protective effect of Zn-metallothionein [Zn-Mt] on the toxicity of diazinon, mancozeb and their mixture on rats

The joint action of pesticides that have similar chemical structures and mode of toxic action can be predicted. However, this approach and other modeling techniques often provide little insight into the observed toxicity produced by mixtures of pesticides from different classes. The present study shows significant decrease in body weight gain after all exposure periods to diazinon and its mixture with mancozeb. In case of Mancozeb, the percentage body weight gain decreased significantly only after 42 days intake in drinking water. The injection of Zn-MT lead to recover of body weight gain especially in the case of the exposure to diazinon and mancozeb, separately. In case of mixture exposure, Zn-MT treatment reduced the effect until 28 days but the decreasing in body weight gain was still significant [p < 0.05] under the long term exposure until the end of the experiment period. Also a decrease in the activity of plasma cholinesterase after 30 days exposure to mancozeb and its mixture with diazinon was observed and was highly significant [p < 0.01] after 90 days of exposure to diazinon, mancozeb and their mixture. Zn-MT played a role to recover the cholinesterase activity completely in diazinon-treated animals and significantly [p < 0.05] in both mancozeb and the mixture. Alkaline phosphatase was significantly inhibited in plasma after 30 and 90 days in all treatments [p < 0.01] and the injection of Zn-MT leads to a decrease in the injury. The same trend was found in the case of the alkaline phosphatase activity in the liver. The kidney's alkaline posphatase was more tolerant against the effect of both diazinon, mancozeb and their mixture

Efeito tóxico dos praguicidas maneb e paraquat sobre a atividade da enzima antioxidante catalase em ratos / Toxic effect of pesticides maneb and paraquat on catalase antioxidant enzyme activity in rats

Os radicais livres estão envolvidos em um grande número de enfermidades do ser humano.O cérebro tem níveis baixos de enzimas antioxidantes e um conteúdo lípidico elevado, tornando-se muito susceptível ao ataque de espécies reativas de oxigênio.Neste trabalho avaliou-se a lipoperoxidação em hipocampo e a atividade da enzima catalase em estriado e hipocampo de ratos tratados com o fungicida maneb (30 mg/kg) e o herbicida paraquat (10 mg/kg).Não houve alteração na lipoperoxidação nem na atividade enzimática no hipocampo dos animais tratados com ambos os praguicidas, porém foi observada uma inibição da catalase no estriado dos ratos tratados com maneb e com paraquat.Com estes resultados pode-se sugerir, de forma preliminar, uma ação tóxica maior sobre centros dopaminérgicos.Estudos sobre a toxicidade destes compostos são essenciais na compreensão do papel destes praguicidas e dos radicais livres na etiologia das doenças

Fungitoxic action of dithanes in presence of surfactant micelles.

A rationale of arriving at the concentration of surfactant additives in the pesticidal formulations has been discovered. Fungitoxic activity of each of the two dithanes, Dithane M-45 (maneb) and Dithane Z-78 (zineb) has been estimated in the presence of various concentrations of three surfactants namely sodium lauryl sulphate, cetyl pyridinium chloride and Tween 80. Data reveal that the concentration of the surfactant additives in the pesticidal formulations should be at least equal to its critical micelle concentration (CMC) for enhanced biological activity. This rationale for the concentration of surfactant additives in the pesticidal formulation has so far not been clearly brought out in the literature. Since biological activity of the pesticides is enhanced in the presence of surfactant additives the present study is relevant to the reduction of environmental pollution due to pesticide residues.