萝卜花色苷的结构研究

Chemical Structures of Anthocyanins in Red Radishes

红皮白心萝卜的色素提取物经大孔树脂XAD-7HP和葡聚糖凝胶Sephadex LH-20纯化后,结合半制备色谱制备花色苷单体,最后通过LC-MSn和NMR技术手段对萝卜花色苷单体的结构进行分析。通过LC-MSn鉴定出萝卜皮中主要存在四种主要的花色苷,都是以天竺葵色素为苷元,带一个单糖和一个二糖的花色苷衍生物,即以天竺葵-3-槐糖苷-5-葡糖苷为基本结构,带有一个或是两个酰基化的基团,如丙二酸、阿魏酸或香豆酸。经由1H NMR方法,其中三种花色苷的具体结构鉴定为:3-[6-(对香豆酰)-L-葡萄苷(2→1)-葡糖苷]-5-D-吡喃葡糖苷天竺葵素、3-[6-(阿魏酰)-L-葡萄苷(2→1)-葡糖苷]-5-D-吡喃葡糖苷天竺葵素、3-[6-(对香豆酰)-L-葡萄苷(2→1)-葡糖苷]-5-[(6-丙二酰)-D-吡喃葡糖苷]天竺葵素。通过质谱信息和文献报道,第四种花色苷的结构应为3-[6-(阿魏酰)-L-葡糖苷(2→1)-葡糖苷]-5[-(6-丙二酰)-D-吡喃葡糖苷]天竺葵素。

Radish anthocyanins were isolated from pigment-riched extracts of red radish by using XAD-7HP and Sephadex LH-20 for purification, and half prepared liquid chromatograph （HPLC） for preparation of anthocyanin monomer. The anthocyanin structures were analyzed using LC-MSn and NMR. Four anthocyanins in red radishes were identified as pelargonidin derivatives with one or two sugar moieties and some with acylation. By 1H NMR analysis, three anthocyanins were identified as pelargonidin-3-（6-coumaroyl）- sophoroside-5-D- pyranoglucoside, pelargonidin-3-（6-feruloyl）-sophoroside-5-D-pymnoglucoside, and pelargonidin-3-（6-coumaroyl）- sophoroside-5-（6-malonyl）- pyranoglucoside. In addition, pelargonidin-3-（6-feruloyl）-sophoroside-5-（6-malonyl） -D-pyranoglucoside as the fourth anthocyanin has been found in red radishes by mass spectrum data.