Dithiothreitol (DTT) rescues mitochondria from nitrofurantoin-induced mitotoxicity in rat.

Nitrofurantoin (N-(5-nitro-2-furfurylidine) 1-amino-hydantoine; NIT) is mainly used for the treatment of acute urinary tract infections. However, its administration can be associated with liver failure or cirrhosis. The aim of this study was to determine whether NIT is a mitochondrial toxicant, if so, what mechanism(s) is involved. The rat liver mitochondria were isolated and treated with different doses of NIT alone or in combination with a reagent of choice for protecting thiol groups, dithiothreitol (DTT). Several mitochondrial parameters, including succinate dehydrogenase activity (also called 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyl tetrazolium bromide assay), lipid peroxidation, superoxide dismutase activity, Reduced glutathione (GSH), and oxidized glutathione (GSSG), and GSSG (oxidized glutathione) levels were determined. The results from this study showed that simultaneous treatment of mitochondria with NIT and DTT significantly reduces the toxicity. Here, we provide evidence that mitochondrial dysfunction followed by depletion of reduced glutathione can be reversed by DTT administration.

Evaluation of antioxidant and antigenotoxic activity of two flavonoids from Rhamnus alaternus L. (Rhamnaceae): kaempferol 3-O-ß-isorhamninoside and rhamnocitrin 3-O-ß-isorhamninoside.

The antioxidant activity of kaempferol 3-O-ß-isorhamninoside (K3O-ir) and rhamnocitrin 3-O-ß-isorhamninoside (R3O-ir), isolated from the leaves of Rhamnus alaternus L., was determined by the ability of each compound to inhibit NBT photoreduction and to scavenge the free radical ABTS(+)(.). Genotoxic and antigenotoxic activities were assessed using the SOS chromotest. At a concentration of 150 µg/assay the two compounds showed the most potent inhibitory activity against superoxide anion by respectively 80.4% and 85.6%. K3O-ir was a very potent radical scavenger with an IC(50) value of 18.75 µg/ml. Moreover, these two compounds exhibit an inhibitory activity against genotoxicity induced by nitrofurantoine and aflatoxine B1 using the SOS chromotest bacterial assay system in the presence of Escherichia coli PQ37 strain. In this study, we have also evaluated correlation between antigenotoxic and antioxidant effects of K3O-ir and R3O-ir. The highest correlation was showed with R3O-ir (r=0.999).

Phenolic constituents of galla Rhois with hepatoprotective effects on tacrine- and nitrofurantoin-induced cytotoxicity in Hep G2 cells.

The bioassay-guided fractionation of the MeOH extract of Galla Rhois furnished two hepatoprotective compounds, an equilibrium mixture of 3-galloyl-gallic acid and 4-galloyl-gallic acid isomers (3), 1,2,3,4,6-penta-O-galloyl-beta-D-glucose (4), and two inactive phenolic compounds, gallic acid methyl ester (1) and gallic acid (2). Compounds 3 and 4 showed significant hepatoprotective effects with EC50 values of 70.39+/-5.4 and 29.51+/-0.7 microM, respectively, against tacrine-induced cytotoxicity, and 150.9+/-6.4 and 23.81+/-0.5 microM, respectively, against nitrofurantoin-induced cytotoxicity in Hep G2 cells.

Mitigation of nitrofurantoin-induced toxicity in the perfused rat liver.

1. Nitrofurantoin is an antimicrobial agent which produces hepatotoxicity caused by the redox cycling of the nitro group and its radical anion. This futile cycling triggers a complex series of events known collectively as oxidative stress. 2. Our goal was to determine treatment strategies which could mitigate nitrofurantoin-induced toxicity in the isolated perfused rat liver. We co-infused various agents which blocked early or late events in the progression to toxicity. Tissue levels of glutathione and protein thiols were measured as indicators of the progression to toxicity and lactate dehydrogenase leakage into the perfusate was used as a marker of irreversible cell death. 3. Five treatments significantly (P < 0.05) decreased LDH leakage (reported as thousands of units accumulated in perfusate at 300 min, mean+/-standard error, n = 3-4) when compared to nitrofurantoin alone (274 +/- 37). These treatments were adenosine-2'-monophosphate (120 +/- 53), penicillamine (90 +/- 29), N-(2-mercaptopropionyl)-glycine (120 +/- 49) and bromosulfophthalein with (80 +/- 29) or without 5,5'-difluro-1,2-bis(O-aminophenoxy)ethane-N,N,N'N'-tetraace tic acid (101 +/- 46). Two other treatments, N-acetylcysteine (183 +/- 7) and dithiothreitol (166 +/- 59) delayed the onset of toxicity. Finally, calpeptin (319 +/- 34) which blocks activation of nonlysosomal proteases was ineffective. 4. We concluded that early intervention on the pathway to toxicity was most effective. The strategies detailed here may prove beneficial in treating hepatotoxicity seen following nitrofurantoin therapy.

Cardiotoxic effects of nitrofurantoin and tertiary butylhydroperoxide in vitro: are oxygen radicals involved?

