Biological activity of polyphenol extracts from different plant sources

In experiments on rats, five diets without or supplemented with polyphenol extracts from different sources (flavons from skullcap, catechins from green tea, anthocyanins from chokeberry and condensed tannins from faba bean) were applied. Obtained results suggested that when catechin extracts were added to the diets in large amounts (0.8%), beneficial effects (reduction of total cholesterol and LDL fraction in serum) were observed, but also reduction in protein digestibility and protein efficiency ratio (from 94.6 to 93.1% and from 2.57 to 2.40, respectively), compared to the control group. All extracts decreased the activity of erythrocyte superoxide dismutase and increased the activity of alanine aminotransferase in the serum. Only the tannin extract decreased the content of calcium in femur. More profitable biological properties were found for catechin extract from green tea and flavons extract from skullcap, compared to anthocyanins from chokeberry and condensed tannins from faba bean. (C) 2002 Elsevier Science Ltd. All rights reserved.