Antioxidant activity and phytochemical composition of Osmanthus fragrans' pulps

• Eight compounds were isolated from O. fragrans' pulps for the first time.
• DPPH, ABTS, and FRAP assays are used for evaluating the antioxidant capacity.
• n-Butanol fraction (NBF) shows the best antioxidant activity.
• Salidroside and phillyrin may be for the antioxidant activity in NBF.

Purification of the ethanol extract of Osmanthus fragrans' pulps led to the isolation of eleven compounds, namely 5-hydroxymethylfurfural (1), hydroxytyrosol (2), pinoresinol (3), oleoside-7,11-dimethyl ester (4), oleoside-11-methyl ester (5), verbenalin (6), phillyrin (7), salidroside (8), β-sitosterol (9), octadecanoic acid (10), and octane (11). Their structures were identified by mass and various nuclear magnetic resonance spectroscopic techniques. All compounds except for 5, 7, and 9 were isolated from O. fragrans for the first time. Ethanol extract and its fractions of O. fragrans' pulps were investigated for their antioxidant properties using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2′,2′-azinobis (3-ethylbenzothiazline-6-sulfonic acid) (ABTS) radical scavenging capacity assay, and ferric reducing antioxidant potential (FRAP) assay. Based on the antioxidant experiments of crude ethanol extract and its fractions, n-butanol fraction shows the best antioxidant activity, salidroside and phillyrin may be the highest contributors and responsible for the antioxidant activity in the n-butanol fraction.