Dibenzocycloheptanoids from the Leaves of Cinnamomum subavenium
Five dibenzocycloheptatrienes (1?3, 5, and 6) and one dibenzocycloheptadiene (8) together with 16 known compounds were isolated from the leaves of Cinnamomum subavenium. Application of HPLC-SPE-NMR to a selected fraction afforded two additional dibenzocycloheptatrienes (4, 7). The glycosides 2?7 comprise two diastereomers because of the chiral glycosyl moiety and the axial chirality of the biphenyl system. Their structures were elucidated via ECD and 2D NMR analyses and chemical degradation. Subavenosides D (5) and E (6) showed moderate inhibitory activity against α-glucosidase type IV from Bacillus stearothermophilus with IC50 values of 50.7 and 19.0 ?M, respectively.