Glucose Uptake-Stimulating Galloyl Ester Triterpenoids from <i>Castanopsis sieboldii</i>
Hyun Woo Kim, Eun Jin Park, Hyo Moon Cho, Jin‐Pyo An, Young‐Won Chin, Jinwoong Kim, Sang Hyun Sung, Won Keun Oh
Abstract
Using molecular networking-guided isolation, three new galloyl ester triterpenoids (1–3), two new hexahydroxydiphenic acid-conjugated triterpenoids (6 and 7), and four known compounds (4, 5, 8, and 9) were isolated from the fruits and leaves of Castanopsis sieboldii. The chemical structures of 1–3, 6, and 7 were elucidated on the basis of interpreting their NMR, HRESIMS, and ECD spectra. All compounds (1–9) were evaluated for their glucose uptake-stimulating activities in differentiated adipocytes using 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-d-glucose as a fluorescent-tagged glucose probe. Compounds 2 and 9 resulted in a 1.5-fold increase in glucose uptake. Among them, compound 2 from the fruits showed an upregulation of p-AMPK/AMPK ratio in differentiated C2C12 myoblasts to support the mechanism proposed of glucose uptake stimulation.