Hematological problems are associated with Coronavirus disease 2019 (COVID-19). Respiratory impairment is the higher point studied, although without experimental studies related to the oxygen transport performed by erythrocytes. Therefore, we decided to investigate if erythrocytes from COVID-19 patients have their functionality changed. The case-control study included hospitalized patients with a positive real-time polymerase chain reaction (RT-PCR) result admitted to University Hospital. Volunteers (negative RT-PCR results) were recruited as a control group. Thus, we assessed different erythrocytes parameters, oxidative stress markers, and biophysical studies using whole blood and isolated hemoglobin. We found a decrease of 51% in oxygen uptake and reduced antioxidant enzyme activity in COVID-19 patients compared to controls. Raman spectrometry showed structural changes in the hemoglobin and lipids of the erythrocytes from COVID-19 patients; thus, these results were consolidated with an increase in Young’s modulus in erythrocytes followed by morphology changes. Besides, isolated hemoglobin from COVID-19 patients has a distinct interaction profile using a ligand model compared to the control. COVID-19 leads to structural, functional, and morphological damage to human erythrocytes. Our data showed structural and molecular changes and induction of oxidative stress in erythrocytes by COVID-19, a new perspective on the contribution of erythrocytes to a respiratory commitment in COVID-19.

In this study, the interaction between benzothiazole (BTA, concentration of a drug required for 50% inhibition in vitro (IC50) = 0.77 mM) and benzimidazole (BIA, IC50 = 2.14 mM) with urease was quantitatively assessed, using UV-Vis, molecular fluorescence, and circular dichroism. The results showed that both compounds interact with urease by a static fluorescence quenching mechanism with a non-fluorescent complex formation. The main forces responsible for stabilizing the supramolecular complex between BTA and urease were hydrophobic while, for BIA, van der Waals interactions and hydrogen bonds were the main ones. Urease conformation changes due to the interaction process were analyzed by circular dichroism and synchronous fluorescence. Besides, a competitive assay with substrate and inhibitors was used to evaluate the preferential urease site of interaction with BTA and BIA. Our experimental and theoretical studies supported that both, BTA and BIA, are mixed-inhibitors of ureases with a slight preference to the active site of such enzymes. Finally, both BTA and BIA showed to possess anti-Helicobacter pylori (one reference strain and six clinical isolates) activity, presenting minimal inhibitory concentration (MIC) values ranging from 38-150 and 20-164 µM, respectively. The urease inhibitors omeprazole and hydroxyurea showed MIC values in the range of 46-185 µM and 1683-> 3366 µM, respectively.

This study aimed to prepare a complex of 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and 6CN10, a poorly water soluble 2-aminothiophene derivative with antifungal properties, by freeze-drying technique. The complex was characterized by thermal analysis, infrared/Raman spectroscopy, X-ray diffraction and scanning electron microscopy. In addition, we used the data of the phase solubility study, 1H, and 2D NMR spectroscopy and molecular modeling in order to investigate the interactions between 6CN10 and HP-β-CD. The apparent solubility of 6CN10 with HP-β-CD increased more than 29 fold. The phase solubility assay in water at 25 ºC showed an AP-type curve, with an apparent stability constant K1:1 and K1:2 of 96 and 0.1989 M-1, respectively. The results of IR, NMR and docking indicate that 6CN10 is able to form complexes with HP-β-CD (1:1 and 1:2 stoichiometric ratios), generating the formation of inclusion and preferably, non-inclusion complexes. The antifungal activity against Cryptococcus neoformans demonstrated the superior performance of the complex (46.66 µg mL-1) when compared with the free drug (166.66-333.33 µg mL-1). The present study provides useful information for the potential application of complexation with low soluble compounds and about the type of complex formation between 6CN10 and HP-β-CD.

Quantitative interaction of twelve β-carboline derivatives with calf thymus deoxyribonucleic acid (ctDNA) using spectroscopic techniques was evaluated. The values of the binding constants (Kb) obtained for the complexes formed with the ctDNA ranged from 3.30 × 102 to 1.82 × 106 mol L−1, being the β-carbolines with the N,N-dimethylaminophenyl group at position 1 the ones which presented the highest Kb values. The binding mode between the β-carbolines evaluated and ctDNA was proposed from the KI assay, competition with ethidium bromide, and DNA thermal denaturation profile (Tm), where it was possible to infer that the evaluated alkaloids interact with ctDNA preferably via intercalation. Additionally, the correlation of Kb values obtained with the IC50 of seven human cancer cell lines was carried out. From this study, it was possible to observe a linear relation among most of the evaluated derivatives, obtaining r2 values from 0.5360 to 0.9600. In addition, in silico molecular docking was performed to corroborate the experimental results.

