RESUMO
The present study shows the factors that modulate the photodamage promoted by phenothiazines. Cytochrome c was irradiated with UV light for 120 min, over a pH range from 4.0 to 8.0, in the absence and in the presence of different concentrations of thioridazine (TR) and fluphenazine (FP). In the absence of phenothiazines, the maximal rate of a Soret band blue shift (nm/min) from 409 to 406 nm was obtained at pH 4.0 (0.028 nm/min). The presence of phenothiazines at the concentration range 10-25 µmol/L amplified and accelerated a cytochrome c blue shift (409 to 405 nm, at a rate = 0.041 nm/min). Above 25 µmol/L, crescent concentrations of phenothiazines contributed to cytochrome c protection with (maximal at 2500 µmol/L). Scanning electronic microscopy revealed the formation of nanostructures. The pH also influenced the effect of low phenothiazine concentrations on cytochrome c. Thus, the predominance of phenothiazine-promoted cytochrome c damage or protection depends on a balance of the following factors: the yield of photo-generated drug cation radicals, which is favored by acidic pH; the stability of the cation radicals, which is favored by the drug aggregation; and the cytochrome c structure, modulated by the pH.
Assuntos
Citocromos c/química , Citocromos c/metabolismo , Flufenazina/química , Flufenazina/farmacologia , Tioridazina/química , Tioridazina/farmacologia , Raios Ultravioleta , Animais , Relação Dose-Resposta a Droga , Radicais Livres/metabolismo , Concentração de Íons de Hidrogênio , Oxirredução/efeitos dos fármacos , Oxirredução/efeitos da radiação , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologiaRESUMO
The purpose of this study was to develop a method for the stereoselective analysis of thioridazine-2-sulfoxide (THD-2-SO) and thioridazine-5-sulfoxide (THD-5-SO) in culture medium and to study the biotransformation of rac-thioridazine (THD) by some endophytic fungi. The simultaneous resolution of THD-2-SO and THD-5-SO diastereoisomers was performed on a CHIRALPAK AS column using a mobile phase of hexane:ethanol:methanol (92:6:2, v/v/v)+0.5% diethylamine; UV detection was carried out at 262 nm. Diethyl ether was used as extractor solvent. The validated method was used to evaluate the biotransformation of THD by 12 endophytic fungi isolated from Tithonia diversifolia, Viguiera arenaria and Viguiera robusta. Among the 12 fungi evaluated, 4 of them deserve prominence for presenting an evidenced stereoselective biotransformation potential: Phomopsis sp. (TD2) presented greater mono-2-sulfoxidation to the form (S)-(SE) (12.1%); Glomerella cingulata (VA1) presented greater mono-5-sulfoxidation to the forms (S)-(SE)+(R)-(FE) (10.5%); Diaporthe phaseolorum (VR4) presented greater mono-2-sulfoxidation to the forms (S)-(SE) and (R)-(FE) (84.4% and 82.5%, respectively) and Aspergillus fumigatus (VR12) presented greater mono-2-sulfoxidation to the forms (S)-(SE) and (R)-(SE) (31.5% and 34.4%, respectively).
