植物五环三萜类化合物生物合成途径研究进展

五环三萜类化合物是一类重要的植物次生代谢产物,由6个异戊二烯单元组成,在自然界中普遍存在,具有广泛的药理作用。五环三萜类化合物结构丰富多样,根据其苷元的不同,可分为齐墩果烷型、羽扇豆烷型、乌苏烷型和木栓烷型4大类。植物五环三萜类化合物主要由甲羟戊酸途径和戊糖磷酸途径合成,2,3-环氧角鲨烯前体在氧化鲨烯环化酶的作用下环化为不同的骨架,继而在细胞色素P450以及糖基转移酶的修饰下形成多种皂苷。综述了植物五环三萜类化合物生物合成途径的研究进展,对参与合成途径的关键家族基因进行系统分析和催化机制的解读,为寻找未知五环三萜类化合物生物合成途径关键基因和五环三萜化合物异源生物合成提供参考。

Research progress on biosynthesis pathway of pentacyclic triterpenoids in plants

Pentacyclic triterpenoids are secondary metabolites from plants composed of six isoprene units, which are ubiquitous in nature with extensive pharmacological effects. Pentacyclic triterpenoids display a variety of structures. Based on the carbon skeleton, they are divided into four common subgroups:oleanane, lupane, ursane, and xylene. Biosynthesis of pentacyclic triterpenoids in plants proceeds via mevalonate pathway and 2-C-methyl-derythritol 4-phosphate pathway. Under the catalysis of oxidosqualene cyclase, 2,3-oxidosqualene is biosynthetically oxidized to various cyclic triterpene skeletons. Cyclized triterpenes are further oxidized by cytochrome P450-dependent monooxygenases and subsequently glycosylated by uridine diphosphate-glucosyltransferases to form various saponins. Research progress on biosynthesis pathway of pentacyclic triterpenoids in plants are reviewed in this paper. In addition, key family genes involved in the synthesis pathway are systematically analyzed and catalytic mechanism is interpreted, in order to provide a reference for finding key genes for biosynthesis pathway of pentacyclic triterpenoids and heterobiosynthesis of pentacyclic triterpenoids.