New sesquiterpenoids from the dried flower buds of Tussilago farfara and their inhibition on NO production in LPS-induced RAW264.7 cells

Three new sesquiterpenoids, 1α-(3″-ethyl-cis-crotonoyloxy)-8-angeloyloxy-3β,4β-epoxy-bisabola-7(14),10-diene (1), 7β-angeloyloxy-14-hydroxy-notonipetranone (2) and 1α-hydroxy-7β-(4-methylsenecioyloxy)-oplopa-3(14)Z,8(10)-dien-2-one (3) were isolated from ethanolic extract of the dried flower buds of Tussilago farfara L., along with nine known sesquiterpenoids (4–12). All of these compounds were evaluated for their effect on the inhibition of nitric oxide (NO) production induced by lipopolysaccharide in macrophage cell line RAW 264.7 and exhibited inhibitory activity on NO production in a dose-dependent manner. 7β-(4-Methylsenecioyloxy)-oplopa-3(14)E,8(10)-dien-2-one (8) was proved to be the best among these tested sesquiterpenoids with an IC50 value of 10.80 μM.