Chemical Constituents from Euphorbia esula

Euphorbia esula is widely distributed across China, Central Asia and other regions worldwide. For centuries, it has been applied in folk and traditional medicine as a cure for diverse ailments. Nevertheless, the bioactive components responsible for anti-inflammatory and cytotoxic effects remain incompletely identified. In this study, two undescribed chemical constituents, a pyrrole alkaloid (1) and a loliolide analogue (2), alongside nine known components (3–11) were separated from the aerial parts of Euphorbia esula indigenous to Uzbekistan. Their chemical structures were comprehensively elucidated utilizing HRESIMS, NMR, IR and UV spectroscopy. Corresponding absolute configurations were determined based on comparison of experimental and calculated ECD data. Compounds 3–11 were firstly isolated from Euphorbia esula, among which 4, 5, 7 and 9–11 were yielded from the genus Euphorbia for the first time. Chemically, the discovery of various skeletons covering pyrrole alkaloids (1, 9), norisoprenoids (2–8), furanone (10) and unusual cyclooct-2-enone (11) particularly highlighted the structural diversity. Bioactivity assays revealed that some compounds (1, 3, 5, 6, 7 and 8) exhibited certain anti-inflammatory effects via inhibiting the NO release in LPS-induced RAW 264.7 macrophages.