Diterpenoids from the whole plants of Croton yunnanensis and their bioactivities.
Su XM, Liang Q, Hu JX, Zhang XM, Jia RL, Xu WH.
Four new 19-nor-clerodane diterpenoids (1-4), one new 15,16-dinor-ent-pimarane diterpenoid (5) together with four known diterpenoids (6-9) were isolated from whole plants of Croton yunnanensis. The structures of these compounds were determined by extensive spectroscopic methods including 1D, 2D NMR, HR-ESI-MS, and by comparing their NMR data with those of previously reported compounds. The experimental and calculated electronic circular dichroism data were used to define their absolute configurations. The <sup>1</sup>H and <sup>13</sup>C NMR spectra of 6 were completely assigned for the first time. All isolated compounds (1-9) were evaluated for their cytotoxic activities against five human cancer cell lines (including SMMC-7721, HL-60, A-549, MCF-7, and SW-480), and anti-inflammatory activities in LPS-induced RAW264.7 macrophages. Crotonyunnan E (5) exhibited selective cytotoxicities against three tumor cell lines, SMMC-7721 (human hepatoma cells, IC<sub>50</sub> 4.47 ± 0.39 μM), HL-60 (human premyelocytic leukemia, IC<sub>50</sub> 14.38 ± 1.19 μM), and A-549 (human lung cancer cells, IC<sub>50</sub> 27.42 ± 0.48 μM), while none of the compounds showed obviously anti-inflammatory activities at 50 μM level.