Ethanolic extract from leaves of tithonia diversifolia induces apoptosis in HCT-116 cells through oxidative stress.

Tithonia diversifolia is a perennial bushy plant found in South America with significant ethnopharmacological importance as an antimalarial, antidiabetic, antibacterial, and anticancer agent. The aim of the present study was to determine the cytotoxicity of the ethanolic extract from leaves of T. diversifolia (TdE) on human cancer cell lines (HCT-116, SNB-19, NCIH-460 and MCF-7), as well as the mechanism of action involved in cell death and cellular modulation of oxidative stress. The TdE exhibited significant activity with IC50 values ranging from 7.12 to 38.41 µg/ml, with HCT-116 being the most sensitive cell line. Subsequent experiments were conducted with HCT-116 cell line. TdE decreased the number of viable cells, followed by induction of apoptotic events, increase in mitochondrial membrane permeabilization, and enhanced G2/M phase of the cell cycle. Pro-oxidative effects including elevated acidic vesicular organelle formation, lipid peroxidation, and nitric oxide by-products, as well as reduced levels of intracellular glutathione and reactive oxygen species production were also observed following incubation with TdE, which may lead to DNA damage followed by apoptotic cell death. These results demonstrate the potential of TdE ethanolic leaf extraction for biological activity and enhance the importance of continuing to study natural sources of plants for the development of anticancer agents.

In vitro evaluation of cytotoxic potential of essential oil extracted from leaves of Croton heliotropiifolius Kunth in human tumor cells.

Croton heliotropiifolius Kunth, popularly known as "velame," is a shrub that resides in northeastern Brazil. The essential oil of C. heliotropiifolius contains high concentrations of volatile compounds in the leaves and is widely used in folk medicine for many purposes as an antiseptic, analgesic, sedative, and anti-inflammatory agent. Due to the apparent limited amount of information, the aim of this study was to determine the cytotoxic potential of essential oil extracted from leaves of C. heliotropiifolius, utilizing different human cancer cell lines (HL-60, leukemia; HCT-116, colon; MDA-MB435, melanoma; SF295, glioblastoma) and comparison to murine fibroblast L929 cell line. The chemical characterization of the essential oil revealed the presence of large amounts of monoterpenes and sesquiterpenes, the majority of which were aristolene (22.43%), germacrene D (11.38%), ɣ-terpinene (10.85%), and limonene (10.21%). The essential oil exerted significant cytotoxicity on all cancer cells, with low activity on murine L929 fibroblasts, independent of disruption of cell membranes evidenced by absence of hemolytic activity. The cytotoxicity identified was associated with oxidative stress, which culminated in mitochondrial respiration dysfunction and direct or indirect DNA damage (strand breaks and oxidative damage), triggering cell death via apoptosis. Our findings suggest that extracts of essential oil of C. Heliotropiifolius may be considered as agents to be used therapeutically in treatment of certain cancers.

Própolis vermelha e ação antifúngica: potencialidades e desafios / Red própolis and antifungal activity: potentialities and challenges / Propóleo rojo y acción antifúngica: potencialidades y desafíos

Introdução: a própolis é uma composição resinosa produzida por abelhas e utilizada em suas colmeias contra microrganismos. Existem diversos tipos desse composto, sendo o de coloração vermelha o último espécime relatado na literatura. Assim, dentre suas aplicabilidades, a atividade antifúngica da própolis vermelha tem sido explorada com vistas a ampliar sua ação terapêutica. Objetivo: explorar estudos acerca da ação antifúngica da própolis vermelha, identificando suas potencialidades e desafios. Metodologia: foi realizada uma revisão integrativa nas bases de dados bibliográficos MEDLINE (via PubMed), SciELO e Google Acadêmico, complementada por uma diligência nas bases de ensaios clínicos ReBEC e Clinical Trials. Em seguida todos os estudos selecionados foram explorados para obtenção do cenário atual sobre o tema. Resultados: foram incluídos 08 estudos, sendo 01 deles um ensaio clínico. Os estudos comprovam a ação antifúngica da própolis vermelha, principalmente contra Candida spp. e Paracoccidioides brasiliensis, e evidenciam a maior potência fungicida deste composto em detrimento de outros tipos de própolis. Conclusão: a ação antifúngica da própolis vermelha mostra-se uma potencialidade em diversos estudos. Entretanto, o volume de pesquisas científicas relativas a esse tema é insuficiente e a complexidade desse composto configura-se como um desafio à sua aplicabilidade.

