Elsevier

Biochemical Pharmacology

Volume 58, Issue 11, 1 December 1999, Pages 1765-1773
Biochemical Pharmacology

Original Articles
Reaction of metformin with dicarbonyl compounds. possible implication in the inhibition of advanced glycation end product formation

https://doi.org/10.1016/S0006-2952(99)00263-4Get rights and content

Abstract

Dicarbonyl compounds such as methylglyoxal and glyoxal are extremely reactive glycating agents involved in the formation of advanced glycation end products (AGEs), which in turn are associated with diabetic vascular complications. Guanidino compounds such as aminoguanidine appear to inhibit AGE formation by reacting with α-dicarbonyl compounds. The aim of this work was to study whether the antihyperglycemic agent metformin (a guanidine-like compound) might react with reactive α-dicarbonyls. Metformin was incubated at pH 7.4 and 37° in the presence of either methylglyoxal or glyoxal and reaction products analysed by HPLC coupled to mass tandem spectrometry. AGE formation on albumin by methylglyoxal and glyoxal in the presence or absence of metformin was also studied by measuring the fluorescence at 370/440 nm after albumin–AGE isolation by ultrafiltration. As a standard for mass spectra analysis, a metformin–methylglyoxal adduct was chemically synthesised and characterised as a triazepinone (2-amino-4-(dimethylamino)-7-methyl-5,7-dihydro-6H-[1,3,5]triazepin-6-one). The results obtained showed that metformin strongly reacted with methylglyoxal and glyoxal, forming original guanidine–dicarbonyl adducts. Reaction kinetic studies as well as mass fragmentation spectra of the reaction products were compatible with the presence of triazepinone derivatives. In the presence of metformin, AGE-related fluorescence after albumin incubation with either glyoxal or methylglyoxal was decreased by 37% and 45%, respectively. These results suggest that besides its known antihyperglycemic effect, metformin could also decrease AGE formation by reacting with α-dicarbonyl compounds. This is relevant to a potential clinical use of metformin in the prevention of diabetic complications by inhibition of carbonyl stress.

Section snippets

Materials

Methylglyoxal and globulin-free BSA were purchased from Sigma. Glyoxal and 3-amino-1,2,4-triazine were purchased from Aldrich. Metformin was obtained from Lipha S.A.

Chemical synthesis of triazepinone

Methylglyoxal (0.21 mol; 34 mL of a 40% aqueous solution) was added between 0° and +5° to a solution of 0.2 mol of N,N-dimethylbiguanide base in 100 mL of water. The reaction mixture was stirred for 1 hr at 5° and for a further 4 hr at 20°. A crystalline precipitate was obtained, washed with water, and evaporated in vacuum to

Characterisation of synthetic triazepinone

As a standard for mass spectrometry analysis, a synthetic metformin–methylglyoxal adduct was chemically prepared and characterised. This product had the following characteristics: melting point 264–266°, elemental analysis (calculated/found): C 45.94/45.89%, H 7.29/7.15%, N 38.03/38.22%, O 8.65/8.73%. Mass spectrum showed a molecular mass of 183 compatible with the calculated molecular mass of 183.21 for C7H13N5O. The infrared spectra of this compound exhibited the absorptions assignable to C =

Discussion

Metformin is an oral antihyperglycemic agent used for the management of non-insulin-dependent diabetes mellitus (NIDDM). It is structurally related to guanidines, which elicit a marked interest in glycation studies and in the prevention of diabetic complications. The most studied guanidine compound with a clear inhibitory effect on AGE formation is aminoguanidine [14]. Several groups have shown that this compound was quite effective in inhibiting the formation of AGEs in vitro and in vivo[2].

Acknowledgements

We thank Dr. N. Chanon and Dr. T. Passemard for their collaboration with chemical analysis of the synthetic triazepinone as well as Patricia Lévêque for her technical assistance. We also thank Dr E. Michoud and Dr. E. Véricel for helpful discussions.

References (29)

  • Y Tanaka et al.

    Inhibitory effect of metformin on formation of advanced glycation end products

    Curr Ther Res Clin Exp

    (1997)
  • H Vlassara et al.

    Pathogenic effects of advanced glycosylationBiochemical, biologic, and clinical implications for diabetes and aging

    Lab Invest

    (1994)
  • R Bucala et al.

    Advanced glycosylation end products in diabetic complications

    Diabetes Rev

    (1995)
  • A.M Schmidt et al.

    Cellular receptors for advanced glycation end products

    Arterioscler Thromb

    (1994)
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