Avaliação da atividade mutagênica de complexos heterolépticos de Rutênio(II) com atividade anti - Mycobacterium tuberculosis

A tuberculose (TB) é classificada como a segunda causa de morte por um único agente infeccioso, o Mycobacterium tuberculosis. Crescentes incidências de cepas resistêntes a múltiplas drogas (MDR) estão emergindo como uma ameaça global à saúde. Além disso, os medicamentos padrões da terapia são incapazes de controlar o surto de TBMDR e os casos de co-infecção com HIV. Nos últimos anos, um grande número de grupos de pesquisa têm dedicado a sua atenção para o desenvolvimento de agentes antimicobacterianos específicos e de baixo custo, direcionados às cepas MDR. Novos estudos apontam os complexos de rutênio(II) como uma promissora alternativa na terapia anti-TB. Esses complexos vêm sendo testados contra diversas bactérias e estudos atuais indicaram excelentes resultados contra cepas de TB-MDR. Todavia, mesmo com resultados promissores, é imprescindível avaliar seus efeitos toxicológicos, a fim de garantir um uso seguro à saúde humana. Nesse contexto, a avaliação do potencial mutagênico é fundamental para assegurar seu uso sem demonstrar riscos no desenvolvimento de cânceres, bem como outras doenças desencadeadas por alterações no DNA. Baseados nisso, este trabalho teve como objetivo, avaliar os efeitos mutagênicos de três complexos de rutênio(II), com promissora atividade anti-TB-MDR, denominados de SCAR 4, SCAR 5 e SCAR 6 por meio dos ensaios de mutação gênica reversa nas cepas TA1535 TA98, TA97a, TA100 e TA102 de Salmonella typhimurium (Teste de Ames) e pelo ensaio do micronúcleo citoma com bloqueio da citocinese (CBMN-cit) em cultura de células CHO-K1 e HepG2. Em ambos os ensaios, foram utilizados modelos onde foi possível avaliar o efeito da metabolização dos complexos. O ensaio de sobrevivência clonogênica foi utilizado para avaliar o efeito antiproliferativo nas linhagens CHO-K1 e HepG2, além de selecionar...Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

In Vitro Evaluation of Acellular Collagen Matrices Derived from Porcine Pericardium: Influence of the Sterilization Method on Its Biological Properties

The aim of this study were characterize acellular collagen matrices derived from porcine pericardium (PP) and to evaluate their properties after sterilization by ethylene oxide and gamma ray. PP matrices were subjected to alkaline hydrolysis (AH), and samples were characterized for biological stability, membrane thickness measurements, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Subsequently, the matrices were frozen, lyophilized and sterilized by ethylene oxide or gamma radiation. For in vitro assays, CHO-K1 cell culture was used and evaluated for cytotoxicity, clonogenic survival assay, genotoxicity and mutagenicity. Analysis of variance (ANOVA) was used, followed by Dunnett’s post-test, with a significance level of 5%. After AH, there was no significant change in matrix thickness. The relative biodegradability of the material after implantation was observed. Morphology and dimensions had small changes after AH. As for cell viability, none of the tested matrices showed a statistically significant difference (p > 0.05; Dunnett) regardless of the sterilization method. Furthermore, it was found that PP matrices did not interfere with the proliferation capacity of CHO-K1 cells (p > 0.05; Dunnett). As for genotoxicity, when sterilized with ethylene oxide (NP, P12 and P24), it showed genotoxic potential, but it was not genotoxic when sterilized by gamma radiation. No mutagenic effects were observed in either group. PP-derived collagen matrices hydrolyzed at different times were not cytotoxic. It is concluded that the best method of sterilization is through gamma radiation, since no significant changes were observed in the properties of the PP matrices

Non-mutagenic Ru(II) complexes : cytotoxicity, topoisomerase IB inhibition, DNA and HSA binding.

Herein we discuss five ruthenium(II) complexes with good cytotoxicity against cancer cells. These complexes are named [Ru(tzdt)(bipy)(dppb)]PF6 (1), [Ru(mmi)(bipy)(dppb)]PF6 (2), [Ru(dmp)(bipy)(dppb)]PF6 (3), [Ru(mpca)(bipy)(dppb)]PF6 (4) and [Ru(2mq)(bipy)(dppb)]PF6 (5), where tzdt = 1,3-thiazolidine-2-thione, mmi = mercapto-1-methyl-imidazole, dmp = 4,6-diamino-2-mercaptopyrimidine, mpca = 6-mercaptopyridine-3-carboxylic acid, 2mq = 2-mercapto-4(3H)-quinazolinone, bipy = 2,2?-bipyridine and dppb = 1,4-bis(diphenylphosphino)butane. In vitro cell culture experiments revealed significant cytotoxic activity for 1?5 against MDA-MB-231, MCF-7, A549, DU-145 and HepG2 tumor cells, higher than that for the standard anticancer drug cisplatin. Compound/DNA interaction studies were carried out showing that 1?5 interact with DNA by electrostatic force of attraction or by hydrogen bonding. Moreover, the complexes interact, moderately and spontaneously, with human serum albumin (HSA) through the hydrophobic region. The five complexes are able to inhibit the DNA supercoiled relaxation mediated by human topoisomerase IB (TopIB), and complex 1 is found to be the most efficient TopIB inhibitor among the five compounds. The inhibitory effect and analysis of different steps of the TopIB catalytic cycle indicate that complex 1 inhibits the cleavage reaction impeding the binding of the enzyme to DNA and has no effect on the religation step. Complexes 1, 2 and 3 did not show mutagenic activity when they were evaluated by the cytokinesis-block micronucleus cytome assay in HepG2 cells and the Ames test in the presence and absence of mouse liver S9 metabolic activation. Therefore, it is necessary to perform further in-depth analysis of the therapeutic potential of these promising ruthenium complexes as anticancer drugs

Mutagenicity and chemopreventive activities of Astronium species assessed by Ames test

In the neotropical savannah, Astronium species are used in popular medicine to treat allergies, inflammation, diarrhea and ulcers. Given that natural products are promising starting points for the discovery of novel potentially therapeutic agents, the aim of the present study was to investigate the mutagenic and antimutagenic activities of hydroalcoholic extracts of Astronium spp. The mutagenicity was determined by the Ames test on Salmonella typhimurium strains TA98, TA97a, TA100 and TA102. The antimutagenicity was tested against the direct-acting and indirect-acting mutagens. The results showed that none of the extracts induce any increase in the number of revertants, demonstrating the absence of mutagenic activity. On the other hand, the results on the antimutagenic potential showed a moderate inhibitory effect against NPD and a strong protective effect against B[a]P and AFB1. This study highlights the importance of screening species of Astronium for new medicinal compounds. The promising results obtained open up new avenues for further study and provide a better understanding the mechanisms by which these species act in protecting DNA from damage. However, further pharmacological and toxicological investigations of crude extracts of Astronium spp., as well as of its secondary metabolites, are necessary to determine the mechanism(s) of action to guarantee their safer and more effective application to human health