The effect of treating grapes with six fungicides, applied under critical agricultural practices (CAP) on levels
of phenolic compounds and antioxidant activity of red wines of Monastrell variety was studied. Vini-
fications were performed through addition of active dry yeast (ADY). Measurement of phenolic
compounds was made with HPLC-DAD. Determination of antioxidant activity was through reaction of
the wine sample with the DPPH radical. The wine prepared from grapes treated with quinoxyfen shows
a greater increase of phenolic compounds than the control wine. In contrast, the wine obtained from
grapes treated with trifloxystrobin showed lower total concentration of phenolic compounds, including
stilbenes, whilst treatments with kresoxim-methyl, fluquinconazole, and famoxadone slightly reduced
their content. Hence, the use of these last four fungicides could cause a decrease in possible health benefits
to consumers. Antioxidant activity hardly varied in the assays with quinoxyfen, fluquinconazole and
famoxadone, and decreased in the other wines.