1. Influence of l-pyroglutamic acid on the color formation process of non-enzymatic browning reactions.
Lothar W Kroh, Martin Kaufmann, Steffen Wegener. Food Chem. 2017 Oct 1; 232: 450-454. DOI: 10.1016/j.foodchem.2017.04.046. PMID: 28490097.
Heating aqueous d-glucose model reactions with l-glutamine and l-alanine yielded similar colored solutions. However, size-exclusion chromatography (SEC) revealed that both non-enzymatic browning reactions proceeded differently. Due to a fast occurring cyclization of l-glutamine to pyroglutamic acid, the typical amino-carbonyl reaction was slowed down. However, l-glutamine and l-alanine model reactions showed the same browning index. Closer investigations could prove that l-pyroglutamic acid was able to influence non-enzymatic browning reactions. SEC analyses of d-glucose model reactions with and without l-pyroglutamic acid revealed an increase of low molecular colored compounds in the presence of l-pyroglutamic acid. Polarimetric measurements showed a doubling of d-glucose mutarotation velocity and HPLC analyses of d-fructose formation during thermal treatment indicated a tripling of aldose-ketose transformation in the presence of l-pyroglutamic acid, which are signs of a faster proceeding non-enzymatic browning process. 2-Pyrrolidone showed no such behavior, thus the additional carboxylic group should be responsible for the observed effects.
2. Synthesis and bioactivities evaluation of l-pyroglutamic acid analogues from natural product lead.
Xiao-Ting Li, Wen-Jun Wu, Fang-Li Gang, Feng Zhu, Jie-Lu Wei, Ji-Wen Zhang. Bioorg Med Chem. 2018 Sep 1; 26(16): 4644-4649. DOI: 10.1016/j.bmc.2018.07.041. PMID: 30119995.
A series of l-pyroglutamic acid analogues from natural product lead were designed and synthesized, as well as their antifungal activities against Phytophthora infestans, neuritogenic activities, antibacterial activities and anti-inflammatory activities are described. The bioassays and SAR study showed that the majority of l-pyroglutamic acid esters have a significant antifungal activity against P. infestans, especially 2d and 2j demonstrated the best activities with EC50values of 1.44 and 1.21 μg mL-1, which were about seven times that of commercial azoxystrobin (7.85 μg mL-1). Moreover, compounds 2e, 2g and 4d displayed anti-inflammatory activity against LPS-induced NO production in BV-2 microglial cells; neuritogenic activity in NGF-induced PC-12 cells is the same activity. This study demonstrates that compounds 2d and 2j are potential drugs to control P. infestans.
3. A new endogenous anxiolytic agent: l-pyroglutamic acid.
M Beni, F Moroni, D E Pellegrini-Giampietro. Fundam Clin Pharmacol. 1988; 2(2): 77-82. DOI: 10.1111/j.1472-8206.1988.tb00623.x. PMID: 2455680.
By use of a simple anticonflict procedure (Vogel test), it was demonstrated that L-pyroglutamic acid (L-pyrrolidone carboxylic acid [L-PCA]), an amino acid naturally occurring in mammalian tissues and fluids, possesses anxiolytic activity. This tissues and fluids, possesses anxiolytic activity. This effect was stereospecific (D-PCA was inactive) and, in the rat, it was not associated with a decrease in motor activity. Ro 15-1788, a benzodiazepine antagonist, did not modify L-PCA actions. Furthermore, anxiolytic doses of the amino acid did not change the content of 5-hydroxytryptamine (5-HT) or of 5-hydroxyindoleacetic acid (5-HIAA) in the rat cortex and hippocampus. These results suggest that the mechanism of the anxiolytic activity of L-PCA is different from that of the benzodiazepines and of 5-HT1a agonists.
