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-(β- d-glucopyranosyl)-caffeyl )-β- d-glucopyranosyl )-6-O-(trans-4-O-(6-O-(trans- caffeyl)-β- d-glucopyranosyl)-caffeyl )-β- d-glucopyranoside ]-5-O-[β-rm d-glucopyranoside] pelargonidin 3-O-[2-O-(6-O-(trans- caffeyl)-β- d-glucopyranosyl )-6-O-(trans-4-O-(6-O-(trans- caffeyl)-β- d-glucopyranosyl )- caffeyl)-β- d-glucopyranoside ]-5-O-[β- d-glucopyranoside ] and pelargonidin 3-O-[2-O-(6-O-(trans- caffeyl)-β- d-glucopyranosyl )-6-O-(trans- caffeyl)-β- d-glucopyranoside ]-5-O- [β- d-glucopyosdide ] . Another anthocyanin was pelargonidin 3- O-[2- O-(glucosylcaffeylglucosyl)-6- O-(caffeyl)-glucoside]-5-gluoside, 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.