Benznidazole-induced ultrastructural alterations in rat adrenal cortex. Mechanistic studies.

Benznidazole (Bz) (N-benzyl-2-nitro-1-imidazole acetamide) is a drug used against Chagas' disease, a parasitic disease afflicting several millions of Latin Americans. Bz administration to Sprague-Dawley male rats at 100 mg/kg p.o. caused subcellular alterations in the adrenal cortex involving fasciculata and reticularis zones but not in the glomerulosa. There is Bz nitroreductase activity in the adrenal microsomal and mitochondrial fractions but most of it is localized in mitochondria. Activity in the two fractions requires NADPH under anaerobic conditions. Mitochondrial Bz nitroreductase activity was inhibited by oxygen. A minor but statistically significant inhibition was observed in mixtures incubated under carbon monoxide. Microsomal Bz nitroreductase activity was not detected under oxygen atmosphere and was not inhibited under carbon monoxide. No Bz nitroreductase activity mediated by xanthine oxidase or aldehyde oxidase was detected in the cytosolic fraction from rat adrenals. Electron microscopic examination of the adrenal cortex from Bz-treated animals revealed cells with marked lipid accumulation and alterations in nuclei, endoplasmic reticulum and mitochondria in the reticularis and fasciculata zones. In vitro results suggest a Bz nitroreductive activation, with minor or null P-450 participation, leading to reactive metabolites able to cause damage in various organelles.

Reductive biotransformation of xenobiotics by the sheep ruminal content.

1. Sheep ruminal content was able to reduce nitro groups from nitrobenzene and azo groups from dimethylamino-azobenzene. 2. Results might be of interest in relation to ruminants exposed to environmental chemicals via oral route. 3. Biotransformation of xenobiotics in rumen might give to deleterious products appearing later in meat and/or milk or harming the ruminant itself.

Interaction of benznidazole reactive metabolites with nuclear and kinetoplastic DNA, proteins and lipids from Trypanosoma cruzi.

Epimastigotes of Trypanosoma cruzi (Tulahuen strain Tul 0 stock) biotransform benznidazole (N-benzyl-2-nitro-1-imidazole acetamide) to reactive metabolites that bind covalently to DNA, proteins and lipids of the parasite. These effects might be related to the trypanocidal action of benznidazole, a chemotherapeutic agent against Chagas' disease.

Toxic effects of nifurtimox and benznidazole, two drugs used against American trypanosomiasis (Chagas' disease).

American trypanosomiasis (Chagas' disease) is an endemic parasitic disease afflicting more than 20 million persons in Latin America. Two drugs are currently being used for treatment of the acute phase of Chagas' disease: 4-[(5-nitrofurfurylidene)amino-3-methylthiomorpholine-1,1-di oxide] (Nifurtimox; Nfx) and (N-benzl-2-nitro-1-imidazole acetamide) (Benznidazole; Bz). Nfx and Bz have serious undesirable effects, which have been reported during their clinical use, including anorexia and weight loss, nausea and vomiting, nervous excitation, insomnia, psyche depressions, convulsions, vertigo, headache, sleepiness, myalgias, arthralgias, loss of balance, disorientation, forgetfulness, paresthesias, adynamia, acoustic phenomena, peripheral neuropathies, gastralgia, mucosal edema, hepatic intolerance, skin manifestations, and intolerance to drinking alcohol. Effects in the central and peripheral nervous system of Nfx were also reproduced in animals. Signs of testicular and ovarian injury were reported for both Nfx and Bz, the effects of Bz being in general less intense than those of Nfx. Both drugs evidenced mutagenicity. In light of the present knowledge about the toxicity of Nfx and Bz, further studies on the mutagenic, teratogenic, carcinogenic, and reproductive effects of both drugs are recommended. Lack of information is particularly serious for Bz. Studies on Nfx and Bz biotransformation, activation to reactive metabolites, and potential mechanisms for their toxic effects were analyzed. Risk-benefit considerations of the use of Nfx and Bz were made and an analysis of the need for research on Chagas' disease chemotherapy was also performed.