Influence of trans-cis isomerisation of coumaric acid substituents on colour variance and stabilisation in anthocyanins.

The recently isolated pigments from Petunia integrifolia and Triteleia bridgesii present a distinct feature that sheds new light on the understanding of intramolecular copigmentation of anthocyanins. These are among the infrequent anthocyanins that naturally present a coumaric acid substituent in both cis and trans forms. As a consequence, the two isomers demonstrate substantial variations of their thermodynamic and kinetic constants and also colour properties. A possible explanation for these characteristics is presented, making use of molecular modelling and taking into account the three-dimensional structures of the pigments.

Acylated delphinidin 3-rutinoside-5-glucosides in the flowers of Petunia reitzii.

Two acylated anthocyanins were isolated from selected individuals of Petunia reitzii, and identified to be delphinidin 3-O-[6-O-(4-O-(4-O-(6-O-(trans-caffeoyl)-beta-D-glucopyranosyl)-tr ans-p-coumaroyl)-alpha-L-rhamnopyranosyl)-beta-D-glucopyranoside]- 5-O-[beta-D-glucopyranoside] and delphinidin 3-O-[6-O-(4-O-(4-O-(beta-D-glucopyranosyl)-trans-p-coumaroyl)-alph a-L-rhamnopyranosyl)-beta-D-glucopyranoside]-5-O-[beta-D-glucopyranoside ]. Nine known anthocyanins were also identified.

Differences in the floral anthocyanin content of red petunias and Petunia exserta.

In order to resolve a conflict between previous papers regarding the floral anthocyanins of red flowers of Petunia exserta, a naturally occurring species, the HPLC profile of this species was compared with that of commercial red garden petunias. Both HPLC profiles extremely superficially resemble each other in terms of relative amounts and retention times of the major anthocyanins. However, co-elution on HPLC of the mixed sample resulted in clear separation of the components. Three major anthocyanins in red petunias were determined to be cyanidin 3-sophoroside, cyanidin 3-glucoside and peonidin 3-glucoside, which exhibited similar behaviors on HPLC to delphinidin 3-glucoside. delphinidin-3-rutinoside and petunidin 3-rutinoside, respectively, the major floral anthocyanins of P. exserta.

Anthocyanins in flowers of genus Rosa, sections Cinnamomeae (=Rosa), Chinenses, Gallicanae and some modern garden roses.

Forty-four taxa of three sections (Cinnamomeae (=Rosa) 26, Chinenses 8 and Gallicanae 10) and eight modern garden roses in the genus Rosa were surveyed for their floral anthocyanins. Eleven anthocyanins: 3-glucosides and 3,5-diglucosides of cyanidin (Cy), pelargonidin (Pg) and peonidin (Pn), 3-rutinosides and 3-rho-coumaroylglucoside-5-glucosides of Cy and Pn, and Cy 3-sophoroside, were isolated from flowers of these taxa and identified by chemical and spectroscopic techniques. Four anthocyanins: Cy 3-rutinoside, Pn 3-rutinoside, Pn 3-rho-coumaroylglucoside-5-glucoside and Cy 3-sophoroside were found for the first time in Rosa flowers.Investigated sections of wild roses showed characteristic distribution of anthocyanins. Cy 3,5-diglucoside was the dominant anthocyanin detected in all three sections, but accumulation of Pn 3,5-diglucoside distinguished sections Cinnamomeae from other sections, and the occurrence of Cy 3-glucoside separates section Chinenses from others.Cy 3-sophoroside was detected in large amount in some taxa of section Cinnamomeae: e.g., R. moyesii and its related cultivars, and R. rugosa cv. Salmon Pink. The acylated Cy glycoside was found in all sections and also in some modern garden roses, while the acylated Pn glycoside was detected in the section Cinnamomeae, but not in sections Chinenses and Gallicanae. According to anthocyanin distribution patterns, eight groups were classified chemotaxonomically in genus Rosa.

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.

Acylated pelargonidin 3-sambubioside-5-glucosides in Matthiola incana.

