Acylated Cyanidin 3-sophoroside-5-glucosides from the Purple Roots of Red Radish (Raphanus sativus L.) 'Benikanmi'

Four new acylated cyanidin glycosides were isolated from the purple root peers of Raphanus sativus L. 'Benikanmi', along with five known anthocyanins. These pigments were based on cyanidin 3-sophoroside-5-glucoside, and acylated diversely with malonic,p-coumaric, caffeic, and ferulic acids. Two pigments of these four new anthocyanins were determined to be cyanidin 3-O-[2-O-(beta-glucopyranosyl)-6-O-(trans-feruloyl)-beta-glueopyranoside]-5-O-[6-O-(malonyl)-beta-glueopyranoside] and cyanidin 3-[2-(glucosyl)-6-(cis-p-coumaroyl)-glucoside]-5-[6-(malonyl)-glucoside] by chemical and spectroscopic methods. Since two other new pigments were obtained in small quantities, their structures were tentatively assigned to be malonyl cyanidin 3-sophoroside-5-glucoside and malonyl cyanidin 3-[2-(glucosyl)-6-(trans-caffeoyl)-glucoside]-5-glucoside, mainly on the basis of their spectroscopic data. From the results, the potential of these purple root anthocyanins as natural food colorants is discussed.