Introduction: propolis is a resinous composition produced by compounds and used in their hives against microorganisms. There are several types of this compound, the red one is the last specimen reported in the literature. Thus, among its applicability, the antifungal activity of red propolis has been explored as a path to expand its therapeutic action. Objective: to explore studies about the antifungal action of red propolis, identifying its potentialities and challenges. Methodology: Na integrative review was carried out in the bibliographic databases MEDLINE (via PubMed), SciELO and Google Scholar, complemented by a diligence in ReBEC and Clinical Trials databases. Then, all selected studies were explorers to obtain the current scenario on the subject. Results: 08 studies were included, which 01 of them was a clinical trial. Studies prove the antifungal action of red propolis, mainly against Candida spp. and Paracoccidioides brasiliensis, and show the greater fungicidal power of this compound compared to other types of propolis. Conclusion: the antifungal action of red propolis shows potential in several studies. However, the volume of scientific research on this theme is insufficient and the complexity of this compound represents a challenge to its applicability.

Introducción: el propóleo es una composición resinosa producida por las abejas y utilizada en sus colmenas contra los microorganismos. Existen varios tipos de este compuesto, siendo el rojo el último ejemplar reportado en la literatura. Así, entre sus posibilidades de aplicación, se ha explorado la actividad antifúngica del propóleo rojo con vistas a ampliar su acción terapéutica. Objetivo: explorar estudios sobre la acción antifúngica del propóleo rojo, identificando sus potencialidades y desafíos. Metodología: Se realizó una revisión en las bases de datos bibliográficas MEDLINE (vía PubMed), SciELO y Google Scholar, complementada con una diligencia en las bases de datos de ensayos clínicos ReBEC y Clinical Trials. Luego se exploraron todos los estudios seleccionados para obtener el escenario actual sobre el tema. Resultados: Se incluyeron 08 estudios, 01 de los cuales fue un ensayo clínico. Los estudios demuestran la acción antifúngica del propóleo rojo, principalmente contra Candida spp. y Paracoccidioides brasiliensis, y muestran el mayor poder fungicida de este compuesto en detrimento de otros tipos de propóleos. Conclusión: la acción antifúngica del propóleo rojo muestra potencial en varios estudios. Sin embargo, el volumen de investigación científica sobre este tema es insuficiente y la complejidad de este compuesto representa un desafío para su aplicabilidad.

Hellebrigenin triggers death of promyelocytic leukemia cells by non-genotoxic ways.

Bufadienolides are digitalis-like aglycones mainly found in skin secretions of toads. Among their biological properties, the mechanisms of antiproliferative action on tumor cells remain unclear for many compounds, including against leukemia cells. Herein, it was evaluated the mechanisms involved in the antiproliferative and genotoxic actions of hellebrigenin on tumor cell lines and in silico capacity to inhibit the human topoisomerase IIa enzyme. Firstly, its cytotoxic action was investigated by colorimetric assays in human tumor and peripheral blood mononuclear cells (PBMC). Next, biochemical and morphological studies were detailed by light microscopy (trypan blue dye exclusion), immunocytochemistry (BrdU uptake), flow cytometry and DNA/chromosomal damages (Cometa and aberrations). Finally, computational modelling was used to search for topoisomerase inhibition. Hellebrigenin reduced proliferation, BrdU incorporation, viability, and membrane integrity of HL-60 leukemia cells. Additionally, it increased G2/M arrest, internucleosomal DNA fragmentation, mitochondrial depolarization, and phosphatidylserine externalization in a concentration-dependent manner. In contrast to doxorubicin, hellebrigenin did not cause DNA strand breaks in HL-60 cell line and lymphocytes, and it interacts with ATPase domain residues of human topoisomerase IIa, generating a complex of hydrophobic and van der Waals interactions and hydrogen bonds. So, hellebrigenin presented potent anti-leukemic activity at concentrations as low as 0.06 µM, a value comparable to the clinical anticancer agent doxorubicin, and caused biochemical changes suggestive of apoptosis without genotoxic/clastogenic-related action, but it probably triggers catalytic inhibition of topoisomerase II. These findings also emphasize toad steroid toxins as promising lead antineoplasic compounds with relatively low cytotoxic action on human normal cells.

Synergistic Antigenotoxic and Antioxidant Action of Gum Arabic and Eugenol in Rat Liver Following Induction of Colorectal Carcinogenesis.

