Arteannoides U-Z: Six undescribed sesquiterpenoids with anti-inflammatory activities from the aerial parts of Artemisia annua (Qinghao)

Abstract

Four previously unreported sesquiterpenoid diasteromers, arteannoides U-X (1-4), together with one new norsesquiterpenoid 5 (arteannoide Y) and one undescribed rearranged cadinene sesquiterpenoid 6 (arteannoide Z) were obtained from the dried aerial parts of Artemisia annua (Qinghao). Notably, arteannoides U-X (1-4) are four stereoisomers that possess the same molecules and the same planar connectivity, but differ from each other in configuration at a certain stereocenter. Their accurate structures were unambiguously identified and distinguished by extensive spectroscopic analyses, NMR calculations with DP4+ analysis, electronic circular dichroism (ECD) calculations and X-ray diffraction analyses. Compounds 1, 3, and 4 showed inhibitory activities against the production of inflammatory cytokines (PGE₂, NO, IL-6 and TNF-α) in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages.

Keywords: Anti-inflammatory activity; Artemisia annua; NMR calculations; Sesquiterpenoids.