Effect of garlic sulphur-containing compounds on Nε-(carboxyethyl)lysine formation in a glucose-lysine mode l system

Garlic, widely used as a flavour enhancer in home cooking, is rich in sulphur-containing compounds. In this article, the effect of garlic sulphur-containing compounds on Nε-(carboxyethyl)lysine (CML) formation was investigated in a glucose-lysine model system. The results revealed that freeze-dried garlic powder had better antioxidant activity than hot air-dried garlic powder. The 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and ·OH scavenging rates of freeze-dried garlic powder were 55.62%, 55.00%, and 62.65%, respectively, while those of hot air-dried garlic powder were 52.12%, 43.97%, and 57.49%. And the main sulphur-containing compounds were identified as alliin and S-allyl-L-cysteine, allicin, diallyl sulphide, diallyl disulphide, diallyl trisulphide. The generation of both advanced glycation end products (AGEs) and CML was hindered by garlic sulphur-containing compounds. Diallyl disulphide showed the highest inhibition of AGEs and CML at the concentration of 160 mg/L with an inhibition rate of 28.33% for AGEs and 22.59% for CML. The garlic sulphur-containing compounds also had significant inhibitory effects on the CML precursor glyoxal. Furthermore, the sulphur-containing compounds had the ability to directly trap glyoxal. With the exception of allicin, which had a weak ability to capture glyoxal, the other sulphur-containing compounds had a comparable ability to capture glyoxal. In addition, it was found that garlic sulphur-containing compounds had good scavenging effect on the RO· radicals, and alliin had the strongest scavenging ability of RO· radicals. Garlic sulphur-containing compounds could regulate the generation of AGEs and CML by capturing the precursor of CML and scavenging free radical pathways.