Ruthenium nitrosyl compounds. Chemical equilibrium, involvement in vegetal systems and cytotoxicity in cancer / Nitrosilos complexos de rutênio. Equilíbrio químico, envolvimento em sistemas vegetais e citotoxicidade em modelos de câncer

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The product of the reaction of trans-[Ru(NH3)4P(OEt) 3H2O]2+ with nitrite ions depends on the hydrogenionic concentration of the medium. In solutions with pH > 10, the final compound is the trans-[Ru(NH3)4P(OEt) 3NO2]+ (1,1 x 103 M-1.s-1), wich is quantitatively converted into the trans-[Ru(NH3)4P(OEt) 3NO]3+ in acid solutions (CH+ > 10-5 mol.L-1; kobs = 2.2 x 10-3 s-1 at pH 4). This reaction presents two different steps with distinct rate constants, being the first step faster than the second. Then, the first process was attributed to the formation of both the isomers, trans-[Ru(NH3)4P(OEt)3NO2]+ and trans-[Ru(NH3)4P(OEt)3ONO]+ (1.1 x 103 M-1s-1; pH 11). The slowest step was then attributed to the isomerization of the nitrito compound, O-bonded, to the nitro compound, Nbonded, which presents more stability (6.9 x 102 M-1s-1; pH 11). In vitro studies were used to evaluate the cytotoxicity of some nitrosyl ruthenium compounds type trans-[Ru(NO)(NH3)4L]3+ and trans-[Ru(NH3)4L(SO4)]+ against some cancer cells models. The compounds showed significant results against human leukemia (Jurkat) and murine melanoma (B16F10-Nex2). The compounds also showed citotoxicity against human breast adenocarcinoma cell line (MCF-7), however the compounds were less active in this culture. In vivo studies with B16F10-Nex2 and the ruthenium compounds suggests that intraperitoneally applications of the complexes delays tumor growth and prolongs animal survival rate. The results also indicates that the compounds should induce a caspase-independent death of the tumor cell. The application of the nitrosyls, SNP and [Ru(NO)Hedta], in embryogenic suspension cultures of Araucaria angustifolia promotes an increase at the fresh mass percent comparing with the control samples. This effect was inhibit when the compound PTIO, a NO scavenger, was added to the samples prepared with NO donors. After 21 days of cellular culture, fluorimetric methods for NO detection showed that the samples prepared with SNP and [Ru(NO)Hedta] presents higher intra and extracellular NO concentrations than control. Morphological organization of embryogenic suspension cultures of A. angustifolia were also influenced by the addition of NO, the cultures with the donors showed increased embriogenic cells numbers relating to the control.

ASSUNTO(S)

fosfito phosphite araucaria araucária nitrosyl rutênio câncer ruthenium cancer nitrosilos

ACESSO AO ARTIGO

Documentos Relacionados