Benzobicyclic ketones, cycloheptenone oxide derivatives, guaiane-type sesquiterpenes, and alkaloids isolated from Taraxacum mongolicum Hand.-Mazz.

Abstract

Ten previously undescribed compounds, including two benzobicyclic ketones, one cycloheptenone oxide derivative, three guaiane-type sesquiterpenes, and four alkaloids, along with one known cycloheptenone oxide derivative, were isolated from the whole plants of Taraxacum mongolicum Hand.-Mazz. Their structures were elucidated by UV, IR, HR-ESI-MS, 1D and 2D NMR spectroscopy, ECD spectroscopy, or X-ray diffraction analysis. Notably, benzobicyclic ketones have never been isolated from nature before. The 70% EtOH–H2O extract of T. mongolicum displayed a significant inhibitory activity (33%) against croton oil-induced mouse ear edema. The two cycloheptenone oxide derivatives exhibited anti-inflammatory activities at 10 μM and significantly reduced the nitric oxide (NO) and interleukin-6 (IL-6) levels in RAW 264.7 macrophages induced by lipopolysaccharide (LPS), with inhibitory rates of 26.4–64.4%.