No abstract

Three promising antimycobacterium tuberculosis ruthenium(II) complexes with the deprotonated ligands 2-hydroxynicotinic acid (2-OHnicH), 6-hydroxynicotinic acid (6-OHnicH) and 3-hydroxypicolinic acid (3-OHpicH) were synthesized and characterized. Structural analysis revealed three different coordination modes depending of the hydroxypyridinecarboxylate ligand. In the complex [Ru(2-OHnic)(dppb)(bipy)]PF 6 (1), the 2-OHnic anion is coordinated by the O,O-chelating mode (via carboxylate group and phenolate oxygen), in the [Ru(6-OHnic)(dppb)(bipy)]PF 6 (2) a O-O chelation by the carboxylate group is observed for the 6-OHnic ligand and for the complex [Ru(3-OHpic)(dppb)(bipy)]PF 6 (3) a N,O-chelating mode (via carboxylate) occurs to the 3-OHpic anion. The compounds were evaluated for activity against Mycobacterium tuberculosis H 37 Rv ATCC 27294 using Resazurin Microtitre Assay (REMA) plate method and cytotoxicity in VERO CCL-81 cell line. All the synthesized compounds exhibited good antimycobacterial activity and a completely lack of cytotoxicity activity, indicating a good selectivity index.

New complexes with the formula [RuCl(CO)(dppb)(N–N)]PF6 were prepared by varying the CO position as well as the diimine ligand.

Six new complexes of Ru(II)/phenanthroline/1,4-bis(diphenylphosphino)butane containing amino acids (Glycine, L-Alanine, L-Valine, L-Tyrosine, L-Methionine or L-Tryptophan) were synthesized and characterized by IR, 31 P{ 1 H}, 13 C and 1 H NMR spectroscopies and cyclic voltammetry experiments. These data suggest the presence of diastereoisomers, except for the complex with glycine, amino acid that does not exhibit chiral carbon. The compounds are active against the MDA-MB-231 tumor cells and against Mycobacterium tuberculosis. The cationic ruthenium complexes with amino acids, reported here, show similar cytotoxicity against the MDA-MB-231 tumor cells. When compared with analogs complexes containing 2,2 0 -bipyridine as ligands, instead of 1,10-phenatroline, the new complexes studied here are, in general, roughly twice more active than the 2,2 0 -bipyridine ones and their IC 50 values comparable with the cisplatin. In addition, low MICs values were obtained against Mycobacterium tuberculosis compared with the reference drugs, cycloserine and ethambutol.

A straightforward organocatalyzed asymmetric addition of oxazole-2(3H)-thiones to α,β-unsaturated ketones is described. This additive-free Michael reaction in the presence of chiral cinchonine-derived primary amines as catalysts has proven to be highly effective for a wide range of cyclic and acyclic enones, leading to the Michael adducts in very good yields and excellent enantioselectivities. The absolute configuration (R) of compound 5j was unambiguously assigned by X-ray diffraction analysis. Furthermore, experimental and theoretical studies were performed and a mechanism is presented and discussed for this novel reaction.