Components with Anti-Diabetic Activity Isolated from the Leaves and Twigs of Glycosmis pentaphylla Collected in Vietnam

A phytochemical investigation of the leaves and twigs of Glycosmis pentaphylla (Rutaceae), collected in Vietnam, yielded three new compounds named glyfuran (1), glyphyllamide (2), and glyphyllazole (3), along with twenty-five known compounds (4–28). The structures of isolates were determined by IR, MS, NMR, and UV data analyses. In the anti-diabetic activity screening, (+)-isoaltholacton (4), glycoborinine (17), 2′,4′-dihydroxy-4,6′-dimethoxychalcone (24), and flavokawain A (25) simultaneously exhibited inhibition of dipeptidyl peptidase-4 (DPP4) and stimulation of the glucagon-like peptide-1 (GLP-1) secretion on the murine intestinal secretin tumor cell line (STC-1).