Abietane diterpenoids from Isodon inflexus

Four abietane Diterpenoids, inflexanin C, inflexanin D, inflexuside A and inflexuside B, were isolated from the aerial parts of Isodon inflexus. Their respective structures were established by NMR, mass spectrometry and CD as (+)-(1S,4R,5S,7S,8S,10S,13S)-1,7,18-trihydroxy-abieta-9(11)-ene-12-one 1-monoacetate, (+)-(1S,4R,5S,10S,13S)-1,18-dihydroxy-abieta-7,9(11)-diene-12-one 1-monoacetate, (-)-(1S,5S,10S,11R,13R)-1,11,13-trihydroxy-abieta-8-ene-7-one 1-O-β-D-glucopyranoside and (-)-(1S,5S,10S,11R,13R)-1,11,13-trihydroxy-abieta-8-ene-7-one 1-O-(2-O-coumaroyl)-β-D-glucopyranoside. All compounds showed strong inhibitory activity against nitric oxide (NO) production in RAW264.7 lipopolysaccaride (LPS)-activated macrophages.