OBJECTIVE: Much research has been conducted to identify natural antioxidant and antimutagenic compounds capable of preventing, reverting or treating conditions caused by oxidative stress and genotoxicity. In this study we evaluated the effects of 10% gum arabic (GA) and eugenol (EUG) on hepatic oxidative stress and genotoxicity induced by dimethylhydrazine (DMH) in rats. METHODS: The prevention arm of the study included 4 control groups and 4 experimental groups. Once a week for 20 weeks, the controls received saline s.c. while the experimental groups received DMH at 20 mg/kg s.c. During the same period and for an additional 9 weeks, the animals received either water, 10% GA , EUG or 10% GA + EUG  by gavage. The treatment arm of the study included 4 control groups and 4 experimental groups. Once a week for 20 weeks, the controls received saline s.c. while the experimental groups received DMH at 20 mg/kg s.c. During the subsequent 9 weeks, the animals received either water, 10% GA, EUG or 10% GA + EUG  by gavage. Finally, the livers were harvested for histopathological study with HE, measurement of genotoxicity and oxidative stress. RESULT: Genotoxicity and oxidative stress were found to be significantly lower in Group XII (animals treated concomitantly with GA and EUG). This is the first study to observe the synergistic action of GA and EUG administered concomitantly in this scenario. CONCLUSION: Indicating a synergistic antigenotoxic and antioxidant effect on liver cells in rats with DMH-induced colorectal carcinogenesis.

Evaluation of interactions of silibinin with the proteins ALS3 and SAP5 against Candida albicans / Avaliação das interações da silibinina com as proteínas ALS3 e SAP5 contra Candida albicans

Objective: to evaluate the molecular interaction of silibinin with the targets ALS3 and SAP5. Methodology: Molecular docking protocols were conducted to analyze the binding interaction of silibinin with ALS3 and SAP5. Results: Eleven interactions of ALS3 with silibinin and four with fluconazole were found, while six interactions were observed of SAP5 with silibinin and four with fluconazole. Conclusion: Molecular docking between silibinin and ALS3 identified important interactions, but no significant interactions were observed with SAP5, even though silibinin can exhibit affinity and interactions with other SAP5 sites.

Objetivo: Avaliar a interação molecular da silibinina com os alvos ALS3 e SAP5. Metodologia: Protocolos de docking molecular foram conduzidos para analisar a interação de ligação da silibinina com ALS3 e SAP5. Resultados: Foram encontradas onze interações de ALS3 com silibinina e quatro com fluconazol, enquanto seis interações foram observadas de SAP5 com silibinina e quatro com fluconazol. Conclusão: Docking molecular entre silibinina e ALS3 identificou interações importantes, mas não foram observadas interações significativas com SAP5, embora a silibinina possa apresentar afinidade e interações com outros sítios SAP5.

Mutagenic Evaluation of Fluoxetine and Fluoxetine-Galactomannan Complex Through the Analysis of Chromosomal Aberrations in Human Peripheral Leukocytes and Salmonella typhimurium/Microssome Assay / Avaliação Mutagênica de Fluoxetina e Complexo Fluoxetina-Galactomanana Através da Análise de Aberrações Cromossômicas em Leucócitos Periféricos Humanos e em Salmonella typhimurium / Ensaio Microssômico

Objectives: The purpose of this study was to evaluate the mutagenic potential of fluoxetine and fluoxetine-galactomannan. Methods: Chromosomal aberration test and Salmonella typhimurium/microsome mutagenicity assay. Results: The results showed that fluoxetine (250 µg/mL) can cause chromosomal breaks of treated leukocytes and increase the frequency of reversion of the tester strains of S. typhimurium / microsome assay only at the highest concentration (5 mg/mL), while fluoxetine encapsulated in galactomannan did not cause these changes (leukocytes and S. typhimuriums strains). Conclusion: In summary, fluoxetine showed a mutagenic effect detectable only at high concentrations in both eukaryotic and prokaryotic models. Furthermore, the fluoxetine/galactomannan complex, in this first moment, prevented the mutagenicity attributed to fluoxetine, emphasizing that the present encapsulation process can be an alternative in preventing these effects in vitro.

