Analu Rocha Costa

Benzenesulfonylpiperazines have been previously identified as a promising class against Chagas disease and leishmaniasis, two parasitic neglected tropical diseases. Thus, the pharmacokinetic profile of two potential leads against visceral leishmaniasis was assessed in vitro. Both lead candidates 1 and 2 exhibited a satisfactory ADME profile, with 2 proving slightly superior in terms of metabolic stability. Therefore, after complementary toxicity assessment which revealed that 2 did not exert hepatotoxicity in vitro or acute toxicity in vivo, the evaluation of its efficacy in a mouse model highlighted that 2 indeed displays antileishmanial efficacy in vivo. Albeit moderate at a dose of 50 mg/kg/day, its efficacy increased at a dose of 100 mg/kg/day, reducing the parasite burden by 90% in the spleen of infected mice, though safety concerns were raised at this dose. In vitro investigation of its mode of action revealed that 2 exerts a cytostatic effect on Leishmania infantum promastigotes, promoting cell cycle arrest during the G0/G1 phase which may potentially be linked to the production of reactive oxygen species.

Ru( ii )-naphthoquinone complexes are effective against human triple-negative breast cancer (MDA-MB-231). Flow cytometry and western blotting confirmed the mechanism of action via apoptosis induced by reactive oxygen species (ROS).

Non-mutagenic ruthenium(ii)–phosphine complexes stop tumor growth in MCF-7 3D spheroids and induce apoptosis via mitochondrial damage.

The search for new metal-based anticancer drug candidates is a fundamental task in medicinal inorganic chemistry. In this work, we assessed the potential of two new Ru(II)–phosphine–mercapto complexes as potential anticancer agents. The complexes, with the formula [Ru(bipy)(dppen)(Lx)]PF₆ [(1), HL1 = 2-mercapto–pyridine and (2), HL2 = 2-mercapto–pyrimidine, bipy = 2,2′-bipyridine, dppen = cis-1,2-bis(diphenylphosphino)-ethylene] were synthesized and characterized by nuclear magnetic resonance (NMR) [¹H, ³¹P(¹H), and ¹³C], high resolution mass spectrometry (HR-MS), cyclic voltammetry, infrared and UV-Vis spectroscopies. Complex 2 was obtained as a mixture of two isomers, 2a and 2b, respectively. The composition of these metal complexes was confirmed by elemental analysis and liquid chromatography-mass spectrometry (LC-MS). To obtain insights into their lipophilicity, their distribution coefficients between n-octanol/PBS were determined. Both complexes showed affinity mainly for the organic phase, presenting positive log P values. Also, their stability was confirmed over 48 h in different media (i.e., DMSO, PBS and cell culture medium) via HPLC, UV-Vis and ³¹P{¹H} NMR spectroscopies. Since enzymes from the P-450 system play a crucial role in cellular detoxification and metabolism, the microsomal stability of 1, which was found to be the most interesting compound of this study, was investigated using human microsomes to verify its potential oxidation in the liver. The analyses by LC-MS and ESI-MS reveal three main metabolites, obtained by oxidation in the dppen and bipy moieties. Moreover, 1 was able to interact with human serum albumin (HSA). The cytotoxicity of the metal complexes was tested in different cancerous and non-cancerous cell lines. Complex 1 was found to be more selective than cisplatin against MDA-MB-231 breast cancer cells when compared to MCF-10A non-cancerous cells. In addition, complex 1 affects cell morphology and migration, and inhibits colony formation in MDA-MB-231 cells, making it a promising cytotoxic agent against breast cancer.

Coordination compounds of copper exhibit cytotoxic activity and are suitable for the search for novel drug candidates for cancer treatment. In this work, we synthesized three copper(II) carboxylate complexes, [Cu₂(3-(4-hydroxyphenyl)propanoate)₄(H₂O)₂]·2H₂O (C1), [Cu₂(phenylpropanoate)₄(H₂O)₂] (C2) and [Cu₂(phenylacetate)₄] (C3), and characterized them by elemental analysis and spectroscopic methods. Single-crystal X-ray diffraction of C1 showed the dinuclear paddle-wheel arrangement typical of Cu–carboxylate complexes in the crystal structure. In an aqueous solution, the complexes remain as dimeric units, as studied by UV-visible spectroscopy. The lipophilicity (partition coefficient) and the DNA binding (UV visible and viscosity) studies evidence that the complexes bind the DNA with low K_b constants. In vitro cytotoxicity studies on human cancer cell lines of metastatic breast adenocarcinoma (MDA-MB-231, MCF-7), lung epithelial carcinoma (A549) and cisplatin-resistant ovarian carcinoma (A2780cis), as well as a nontumoral lung cell line (MRC-5), indicate that the complexes are cytotoxic in cisplatin-resistant cells.

