Black garlic melanoidins inhibit in vitro α‐amylase and α‐glucosidase activity: the role of high‐molecular‐weight fluorescent compounds

Abstract

BACKGROUND Black garlic (Allium sativum L.) melanoidins (MLDs) are produced by Maillard reaction under high temperature and high humidity, and has a variety of biological activities. The aim of this study was to analyze the structural characteristics and investigate α‐amylase and α‐glucosidase in vitro inhibitory activity of black garlic MLDs. RESULTS Spectroscopic and chemical analysis revealed that black garlic MLDs were heterogeneous macromolecular polymers with a skeletal structure similar to sugar chains. Molecular weight distribution and 3DEEM fluorescence showed that black garlic MLDs were composed of high‐molecular‐weight colorants with strong fluorescence properties. The polarity of black garlic MLDs was related to the fluorescence groups. The results of physicochemical properties proved that the polarity difference of black garlic MLDs was related to the elemental composition, resulting in differences in fluorescence, thermodynamic and apparent characteristics. MLDs with higher levels of fluorescent intensity (BG20 and BG40) had stronger inhibitory effects on α‐amylase and α‐glucosidase than BGW, and hydrolysis of fluorescent groups attenuated the inhibitory activity. The median inhibitory concentration (IC50) of black garlic MLDs against enzymes was positively correlated with the concentration, and the kinetic results detected non‐competitive and mixed types of inhibition. CONCLUSION High‐molecular‐weight fluorescent components of black garlic MLDs played a crucial role in the inhibitory activities of α‐amylase and α‐glucosidase, and the inhibitory ability was positively correlated with concentration. Black garlic MLDs had the potential to block postprandial glucose rise. © 2023 Society of Chemical Industry.

Novel Fluorometric Assay of Antiglycation Activity Based on Methylglyoxal-Induced Protein Carbonylation

“…In addition, potential byproducts resulting from dicarbonyl compounds may interfere with this evaluation method. For example, melanoidin, a product other than AGEs produced in the Maillard reaction, has been reported to have fluorescent properties [52], and its interference cannot be ignored. Practically, if the coexisting interfering substances are trace amounts, this problem may be solved by subtracting the fluorescence intensity of the blank, excluding the lysozyme.…”

Colorants and Antioxidants Deriving from Methylglyoxal and Heterocyclic Maillard Reaction Intermediates

“…Their daily intake through the human diet is estimated to be around 10 g on a basis of frequently consumed food such as coffee and bread [ 9 ]. The consumption of melanoidins was found to be beneficial for the digestive system due to their antidiabetic [ 10 ], prebiotic [ 11 ], and antioxidant effects [ 12 , 13 ]. However, genotoxic [ 14 ] and pro-oxidative [ 15 ] properties are also discussed quite controversially in the context of an overconsumption of processed food [ 16 , 17 , 18 ].…”