Imai Shinsuke, Akita Kaori, Tomotake Muneaki, Sawada Hiroshi
Somatech Center, House Foods Corporation, 1-4 Takanodai, Yotsukaido, Chiba 284-0033, Japan.
J Agric Food Chem. 2006 Feb 8;54(3):843-7. doi: 10.1021/jf0519818.
By using a model reaction system representing blue-green discoloration that occurs when purees of onion (Allium cepa L.) and garlic (Allium sativum L.) are mixed, we isolated two pigment precursors (PPs) and a reddish-purple pigment (PUR-1) and determined their chemical structures. PPs were isolated from a heat-treated solution containing color developer (CD) and either l-valine or l-alanine, and their structures were determined as 2-(3,4-dimethylpyrrolyl)-3-methylbutanoic acid (PP-Val), and 2-(3,4-dimethyl-1H-pyrrolyl) propanoic acid (PP-Ala), respectively. Next, PUR-1 was isolated from a heat-treated solution containing PP-Val and allicin, and its structure was determined as (1E)-1-(1-((1S)-1-carboxy-2-methylpropyl)-3,4-dimethyl-1H-pyrrol-2-yl)-prop-1-enylene-3-(1-((1S)-1-carboxy-2-methylpropyl)-3,4-dimethyl-1H-pyrrol-2-ylidenium). The structure of PUR-1 suggested that PP molecules containing a 3,4-dimethyl pyrrole ring had been cross-linked by an allyl group of allicin to form conjugated pigments. While PUR-1 is a dipyrrole compound exhibiting a reddish-purple color, a color shift toward blue to green can be expected as the cross-linking reaction continues to form, for example, tri- or tetrapyrrole compounds.
通过使用一个模型反应系统，该系统模拟了洋葱（葱属植物）和大蒜（蒜属植物）泥混合时出现的蓝绿色变色现象，我们分离出了两种色素前体（PPs）和一种红紫色色素（PUR-1），并确定了它们的化学结构。PPs是从含有显色剂（CD）和L-缬氨酸或L-丙氨酸的热处理溶液中分离出来的，它们的结构分别被确定为2-(3,4-二甲基吡咯基)-3-甲基丁酸（PP-Val）和2-(3,4-二甲基-1H-吡咯基)丙酸（PP-Ala）。接下来，PUR-1是从含有PP-Val和大蒜素的热处理溶液中分离出来的，其结构被确定为(1E)-1-(1-((1S)-1-羧基-2-甲基丙基)-3,4-二甲基-1H-吡咯-2-基)-丙-1-烯基-3-(1-((1S)-1-羧基-2-甲基丙基)-3,4-二甲基-1H-吡咯-2-基亚铵)。PUR-1的结构表明，含有3,4-二甲基吡咯环的PP分子已被大蒜素的烯丙基交联形成共轭色素。虽然PUR-1是一种呈现红紫色的二吡咯化合物，但随着交联反应继续形成，例如三吡咯或四吡咯化合物，可以预期颜色会向蓝绿色转变。
