Kodera Yukihiro, Kurita Masahiro, Nakamoto Masato, Matsutomo Toshiaki
Central Research Institute, Wakunaga Pharmaceutical Co., Ltd., Akitakata-shi, Hiroshima 739-1195, Japan.
Exp Ther Med. 2020 Feb;19(2):1574-1584. doi: 10.3892/etm.2019.8393. Epub 2019 Dec 27.
Raw garlic contains characteristic compounds, such as -alk(en)ylcysteine sulfoxides, γ-glutamyl--alk(en)-ylcysteines and polysaccharides. These compounds undergo various transformation processes during the aging process. Among these compounds, the change of sulfur-containing molecules is diverse and time-dependent. Previously, by means of the liquid chromatography (LC)/LC-mass spectrometry (MS) method, a number of unidentified peaks corresponding to candidates of sulfur-containing molecules were detected in the chromatogram of aged garlic extract (AGE), and identified using MS and nuclear magnetic resonance (NMR). The production mechanisms of these compounds were then examined by model reactions and laboratory experiments mimicking the aging process. Three γ-glutamyl tripeptides [γ-glutamyl-γ-glutamyl--methylcysteine, γ-glutamyl-γ-gluta-myl--allylcysteine (GGSAC), γ-glutamyl-γ-glutamyl--1-propenylcysteine], γ-glutamyl--allylmercaptocysteine (GSAMC) and -1-propenylcysteine (-S1PC) were isolated and identified. GGSAC was produced from GSAC through the enzymatic reaction catalyzed by γ-glutamyltranspeptidase (GGT), and two other tripeptides could be produced in similar reactions. GSAMC was produced by the reaction between γ-glutamyl dipeptides and allicin. Furthermore, GSAMC was a precursor compound of -allyl-mercaptocysteine (SAMC), and thus it was produced from GSAMC by GGT. -S1PC was produced from -S1PC by the isomerization reaction. A number of other compounds were also identified, including Maillard reaction products; however, their production mechanisms have not been elucidated. In this review, we present the changes in characteristic constituents in raw garlic and garlic extract during the aging process and discuss their production mechanisms involving the various chemical and enzymatic reactions.
生蒜含有多种特征性化合物，如α-烯丙基（烯）半胱氨酸亚砜、γ-谷氨酰-α-烯丙基（烯）半胱氨酸和多糖。这些化合物在陈化过程中会经历各种转化过程。在这些化合物中，含硫分子的变化多样且与时间相关。此前，通过液相色谱（LC）/液相色谱-质谱（MS）方法，在陈化大蒜提取物（AGE）的色谱图中检测到了许多与含硫分子候选物相对应的未鉴定峰，并通过质谱和核磁共振（NMR）进行了鉴定。然后通过模拟陈化过程的模型反应和实验室实验研究了这些化合物的生成机制。分离并鉴定出了三种γ-谷氨酰三肽[γ-谷氨酰-γ-谷氨酰-α-甲基半胱氨酸、γ-谷氨酰-γ-谷氨酰-α-烯丙基半胱氨酸（GGSAC）、γ-谷氨酰-γ-谷氨酰-α-1-丙烯基半胱氨酸]、γ-谷氨酰-α-烯丙基巯基半胱氨酸（GSAMC）和α-1-丙烯基半胱氨酸（α-S1PC）。GGSAC是由GSAC通过γ-谷氨酰转肽酶（GGT）催化的酶促反应生成的，另外两种三肽也可通过类似反应生成。GSAMC是由γ-谷氨酰二肽与大蒜素反应生成的。此外，GSAMC是α-烯丙基巯基半胱氨酸（SAMC）的前体化合物，因此它是由GGT作用于GSAMC生成的。α-S1PC是由α-S1PC通过异构化反应生成的。还鉴定出了许多其他化合物，包括美拉德反应产物；然而，它们的生成机制尚未阐明。在这篇综述中，我们介绍了生蒜和大蒜提取物在陈化过程中特征成分的变化，并讨论了它们涉及各种化学和酶促反应的生成机制。
