α-Glucosidase inhibitory flavonoids of Actinidia arguta fruits: Comparison of different cultivars

Actinidia arguta (Siebold & Zucc.) Planch. ex Miq. is one of the major species of the genus Actinidia and has distinct characteristics such as small size and smooth-fruited. The fruits of A. arguta are rich in essential nutrients and bioactive compounds. Due to their tolerance to low temperatures, they can be cultivated in Asia and several varieties have been developed for better efficacy. Investigation of the fruits of A. arguta through extensive chromatographic techniques yielded 22 flavonoid derivatives including one new compound. The new compound, argutiflavone (13), had a flavanone structure with a glucose and an acetylated rhamnose according to the 1D and 2D NMR and MS data. The isolated compounds showed antioxidant and α-glucosidase inhibitory activity although the efficacy differed depending on the structures. Among the isolated compounds, flavolignans (20–22) exerted the strongest efficacy among isolated compounds. Four cultivars of A. arguta fruits contained high amounts of flavonoids. Taken together, the fruits of A. arguta, which contains a high content of flavonoids, will be beneficial to health based on their actions.