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 with alcohol dependence. Methods: Polysaccharides were extracted from P. kingianum using water decoction and ethanol precipitation. Fraction PKP84 was isolated using various methods, such as grading-alcoholic precipitation and Sephadex G-100 column chromatography. The physicochemical properties of PKP84 were analyzed using thermogravimetric analysis. The structural characteristics of PKP84 were identified using circular dichroism, scanning electron microscopy, and Congo red experiment. Results: Intervention with PKP84 significantly decreased alcohol levels (P<0.05) in D. melanogaster and reduced the alcohol preference index value to less than zero after 3 d. Moreover, PKP84 increased the activities of certain antioxidant enzymes, such as catalase, and notably decreased malondialdehyde levels (P<0.01). PKP84 had a triple helical structure composed of glucose, galactose, xylose, and rhamnose, and its molecular weight was 1.7×10⁵ Da. There was a strong positive Cotton effect near 212 nm and a weak negative Cotton effect near 198 nm. The micromorphology of PKP84 was complex and multibranched. PKP84 thermally lost weight at the range of 214~390 ℃, and the average weight loss rate was approximately 49%. Conclusion: PKP84 reverses alcohol preference and alleviates oxidative stress in D. melanogaster with alcohol dependence. These findings support the potential application of P. kingianum in the prevention and treatment of alcohol dependence.