Acylated pelargonidin glycosides from the red-purple flowers of Iberis umbellata L. and the red flowers of Erysimum × cheiri (L.) Crantz (Brassicaceae)

Abstract

Five previously undescribed acylated pelargonidin 3-sophoroside-5-glucosides (pigments 2-6) were isolated from the red-purple flowers of Iberis umbellata L. 'Candycane Rose' and 'Candycane Red', in addition to a known one (pigment 1). The structures of five undescribed acylated anthocyanins were determined by chemical and spectroscopic methods to be pelargonidin 3-O-[2-O-(2-O-("acyl-A")-β-glucopyranosyl)-6-O-("acyl-B")-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside], in which the "acyl-A" group was either trans-sinapic (2), trans-ferulic (3), trans-sinapic (4), trans-ferulic (5), or trans-ferulic acid (6), and "acyl-B" was either glucosyl-trans-p-coumaric acid (2), glucosyl-trans-p-coumaric acid (3), trans-feruloyl-glucosyl-trans-p-coumaric acid (4), trans-feruloyl-glucosyl-trans-p-coumaric acid (5), or glucosyl-trans-feruloyl-glucosyl-trans-p-coumaric acid (6). Moreover, three previously undescribed acylated pelargonidin 3-sambubioside-5-glucosides (pigments 7, 8, and 10) and one undescribed acylated pelargonidin 3-(3^X-glucosylsambubioside)-5-glucoside (pigment 9) were isolated from the red flowers of Erysimum × cheiri (L.) Crantz 'Aurora' as major anthocyanins. The structures of the three undescribed acylated pelargonidin 3-sambubioside-5-glucosides were determined to be pelargonidin 3-O-[2-O-(2-O-("acyl-C")-β-xylopyranosyl)-6-O-("acyl-D")-β-glucopyranoside]-5-O-(β-glucopyranoside), in which the "acyl-C" group was either non (7), non (8), or trans-p-coumaric acid (10) and "acyl-D" was either trans-p-coumaric (7), trans-ferulic (8), or trans-p-coumaric acid (10). Moreover, a previously undescribed acylated pelargonidin 3-(3^X-glucosylsambubioside)-5-glucoside was identified to be pelargonidin 3-O-[2-O-(2-O-(trans-p-coumaroyl)-3-O-(β-glucopyranosyl)-β-xylopyranosyl)-6-O-(trans-p-coumaroyl)-β-glucopyranoside]-5-O-(β-glucopyranoside) (9). In addition, the distribution of anthocyanidins structural elements in 24 Brassicaceous species is compared.

Keywords: Acylated pelargonidin 3-sambubioside-5-glucoside; Acylated pelargonidin 3-sophoroside-5-glucoside; Brassicaceae; Erysimum × cheiri (L.) Crantz.; Ferulic acid; Iberis umbellata L.; Malonic acid; Sinapic acid; p-Coumaric acid.