The effect of geographic variation on chemical composition, antioxidant and hypoglycemic activities of Morus alba L. polysaccharides

Morus alba L. is an edible fruit with multiple medical function. To reveal the geographic variation pattern of polysaccharide content in the mulberry fruits and its antioxidant and hypoglycemic activities, the fruit samples were collected and analyzed from seven geographic locations throughout the distribution areas in China. The polysaccharide content in the mulberry fruits ranged from 4.13 ± 0.04% to 1.07 ± 0.07%. All the polysaccharides derived from mulberry fruit showed certain antioxidant and hypoglycemic activities with a significant variation. Significant differences were observed among polysaccharide content, antioxidant activity, and sunshine hours, but no clear geographical or polysaccharide content variation patterns were observed for hypoglycemic activity. Pearson correlation analysis indicated that the annual average sunshine hours was significantly correlated to the polysaccharide content and antioxidant activity. According to the polysaccharide contents and bioactivities, certain natural populations of M. alba L. such as Xinjiang, Hunan, and Anhui were recommended for food and medical use in future. PRACTICAL APPLICATIONS: Morus alba L. belonging to the family Moraceae, is cultivated across an extensive range of geographical, climatic, and soil conditions. Polysaccharides from mulberry fruit have been proved to have the function of enhancing immunity, antiaging, anti‐inflammatory, antioxidant, hypolipidemic, and hypoglycemic effects with no toxic record in clinic. It has been reported that the phytochemicals accumulation in plants is greatly affected by genetic, climatic, and harvesting factors during the growing period. We revealed the geographic variation pattern of polysaccharide content in the mulberry fruits and its antioxidant activity. Based on the polysaccharide contents and bioactivities, certain natural populations of M. alba L. such as Xinjiang, Hunan, and Anhui were recommended for food and medical use in future. The information obtained by this study could be useful for the selection of natural populations with adequate polysaccharide content, as well as high food and medical use for M. alba L.