New phenolic triterpenes from Maytenus blepharodes. Semisynthesis of 6-deoxoblepharodol from pristimerin

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• 作者：Rodrí ; guez ; Fé ; lix M. ; Ló ; pez ; Manuel R. ; Jimé ; nez ; Ignacio A. ; et. al.
• 关键词：Phenolic triterpenes ; Semisynthesis ; Maytenus blepharodes ; Celastraceae
• 刊名：Tetrahedron
• 出版年：2005
• 期刊代码：107_00404020
• 类别：ch
• 出版时间：February 28, 2005
• 卷：61
• 期：9
• 页码：2513-2519
• 文件大小：367 K

摘要

Four new phenolic triterpenes with a 24-nor-D:A-friedoleane skeleton, isoblepharodol, 7-oxoblepharodol, blepharotriol and 6-deoxoblepharodol, were isolated from Maytenus blepharodes. Their structures were elucidated on the basis of spectroscopic analysis, including homo and heteronuclear correlation NMR experiments (COSY, ROESY, HSQC, and HMBC). The semisynthesis of 6-deoxoblepharodol and its epimer at C-8 was achieved by catalytic reduction of pristimerin, a quinone-methide triterpene present in the plant. The biosynthetic formation of the phenolic triterpenes isolated from this species is also discussed. The compounds were assayed for antimicrobial and cytotoxic activities.