- Photolytic and photocatalytic degradation of nitrofurantoin and its photohydrolytic products
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TiO2 based photocatalytic degradation of nitrofurantion (NFT), a widely used drug, and its primary decomposition products, nitrofuraldehyde (NFA) and aminohydantoin (AHD) was investigated and compared to their photolysis in aerobic systems. UV–vis spectrophotometry, pH, IC, and HPLC measurements were applied to follow the changes during the irradiations and subsequently, in the dark. After a fast anti→syn (or trans→cis) photoisomerization of NFT (giving i-NFT), a slower photohydrolysis of both isomers took place upon UV excitation, leading to the formation of NFA and AHD. i-NFT proved to be more reactive than NFT; it underwent hydrolysis in the dark, too. While photolysis could not totally convert NFT and i-NFT within 120 min, they disappeared within 90 min during the photocatalysis under the same irradiation conditions, along with the degradation of NFA and AHD, and the accumulation of a rather stable intermediate identified as 5-hydroxyfuran-2-carbaldehyde, formed from NFA. The direct photolysis of NFA also gave this characteristic intermediate along with its several derivatives formed via addition or condensation then redox transformations. They very slowly decomposed in photolysis, while totally disappeared during photocatalysis of NFA, producing polar aliphatic intermediates. Direct irradiation could not convert AHD, while photocatalysis led to its significant degradation in aerobic system. These results indicate that TiO2 based photocatalysis is suitable for the efficient decomposition of NFT and their photoderivatives.
- Szabó-Bárdos, Erzsébet,Cafuta, Andrea,Heged?s, Péter,Fónagy, Orsolya,Kiss, Gyula,Babi?, Sandra,?kori?, Irena,Horváth, Ottó
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- Microsomal oxidative stress induced by NADPH is inhibited by nitrofurantoin redox biotranformation
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Nitrofurantoin is used in the antibacterial therapy of the urinary tract. This therapy is associated with various adverse effects whose mechanisms remain unclear. Diverse studies show that the nitro reductive metabolism of nitrofurantoin leads to ROS generation. This reaction can be catalyzed by several reductases, including the cytochrome P450 (CYP450) reductase. Oxidative stress arising from this nitro reductive metabolism has been proposed as the mechanism underlying the adverse effects associated with nitrofurantoin. There is, however, an apparent paradox between these findings and the ability of nitrofurantoin to inhibit lipid peroxidation provoked by NADPH in rat liver microsomes. This work was aimed to show the potential contribution of different enzymatic systems to the metabolism of this drug in rat liver microsomes. Our results show that microsomal lipid peroxidation promoted by NADPH is inhibited by nitrofurantoin in a concentration-dependent manner. This suggests that the consumption of NADPH in microsomes can be competitively promoted by lipid peroxidation and nitrofurantoin metabolism. The incubation of microsomes with NADPH and nitrofurantoin generated 1-aminohidantoin. In addition, the biotransformation of a classical substrate of CYP450 oxidative system was competitively inhibited by nitrofurantoin. These results suggest that nitrofurantoin is metabolized through CYP450 system. Data are discussed in terms of the in vitro redox metabolism of nitrofurantoin.
- Aracena,Lazo-Hernandez,Molina-Berrios,Sepulveda,Reinoso,Larrain,Navarro,Letelier
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p. 129 - 136
(2014/01/06)
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- PROCESS FOR STRAIGHTENING KERATIN FIBRES WITH A HEATING MEANS AND DENATURING AGENTS
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The invention relates to a process for straightening keratin fibres, comprising: (i) a step in which a straightening composition containing at least two denaturing agents is applied to the keratin fibres, (ii) a step in which the temperature of the keratin fibres is raised, using a heating means, to a temperature of between 110 and 250° C.
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