Isolation and structure elucidation of two new cassane derivatives from the seed kernels of Caesalpinia sinensis

Two new cassane-type derivatives (1–2), together with three known compounds (3–5), were isolated from the seed kernels of Caesalpinia sinensis. Their structures were elucidated on the basis of interpretation of comprehensive spectroscopic data, including HRESIMS and 1D/2D NMR spectroscopy, and the absolute configuration were established by means of ECD calculation. Compound 2, possessing a 16-degradative cassane skeleton, was rarely encountered in cassane diterpenoids isolated from the genus Caesalpinia. All compounds were evaluated for their anti-inflammatory activities against the overproduction of NO in LPS-stimulated RAW 264.7 macrophages, and compounds 1–5 could inhibit production of NO at the concentration of 50 μM.