Chemical Constituents from Coleus strobilifer and Their Xanthine Oxidase Inhibitory Activity.

Coleus strobilifer, the dried rhizome and root of Coleus strobilifer (Roxb.) A.J. Paton, is widely used for dampness-detoxification and detumescence in Chinese folklore. This study marks the first comprehensive investigation into the chemical composition of the whole herb of C. strobilifer, leading to the isolation and identification of two new abietane diterpenes, 10R-carnosuain (1) and 10R-coleon U-3-one (2), along with 34 known compounds (3-36) isolated from C. strobilifer for the first time. Their structures were unambiguously elucidated by analyses of NMR, HRESIMS, IR, CD, and single-crystal X-ray diffraction data, and comparison with the literature. All the isolated compounds were screened for their xanthine oxidase (XO) inhibitory activity. Among them, apigenin (8), luteolin (9), and esculetin (29) showed moderate XO inhibitory activity with IC50 values of 0.034 ± 0.004, 0.067 ± 0.005, and 0.284 ± 0.01 mM, respectively.