Flavonoids and other constituents with insulin secretion activity from Pseudarthria hookeri

Three new flavonoids viz., pseudarflavones A (1) and B (2) and 6,7-(2 '',2 ''-dimethylchromano) flavanone (3), were isolated from Pseudarthria hookeri together with thirteen known compounds: boeravinone L (5), gancaonin P (4), dorsamin F (10), emodin (6), 6-prenylpinocembrin (7), hiravanone (11), dorsmanin I (12), 6,8-diprenyleriodictyol (13), 6-prenyl-3'-methoxyeriodictyol (14), oblonginol (15), orobol (16), protocatechuic acid (17) and alpha-terthienyl (18). Their structures were elucidated by IR, MS, 1D and 2D NMR spectroscopic techniques and by comparison with data reported in the literature. Chemical transformations were also employed to confirm some assignments. The insulin secretory activity of compounds (1, 3-18) was evaluated on isolated mice islets. Compounds (1, 3, 5 and 12) showed a mild effect on glucose stimulated insulin secretion while compounds (4, 10, 14 and 16) were found to display moderate insulin secretory activities of 247.5%, 404.8%, 350.7% and 291.8% respectively, in comparison to the control. The tested compounds showed no toxic effect on MIN-6 and 3T3 cell lines up-to 400 mu M. These results demonstrated that compounds (10) and (14) showed a potential to be considered as new insulin secretagogues and that further development of their derivatives may increase their insulinotropic potential. (C) 2016 Phytochemical Society of Europe. Published by Elsevier Ltd. All rights reserved.