Bioactive Diterpenoids and Flavonoids from the Aerial Parts of Scoparia dulcis

Six new diterpenoids, 4-epi-7 alpha-O-acetylscoparic acid A (1), 7 alpha-hydroxyscopadiol (2), 7 alpha-O-acetyl-8,17 beta-epoxyscoparic acid A (3), neo-dulcinol (4), dulcinodal-13-one (5), and 4-epi-7 alpha-hydroxydulcinodal-13-one (6), and a new flavonoid, dillenetin 3-O-(6 ''-O-p-coumaroyl)-beta-D-glucopyranoside (10), along with 12 known compounds, were isolated from the aerial parts of Scoparia dulcis. The 7S absolute configuration of the new diterpenoids 1-4 and 6 was deduced by comparing their NOESY spectra with that of a known compound, (7S)-4-epi-7-hydroxyscoparic acid A (7), which was determined by the modified Mosher's method. The flavonoids scutellarein (11), hispidulin (12), apigenin (15), and luteolin (16) and the terpenoids 4-epi-scopadulcic acid B (9) and betulinic acid (19) showed more potent a-glucosidase inhibitory effects (with IC50 values in the range 13.7-132.5 mu M) than the positive control, acarbose. In addition, compounds 1, 11, 12, 15, 16, and acerosin (17) exhibited peroxisome proliferator-activated receptor gamma (PPAR-gamma) agonistic activity, with EC50 values ranging from 0.9 to 24.9 mu M.