Objetivos: avaliar o potencial mutagênico da fluoxetina e da fluoxetina-galactomanana. Métodos: Teste de aberração cromossômica e ensaio de mutagenicidade de Salmonella typhimurium /microssoma. Resultados: a fluoxetina (250 µg/mL) pode causar quebras cromossômicas de leucócitos tratados e aumentar a frequência de reversão das cepas testadoras de S. typhimurium /microssoma apenas na concentração mais alta (5 mg/mL), enquanto a fluoxetina encapsulada em galactomanano não causou essas alterações (leucócitos e cepas de S. typhimurium). Conclusão: a fluoxetina mostrou um efeito mutagênico detectável apenas em altas concentrações em modelos eucarióticos e procarióticos. Além disso, o complexo fluoxetina/galactomanan, neste primeiro momento, evitou a mutagenicidade atribuída à fluoxetina, ressaltando que o presente processo de encapsulamento pode ser uma alternativa na prevenção desses efeitos in vitro.

Study of the interactions of di- and tri-terpenes from Stillingia loranthacea with the enzyme NSP16-NSP10 of SARS-CoV-2 / Estudo das interações de di- e tri-terpenos de Stillingia loranthacea com a enzima NSP16-NSP10 de SARS-CoV-2

Objective: This study aimed to evaluate the interactions of di- and tri-terpenes from Stillingia loranthacea with the enzyme NSP16-NSP10 of SARS-CoV-2, important for viral replication. Methods: The molecular docking technique was used to evaluate this interaction. Results: The analysis showed that the evaluated compounds obtained RMSD values of 0.888 to 1.944 Å and free energy of -6.1 to -9.4 kcal/mol, with the observation of hydrogen bonds, salt bridges, and pi-sulfur, pi-alkyl, and hydrophobic interactions. Conclusion: Thus, the results obtained show the potential of the compounds analyzed against the selected target. Since computer simulations are only an initial step in projects for the development of antiviral drugs, this study provides important data for future research.

Objetivo: avaliar as interações de di- e tri-terpenos de Stillingia loranthacea com a enzima NSP16-NSP10 de SARS-CoV-2, importante para a replicação viral. Métodos: A técnica de docking molecular foi utilizada para avaliar essa interação. Resultados: A análise mostrou que os compostos avaliados obtiveram valores de RMSD de 0,888 a 1,944 Å e energia livre de -6,1 a -9,4 kcal/mol, observando-se ligações de hidrogênio, pontes salinas e pi-enxofre, pi-alquil, e interações hidrofóbicas. Conclusão: Assim, os resultados obtidos mostram o potencial dos compostos analisados frente ao alvo selecionado. Como as simulações computacionais são apenas um passo inicial nos projetos de desenvolvimento de medicamentos antivirais, este estudo fornece dados importantes para pesquisas futuras.

Virtual screening based on molecular docking of lysosomotropic compounds as therapeutic agents for COVID-19 / Triagem virtual baseada no encaixe molecular de compostos lisossomotrópicos como agentes terapêuticos para COVID-19

Objective: Analyze lysosomotropic agents and their action on COVID-19 targets using the molecular docking technique. Methods: Molecular docking analyses of these lysosomotropic agents were performed, namely of fluoxetine, imipramine, chloroquine, verapamil, tamoxifen, amitriptyline, and chlorpromazine against important targets for the pathogenesis of SARS-CoV-2. Results: The results revealed that the inhibitors bind to distinct regions of Mpro COVID-19, with variations in RMSD values from 1.325 to 1.962 Å and binding free energy of -5.2 to -4.3 kcal/mol. Furthermore, the analysis of the second target showed that all inhibitors bonded at the same site as the enzyme, and the interaction resulted in an RMSD variation of 0.735 to 1.562 Å and binding free energy ranging from -6.0 to -8.7 kcal/mol. Conclusion: Therefore, this study allows proposing the use of these lysosomotropic compounds. However, these computer simulations are just an initial step toward conceiving new projects for the development of antiviral molecules.

Objetivo: aAnalisar agentes lisossomotrópicos e sua ação em alvos de COVID-19 usando a técnica de docking molecular. Métodos: Foram realizadas análises de docagem molecular destes agentes lisossomotrópicos, nomeadamente de fluoxetina, imipramina, cloroquina, verapamil, tamoxifeno, amitriptilina e clorpromazina contra alvos importantes para a patogenia do SARS-CoV-2. Resultados: Os resultados revelaram que os inibidores se ligam a regiões distintas do Mpro COVID-19, com variações nos valores de RMSD de 1.325 a 1.962 Å e energia livre de ligação de -5,2 a -4,3 kcal/mol. Além disso, a análise do segundo alvo mostrou que todos os inibidores se ligaram no mesmo sítio da enzima, e a interação resultante em uma variação de RMSD de 0,735 a 1.562 Å e energia livre de ligação variando de -6,0 a -8,7 kcal/mol. Conclusão: Portanto, este estudo permite propor o uso desses compostos lisossomotrópicos. No entanto, essas simulações em computador são apenas um passo inicial para a concepção de novos projetos para o desenvolvimento de moléculas antivirais.

