In diabetes increased protein glycosylation presents a major macrovascular and microvascular complications including neuropathy, retinopathy, atherosclerosis and Alzheimer’s disease. Recently we reported structurally defined flavonoids present in Okra Seed Extract (OSE) as inhibitors of protein glycation. Comparative studies on the efficacy of OSE with well-established drugs metformin and 2-aminoguanidine showed similar inhibitory activity without cytotoxic effects. Inhibitory activity was measured via specific fluorescence excitation wavelength (Ex) at 360 nm and emission wavelength at 460 nm, SDS gels and AGE-associated changes in protein concentration via Nanodrop spectrophotometer. Further experiments on binding and modification of proteins such as human serum albumin and lysozyme with the highly reactive metabolite of glucose, methylglyoxal was studied under physiological conditions. When treated with the inhibitor metformin, the incubation mixture showed the formation of triazepinone, an adduct of metformin with methylglyoxal. Mass spectral analysis of the initial condensation adduct exhibited m/z =202 which after cyclization provided triazepinone, m/z=184. In order to characterize the final cyclized product triazepinone and to study its metabolism a mixture of metformin and methylglyoxal under physiological conditions after gentle stirring was carefully irradiated in the microwave for 50 seconds at 5 seconds interval and provided triazepinone in 80-86% yield. After evaporation of methanol under nitrogen the resultant mixture was resolved and analyzed via analytical and preparatory thin-layer chromatography (Aluminium backed pre-coated SIL G/UV254 TLC plates in the solvent system: CHCl3:CH3OH (19:0.9 v/v Rf 0.88). Triazepinone is excreted in the urine of diabetes patients treated with metformin thus eliminating the toxic methylglyoxal. We believe a facile one-step green synthesis of triazepinone will be helpful in studies dealing with the uremia conditions in diabetes patients suffering from end-stage renal disease.

Facile microwave-induced rapid synthesis of triazepinone: An adduct of metformin and methylglyoxal

249th National Meeting (2015)

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