Tirucallane triterpenoids from the stems of Brucea mollis

Three new tirucallane triterpenoids, brumollisols A-C (1-3, resp.), together with five known analogues, (23R,24S)-23,24,25-trihydroxytirucall-7-ene-3,6-dione (4), piscidinol A (5), 24-epipiscidinol A (6), 21α-methylmelianodiol (7), and 21β-methylmelianodiol (8), were isolated from an EtOH extract of the stems of Brucea mollis. Their structures were elucidated by means of spectroscopic methods including 1D- and 2D-NMR techniques and mass spectrometry. In the in vitro assays, compound 6 exhibited significant cytotoxic activity against A549 and BGC-823 cancer cells with IC50 values of 1.16 and 3.01 μM, respectively. At a concentration of 10 μM, compounds 1-5, 7, and 8 were found to inhibit NO production in mouse peritoneal macrophages with inhibitory ratios ranging from 39.8±7.7 to 68.2±4.5%.