Trapping of Methylglyoxal by Curcumin in Cell-Free Systems and in Human Umbilical Vein Endothelial Cells

Abstract

Curcumin, the most active compound of curcuminoids, has been shown to inhibit formation of advanced glycation end products (AGEs) in streptozotocin-induced diabetic rats. However, little is known on whether curcumin may trap methylglyoxal (MGO), a major reactive dicarbonyl compound, to inhibit AGE formation. We found that one molecule of curcumin effectively trapped one molecule of MGO at a 1:3 ratio at 24 h of incubation under physiological conditions (pH 7.4, 37 °C). Curcumin decreased N(ε)-(carboxymethyl)lysine (CML) expression in human umbilical vein endothelial cells. We further used two curcumin analogues, dimethoxycurcumin (DIMC) and ferulic acid, to investigate the possible MGO-trapping mechanism of curcumin. Results reveal that DIMC, but not ferulic acid, exhibited MGO-trapping capacity, indicating curcumin traps MGO at the electron-dense carbon atom (C10) between the two keto carbon groups. Thus, curcumin may prevent MGO-induced endothelial dysfunction by directly trapping MGO.

Hypoglycemic activity of curcumin synthetic analogues in alloxan-induced diabetic rats

“…Perhaps enolic form of heptadienone or pentadienone scaffolds of these synthesized compounds might act as an electron donor, which is very common mechanism for the scavenging activity of phenolic antioxidant to alter characteristics of glucose molecules 23 . Moreover, the hypoglycemic activities observed for these compounds were in agreement with previous findings on these analogues [24][25][26][27] .…”

Protective effects of cyanidin-3-rutinoside against monosaccharides-induced protein glycation and oxidation

“…Other phytochemical compounds, curcumin and silymarin have been recognized as powerful antioxidants. They have been found to inhibit AGEs formation in in vitro and diabetic animal models [32][33][34].…”

Formation of α-dicarbonyl compounds in cookies made from wheat, hull-less barley and colored corn and its relation with phenolic compounds, free amino acids and sugars

“…Trapping of α-dicarbonyl compounds under physiological conditions has been studied widely, and it has been shown that α-dicarbonyl compounds react with certain positions on the phenol ring via electrophilic aromatic substitution [21,22]. Catechins [22,23], curcumin [24], daidzein [25], genistein [25,26], theaflavins [23], phloretin [27], phenolic acids [28], fruit and vegetable seed extracts [29] have been shown to trap dicarbonyl compounds. Effect of phenolic compounds on trapping α-dicarbonyl compounds during food processing was focused mainly on flavor development [30][31][32][33].…”