RESUMO
Searching for a more effective chemotherapy for the treatment of Human African trypanosomiasis, the disease caused by the parasite Trypanosoma brucei, and cancer, in the current work five new [PtII(L)(dppf)](PF6) compounds, with HLâ¯=â¯8-hydroxyquinoline derivatives and dppfâ¯=â¯1,1'-bis(diphenylphosphino)ferrocene, were synthesized and fully characterized. Crystal structures of three compounds were solved by XRD. The compounds displayed fairly good activity against bloodstream T. brucei, with IC50 values in the submicromolar range (IC50: 0.14-0.93⯵M), and good selectivity towards the pathogen (SI: 11 - 48) with respect to mammalian macrophages (cell line J774). Coordination to the {Pt-dppf} moiety led, in most cases, to an enhancement of the activity in respect to the bioactive ligands (11 to 41 fold). Cytotoxicity was assessed against wildtype (A2780) and cisplatin-resistance (A2780cisR) ovarian cancer cell lines. Four [PtII(L)(dppf)](PF6) compounds were more active (IC50: 1.2-4.4⯵M) than cisplatin (IC50: 26.0⯵M) on A2780 cells and showed far superior activity than the reference drug against A2780cisR cells. Platinum levels in A2780 cells showed poor correlation between cellular uptake and the cytotoxic activity. All the complexes interacted with DNA and the most active ones induced reactive oxygen species (ROS) formation which suggested that the mechanism of action for these complexes may be mediated by oxidative stress and interaction with DNA that could act as a potential molecular target for this type of complexes. Some complexes of this series could be considered new hits for the development of prospective agents against trypanosomatid parasites and ovarian cancer.
Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Compostos Ferrosos/química , Hidroxiquinolinas/química , Ferro/química , Platina/química , Trypanosoma brucei brucei/efeitos dos fármacos , Animais , Antineoplásicos/síntese química , Linhagem Celular , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cricetulus , Humanos , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Camundongos , Estrutura Molecular , Espécies Reativas de Oxigênio/metabolismo , Difração de Raios XRESUMO
Searching for prospective agents against infectious diseases, four new ferrocenyl derivatives, [M(L)(dppf)4](PF6), with Mâ¯=â¯Pd(II) or Pt(II), dppfâ¯=â¯1,1'-bis(dipheny1phosphino) ferrocene and HLâ¯=â¯tropolone (HTrop) or hinokitiol (HHino), were synthesized and characterized. Complexes and ligands were evaluated against the bloodstream form of T. brucei, L. infantum amastigotes, M. tuberculosis (MTB) sensitive strain and MTB clinical isolates. Complexes showed a significant increase of the anti-T. brucei activity with respect to the free ligands (>28- and >46-fold for Trop and 6- and 22-fold for Hino coordinated to Pt-dppf and Pd-dppf, respectively), yielding IC50 valuesâ¯<â¯5⯵M. The complexes proved to be more potent than the antitrypanosomal drug Nifurtimox. The new ferrocenyl derivatives were more selective towards the parasite than the free ligands. The Pt compounds were less toxic on J774 murine macrophages (mammalian cell model), than the Pd ones, showing selectivity index values (SIâ¯=â¯IC50 murine macrophage/IC50T. brucei) up to 23. Generation of the {M-dppf} compounds lead to a slightly positive impact on the anti-leishmanial potency. Although the ferrocenyl derivatives were more active on sensitive MTB than the free ligands (MIC90â¯=â¯9.88-14.73⯵M), they showed low selectivity towards the pathogen. Related to the mechanism of action, the antiparasitic effect cannot be ascribed to an interference of the compounds with the thiol-redox homeostasis of the pathogen. Fluorescence measurements pointed at DNA as a probable target of the new compounds. [Pt(Trop)(dppf)](PF6) and [Pt(Hino)(dppf)](PF6) could be considered prospective anti-T. brucei agents that deserve further research.