Antioxidant and Antigenotoxic Actions of Gum Arabic on the Intestinal Mucosa, Liver and Bone Marrow of Swiss Mice Submitted to Colorectal Carcinogenesis.

Colorectal carcinogenesis is characterized by oxidative stress and the formation of aberrant crypts in its initial stages. Gum arabic (GA) is a natural product with antioxidant properties, and, therefore, supposed antitumor action. The aim of this study was to evaluate the effects of GA on the formation of aberrant crypts, as well as the local, hepatic, and systemic genotoxicity and oxidative stress. We induced colorectal carcinogenesis in Swiss male mice, afterwards treated them with water, 2.5% GA or 5% GA via gavage for twelve weeks and then performed surgery in order to obtain samples to analysis (proximal and distal colon, liver, blood, and bone marrow). The number of aberrant crypts in the GA-treated animals was lower than in the control groups. Likewise, there was a decline of colonic, hepatic, and systemic genotoxicity and oxidative stress. These results reflect the antioxidant role of GA and may lead to the development of treatments that inhibit colorectal carcinogenesis.

Effects of ketamine in methicillin-resistant Staphylococcus aureus and in silico interaction with sortase A.

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the main human pathogens and is responsible for many diseases, ranging from skin infections to more invasive infections. These infections are dangerous and expensive to treat because these strains are resistant to a large number of conventional antibiotics. Thus, the antibacterial effect of ketamine against MRSA strains, its mechanism of action, and in silico interaction with sortase A were evaluated. The antibacterial effect of ketamine was assessed using the broth microdilution method. Subsequently, the mechanism of action was assessed using flow cytometry and molecular docking assays with sortase A. Our results showed that ketamine has a significant antibacterial activity against MRSA strains in the range of 2.49-3.73 mM. Their mechanism of action involves alterations in membrane integrity and DNA damage, reducing cell viability, and inducing apoptosis. In addition, ketamine had an affinity for S. aureus sortase A. These results indicate that this compound can be used as an alternative to develop new strategies to combat infections caused by MRSA.

Early maternal separation enhances melanoma progression in adult female mice by immune mechanisms.

Maternal separation (MS) is a risk factor for major depressive disorder. Both cancer and depression seem to share a common biological link. Here, we evaluated the progression of melanoma and the underlying mechanisms related to this progression, namely cell proliferation and apoptosis, in adult female mice exposed to MS. Female C57BL/6 mice were exposed to MS for 60 min/day during the first 2 postnatal weeks (here called MS mice) or left undisturbed (here called non-MS mice). Melanoma cells were inoculated subcutaneously into the axillary region of adult animals, and tumor progression was evaluated for 25 days. Adult MS mice presented depressive-like behavior and working memory deficits. MS accelerated murine melanoma growth by mechanisms related to decreased apoptosis and increased cell proliferation rate, such as increased expression of IL-6 and mTOR. MS stimulated eukaryotic elongation factor 2 expression and increased the number of circulating monocytes and DNA damage in peripheral blood leukocytes, an effect associated with oxidative DNA damage. In conclusion, MS accelerated the progression of murine melanoma by mechanisms related to tumor proliferation and apoptosis, revealing a relationship between adverse childhood experiences and cancer progression, particularly melanoma.

Anti-MRSA activity of curcumin in planktonic cells and biofilms and determination of possible action mechanisms.

