A new anti-inflammatory monoterpenoid indole alkaloid from the trunk of Nauclea officinalis

Two monoterpenoid indole alkaloids including one undescribed alkaloid, naucleficine B (1), and a known alkaloid glycoside, strictosamide (2) were isolated from ethyl acetate fraction of the 95% ethanol extract from the trunk of Nauclea officinalis, together with three known non-alkaloid components, (+)-medioresinol (3), protocatechuic acid (4), and benzoic acid (5). Their structures were elucidated on the basis of extensive spectroscopic analysis and X-ray diffraction. Compounds 1 and 2 exhibited potent anti-inflammatory effects in cigarette smoke extract (CSE)-stimulated RAW 264.7 and THP-1 macrophages. These compounds significantly suppressed nitric oxide (NO) generation, reduced the secretion of inflammatory mediators, and inhibited the activation of inflammation-related proteins.