RESUMO
The synthesis of five 2-arylnaphtho[2,3-d]oxazole-4,9-dione derivatives was accomplished by refluxing 2-amino-3-bromo-1,4-naphthoquinone with appropriate benzoyl chloride analogs at elevated temperatures. In vitro anticancer evaluation of these compounds was performed on androgen-dependent, LNCaP, and androgen-independent, PC3, human prostate cancer cell lines. In general, these compounds displayed slightly stronger cytotoxicity on the androgen-dependent LNCaP than on the androgen-independent PC3 prostate cancer cell lines. The meta-substituted 2-(3-Chloro-phenyl)-naphtho[2,3-d]oxazole-4,9-dione (10) appear to display the best cytotoxicity on both cell lines with an IC(50) of 0.03 µM on LNCaP and 0.08 µM on PC3 after 5 days of exposure.
Assuntos
Androgênios/farmacologia , Benzoxazóis/síntese química , Benzoxazóis/farmacologia , Naftoquinonas/síntese química , Naftoquinonas/farmacologia , Oxazóis/síntese química , Oxazóis/farmacologia , Neoplasias da Próstata/patologia , Benzoxazóis/química , Benzoxazóis/uso terapêutico , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Cristalografia por Raios X , Humanos , Concentração Inibidora 50 , Masculino , Naftoquinonas/química , Naftoquinonas/uso terapêutico , Oxazóis/química , Oxazóis/uso terapêutico , Neoplasias da Próstata/tratamento farmacológicoRESUMO
(E)-4-Hydroxy-3-methylbut-2-enyl diphosphate synthase (GcpE/IspG) converts 2-C-methyl-D-erythritol-2,4-cyclodiphosphate (MEcPP) into (E)-4-hydroxy-3-methyl-but-2-enyl diphosphate (HMBPP) in the penultimate step of the methyl-erythritol phosphate (MEP) pathway for isoprene biosynthesis. MEcPP is a cyclic compound and the reaction involves the opening of the ring and removal of the C3 hydroxyl group consuming a total of two electrons. The enzyme contains a single [4Fe-4S] cluster in its active site. Several paramagnetic species are observed in steady-state and pre-steady-state kinetic studies. The first signal detected is from a transient species that displays a rhombic electron paramagnetic resonance (EPR) signal with g(xyz) = 2.000, 2.019, and 2.087 (FeS(A)). A second set of EPR signals (FeS(B)) accumulated during the reaction. Labeling studies with (57)Fe showed that all species observed are iron-sulfur-based. (31)P-ENDOR measurements on the FeS(A) species showed a weak (31)P coupling which is in line with binding of the substrate to the enzyme in close proximity of the active-site cluster. On the basis of the EPR/ENDOR measurements, we propose a direct binding of the substrate to the [4Fe-4S] cluster during the reaction, and therefore that the iron-sulfur cluster is directly involved in a reductive elimination of a hydroxyl group. The FeS(B) signal also showed (31)P coupling; in this case, however, it could be shown that the signal is due to the binding of the reaction product HMBPP to the active site cluster.
Assuntos
Alquil e Aril Transferases/metabolismo , Alquil e Aril Transferases/química , Espectroscopia de Ressonância de Spin Eletrônica , CinéticaRESUMO
The GcpE enzyme converts 2-C-methyl-D-erythritol-2,4-cyclodiphosphate (MEcPP) into (E)-4-hydroxy-3-methyl-but-2-enyl diphosphate (HMBPP) in the penultimate step of the DOXP pathway for isoprene biosynthesis. Purification of the enzyme under exclusion of air leads to a preparation that contains solely [4Fe-4S] clusters. Kinetic studies showed that in the presence of the artificial reductant dithionite and MEcPP a new transient iron-sulfur-based signal is detected in electron paramagnetic resonance (EPR) spectroscopy. Similarity of this EPR signal to that detected in ferredoxin:thioredoxin reductase indicates that during the reaction an intermediate is directly bound to the active-site cluster.