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

## TL;DR

This study identifies new compounds in Coleus strobilifer and finds some with xanthine oxidase inhibitory activity, which may help in dampness and swelling treatments.

## Contribution

The first comprehensive investigation into the chemical composition of Coleus strobilifer and discovery of two new abietane diterpenes.

## Key findings

- Two new abietane diterpenes, 10R-carnosuain and 10R-coleon U-3-one, were isolated from Coleus strobilifer.
- Apigenin, luteolin, and esculetin showed moderate xanthine oxidase inhibitory activity with low IC50 values.
- 34 known compounds were isolated from the plant for the first time.

## Abstract

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.