Monoterpenoid indole alkaloids from the fruits of Gelsemium elegans and their anti-inflammatory activities

Two novel monoterpenoid indole alkaloids (MIAs), gelsechizines A-B ( 1 – 2 ), along with four known ones ( 3 – 6 ) were isolated from the fruits of Gelsemium elegans . Compound 1 features a new carbon skeleton with two additional carbon atoms forming a 4-methylpyridine unit. Their structures with absolute configurations were elucidated by NMR, MS, X-ray diffraction and electronic circular dichroism (ECD) calculations. Compounds 1 – 3 showed significant anti-inflammatory effects in vivo and in vitro , which may be related to the inhibition of the trecruitment of neutrophils and macrophages as well as the secretion of TNF- α and IL-6. Preliminary structure–activity relationship analysis revealed that the β - N -acrylate moiety plays an important role in the anti-inflammatory effect.