Inhibition of in vitro pyrraline formation by L-arginine and polyamines.

Glycation of biomolecules such as proteins, nucleic acids and lipids leading to the formation of advanced glycation end products (AGEs) may be a major contributor to the pathological manifestations of diabetes mellitus. Several studies have shown that the chemical inhibition of AGEs formation results in attenuation of diabetic complications. We tested the in vitro inhibition of pyrraline formation on bovine serum albumin and L-lysine by L-arginine and the polyamines putrescine, cadaverine, spermidine and spermine. Among the inhibitors, L-arginine and spermine potently inhibited pyrraline formation. This effect could be related to the presence of the guanidino group in L-arginine and four amino groups in spermine, but this inhibitory effect was also shown by putrescine, cadaverine and spermidine, suggesting that these natural compounds may have a novel therapeutic potential in preventing diabetic complications. A significant unexpected observation emerged when experiments were carried out with aminoguanidine. It showed increased absorbance produced by a non-identified compound whose peak appears at 285 nm, but this aspect remains to be investigated.