Faculty of Pharmaceutical Sciences, Hoshi University, Shinagawa, Tokyo 142-8501, Japan.
Phytochemistry. 2012 Aug;80:99-108. doi: 10.1016/j.phytochem.2012.04.011. Epub 2012 Jun 13.
Three covalent anthocyanin-flavonol complexes (pigments 1-3) were extracted from the violet-blue flower of Allium 'Blue Perfume' with 5% acetic acid-MeOH solution, in which pigment 1 was the dominant pigment. These three pigments are based on delphinidin 3-glucoside as their deacylanthocyanin and were acylated with malonyl kaempferol 3-sophoroside-7-glucosiduronic acid or malonyl-kaempferol 3-p-coumaroyl-tetraglycoside-7-glucosiduronic acid in addition to acylation with acetic acid. By spectroscopic and chemical methods, the structures of these three pigments 1-3 were determined to be: pigment 1, (6(I)-O-(delphinidin 3-O-(3(I)-O-(acetyl)-β-glucopyranoside(I))))(2(VI)-O-(kaempferol 3-O-(2(II)-O-(3(III)-O-(β-glucopyranosyl(V))-β-glucopyranosyl(III))-4(II)-O-(trans-p-coumaroyl)-6(II)-O-(β-glucopyranosyl(IV))-β-glucopyranoside(II))-7-O-(β-glucosiduronic acid(VI)))) malonate; pigment 2, (6(I)-O-(delphinidin 3-O-(3(I)-O-(acetyl)-β-glucopyranoside(I))))(2(VI)-O-(kaempferol 3-O-(2(II)-O-β-glucopyranosyl(III))-β-glucopyranoside(II))-7-O-(β-glucosiduronic acid(VI)))); and pigment 3, (6(I)-O-(delphinidin 3-O-(3(I)-O-(acetyl)-β-glucopyranoside(I))))(2(VI)-O-(kaempferol 3-O-(2(II)-O-(3(III)-O-(β-glucopyranosyl(V))-β-glucopyranosyl(III))-4(II)-O-(cis-p-coumaroyl)-6(II)-O-(β-glucopyranosyl(IV))-β-glucopyranoside(II))-7-O-(β-glucosiduronic acid(VI)))) malonate. The structure of pigment 2 was analogous to that of a covalent anthocyanin-flavonol complex isolated from Allium schoenoprasum where delphinidin was observed in place of cyanidin. The three covalent anthocyanin-flavonol complexes (pigment 1-3) had a stable violet-blue color with three characteristic absorption maxima at 540, 547 and 618nm in pH 5-6 buffer solution. From circular dichroism measurement of pigment 1 in the pH 6.0 buffer solution, cotton effects were observed at 533 (+), 604 (-) and 638 (-) nm. Based on these results, these covalent anthocyanin-flavonol complexes were presumed to maintain a stable intramolecular association between delphinidin and kaempferol units closely related to that observed between anthocyanin and hydroxycinnamic acid residues in polyacylated anthocyanins. Additionally, an acylated kaempferol glycoside (pigment 4) was isolated from the same flower extract, and its structure was determined to be kaempferol 3-O-sophoroside-7-O-(3-O-(malonyl)-β-glucopyranosiduronic acid).
从葱属“蓝香”的蓝紫色花朵中用 5%乙酸-MeOH 溶液提取了三种共价花色苷-黄酮醇络合物（色素 1-3），其中色素 1 是主要色素。这三种色素以飞燕草素 3-葡萄糖苷为脱酰基花色苷，并与丙二酰基山柰酚 3-山梨糖苷-7-葡萄糖醛酸或丙二酰基山柰酚 3-对香豆酰基-四糖苷-7-葡萄糖醛酸酰化，此外还与乙酸酰化。通过光谱和化学方法，确定这三种色素 1-3 的结构为：色素 1，（6（I）-O-（飞燕草素 3-O-（3（I）-O-（乙酰基）-β-吡喃葡萄糖苷（I）））（2（VI）-O-（山柰酚 3-O-（2（II）-O-（3（III）-O-（β-吡喃葡萄糖基（V））-β-吡喃葡萄糖基（III））-4（II）-O-（反式对香豆酰基）-6（II）-O-（β-吡喃葡萄糖基（IV））-β-吡喃葡萄糖苷（II）））-7-O-（β-葡萄糖醛酸（VI））））丙二酸盐；色素 2，（6（I）-O-（飞燕草素 3-O-（3（I）-O-（乙酰基）-β-吡喃葡萄糖苷（I）））（2（VI）-O-（山柰酚 3-O-（2（II）-O-β-吡喃葡萄糖基（III））-β-吡喃葡萄糖苷（II））-7-O-（β-葡萄糖醛酸（VI））））；色素 3，（6（I）-O-（飞燕草素 3-O-（3（I）-O-（乙酰基）-β-吡喃葡萄糖苷（I）））（2（VI）-O-（山柰酚 3-O-（2（II）-O-（3（III）-O-（β-吡喃葡萄糖基（V））-β-吡喃葡萄糖基（III））-4（II）-O-（顺式对香豆酰基）-6（II）-O-（β-吡喃葡萄糖基（IV））-β-吡喃葡萄糖苷（II）））-7-O-（β-葡萄糖醛酸（VI））））丙二酸盐。色素 2 的结构类似于从葱属中分离出的共价花色苷-黄酮醇络合物，其中观察到飞燕草素代替矢车菊素。三种共价花色苷-黄酮醇络合物（色素 1-3）在 pH5-6 缓冲溶液中具有稳定的蓝紫色，在 540、547 和 618nm 处有三个特征吸收最大值。根据色素 1 在 pH6.0 缓冲溶液中的圆二色性测量，在 533（+）、604（-）和 638（-）nm 处观察到棉花效应。基于这些结果，这些共价花色苷-黄酮醇络合物被认为在飞燕草素和山柰酚单元之间保持着与多酰化花色苷中观察到的花色苷和羟基肉桂酸残基之间密切相关的稳定的分子内缔合。此外，从同一花朵提取物中分离出一种酰化山柰酚糖苷（色素 4），其结构确定为山柰酚 3-O-山梨糖苷-7-O-（3-O-（丙二酰基）-β-吡喃葡萄糖醛酸）。
