Abstract: This study aimed to investigate the effects of different stages of blooming and processing on the compositional characteristics and in vitro bioactivities of crude polysaccharides from jasmine flowers. Blooming flowers, unopened buds, spent flowers after essential oil extraction, and spent flowers after tea scenting were used as raw materials for preparation of crude polysaccharides by hot water extraction. The extraction yield, basic chemical composition, monosaccharide composition, in vitro antioxidant and digestive enzyme inhibitory activities of crude polysaccharides from the four materials were systematically compared, and the correlation between compositional characteristics and bioactivities were further analyzed. The results showed that extraction methods and raw materials significantly affected the yield of crude polysaccharides (P < 0.05). Hot water extraction resulted in relatively higher yields ranging from 13.91% to 19.46%, with the highest yield obtained from unopened buds (19.46%). Chemical composition analysis revealed significant differences among the four crude polysaccharide samples in total sugar, uronic acid, protein, total phenolic, and total flavonoid contents. Crude polysaccharides from unopened buds showed the highest total sugar (43.15%) and uronic acid (17.59%) contents. Monosaccharide composition analysis indicated that all samples were heteropolysaccharides mainly composed of arabinose, galactose, glucose, rhamnose, xylose, mannose, and uronic acids, although their proportions varied among samples. In vitro bioactivity evaluation showed that crude polysaccharides from unopened buds exhibited relatively stronger 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (79.20% at 1.2 mg/mL) and inhibitory activities against α-amylase and α-glucosidase (60.23% and 42.92% at 5 mg/mL, respectively). Crude polysaccharides from spent flowers after tea scenting showed relatively high 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical scavenging activity (99.14% at 5 mg/mL). All polysaccharide samples exhibited moderate to low inhibitory effects against pancreatic lipase, with the highest value of 34.62%. Correlation analysis indicated that total sugar and uronic acid contents tended to be positively correlated with several antioxidant and enzyme inhibitory activities. In conclusion, crude polysaccharides from jasmine flowers at the different stages of blooming and processing exhibited in vitro antioxidant and digestive enzyme inhibitory activities. The by-products from jasmine essential oil extraction and tea scenting can serve as potential polysaccharide resources, laying the foundation for the high-value utilization of jasmine flowers.

Key words: crude polysaccharides from jasmine flowers; raw material state; monosaccharide composition; in vitro bioactivity; processing by-products