids and gallic acid, main ingredient in DRFR-A was determined as 63.73% and 24.67%, respectively. CONCLUSION: This study provides a reliable data and lays the foundation for the development and utilization of rose residue, and hence for the full utilization of rose resources.