Chisopanins A-K, 11 new protolimonoids from Chisocheton paniculatus and their anti-inflammatory activities.

Eleven new protolimonoids, chisopanins A-K (1-11), were isolated from the twigs of Chisocheton paniculatus, as well as thirteen known (12-24) protolimonoids. The structures were elucidated on the basis of spectroscopic analysis, X-ray crystallographic analysis, and chemical methods. Chisopanins A and B (1 and 2) possessing uncommon hemiketal tetrahydropyran ring at C-17 showed the most potent inhibitory activities on lipopolysaccharide-stimulated inflammation factor-release with IC(50) values at 5.4 and 7.9 μM for NO, and at 26.9 and 30.7 μM for TNF-α, respectively. In addition, compounds 5-7, 9, 12, 13, and 20 were potent to inhibit NO production with IC(50) value lower than 10 μM.