Abstract
Investigation of the roots of Tripterygium wilfordii Hook. f. resulted in the isolation of nine sesquiterpene pyridine alkaloids (SPAs), including four previously undescribed compounds 1-4. The structures of all compounds were elucidated by extensive spectroscopic analysis, including NMR and HRESIMS. In particular, compound 1 was found to possess an unprecedented cage-like ether moiety, representing the first report of such a structural feature within this class of alkaloids. All isolated compounds were evaluated for their anti-inflammatory activity using a lipopolysaccharide (LPS)-induced RAW264.7 macrophage model. Compounds 1, 2, and 4 exhibited significant inhibition of nitric oxide (NO) production, with IC(50) values of 7.14 ± 1.89, 8.55 ± 0.37, and 14.76 ± 0.39 μM. Furthermore, compounds 1 and 2 suppressed the secretion of key pro-inflammatory cytokines, including TNF-α, IL-6, and IL-1β, in the same cellular model. These results not only enhanced the structural diversity of SPAs identified from T. wilfordii, but also highlight their potential as promising anti-inflammatory lead compounds.