Publications by authors named "Roberto Santana Da Silva"

Carbonized polymer dots (CPDs) were obtained by using microwave irradiation under the same conditions. However, different carbogenic precursors were used, such as aromatic diamine molecules, -phenylenediamine (-OPDA), and 3,4-diaminobenzoic acid (3,4-DABA). Both carbon nanoparticles showed different structural results based on Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and atomic force microscopy analyses.

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Efforts to find compounds selectively affecting cancer cells while sparing normal ones have continued to grow. Nitric oxide (NO) is critical in physiology and pathology, including cancer. It influences cellular processes like proliferation, apoptosis, and angiogenesis.

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Epigallocatechin-3-gallate (EGCG), a polyphenol derived from Green Tea, is one of the sources of natural bioactive compounds which are currently being developed as medicinal ingredients. Besides other biological activities, this natural compound exhibits anti-cariogenic effects. However, EGCG has low physical-chemical stability and poor bioavailability.

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Postmenopausal osteoporosis and poor dietary habits can lead to overweightness and obesity. Bisphosphonates are the first-line treatment for osteoporosis. However, some studies show that they may increase the risk of osteonecrosis of the jaw.

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Carbon dots (CDs) exhibit luminescence, biocompatibility, and higher water solubility. This material has been developed for biological applications, specifically in bioimaging. In this work, the gelatin carbon dots (CD) was obtained from commercial gelatin using a hydrothermal method in domestic microwave, and the suppression fluorescent mechanism were enhanced by the addition of the [Ru(bdq)(NO)(tpy)] (Rubdq-NO) complex ion.

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cis-[Ru(bpy)2(py)NO2](PF6) (RuBPY) is a ruthenium complex nitric oxide (NO) donor that presents a nitrite in its moiety and has been shown to induce vasodilation in various arteries, as well as arterial pressure reduction with no changes in heart rate. Because vascular tone is highly dependent on the cytosolic calcium concentration ([Ca ]c), the current study aimed to investigate the effects of RuBPY on the intracellular mobilization of calcium stores of rat aortic vascular smooth muscle cells. Vascular reactivity experiments were performed in isolated aortic rings that were contracted with a high concentration of KCl or phenylephrine (Phe).

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Introduction: Although epigallocatechin-3-gallate (EGCG) from green tea has been successfully used in the prevention and treatment of several infectious and immunoinflammatory diseases because of its proven anti-inflammatory, antioxidant, antimicrobial, and antiresorptive role, its use as an intracanal dressing has not been proposed. The aim of this study was to develop a formulation based on EGCG for endodontic use by assessing its physicochemical and biological properties.

Methods: Initially, physicochemical characterization of EGCG was performed by ultraviolet-visible and fluorescence spectroscopy to evaluate if the properties were maintained in acidic pH and time (1-6, 24, and 27 hours).

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Catecholamines participate in angiogenesis, an important tumor development process. However, the way catecholamines interact with their receptors has not been completely elucidated, and doubts still remain as to whether these interactions occur between catechol and/or amine sites and particular amino acid residues on the catecholamine receptors. To evaluate how catechol and amine groups contribute to angiogenesis, we immobilized the catechol site through ruthenium ion (Ru) coordination, to obtain species with the general formula [Ru(NH)(catecholamine-R)]Cl.

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Background: Several metal-based molecules that display cytotoxicity against multiple cell lines have been pursued in an attempt to fight against cancer and to overcome the typical side effects of drugs like cisplatin. In this scenario, ruthenium complexes have been extensively studied due to their activity in both in vitro and in vivo biological systems, including various cancer cell strains.

Objective: We aimed to develop a method to synthesize novel [Ru(NO)(bpy)L] complexes containing amino acid ligands by using an alternative Click Chemistry approach, namely the copper azide-alkyne cycloaddition reaction (CuAAC reaction), to construct nitrosyl/nitrite complexes bearing a modified lysine residue.

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Trinuclear ruthenium complexes with orthometalated phenazines of general formula [Ru3(μ3-O)(μ2-OAc)5(L)(py)2]PF6 (L = dppn, benzo[i]dipyrido[3,2-a:2',3'-c]phenazine, 1; dppz, dipyrido[3,2-a:2',3'-c]phenazine, 2; CH3-dppz, 7-methyldipyrido[3,2-a:2',3'-c]phenazine, 3; Cl-dppz, 7-chlorodipyrido[3,2-a:2',3'-c]phenazine, 4) were investigated for their cytotoxic activity toward the B16F10 murine melanoma and the L929 non-cancer cell lines and against Trypanosoma cruzi (2-4). This study also reports a multi-technique investigation into how complexes 1-4 interact with DNA and human serum albumin, HSA. At concentrations ranging from 2 to 50 μM, all the complexes reduced B16F10 murine melanoma cell viability by over 50%.

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Light irradiation has been used in clinical therapy for several decades. In this context, photobiomodulation (PBM) modulates signaling pathways via ROS, ATP, Ca, while photodynamic therapy (PDT) generates reactive oxygen species by excitation of a photosensitizer. NO generation could be an important tool when combined with both kinds of light therapy.

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This work investigates how the luminescent ruthenium-nitrite complexes cis-[Ru(py-bodipy)(dcbpy)(NO)](PF) (I) and cis-[Ru(py-bodipy)(dcbpy-aminopropyl-β-lactose)(NO)](PF) (II) behave toward the melanoma cancer cell line B16F10. The chemical structure and purity of the synthesized complexes were analyzed by UV-Visible and FTIR spectroscopy, MALDI, HPLC, and H NMR. Spectrofluorescence helped to determine the fluorescence quantum yields and lifetimes of each of these complexes.

