Biological importance of γ-glutamyl-S-methylcysteine of kidney bean (Phaseolus vulgaris L.)

The effects of S-methyl-L-cysteine (SMC) on growth and food intake by rats were investigated and in vivo absorption studies of gamma-glutamyl-S-methyl-L-cysteine and free SMC were performed. The results showed that the peptide is slowly absorbed and only free SMC could be detected in the blood. The diets (10% casein), containing SMC, depressed food intake and animals’ growth. Both effects were proportional to the SMC contents in the diets. The results obtained with pair-fed groups led to the conclusion that the depression in growth was caused by the refusal of the SMC diets. The addition of cystine to the SMC diet only partially restored normal growth. Histological examination of livers, kidneys and spleens of rats fed with SMC showed no tissue alterations, except for a significant increase in the kidney weights. The hematological features did not show any significant differences, but there was a slight increase in erythroid precursors and young forms in the bone marrow, which might indicate an increased erythrocyte turnover. These results suggest that the reduction in food intake could be associated with some defence mechanism against toxic substances.