Assuntos
Antipsicóticos/isolamento & purificação , Asteraceae/microbiologia , Cromatografia Líquida de Alta Pressão/métodos , Fungos/metabolismo , Tioridazina/análogos & derivados , Tioridazina/isolamento & purificação , Amilose/análogos & derivados , Amilose/química , Antipsicóticos/química , Antipsicóticos/metabolismo , Aspergillus fumigatus/isolamento & purificação , Aspergillus fumigatus/metabolismo , Biotransformação , Soluções Tampão , Carbamatos/química , Cromatografia Líquida de Alta Pressão/normas , Meios de Cultura/química , Dietilaminas/química , Etanol/química , Éter/química , Fungos/isolamento & purificação , Hexanos/química , Metanol/química , Phyllachorales/isolamento & purificação , Phyllachorales/metabolismo , Reprodutibilidade dos Testes , Solventes/química , Espectrofotometria Ultravioleta , Estereoisomerismo , Tioridazina/química , Tioridazina/metabolismoRESUMO
The stereoselective kinetic biotransformation of thioridazine, a phenothiazine neuroleptic drug, by endophytic fungi was investigated. In general, the sulfur of lateral chain (position 2) or the sulfur of phenothiazinic ring (position 5) were oxidated yielding the major human metabolites thioridazine-2-sulfoxide and thioridazine-5-sulfoxide. The quantity of metabolites biosynthesized varied among the 12 endophytic fungi evaluated. However, mono-2-sulfoxidation occurred in higher ratio and frequency. Among the 12 fungi evaluated, 4 of them deserve prominence for presenting an evidenced stereoselective biotransformation: Phomopsis sp. (TD2), Glomerella cingulata (VA1), Diaporthe phaseolorum (VR4), and Aspergillus fumigatus (VR12). Both enantiomers of thioridazine were consumed by the fungi; however, the 2-sulfoxidation yielded preferentially the R configuration at the sulfur atom.
Assuntos
Ascomicetos/metabolismo , Aspergillus fumigatus/metabolismo , Tioridazina/metabolismo , Biotransformação , Phyllachorales/metabolismo , Estereoisomerismo , Tioridazina/químicaRESUMO
In this work the interaction of Hydroxyzine, Promethazine and Thioridazine with Langmuir films of dipalmitoylphosphatidylcholine (dpPC) and dipalmitoylphosphatidic acid (dpPA), is studied. Temporal variations in lateral surface pressure (pi) were measured at different initial pi (pi(i)), subphase pH and drug-concentration. Drugs with the smallest (PRO) and largest (HYD) molecular size exhibited the lowest adsorption (k(a)) and the highest desorption (k(d)) rate constant values, respectively. The affinity binding constants (K(b)) obtained in monolayers followed the same profile (K(b,PRO) < K(b,HYD) < K(b,THI)) of the egg-PC/water partition coefficients (P) determined in bilayers. The drug concentration required to reach the half-maximal Deltapi at pi(i) = 14 mN/m (K(0.5)), was very sensitive to pH. The maximal increment in pi upon drug incorporation into the monolayer (deltapi(max)) will depend on the phospholipid collapse pressure (pi(c)), the monolayers's compressibility and drug's size, shape and charge. The higher pi(c) of dpPC lead to higher pi(cut-off) values (maximal pi allowing drug penetration), if compared with dpPA. In dpPC and dpPA pi(cut-off) decreased as a function of the molecular size of the uncharged drugs. In dpPA, protonated drugs became electrostatically trapped at the monolayer surface hence drug penetration, monolayer deformation and pi increase were impaired and the correlation between pi(cut-off) and drug molecular size was lost.
Assuntos
1,2-Dipalmitoilfosfatidilcolina/metabolismo , Hidroxizina/metabolismo , Ácidos Fosfatídicos/metabolismo , Prometazina/metabolismo , Tioridazina/metabolismo , 1,2-Dipalmitoilfosfatidilcolina/química , Ar , Hidroxizina/química , Bicamadas Lipídicas , Ácidos Fosfatídicos/química , Prometazina/química , Propriedades de Superfície , Tioridazina/química , ÁguaRESUMO
We present two methods for the enantioselective analysis of thioridazine (THD) and thioridazine 2-sulfone (THD 2-SO(2)) in human plasma based on liquid-liquid extraction with diethyl ether and chiral resolution of the enantiomers on Chiralpak AD and Chiralcel OD-H columns, respectively. After validation, the methods were used to study the degradation and racemization of both drug and metabolite. Our results showed that both enantiomers of THD and THD 2-SO(2) were stable at varying temperatures, pH, and ionic strengths; however, solubility problems for THD and THD 2-SO(2) enantiomers were observed, mainly at pH 8.5. The influence of light on the stability of the THD and THD 2-SO(2) enantiomers was also studied. Degradation of the THD enantiomers was observed under UV light (254 and 366 nm) while THD 2-SO(2) enantiomers were stable at these wavelengths and also when exposed to visible light.