[en] BACKGROUND: The anti-inflammatory effects of proanthocyanidins (PACs), isolated from blackcurrant (Ribes nigrum L.) leaves, were analysed using carrageenin-induced paw oedema and carrageenin-induced pleurisy in rats. RESULTS: Pretreatment of the animals with PACs (10, 30, 60 and 100 mg/kg, i.p.) reduced paw oedema induced by carrageenin in a dose and time-dependent manner. PACs also inhibited dose-dependently carrageenin-induced pleurisy in rats. They reduced (A) lung injury, (B) pleural exudate formation, (C) polymorphonuclear cell infiltration, (D) pleural exudate levels of TNF-alpha, IL-1beta and CINC-1 but did not affect IL-6 and IL-10 levels. They reduced (E) pleural exudate levels of nitrite/nitrate (NOx). In indomethacin treated rats, the volume of pleural exudate was low, its content in leukocytes and its contents in TNF-alpha, IL-1beta, IL-6 and IL-10 but not in NOx were reduced. These data suggest that the anti-inflammatory properties of PACs are achieved through a different pattern from those of indomethacin. CONCLUSION: These results suggest that the main mechanism of the anti-inflammatory effect of PACs mainly lies in an interference with the migration of the leukocytes. Moreover, PACs inhibited in vivo nitric oxide release.