Grace Mary H, Jin Yinghua, Wilson George R, Coates Robert M
Department of Chemistry, University of Illinois, Urbana, IL 61801, USA.
Phytochemistry. 2006 Aug;67(16):1708-15. doi: 10.1016/j.phytochem.2005.09.026. Epub 2005 Nov 18.
Extraction of Petalostigma pubescens heartwood followed by chromatographic purifications and crystallizations afforded five tricyclic diterpenes: 5,9-syn-rosanes petalostigmones A and B (1 and 2), the erythroxylane petalostigmone C (3), the norditerpene lactone pubescenone (4), and the known ent-cleistanthane diterpene (-)-sonderianol (5). The structures and relative stereochemistry were elucidated by means of spectroscopic methods, chemical correlations, and, in the cases of 1 and 4, by X-ray crystallographic analyses. The new isolates 1-4 are assumed to belong to the same absolute configurational family (9alphaCH3) of ent-pimarane-derived diterpenes as the known co-occurring (-)-5 (10alphaCH3). Biogenetic schemes originating from a common ent-copalyl diphosphate intermediate are presented to rationalize the structures of these natural products. A novel ring contraction-ring expansion mechanism is suggested to account for the 7-membered B ring of pubescenone. Compounds 1-5 were evaluated for their cytotoxicity; sonderianol (5) showed the highest activity against mouse leukemia cell lines L1210, P388 and mouse liver cancer cells HEPA1c1c7.
对柔毛瓣蕊木心材进行提取，随后通过色谱纯化和结晶，得到了五种三环二萜类化合物：5,9-顺式-玫瑰烷类的瓣蕊木酮A和B（1和2）、赤藓烷类的瓣蕊木酮C（3）、降二萜内酯柔毛酮（4）以及已知的对映-贝壳杉烷二萜（-）-桑德利亚醇（5）。通过光谱方法、化学关联以及在化合物1和4的情况下通过X射线晶体学分析确定了其结构和相对立体化学。新分离得到的化合物1-4被认为与已知同时存在的（-）-5（10α-CH3）属于源自对映-海松烷二萜的相同绝对构型家族（9α-CH3）。提出了源自共同的对映-贝壳杉烯二磷酸中间体的生源合成途径，以解释这些天然产物的结构。提出了一种新颖的环收缩-环扩展机制来解释柔毛酮的七元B环。对化合物1-5的细胞毒性进行了评估；桑德利亚醇（5）对小鼠白血病细胞系L1210、P388和小鼠肝癌细胞HEPA1c1c7表现出最高活性。
