Abstract
Phytochemical investigation on the stems of C. tabularis led to the isolation of five new phragmalin-type limonoids and six known ones. The structures of the new compounds 1-5, named chukbularisins A-E, were elucidated by spectroscopic techniques (IR, HRESIMS, 1D and 2D NMR) and comparisons with published data. All the compounds were evaluated for in vitro α-glucosidase inhibitory activity. Compounds 2, 3, 4, 5, and 8 exhibited inhibitory activity against α-glucosidase with IC50 values of 0.06 ± 0.008, 0.04 ± 0.002, 0.52 ± 0.039, 1.09 ± 0.040, and 0.20 ± 0.057 mM, respectively (using acarbose as positive control, IC50 0.95 ± 0.092 mM).