Anti-inflammatory sesquiterpene pyridine alkaloids from Tripterygium wilfordii

During a screening procedure involving higher plants to find novel candidates for use as anti-inflammatory agents, Tripterygium wilfordii Hook. f. was shown to exhibit considerable inhibitory activity. Five new sesquiterpene pyridine alkaloids, tripterygiumines S-W (1-4,15), along with 14 known dihydroagarofuran derivatives, were isolated from the roots of the T. wilfordii Hook. f. Their structures were established by extensive use of spectroscopic techniques, including 1D and 2D NMR spectroscopy and high-resolution mass spectrometry. All compounds were evaluated for their anti-inflammatory activity by measuring the nitric oxide production by the LPS-induced murine macrophage cell line RAW264.7. It was found that 1, 5, and 19 possessed potent nitric oxide inhibitory activity with IC50 values ranging from 2.99 to 28.80 μM, without any effect on the cell viability of RAW264.7 cells. Accordingly, compounds 1, 5, and 19, especially 5, were identified as promising candidates for further scientific investigation of their potential use as anti-inflammatory agents.