Antioxidant and prooxidant properties of a polyphenol-rich extract from Geranium sanguineum L. in vitro and in vivo.

A polyphenol-rich extract from Geranium sanguineum L. (PC) protected biological membranes due to its antioxidant capacity. PC caused a dose-dependent decrease of the osmotic hemolysis of human erythrocytes and increased their resistance against the toxic effect of H(2)O(2); no effect on catalase activity was observed. While PC reduced the accumulation of TBA-reactive products in rat liver microsomes in inducible lipid peroxidation (LPO), the non-induced LPO was not affected. Further the effect of PC on the products of LPO was investigated in the lungs, livers and sera of intact and influenza virus-infected mice (VIM). The infection enhanced LPO in the lungs and livers. In the group of PC-treated VIM, malondialdehyde (MDA) in the lungs and livers was brought to control levels. PC-treatment caused a significant increase of MDA in the lungs of intact mice, a slight one in the livers and did not affect MDA in the sera. Thus the extract exhibited prooxidant characteristics in intact animals as well as antioxidant properties in VIM. The reducing ability of PC on LPO could be an alternative mechanism of its protective effect in experimental influenza infection. Copyright (c) 2008 John Wiley & Sons, Ltd.