Chemical Composition and Antioxidant Activity of Crude Polysaccharide from Citron (Citrus junos Sieb. Ex TANAKA) Seed

The crude polysaccharide (citron seed crude polysaccharide, CSCP) from citron (Citrus junos Sieb. Ex TANAKA) seed was obtained by water extraction and ethanol precipitation. The results of chemical composition analyses of the CSCP observed that neutral sugar content and uronic acid content were 27.70% and 14.70%, respectively. Monosaccharide composition of the CSCP was as follows in the following order: galacturonic acid+glucuronic acid (14.70 mol%)> arabinose (12.85 mol%)> glucose (4.54 mol%)> galactose (4.32 mol%)> mannose (2.70 mol%)> fucose (1.68 mol%)> rhamnose (1.61 mol%). The total polyphenol contents of the CSCP was 30.42 μg/mL and 86.12 μg/mL at 1 mg/mL and 10 mg/mL, respectively (P<0.001). 2,2′-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity was higher at the concentration of the CSCP 10 mg/mL (47.12%) than that of the CSCP 1 mg/mL (14.02%), (P<0.001). The ABTS radical scavenging activity was higher than 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity (14.33%) at the same concentration of the CSCP 10 mg/mL (P<0.001). Consequently, in this study, the crude polysaccharide from citron seed may be as a novel potential antioxidant.