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Background:: The endothelium is a monolayer of cells that extends on the vascular inner surface, responsible for the modulation of vascular tone. By means of the release of nitric oxide (NO), the endothelium has an important protective function against cardiovascular diseases.

Objective:: Verify if cis- [Ru(bpy)2(NO2)(NO)](PF6)2 (BPY) improves endothelial function and the sensibility of conductance (aorta) and resistance (coronary) to vascular relaxation induced by BPY.

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Ultradeformable liposomes (UDLs) as a drug delivery system (DDS), prepared from the unsaturated phospholipid, dioleylphosphocholine (DOPC), and containing the non-ionic surfactant Tween 20 as edge activator, have been explored as topical vehicles for zinc phthalocyanine (ZnPc) and the nitrosyl ruthenium complex [Ru(NH.NHq)(tpy)NO] (RuNO) as a photosensitizers for co-generation of O and NO as reactive species, respectively. However, in order to ensure that ZnPc was present in the UDLs in its monomeric form - essential for maximal ZnPc photophysical properties - it was necessary to replace 40wt% of the DOPC with the saturated phospholipid, dimyristoylphosphocholine (DMPC).

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Candidiasis, a major opportunistic mycosis caused by Candida sp., may comprise life-threatening systemic infections. The incidence of non-albicans species is rising, particularly in South America and they are frequently drug resistant, causing unresponsive cases.

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The aim of the present study was to investigate the photochemical behavior of DHHB and its photostabilizing effect on avobenzone (AVO) in different sunscreen formulations. The formulations were subjected to photostability studies by HPLC and spectrophotometry. In vitro phototoxicity was assessed using 3T3 fibroblast cultures.

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NO donors are compounds that release NO that can be used when the endogenous NO bioavailability is impaired. The compound cis-[Ru(bpy)(py)(NO)](PF) (RuBPY) is a nitrite-ruthenium, since it has a NO in its molecule. The aim of the present study was to evaluate the effect of RuBPY on arterial pressure, as well as on the vascular relaxation of different vascular arteries in renal hypertensive (2K-1C) and normotensive (2K) rats.

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[Ru(Me3[9]aneN3)(bpy)(NO)](BF4)2 ([1](BF4)2) was explored by single-crystal X-ray diffractometry, leading to the first crystal structure of an octahedral {RuNO}(7) complex. The metal resides on the center of a distorted octahedron, with dN-O and ∠Ru-N-O at 1.177(3) Å and 141.

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Purpose: The ruthenium complex cis-[Ru(H-dcbpy-)2(Cl)(NO)] (DCBPY) is a nitric oxide (NO) donor and studies suggested that the ruthenium compounds can inactivate O2-. The aim of this study is to test if DCBPY can revert and/or prevent the endothelial dysfunction.

Methods: Normotensive (2K) and hypertensive (2K-1C) wistar rats were used.

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NO is a potent bronchodilator and NO-donor compounds have demonstrated clinical significance for obstructive airway diseases. This study evaluated the relaxation mechanisms of two NO donors, a ruthenium compound (TERPY), and sodium nitroprusside (SNP), in rat tracheas with ovalbumin-induced asthma (OVA group) and in another control group. The effect of TERPY and SNP was evaluated in tracheal rings in an isolated organ chamber.

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We describe the use of cadmium telluride quantum dots (CdTe QDs) as antennas for the photosensitization of nitric oxide release from a ruthenium nitrosyl complex with visible light excitation. The CdTe QDs were capped with mercaptopropionic acid to make them water-soluble, and the ruthenium nitrosyl complex was cis-[Ru(NO)(4-ampy)(bpy)2](3+) (Ru-NO; bpy is 2,2'-bipyridine, and 4-ampy is 4-aminopyridine). Solutions of these two components demonstrated concentration-dependent quenching of the QD photoluminescence (PL) as well as photoinduced release of NO from Ru-NO when irradiated by 530 nm light.

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Nitric oxide (NO) donors are substances that can release NO. Vascular relaxation induction is among the several functions of NO, and the administration of NO donors is a pharmacological alternative to treat hypertension. This review will focus on the physicochemical description of ruthenium-derived NO donor complexes that release NO via reduction and light stimulation.

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Production of reactive oxygen species has been used in clinical therapy for cancer treatment in a technique known as Photodynamic Therapy (PDT). The success of this therapy depends on oxygen concentration since hypoxia limits the formation of reactive oxygen species with consequent clinical failure of PDT. Herein, a possible synergistic effect between singlet oxygen and nitric oxide (NO) is examined since this scenario may display increased tumoricidal activity.

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This study evaluated the effect of the systemic use of sodium alendronate in rats in vivo. Forty-five Wistar rats aged 36 to 42 days and weighing 200 to 230 g were randomly assigned to a control group (n = 20), which received distilled water, and an experimental group (n = 25), which received 2 weekly doses of 1 mg/kg of chemically pure sodium alendronate. The animals were killed after 60 days of treatment.

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Continuing our interest in tridentate ligands to develop new prototypes of cobalt-based metallodrugs for combating cancer, modifications in the backbone of HL1, [(2-hydroxybenzyl)(2-(pyridil-2-yl)ethyl]amine) were proposed in order to modulate the redox potential of new Co(III) complexes. Three ligands with electron withdrawing groups were synthesized: HL2: [(2-hydroxy-5-nitrobenzyl)(2-(pyridil-2-yl)ethyl]amine); HL3: [(2-hydroxybenzyl)(2-(pyridil-2-yl)ethyl]imine) and HL4: [(2-hydroxy-5-nitrobenzyl)(2-(pyridil-2-yl)ethyl]imine). They were used to obtain the respective mononuclear complexes 2, 3 and 4, which are discussed compared to the previous reported complex 1 (obtained from HL1).

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