Preparation, Characterization and Effects of Fraction PKP84 of Polygonatum kingianum Polysaccharides on Drosophila melanogaster with Alcohol Dependence

Objective: To separate and purify novel fraction PKP84 of Polygonatum kingianum polysaccharides, and to analyze its structure and effects on Drosophila melanogaster suffering from alcohol dependence. Methods: Polysaccharides were extracted from Polygonatum kingianum using water decoction and ethanol precipitation method, and fraction PKP84 was isolated using various methods such as grading-alcoholic precipitation and Sephadex G-100 column chromatography. Physicochemical properties of PKP84 were analyzed by different techniques such as thermogravimetric analysis. Structural characteristics of PKP84 were identified by various methods such as circular dichroism, scanning electron microscopy and Congo red experiment. Results: Interventions with PKP84 significantly decreased alcohol level (P<0.05) in Drosophila melanogaster. PKP84 also reduced alcohol preference index (PI), which was less than zero after 3 d. Besides, PKP84 increased the activities of some antioxidant enzymes such as catalase, and notably decreased malondialdehyde level (P<0.05). PKP84 with triple helical structure was composed of glucose, galactose, xylose and rhamnose, and its molecular weight was 1.7×10⁵ Da. There were a strong positive Cotton effect near 212 nm and a weak negative Cotton effect near 198 nm. The micromorphology of PKP84 was a complex multibranched structure. PKP84 thermally lost weight at the range of 214~390 ℃, and average weight loss rate was approximately 49%. Conclusion: PKP84 can reverse the alcohol preference and alleviates oxidative stress in Drosophila melanogaster suffering from alcohol dependence. These results are helpful to the application of Polygonatum kingianum to prevention and treatment of alcohol dependence.