Actinidia arguta, commonly called hardy kiwifruit or kiwiberry, has cold-resistant properties and can be cultivated in Asia, including Korea. Seven new triterpenoids (2−4 and 8−11) along with eight known triterpenoids were isolated from the leaves of A. arguta through various chromatographic techniques. The new triterpenoids were defined as actiniargupenes A−C (2−4), actinidic acid derivatives with phenylpropanoid constituent units, dehydroisoactinidic acid (8), and actiniargupenes D−F (9−11), asiatic acid derivatives with phenylpropanoid substituents, on the basis of 1D and 2D NMR and MS data. Among the triterpenoids, those with a phenylpropanoid constituent unit showed inhibitory activity on α-glucosidase, which suggested the importance of the phenylpropanoid moiety. Molecular docking analysis demonstrated the interaction between the 4′-OH group of the phenylpropanoid moiety and α-glucosidase.T he genus Actinidia is a deciduous vine belonging to the Actinidiaceae. The species and cultivars of this genus have different physical shapes and tastes. Actinidia arguta, commonly called hardy kiwifruit or kiwiberry, is cold-resistant, in contrast to A. deliciosa (green kiwi) and A. chinensis (gold kiwi). Therefore, they are cultivated in Asia, including Korea. 1 The fruit of A. arguta is widely consumed as fresh fruit. Different parts of this plant including its fruit, leaves, stems, and roots have also been used traditionally for the treatment of various diseases. Previous investigations of hardy kiwifruit reported various activities such as antioxidant, antibacterial, antidiabetic, antiallergic, and anti-inflammatory effects. 2−7 α-Glucosidase is an intestinal enzyme catalyzing the final step of carbohydrate digestion by converting carbohydrates to single monosaccharides. 8,9 Therefore, inhibition of α-glucosidase would delay the digestion and absorption of carbohydrates, resulting in a hypoglycemic effect by controlling postprandial hyperglycemia. Several α-glucosidase inhibitors such as acarbose and voglibose are used for the treatment of carbohydrate-mediated diseases such as diabetes. 10,11 Accordingly, natural products with α-glucosidase inhibitory activity will be beneficial for the treatment and prevention of diabetes and obesity by controlling blood glucose levels. 12−14 Recently, investigation of the leaves of A. arguta reported beneficial effects on diabetes, and phenolic compounds were suggested as active constituents. 15,16 However, its active constituents have not been well characterized. In this study, the isolation and structural elucidation of new triterpenoids are described. In addition, their inhibitory activity on α-glucosidase was also evaluated and analyzed by molecular docking data analysis.