Ten acylated pelargonidin 3-sambubioside-5-glucosides were isolated from the red-purple flowers of Matthiola incana, and also pelargonidin 3-glucoside was isolated from the brownish-red flowers of this plant. FAB mass measurements of 10 acylated anthocyanins gave their molecular ions [M]+ at 903-1195 m/z, which were based on acylated pelargonidin 3-sambubioside-5-glucosides with malonic acid, sinapic acid, p-coumaric acid, caffeic acid and/or ferulic acid. This was confirmed by the analysis of NMR spectra and the experiments of acid and alkaline hydrolysis. By spectral and chemical methods, seven of the 10 pigments were determined to be pelargonidin 3-O-[2-O-(2-O-(acyl-I)-beta-D-xylopyranosyl)- 6-O-(acyl-II)-beta-D-glucopyranoside]-5-O-[6-O-(malonyl)-beta-D- glucopyranoside], in which acyl moieties varied between sinapic, ferulic, caffeic and p-coumaric acids. The occurrence of these pigments was examined in 10 red-purple, 10 salmon-pink, three apricot and three copper colour cultivars of M. incana by HPLC. The acylated pelargonidin 3-sambubioside-5-glucosides were present as the dominant pigments in the red-purple, salmon-pink and apricot colour cultivars. On the other hand, pelargonidin 3-glucoside was present as a dominant anthocyanin in the copper colour cultivars and also pelargonidin 3-sambubioside-5-glucoside was confirmed by HPLC as a minor pigment in the copper colour flowers.

Acylated cyanidin glycosides in the violet-blue flowers of Ipomoea purpurea.

Six acylated cyanidin glycosides were isolated from violet-blue flowers of Ipomoea purpurea. These anthocyanins were all based on cyanidin 3-sophoroside-5-glucoside, acylated with caffeic acid and/or p-coumaric acid. Three anthocyanin structures were elucidated to be cyanidin 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-glucopyran osyl) caffeyl)-beta-D-glucopyranoside]-5-O(-)[beta-D-glucopyranoside], cyanidin 3-O(-)[2-O-(trans-3-O-(beta-D-glucopyranosyl)caffeyl)-beta-D-glucopyrano syl)- 6-O-(trans-caffeyl)-beta-D-glucopyranoside]-5-O(-)[beta-D-glucopyranosid e d and cyanidin 3-O(-)[2-O-(6-O-(trans-caffeyl)-beta-D-glucopyranosyl)-6-O- (trans-caffeyl)-beta-D-glucopyranoside]-5-O(-)[beta-D-glucopyranoside]. These three anthocyanins were present in all 12 violet-blue flower strains as major pigments. The colours of these acylated antocyanins were stabler in neutral solution than their deacyl analogues.

Acylated cyanidin 3-sambubioside-5-glucosides in Matthiola incana.

Four acylated cyanidin 3-sambubioside-5-glucosides were isolated from purple-violet flowers of Matthiola incana and their structures were determined by chemical and spectroscopic methods. Three acylated anthocyanins were cyanidin 3-O-(6-O-acyl-2-O-(2-O-sinapyl-beta-D-xylopyranosyl)-beta-D- glucopyranosides)-5-O-(6-O-malonyl-beta-D-glucopyranosides), in which the acyl group is p-coumaryl, caffeyl or ferulyl, respectively. The remaining pigment is free from malonic acid and was identified as cyanidin 3-O-(6-O-trans-ferulyl-2-O-(2- O-trans-sinapyl-beta-D-xylopyranosyl)-beta-D-glucopyranoside)-5-O- (beta-D-glucopyranoside). Analysis of the anthocyanin constituents in 16 purple-violet cultivars revealed that they contained the above triacylated anthocyanins in variable amounts as main pigments. An aromatic pair of pigments containing sinapic and ferulic acids are considered to produce an important intramolecular effect, making bluish colours in these flowers.

An acylated cyanidin glycoside in the red-purple flowers of x Laeliocattleya cv mini purple.

A new acylated anthocyanin was isolated from the red-purple flowers of x Laeliocattleya cv Mini Purple as one of the major anthocyanins. The structure of this pigment was determined to be cyanidin 3-O-[6-O-(malonyl)-beta-D-glucopyranoside]-7-O-[6-O-(trans-p- coumaryl)-beta-D-glucopyranoside]-3'-O-[6-O-[trans-4-O-[6-O-(trans-p- coumaryl)-beta-D-glucopyranosyl]-p-coumaryl]-beta-D-glucopyranoside] based on spectroscopic methods.