Acylated pelargonidin glycosides in red-purple flowers of Ipomoea purpurea.

Four acylated pelargonidin glycosides were isolated from the red-purple flowers of Ipomoea purpurea. The acylated anthocyanins were all based on pelargonidin 3-sophoroside-5-glucoside, acylated with caffeic acid and/or glucosylcaffeic acids. Three novel anthocyanins were elucidated to be pelargonidin 3-O-[2-O-(6-O-(trans-3-O-(beta-D-glucopyranosyl)-caffeyl)- beta-D-glucopyranosyl)-6-O-(trans-4-O-(6-O-(trans-caffeyl)-beta-D- glucopyranosyl)-caffeyl)-beta-D-glucopyranoside]-5-O- [beta-D-glucopyranoside], pelargonidin 3-O-[2-O-(6-O-(trans-caffeyl)-beta-D-glucopyranosyl)-6-O- (trans-4-O-(6-O-(trans-caffeyl)-beta-D-glucospyranosyl)-ceffeyl )-beta-D- glucopyranoside]-5-O-[beta-D-glucopyranoside] and pelargonidin 3-O[2-O-(2-O-(6-O-(trans-caffeyl)-beta-D-glucopyranosyl)-6-O- (trans-caffeyl)-beta-D-glucopyranoside]-5-O-[beta-D-glucopyoside]. Another anthocyanin was pelargonidin 3-O-[2-O-(glucosylcaffeylglucosyl)-6-O-(caffeyl)-glucoside]-5-gluc oside, which was reported to be present in the red-purple flowers of Pharbitis nil. Apart from the second pigment cited, these are analogous pigments of the violet-blue Ipomoea anthocyanins which are composed of acylated cyanidin glycosides, instead of pelargonidin.