Four new Cu/PPh₃/naphtoquinone complexes were synthesized, characterized (IR, UV/visible, 1D/2D NMR, mass spectrometry, elemental analysis, and X-ray diffraction), and evaluated as anticancer agents. We also investigated the reactive oxygen species (ROS) generation capacity of complex 4, considering the well-established photochemical property of naphthoquinones. Therefore, employing the electron paramagnetic resonance (EPR) “spin trap”, 5,5-dimethyl-1-pyrroline N-oxide (DMPO) technique, we identified the formation of the characteristic •OOH species (hydroperoxyl radical) adduct even before irradiating the solution containing complex 4. As the irradiation progressed, this radical species gradually diminished, primarily giving rise to a novel species known as •DMPO-OH (DMPO + •OH radical). These findings strongly suggest that Cu(I)/PPh₃/naphthoquinone complexes can generate ROS, even in the absence of irradiation, potentially intensifying their cytotoxic effect on tumor cells. Interpretation of the in vitro cytotoxicity data of the Cu(I) complexes considered their stability in cell culture medium. All of the complexes were cytotoxic to the lung (A549) and breast tumor cell lines (MDA-MB-231 and MCF-7). However, the higher toxicity for the lung (MRC5) and breast (MCF-10A) non-tumoral cells resulted in a low selectivity index. The morphological analysis of MDA-MB-231 cells treated with the complexes showed that they could cause decreased cell density, loss of cell morphology, and loss of cell adhesion, mainly with concentrations higher than the inhibitory concentration of 50% of cell viability (IC₅₀) values. Similarly, the clonogenic survivance of these cells was affected only with concentrations higher than the IC₅₀ values. An antimigratory effect was observed for complexes 1 and 4, showing around 20–40% of inhibition of wound closure in the wound healing experiments.

Coordination complexes may act as anticancer agents. Among others, the formation of the complex may facilitate the ligand uptake by the cell. Searching for new copper compounds with cytotoxic activity, the complex Cu-dipicolinate was studied as a neutral scaffold to form ternary complexes with diimines. A series of [Cu(dipicolinate)(diimine)] complexes (where diimine: Phenanthroline, phen, 5-NO₂-phenanthroline, 4-methyl-phenanthroline, neocuproine, 3,4,7,8-tetramethyl-phenanthroline, tmp, bathophenanthroline, bipyridine, dimethyl-bipyridine, as well as the ligand 2,2-dipyridil-amine, bam) were synthesized and characterized both in the solid state, including a new crystal structure of [Cu₂(dipicolinate)₂(tmp)₂]·7H₂O. Their chemistry in aqueous solution was explored by UV/vis spectroscopy, conductivity, cyclic voltammetry, and electron paramagnetic resonance studies. Their DNA binding was analyzed by electronic spectroscopy (determining K_b values), circular dichroism, and viscosity methods. The cytotoxicity of the complexes was assessed on human cancer cell lines MDA-MB-231, MCF-7 (breast, the first triple negative), A549 (lung epithelial) and A2780cis (ovarian, Cisplatin-resistant), and non-tumor cell lines MRC-5 (lung) and MCF-10A (breast). The major species are ternary, in solution and solid state. Complexes are highly cytotoxic as compared to Cisplatin. Complexes containing bam and phen are interesting candidates to study their in vivo activity in triple-negative breast cancer treatment.

Searching for new copper compounds which may be useful as antitumor drugs, a series of new [Cu(L-dipeptide)(batho)] (batho:4,7-diphenyl-1,10-phenanthroline, L-dipeptide: Gly-Val, Gly-Phe, Ala-Gly, Ala-Ala, Ala-Phe, Phe-Ala, Phe-Val and Phe-Phe) complexes were synthesized and characterized. To interpret the experimental IR spectra, [Cu(ala-gly)(batho)] was modelled in the gas phase using DFT at the B3LYP/LANL2DZ level of theory and the calculated vibrational frequencies were analyzed. Solid-state characterization is in agreement with pentacoordinate complexes of the general formula [Cu(L-dipeptide)(batho)]·x solvent, similar to other [Cu(L-dipeptide)(diimine)] complexes. In solution, the major species are heteroleptic, as in the solid state. The mode of binding to the DNA was evaluated by different techniques, to understand the role of the diimine and the dipeptide. To this end, studies were also performed with complexes [CuCl₂(diimine)], [Cu(L-dipeptide)(diimine)] and free diimines, with phenanthroline, neocuproine and 3,4,7,8-tetramethyl-phenanthroline. The cytotoxicity of the complexes was determined on human cancer cell lines MDA-MB-231, MCF-7 (breast, the first triple negative), and A549 (lung epithelial) and non-tumor cell lines MRC-5 (lung) and MCF-10A (breast). [Cu(L-dipeptide)(batho)] complexes are highly cytotoxic as compared to cisplatin and [Cu(L-dipeptide)(phenanthroline)] complexes, being potential candidates to study their in vivo activity in the treatments of aggressive tumors for which there is no curative pharmacological treatment.

Studying molecular interactions of soft biomolecular materials is a key step to the development of novel functional nanostructures with potential application in nanobiotechnology and nanomedicine. In current work we aimed to study the interaction of a rationally designed peptide whose degree of molecular self-association depends on pH, with model membranes employing Fourier transform infrared spectroscopy (FTIR). Two types of model lipid membranes were used, one formed by the DPPC, a lipid with a zwitterionic head group, and consequently electrically neutral, and the other type formed by the DPPG, a lipid with an anionic head group, and therefore negatively charged. The results showed that in the range of pH 6.0–8.0 the peptide P11-4 shows spectral features which are evidence of the presence of peptides with anti-parallel beta-sheet conformation (bands in the range 1625–1615 cm−1 and 1680–1685 cm−1), as also spectral features which indicate the existence of random coil conformation (bands around 1644 cm−1). According to the results obtained by FTIR, it was found that the peptide had its behavior modulated by the interaction with the model membranes. It was observed that DPPG model lipid membranes caused an effect on P11-4 molecular organization state under different pH values, pH 6.0, 7.0 and 8.0, showing the most prominent effect on the basic environment, while the DPPC membranes practically did not affect the peptide self-assembling behavior. Such results are important for the development of novel biomolecular nanostructured materials by the physico-chemical understanding of self-organizing molecular systems.