Langendorff rat hearts were perfused for 15, 30 or 75 min. with the oxygen radical generators nitrofurantoin (0.25 or 0.5 mmol/l) or tertiary butylhydroperoxide (0.25 mmol/l). Both agents reduced the force of contraction and increased the release of glutathione, oxidized glutathione, lactate dehydrogenase and creatine phosphokinase into the perfusion fluid. The tissue concentration of glutathione was reduced. While there were no signs of an increased production of conjugated dienes, the tissue concentration of malondialdehyde was greater than in control experiments. The variability of the latter effect was large, however, and in most cases the increase was not statistically significant. Addition of catalase (100 mU/ml) or catechin (0.5 mmol/l) to the perfusion medium abolished the nitrofurantoin induced release of oxidized glutathione but did not not prevent or attenuate enzyme leakage from the cells and the development of a negative inotropic effect. These results suggest that the cardiotoxic effects of nitrofurantoin and tertiary butylhydroperoxide cannot be explained by the appearance of oxygen radicals alone and that an increased lipid peroxidation is not the mechanism which is primarily responsible for cell death.

Prevention of nitrofurantoin-induced cytotoxicity in isolated hepatocytes by fructose.

Nitrofurantoin is a widely utilized urinary antimicrobial drug which has been associated with pulmonary fibrosis, neuropathy, and hepatitis as well as hemolytic anemia in glucose-6-phosphate dehydrogenase-deficient individuals. Incubation of freshly isolated rat hepatocytes with nitrofurantoin caused oxygen activation as a result of futile redox cycling. Glutathione disulfide (GSSG) was formed and rapidly exported from the cell resulting in complete glutathione (GSH) depletion followed by cell death. However, fructose prevented the export of GSSG from the cell and GSH levels recovered rapidly without cytotoxicity occurring. Fructose did not affect nitrofurantoin metabolism but rapidly depleted cellular ATP levels by approximately 80% which remained depressed during the incubation period. Fructose, however, did not protect hepatocytes from nitrofurantoin-induced cytotoxicity if GSH was depleted beforehand. Protection by fructose only occurred at concentrations which caused ATP depletion. These results suggest that fructose prevents nitrofurantoin-induced toxicity by depleting ATP and thereby preventing the ATP-dependent GSSG efflux. GSSG is retained enabling NADPH and glutathione-reductase to reduce the GSSG back to GSH, thereby protecting the cell from nitrofurantoin-induced oxidative stress.

[Changes in the antibacterial activity of nitrofurantoin preparations induced by peptone and hydrolysates]. / Modificari in activitatea antibacteriana a preparatului nitrofurantoin determinate de peptona si hidrolizate.

The determination of the activity of the product nitrofurantoin (10 and 100 mcg) versus 324 strains of Gram-negative bacteria showed that the diameter of the inhibition zones and the MIC values on a medium with a definite composition (7SG) are considerably larger than on the Mueller-Hinton (MH) medium, in the bacto-tryptose (BT) medium. An increase with 8-12 mm phi or with 2-4 binary dilutions changes the interpretation from resistant, on the MH and BT media into sensitive on the 7SG medium. The low results recorded on the conventional media reveal the existence of an antagonism between peptone and nitrofurantoin, similar to that known for sulfamides. The authors believe that the peptone antagonism has hindered the knowledge of the activity of the nitrofurfural derivatives and the correct assessment of the bacteria sensitivity. They also consider questionable the elimination tendency of the small dosage of microtablets of nitrofurantoin (10 mcg) and sulfamide (30 mcg), since their apparent insufficiency might be due less to the inadequate contraction of substances and more to the inadequate testing media. The results plead for the use of the media with definite chemical composition sulfamide and nitrofuran antagonists free and for reconsideration of several methodologic problems: use of the media with definite chemical composition; introduction of an intermediary dosage of maximum 100 mcg/microtablet; reassessment of the sensitivity categories for sulphafurazole and nitrofurantoin.

Flurbiprofen, a non-steroid anti-inflammatory agent, protects cells against hypoxic cell radiosensitizers in vitro.

Overnight exposure of Chinese hamster cells (V79-753B) to 5 x 10(-5) M flurbiprofen (2-(2-fluoro-4-biphenyl)propionic acid) in vitro reduced the cytotoxic effects of misonidazole, 1-methyl-4-nitro-5-phenoxysulphonylimidazole (NSC 38087) and nitrofurantoin, both in air and in hypoxia at 37 degrees C. Flurbiprofen did not alter the cells' uptake of 14C-misonidazole, nor did it affect the radiosensitivity of aerobic or anaerobic cells, or the degree of hypoxic-cell radiosensitization produced by the sensitizers. When flurbiprofen-treated cells were exposed to melphalan there was no protection against cytotoxicity. These data suggest that flurbiprofen may inhibit the catabolism of radiosensitizers to toxic products and indicate the need to examine whether it will protect against misonidazole-induced toxicity in vivo.