Anti-inflammatory effect of euphane- and tirucallane-type triterpenes isolated from the traditional herb Euphorbia neriifolia L

The Euphorbiaceae plant Euphorbia neriifolia L. is distributed widely in India, Thailand, Southeastern China, and Taiwan and used as a carminative and expectorant to treat several inflammation-related diseases, such as gonorrhoea, asthma, and cancer. In the course of our search for potential anti-inflammatory agents from the titled plant, 11 triterpenes from the stem of E. neriifolia were isolated and reported in our previous endeavor. Given its rich abundance in triterpenoids, the ethanolic extract in this follow-up exploration has led to the isolation of additional eight triterpenes, including six new euphanes-neritriterpenols H and J-N (1 and 3-7)-one new tirucallane, neritriterpenol I (2), and a known compound, 11-oxo-kansenonol (8). Their chemical structures were elucidated on the basis of spectroscopic data, including 1D- and 2D NMR, and HRESIMS spectra. The absolute stereochemistry of neritriterpenols was determined by single-crystal X-ray diffraction analysis, ICD spectra, and DP4+ NMR data calculations. Compounds 1-8 were also evaluated for their anti-inflammatory activity by using lipopolysaccharide (LPS)-stimulated IL-6 and TNF-a on RAW 264.7 macrophage cells. Intriguingly, the euphane-type triterpenes (1 and 3-8) showed an inhibitory effect on LPS-induced IL-6 but not on TNF-a, while tirucallane-type triterpene 2 showed strong inhibition on both IL-6 and TNF-a.

Automated summary

The Euphorbia neriifolia plant, widely found in India, Thailand, Southeastern China, and Taiwan, has anti-inflammatory properties and is used to treat inflammation-related diseases. In this study, additional triterpenes with potential anti-inflammatory effects were isolated from the plant. The chemical structures of these compounds were determined through spectroscopic data analysis, and their anti-inflammatory activity was evaluated. The study found that certain triterpenes showed inhibitory effects on IL-6 and TNF-a, indicating their potential as anti-inflammatory agents.