The invention discloses a novel ellagic tannins alpha-
glucosidase inhibitor and a preparation method thereof. The method comprises the following steps: (1), crushing an immature
rubus chingii hu fruit, using ethyl
alcohol with certain concentration for
reflux extraction, and performing filtering to obtain a
rubus chingii hu extraction solution; (2), performing concentration on the extraction solution, adding deionized water to prepare a suspension, using n-
butanol for extraction, and obtaining a n-
butanol extract; (3), performing concentration on the n-
butanol extract to concrete, after redissolving the concrete in the deionized water, adding a product to a
macroporous resin column, using the ethyl
alcohol for
elution, and obtaining an ethyl
alcohol eluent; (4), after the concentration ofthe ethyl alcohol eluent, redissolving a product in methyl alcohol, adding the product to an OSD column, using methyl alcohol for
elution, collecting the eluent, performing concentration, and obtaining a methyl alcohol concentrated solution; and (5), adjusting the methyl alcohol concentrated solution to suitable concentration, adopting PHPLC (preparative
high performance liquid chromatography) topreparation, and obtaining the new ellagic tannins alpha-
glucosidase inhibitor. The new ellagic tannins alpha-
glucosidase inhibitor is an ellagic tannins compound, which is isolated and identified forthe first time. Compared with common alpha-
glucosidase inhibitor hypoglycemic
drug-
acarbose, the new ellagic tannins alpha-
glucosidase inhibitor has significant higher inhibitory activity on alpha-glucosidase, and has great value in
drug development.