Molecules containing the 4-thiazolidinone ring are known to possess a wide range of biological properties including antimicrobial and anti-inflammatory activities among others. These compounds can be synthesized by cyclization reactions involving alpha-haloacetic acid or alpha-mercaptoacetic acid and employed in several chemoselective reactions. Comprehensive reviews have been written on 4-thiazolidinones in 1961 by Brown and in 1980 by Singh et al. In the recent literature, some new synthesis methods for 4-thiazolidinone derivatives and several reactions have been reported. These advances warrant to review the chemical and biological properties of compounds with this important heterocycle employed in synthetic organic chemistry and medicinal chemistry.

Neste artigo relatam-se os resultados de um estudo in vitro envolvendo a influência da biflorina (uma o-quinona isolada de Capraria biflora L. que possui uma potente atividade antimicrobiana) na marcação do Tc-99m em células vermelhas do sangue, proteínas do plasma, proteínas celulares e em linfócitos. O sangue foi coletado de ratos Wistar e incubado com várias concentrações de biflorina, e soluções de cloreto estanoso (SnCl2) adicionando-se Tc-99m. O plasma (P) e as células vermelhas do sangue (CVS) foram isolados, precipitados e centrifugados, isolando-se as frações solúveis (FS) e insolúveis (FI). A maior concentração de biflorina (100%) é capaz de reduzir a captação do Tc-99m (%ATI) nas CVS e a fixação na FI-P. Uma solução de 0,2 mL de linfócitos (2,5 mL; 1.0 x 10(6) células/mL), obtidos por centrifugação de sangue humano tratado com Ficoll-Hypac, foi incubada com biflorina (0,1 mL). Soluções de cloreto estanoso e Tc-99m foram então adicionadas. Os linfócitos foram separados e o %ATI presente nessas células foi avaliado. Uma redução no %ATI (de 97,85 ± 0,99 a 88,86 ± 5) foi observada para CVS e para FI-P (73,24 ± 5,51 a 20,72 ± 6,95). Os resultados não mostraram decréscimo no %ATI para os linfócitos com biflorina.

In this paper we report the results of an in vitro study involving the influence of biflorin (an o-quinone isolated from Capraria biflora L. that has potent antimicrobial activity) on the Tc-99m labeling of red blood cells, plasma protein, cells protein, and lymphocytes. Blood was withdrawn from Wistar rats and incubated with various concentrations of biflorin, and solutions of stannous chloride and Tc-99m were added. Plasma (P) and red blood cells (RBC) were isolated, precipitated, and centrifuged, and soluble (SF) and insoluble (IF) fractions were isolated. The results show that the highest concentration (100%) of biflorin is able to reduce the uptake of Tc-99m (%ATI) on RBC and the fixation on IF-P. To study the influence of biflorin on 99mTc lymphocyte labeling, human blood was submitted to a technique with Ficoll-Hypac and centrifuged, and white cells were isolated. Lymphocytes (2.5 mL; 1.0 x 10(6) cells/mL) were obtained and a 0.2 mL solution was incubated with biflorin (0.1 mL). Solutions of stannous chloride and 99mTc were added. Lymphocytes were separated and the %ATI bound in these cells was evaluated. A reduction in %ATI (from 97.85 ± 0.99 to 88.86 ± 5) was observed for RBC and for IF-P (73.24 ± 5.51 to 20.72 ± 6.95). In this case the results showed no decrease in %ATI for the lymphocytes with biflorin.

Thiosemicarbazones are a class of compounds known by their chemical and biological properties, such as antitumor, antibacterial, antiviral and antiprotozoal activity. Their ability to form chelates with metals has great importance in their biological activities. Their synthesis is very simple, versatile and clean, usually giving high yields. They are largely employed as intermediates, in the synthesis of others compounds. This article is a survey of some of these characteristics showing their great importance to organic and medicinal chemistry.