Chemical constituents from the flowers of Hypericum monogynum L. with COX-2 inhibitory activity.

Hypericum monogynum L. (Hypericaceae) has been used as a folk Chinese medicine for the treatment of inflammatory related diseases. Cyclooxygenase-2 (COX-2) is a crucial target for the development of agents to treat inflammation. To search for anti-inflammatory compounds from traditional Chinese medicines, a chemical constituent study along with COX-2 inhibitory activity analysis was performed for this plant. In this study, sixteen chemical monomers, including three undescribed oxidative degradation polycyclic polyprenylated acylphloroglucinols (PPAPs, hypemoins C–E), two undescribed PPAPs (hypemoins A and B), and 11 known compounds, were identified from the flowers of H. monogynum. Their structures were characterized by HRESIMS, NMR techniques, ECD, and single crystal X-ray diffraction. Four flavonoid derivatives showed remarkable COX-2 inhibitory activities, with IC 50 values ranging from 0.220 ± 0.006 to 1.655 ± 0.098 μM. Among these compounds, the possible recognition mechanism between quercetin 3-(6″-O-caffeoyl)-β-3-D-galactoside and COX-2 was predicted by molecular docking analysis. Moreover, the multidrug resistance reversal activities for the selected compounds were evaluated. Sixteen chemical monomers, including three undescribed oxidative degradation polycyclic polyprenylated acylphloroglucinols (PPAPs, hypemoins C–E), two undescribed PPAPs (hypemoins A and B), and 11 phenol derivatives were discovered from the flowers of Hypericum monogynum. Four flavonoids showed remarkably COX-2 inhibitory activities with IC 50 values ranging from 0.220 ± 0.006 to 1.655 ± 0.098 μM. [Display omitted] • Five undescribed compounds were isolated from Hypericum monogynum. • Four flavonoids showed remarkably COX-2 inhibitory activities. • The possible recognition mechanism was predicted by molecular docking. • The multidrug resistance reversal activity was also evaluated. [ABSTRACT FROM AUTHOR]