RESUMO
Ochratoxin A (OTA) is a nephrotoxic mycotoxin produced by species of the genus Penicillium and Aspergillus that is present in food and feed as a natural contaminant. It modifies the immune function in animals and inhibits the proliferative response of lymphocytes in vitro. The toxic effect of OTA (0.5, 2, 20 microM) in lympho-proliferative response, natural killer (NK) cell activity, cytotoxic T lymphocytes (CTL) activity and macrophages' bacteriolytic capability was studied in vitro after 1 hour of treatment. The proliferative response of lymphocytes to concanavalin A and lipopolysaccharide was not affected by OTA; the cytotoxic activity of NK cells was dose-dependent decreased; the CTL activity was significantly decreased at the lowest concentration; the bacteriolytic activity of macrophages varied only slightly. These in vitro results reproduced, at least in part, some effects detected previously in vivo. The protein synthesis inhibition and the oxidative metabolism of OTA coupled to the prostaglandin synthesis are probably implicated in NK cells' toxicity, because the effects were reverted by the addition of phenylalanine or piroxicam to the culture medium. The induction of apoptosis seems to be the principal mechanism of action in the CTL effect. The intracellular concentration of OTA after 1 hour was analysed by HPLC and was found to be proportional to the quantity of OTA added to the culture medium for the three cell types; the presence of phenylalanine and piroxicam on the culture medium did not change the intracellular OTA concentration.
Assuntos
Células Matadoras Naturais/efeitos dos fármacos , Subpopulações de Linfócitos/efeitos dos fármacos , Micotoxinas/farmacologia , Ocratoxinas/farmacologia , Linfócitos T Citotóxicos/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Células Cultivadas , Concanavalina A , Inibidores de Ciclo-Oxigenase/farmacologia , Relação Dose-Resposta a Droga , Células Matadoras Naturais/imunologia , Lipopolissacarídeos , Ativação Linfocitária , Subpopulações de Linfócitos/imunologia , Macrófagos/efeitos dos fármacos , Masculino , Fenilalanina/farmacologia , Piroxicam/farmacologia , Inibidores da Síntese de Proteínas/farmacologia , Ratos , Ratos Wistar , Linfócitos T Citotóxicos/imunologiaRESUMO
A liquid-liquid microextraction technique (LPME) has been applied to the extraction of ochratoxin A (OTA) from wine prior to its quantification by HPLC-fluorescence detection. OTA was extracted from wine, through 1-octanol immobilized in the pores of a porous hollow fiber, and introduced into 1-octanol inside the fiber. Recovery was 77%. The method was adequate for quantification of OTA in wine at levels within the range 0.25-10 ng/ml with a LOD of 0.2 ng/ml, and can be a simple and inexpensive alternative to the use of inmunoaffinity columns in order to quantify OTA levels in wine.
