RESUMEN
Norfloxacin (NOR) is a synthetic broad-spectrum fluoroquinolone antibiotic classified as an emerging contaminant. Here, we investigate Mn(III) porphyrin-catalyzed NOR degradation using peroxides or peracids (H2O2, t-BuOOH, or Oxone®) as oxidants. We evaluate three Mn(III) porphyrins: the 1st-generation tetraphenylporphyrin and 2ndâ¯-generation porphyrins bearing halogen atoms at the ortho-positions of the porphyrin macrocycle meso-aryl groups. Experiments were carried out in aqueous medium under mild conditions. NOR degradation was 67%. Products were proposed by mass spectrometry (MS) analysis. Oxone® was the best oxidant for NOR degradation despite its possible decomposition in the reaction medium. The second-generation Mn(III) porphyrins were more resistant than the first-generation Mn(III) porphyrin, indicating that the bulky groups introduced into the porphyrin macrocycle meso-aryl groups led to more robust catalysts. The degradation products did not present cytotoxic behavior under the employed conditions. In conclusion, Mn(III) porphyrin-catalyzed NOR degradation is a promising strategy to degrade fluoroquinolones and other pollutants.
Asunto(s)
Antibacterianos/química , Sistema Enzimático del Citocromo P-450/metabolismo , Manganeso/química , Norfloxacino/química , Porfirinas/análisis , Contaminantes Químicos del Agua/química , Biomimética , Catálisis , Peróxido de Hidrógeno , Oxidación-ReducciónRESUMEN
Atrazine (ATZ) is an herbicide that has been considered an environmental pollutant worldwide. ATZ contaminates groundwaters and can persist in soils for up to a year causing several environmental and health problems. This study aimed to investigate ATZ degradation catalyzed by manganese porphyrins as biomimetic cytochrome P450 models. We used PhIO, PhI(OAc)2, H2O2, t-BuOOH, m-CPBA, or Oxone® as oxidant under mild conditions and evaluated a range of manganese porphyrins as catalyst. Concerning oxidant, iodosylbenzene provided the best result-ATZ degradation catalyzed by one of the studied manganese porphyrins in acetonitrile was as high as 47%. We studied the same catalyst/oxidant systems in natural water from a Brazilian river as solvent and obtained up to 100% ATZ degradation when iodobenzene diacetate was the oxidant, regardless of the manganese porphyrin. Besides the already known ATZ degradation products, we also identified unexpected degradation compounds (ring-opening products). Toxicity tests showed that the latter products were capable of proliferate blood cells because they did not show toxicity under the evaluated conditions.
Asunto(s)
Atrazina/química , Biodegradación Ambiental , Leucocitos Mononucleares/efectos de los fármacos , Porfirinas/química , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Acetonitrilos/química , Biomimética , Brasil , Catálisis , Supervivencia Celular/efectos de los fármacos , Herbicidas , Humanos , Yodobencenos/química , Manganeso/química , Oxidantes/química , Peróxidos/química , Plaguicidas/química , Pruebas de ToxicidadRESUMEN
A range of hydrophobic first-, second-, and third-generation manganese porphyrins (MnPs) was investigated as cytochrome P450 models for degradation of the antibiotic ciprofloxacin (CIP). The experiments were carried out under mild conditions; oxidants such as iodosylbenzene (PhIO), H2O2, and meta-chloroperbenzoic acid were employed. The PhIO system yielded the best results: CIP degradation ranged between 56% and 76%. CIP degradation was not directly related to MnP generation. The second-generation MnP afforded the best result with the advantage that it required less preparation effort as compared to the third-generation MnP. Some new degradation products in MnP-mediated ciprofloxacin degradation were proposed, and the products of the reaction are not cytotoxic under the conditions evaluated.