Chemical constituents from aerial parts of Scoparia dulcis.

Objective: To study the chemical constituents from the aerial parts of Scoparia dulcis. Methods: Various chromatographic techniques were used to separate the constituents and their structures were elucidated using spectroscopic methods and by comparing their data to those reported in the literatures. The α-glucosidase inhibitory activity assay was used to identify potential α-glucosidase inhibitors. Results: Nine compounds were isolated from the aerial parts of S. dulcis. Their structures were identified as Scoparic zolone (1), (2S)-2,7-dihydroxy-2H-1,4-benzoxazin-3(4H)-one (2), (2R)-7-hydroxy-2H-1,4-benzoxazin-3(4H)-one-2-O-ß-d-glucopyranoside (3), (2R)-7-methoxy-2H-1,4-benzoxazin-3(4H)-one-2-O-ß-d-glucopyranoside (4), (2S)-7-hydroxy-2H-1,4-benzoxazin-3(4H)-one-2-O-ß-d-glucopyranoside (5), 6-methoxy-benzoxazolin-2(3H)-one (6), 4-acetonyl-3,5-dimethoxy-p-quinol (7), zizyvoside I (8), and 3,4-dihydroxy benzeneacetic acid (9). Compound 2 showed the potent α-glucosidase inhibitory activity with an IC50 value of (132.8 ± 11.5) µmol/L, which is 28-fold higher than the positive control acarbose. Conclusion: Compound 1 is a new natural product. Compounds 2 and 9 have not been reported in Scoparia before. Compounds 3, 5, 7, 8 are isolated from Scrophulariaceae for the first time.