Biological activity of faba beans proanthocyanidins

The objective of the experiment was to determine whether small amounts of proanthocyanidins (0.1 and 0.3%) may increase the antioxidative properties of the rat diet without exerting an antinutritional effect. Proanthocyanidins of faba bean seed coats were extracted with a mixture of acetone and water (70:30) and lyophilized. The amount of proanthocyanidins was two- or fourfold higher in the experimental diets as compared to the control diet. The addition of proanthocyanidin extract had no significant effect on the coefficients of digestibility of crude protein, daily nitrogen retention and the coefficient of biological value of diet protein. In the blood serum of rats fed diets supplemented with proanthocyanidin extract, there was a slightly higher content of vitamin E and alanine aminotransferase activity, while the content of vitamin A and aspartate aminotransferase activity were similar to those of the control group. In the contents of the rat gut (caecum), a lower activity of beta -glucuronidase was found as compared to the control group, whereas beta -galactosidase was unaffected. The addition of proanthocyanidin extract to diet caused a decrease in the malondialdehyde content in the heart, kidneys, erythrocytes and blood plasma of rats. The results obtained indicate that the amount of proanthocyanidins used did not exert any antinutritional effects, but extended the pool of diet antioxidants and beneficially affected the activity of the large bowel microflora.