Colin F. Timberlake

Identification of an anthocyanin occurring in some red wines

Abstract An anthocyanin-type pigment, vitisin A, was found in small amounts in some red wines and at trace levels in stored grapes. HPLC and spectrophotometric analysis showed that vitisin A exhibited a unique UV-Vis spectrum. Vitisin A was isolated, purified and identified using FAB mass spectrometry and NMR. The aglycone, vitisidin A, is 68 mass units greater than malvidin, accounted for by an additional C 3 O 2 substituent. Further accurate mass determinations and NMR studies of both malvidin 3-glucoside and vitisin A confirmed that vitisin A is based on malvidin 3-glucoside with an additional C 3 O 2 between position 4 and the 5-hydroxyl of the molecule. Five different isomers were distinguished by NMR, namely the flavylium cation, quinonoidal base, chalcone form and two carbinol pseudobases. The assignment of one of the protons remains tentative due to the rapid hydrogen/deuterium exchange. The structure was determined to be 3-formyl-4- d -β-glucopyranosyloxy-8-hydroxy-5-(4-hydroxy-3,5-dimethoxy)phenyl-2-oxo-1,6-dioxa-2,3-dihydrophenalene.

Cyanidin 3-malonylglucoside in Cichorium intybus

Abstract The major anthocyanin of red leaves of Cichorium intybus has been identified as cyanidin 3-O-β-(6-O-malonyl)- d -glucopyranoside by fast atom bombardment mass spectrometry and NMR spectroscopy.

A blue pigment complex in flowers of Salvia patens

Abstract A blue pigment complex, protodelphin, was isolated from the blue flowers of Salvia patens. The absorption spectrum of its aqueous solution has two maxima in the visible region and the blue complex is stable in neutral or acidic aqueous solution. Protodelphin was shown to be composed of delphinidin 3-(6″-p-coumaroylglucoside)-5(6″-malonylglucoside), apigenin 7,4′-diglucoside and magnesium. This was confirmed by the in vitro synthesis of protodelphin from its component parts, malonyl awobanin, apigenin 7,4′-diglucoside and magnesium. The yield of the blue pigment was to a certain extent proportional to the amount of magnesium added to the reaction mixture and the stable blue complex was not obtained without this element. Similar blue complexes were formed by the use of manganese, cobalt, nickel, zinc and cadmium instead of magnesium. The results show the true blue colour of the flowers is manifested by the metallo-anthocyanin which contains magnesium as chelating metal and is a similar complex to commelinin.

Stable blue complexes of anthocyanin-aluminium-3-p-coumaroyl- or 3-caffeoyl-quinic acid involved in the blueing of Hydrangea flower

Abstract In a comparison of the behaviour of three esters of p -coumaroylquinic acid, only 3- p -coumaroylquinic acid formed a stable blue complex with hydrangea anthocyanin (delphinidin-3-glucoside) and aluminium; the 4- and 5-isomers were ineffective. Complex formation was almost identical with that occurring with 3-caffeoylquinic acid. Solutions of both ternary complexes were very stable at pH 3.7 at room temperature. Similar colour augmentation occurred with 3- p -coumaroylquinic acid, aluminium and cyanidin 3-glycoside but not with pelargonidin or malvidin glucosides. It is proposed that aluminium conjugates with the ortho -dihydroxy group of the anthocyanin B ring and the carboxyl and α-hydroxyl groups of the quinic acid moiety and that the complexes are stabilized in the manner of acylated anthocyanins.

Fast atom bombardment mass spectrometry of the anthocyanins violanin and platyconin

Abstract Fast atom bombardment mass spectrometry (FABMS) of the acylated anthocyanin violanin confirmed its molecular mass (919) and gave a fragmentation pattern in agreement with its known structure. FABMS of the more complex flower pigment platyconin gave its accurate molecular mass as 1421.3740 and a fragmentation pattern suggesting that platyconin is delphinidin 3-rutinoside-5-glucoside with two mols of glucosylcaffeic acid attached to the glucose moiety of rutinose in a branched-chain arrangement.

Some unusual anthocyanins occurring naturally or as artifacts

Abstract Artifacts appeared during chromatographic purification of anthocyanins in BAW (butanol-acetic acid-water, 4:1:5); they were shown to be produced by the combined action of acetic and hydrochloric acids during concentration of components eluted from the paper. The extent of their formation depended upon the nature of the sugar, e.g. cyanidin 3-glucoside formed an artifact more readily than cyanidin 3-galactoside. These and similar anthocyanins produced using propionic, butyric and valeric acids instead of acetic acid were assumed to be acylated with the appropriate acid. An artifact of similar type occurred also during solvent development (BAW) of strongly acid solutions of pelargonidin 3-glucoside but not of cyanidin or delphinidin 3-monosides. Two naturally occurring anthocyanins of similar properties found in Cichorium intybus leaves appeared to be acylated derivatives of the main pigment, cyanidin 3-glucoside.

Anthocyanins in Salix species: A new anthocyanin in salix purpurea bark

Abstract Cyanidin 3-glucoside and delphinidin 3-glucoside (minor component) occurred in the bark of Salix purpurea (29 cultivars examined), S. fragilis (3 cvs), S. americana (4 cvs), S. rubra (1 cv.), S. incana (1 cv.), S. aegyptica (1 cv.) and S. alba (3 cvs) and several hybrids. A previously unrecorded anthocyanin was also present in appreciable amounts in the bark of eleven S. purpurea cultivars, notably those with small leaves. In other large-leaved cultivars of S. purpurea (18) it occurred only in traces or was not detected with certainty. A trace was found in one purpurea hybrid, but it was not detected in four others. Small amounts of the new anthocyanin were also found in S. incana (1 cv.), S. fragilis cv. Basfordiana, S. americana cv. Cordata and one hybrid, but were absent from other cultivars of S. fragilis (2) and S. americana (2), and also from S. alba (3), S. aegyptica (1), S. daphnoides (1), S. rubra (1), S. triandra (1), S. viminalis (1) and three hybrids. The new anthocyanin is unique in containing fructose as well as glucose and is based upon a previously undescribed anthocyanidin, possibly dimeric in nature, which is provisionally named purpurinidin.

Anthocyanins in salix species

Abstract The anthocyanin pattern of Salix bark shows some differences between species. S. daphnoides and S. alba contain only cyanidin 3-glucoside; S. phylicifolia , S. nigricans , S. calodendron and S. viminalis contain both cyanidin and delphinidin 3-glucosides; S. triandra and S. amygdalina contain delphinidin, cyanidin and petunidin 3-glucosides.