EXAMINATION BY EPR SPECTROSCOPY OF FREE RADICALS IN MELANINS ISOLATED FROM A-375 CELLS EXPOSED ON VALPROIC ACID AND CISPLATIN

被引：0
|
作者：
Chodurek, Ewa [1 ]
Zdybel, Magdalena [2 ]
Pilawa, Barbara [2 ]
Dzierzewicz, Zofia [1 ]
机构：
[1] Med Univ Silesia, Div Lab Med, Sch Pharm, Dept Biopharm, PL-41200 Sosnowiec, Poland
[2] Med Univ Silesia, Div Lab Med, Sch Pharm, Dept Biophys, PL-41200 Sosnowiec, Poland
来源：
ACTA POLONIAE PHARMACEUTICA | 2012年 / 69卷 / 06期
关键词：
A-375 human melanoma cells; melanin; valproic acid; cisplatin; free radicals; EPR spectroscopy; DOPA-MELANIN; IN-VITRO; MELANOGENESIS; COMPLEXES;
D O I：
暂无
中图分类号：
R9 [药学];
学科分类号：
1007 ;
摘要：
Drug binding by melanin biopolymers influence the effectiveness of the chemotherapy, radiotherapy and photodynamic therapy. Free radicals of melanins take part in formation of their complex with drugs. The aim of this work was to determine the effect of the two compounds: valproic acid (VPA) and cisplatin (CPT) on free radicals properties of melanin isolated from A-375 melanoma cells. Free radicals were examined by an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. EPR spectra were measured for the model synthetic eumelanin DOPA-melanin, the melanin isolated from the control A-375 cells and these cells treated by VPA, CPT and both VPA and CPT. For all the examined samples broad EPR lines (Delta B-pp: 0.48-0.68 mT) with g-factors of 2.0045-2.0060 characteristic for o-semiquinone free radicals were observed. Free radicals concentrations (N) in the tested samples, g-factors, amplitudes (A), integral intensities (I) and linewidths (Delta B-pp) of the EPR spectra, were analyzed. The EPR lines were homogeneously broadened. Continuous microwave saturation of the EPR spectra indicated that slow spin-lattice relaxation processes existed in all the tested melanin samples. The relatively slowest spin-lattice relaxation processes characterized melanin isolated from A-375 cells treated with both VPA and CPT. The changes of the EPR spectra with increasing microwave power in the range of 2.2-70 mW were evaluated. Free radicals concentrations in the melanin from A-375 cells were higher than in the synthetic DOPA-melanin. The strong increase of free radicals concentration in the melanin from A-375 cells was observed after their treating by VPA. CPT also caused the increase of free radicals concentrations in the examined natural melanin. The free radicals concentration in melanin isolated from A-375 cells treated with both VPA and CPT was slightly higher than those in melanin from the control cells.
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页码：1334 / 1341
页数：8
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