α-Pyrones with glucose uptake-stimulatory activity from the twigs of Cryptocarya wrayi

Abstract

Five new α-pyrones, cryptowratones A-E (1–5), and five known congeners (6–10), together with four other known compounds 11–14 were isolated from the twigs of Cryptocarya wrayi. The structures of the new compounds were elucidated on the basis of extensive spectroscopic data analysis and ECD calculations. All α-pyrones except 6 were evaluated for their stimulatory effects on glucose uptake in vitro with CHO-K1/GLUT4 cells. The positive control insulin displayed an approximate 42 ± 0.14% promotion on glucose uptake at 25 μM, compared with the CHO-K1/GLUT4 group. Compounds 1a/2a, 2, 3, and 10 showed a more significant stimulation of glucose uptake than insulin (25 μM) by 36 ± 0.08%, 27 ± 0.12%, 28 ± 0.12%, and 25 ± 0.12% at 1.5 μM, respectively. Immunofluorescence assays indicated the glucose uptake-stimulatory activity of α-pyrones might be correlated with increased GLUT4 translocation.