Three new cassane diterpenoids from the seed kernels of Caesalpinia sinensis

Three new cassane derivatives, caesall FE (1) and caesalminaxin HC-HD (2-3), together with four known compounds (4-7) were separated from the seed kernels of Caesalpinia sinensis, and their structures were elucidated by means of analysis of comprehensive spectroscopic data, especially 1D and 2D NMR and HRESIMS. Compounds 13 represented the new examples of cassane diterpenoids containing an isomerized furan ring fused with an aromatized C ring or conjugated with one additional double bond. Biological evaluation revealed that compounds 1-7 could inhibit the overproduction of NO induced by LPS, and compounds 2 and 4-6 exhibited the inhibitory ration more than 60 % at the concentration of 50 mu M.