Modulation of the antioxidant/pro-oxidant balance, cytotoxicity and antiviral actions of grape seed extracts

•GSEs exhibit antioxidant activity in wild-type, Δcta1, Δgsh1 and Δoye2glr1 strains.•GSEs exhibit pro-oxidant activity in Δsod1 cells.•Proliferation of prostate cancer PC3 and HepG2 2.2.15 cells was inhibited by GSEs.•Cytotoxicity of GSEs was subjective to dose and period of administration.•No antiviral effect of GSEs against HBV was detected in HepG2 2.2.15 cells. Grape seed extracts (GSEs) were investigated in yeast cells harbouring defects in their antioxidant system (regarding the cellular growth and growth recovery from H2O2 insult). GSEs antioxidant activity was detected in wild-type and mutant strains Δcta1, Δgsh1 and Δoye2glr1, while pro-oxidant activity in Δsod1 cells was seen. Assessment of proliferation of prostate cancer PC3 and HBV-replicating HepG2 2.2.15 cells treated with GSEs has shown higher cytotoxicity of red grape seed extract (RW) than white grape seed extract (WW) subjective to dose and period of administration. No antiviral effect was detected by measuring the secreted virion particles in HepG2 2.2.15 cells treated with GSEs. The GSEs play a dual antioxidant/pro-oxidant role in vivo according with the cellular antioxidant system deficiencies and exhibit cytotoxic properties in PC3 and HepG2 2.2.15 cell lines, but no antiviral action against HBV.