The first investigation of phytochemistry on the seed kernels of Caesalpinia sinensis led to the isolation and characterization of six new compounds including three tricyclic-type cassane diterpenoids (1--3) and three norcassane-type diterpenoids (4-6), together with three know compounds (7-9). Compounds 1-9 represented the first discovery of cassane-type diterpenoids from C. sinensis. Their structures were elucidated by a combination of spectroscopic analysis, single-crystal X-ray diffraction experiment and ECD calculation. The characters for compounds 4 and 5 possessing the 15,16-degradative cassane skeleton were observed, which was extremely rare structural type in the genus Caesalpinia. The anti-inflammatory activities of all isolates were evaluated via examining their inhibitory effects against NO production in LPS-simulated RAW 264.7 cells. The results demonstrated that compound 1 exhibited the most significantly inhibitory efficacy with inhibition rate 67.3% at 10 μM. The iNOS enzyme activity assay further revealed that compound 1 showed potent NO inhibitory effect by reducing the enzymatic activity of iNOS.
Keywords: Anti-inflammation; Caesalpinia sinensis; Cassane diterpenoids; iNOS enzyme activity.
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