Extraction and Reglucosylation of Barbarea vulgaris Sapogenins

Abstract

Plants produce a vast array of natural compounds. Many of them are not commercially available, and are thus lacking to be tested as substrates for enzymes. This protocol describes the extraction and acidic hydrolysis of metabolites from Barbarea vulgaris with special focus on saponins and their agylcones (sapogenins). It was developed to determine if some B. vulgaris UDP-glucosyltransferases (UGTs) that were shown to glucosylate commercially available sapogenins, would also accept additional sapogenins from this plant as substrate, which are yet chemically uncharacterized and/or commercially unavailable (Figure 1).Figure 1. Glucosylation reaction catalyzed by UGT73C10-UGT73C13 from Barbarea vulgaris (Augustin et al., 2012). All four enzymes utilize uridine diphosphate glucose (UDP-glc) as glucosyl-moiety donor and different sapogenins such as the oleanane sapogenins oleanolic acid and hederagenin as glucosyl-moiety acceptor. Oleanolic acid and hederagenin both naturally occur in G-type B. vulgaris, where they are predominantly found in their 3-O-cellobiosylated form. Additional saponins from G-type B. vulgaris have been identified by Nielsen et al., 2010. However, the majority of saponins and sapogenins that occur in B. vulgaris remain unidentified., 植物产生大量的天然化合物。 其中许多不是可商购的，因此缺乏作为酶的底物的测试。 该协议描述了从寻常型巴布巴属植物中提取和酸性水解代谢物，特别关注皂苷及其苷元（皂苷元）。 它被开发以确定是否有一些。 显示用于使市售皂苷元葡萄糖基化的普通UDP葡萄糖基转移酶（UGT）也将接受来自该植物的另外的皂苷元作为底物，其仍然是化学上未表征的和/或商业上不可获得的（图1）。