Staphylococcus aureus is a commensal bacterium and opportunistic human pathogen that can cause a wide variety of clinical infections. It is recognized for its ability to acquire antimicrobial resistance, so methicillin-resistant Staphylococcus aureus (MRSA) infections are a global healthcare challenge. Therefore, the development of new therapeutic options and alternative therapies for treatment is necessary. Curcumin, a polyphenolic substance found in the rhizome of turmeric longa L, has been shown to have several therapeutic properties, including antimicrobial activity. The objective of the study was to evaluate the in vitro antibacterial activity of curcumin alone and associated with oxacillin against MRSA strains, to analyze the mechanism of cell death involved in the isolated action of curcumin by means of flow cytometry and molecular docking, and to verify its superbiofilm action. Curcumin showed antibacterial activity in the range of 125-500 µg/mL against the tested strains, since it caused an increase in membrane permeability and DNA fragmentation, as revealed by flow cytometry analysis. Moreover, it was possible to observe interactions of curcumin with wild-type S. aureus DHFR, S. aureus gyrase and S. aureus gyrase complex with DNA, DNA (5'-D(*CP*GP*AP*TP*GP*CP*G)-3') and Acyl-PBP2a from MRSA by molecular docking. Curcumin also had a synergistic and additive effect when associated with oxacillin, and significantly reduced the cell viability of the analyzed biofilms. Thus, curcumin is a possible candidate for pharmaceutical formulation development for the treatment of MRSA infections.

The Effects of the Alkaloid Tambjamine J on Mice Implanted with Sarcoma 180 Tumor Cells.

The tambjamines are a small group of bipyrrolic alkaloids that, collectively, display a significant range of biological activities including antitumor, antimicrobial and immunosuppressive properties. The key objective of the present study was to undertake preclinical assessments of tambjamine J (T-J) so as to determine its in vivo antitumor effects. To that end, sarcoma 180 cells were transplanted in mice and the impacts of the title compound then evaluated using a range of protocols including hematological, biochemical, histopathological, genotoxic and clastogenic assays. As a result it was established that this alkaloid has a significant therapeutic window and effectively reduces tumor growth (by 40 % and 79 % at doses of 10 and 20 mg/kg/day, respectively). In this regard it displays similar antitumor activity to the anticancer agent cyclophosphamide and alters animal weight in an analogous manner.

Cellular and biochemical antileukemic mechanisms of the meroterpenoid Oncocalyxone A.

Oncocalyxone A, a 1,4-benzoquinone derived from Cordia oncocalyx, exhibits anti-inflammatory, antimicrobial and antidiabetic properties. The aim of this study was to (1) examine the cytotoxic actions of oncocalyxone A on human normal and tumor cell lines and (2) determine mechanistic actions underlying effects upon leukemia cells using cellular and molecular techniques. Antiproliferative studies on cancer cell lines, peripheral blood mononuclear cells, and human erythrocytes were performed using colorimetric assays. To understand cytotoxicity, assessments were performed with HL-60 leukemia cells (8, 16.5, or 33 µM) after 24 hr incubation using light and fluorescence microscopy, trypan blue, flow cytometry, Comet assay, western blot of caspases and poly-ADP-ribose polymerase (PARP), and effects on topoisomerase I and II. Oncocalyxone A exhibited cytotoxic action upon HL-60 cells and dividing leukocytes, but minimal hemolytic action on erythrocytes. Mechanistic investigations demonstrated reduction of cell viability, loss of membrane integrity, cell shrinking, chromatin condensation, blebbings, externalization of phosphatidylserine, caspase activation, PARP cleavage, mitochondrial depolarization, and DNA damage. Pre-treatment with N-acetylcysteine 4 mM significantly reduced DNA damage and prevented membrane integrity loss. Oncocalyxone A displayed free radical dependent antileukemic activity via apoptotic pathways and induced DNA damage in HL-60 cells. Oncocalyxone A possesses structural chemical simplicity enabling it to be a cost-effective alternative. These properties justify further improvements to enhance activity and selectivity and the development of pharmaceutical formulations. Abbreviations Acridine orange, AO; ANOVA, analysis of variance; BSA, bovine serum albumin; DI, Damage Index; DMSO, dimethylsulfoxide; EC50, effective concentration 50%; EDTA, ethylenediamine tetraacetic acid; EB, ethidium bromide; HCT-116, colon carcinoma line; HL-60, promyelocytic leukemia line; IC50, inhibitory concentration 50%; MTT, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide; OVCAR-8, ovarian carcinoma line; NAC, N-acetylcysteine, PBMC, peripheral blood mononuclear cells; PBS, phosphate-buffered saline; PI, propidium iodide; PARP, poly-ADP-ribose polymerase; RPMI-1640, Roswell Park Memorial Institute medium; SF-295, glioblastoma line; ROS, reactive oxygen species; 7-AAD, 7-amino-actinomycin D; H2-DCF-DA, 7'-dichlorodihydrofluorescein diacetate.

Chemopreventive effect of troxerutin against hydrogen peroxide-induced oxidative stress in human leukocytes through modulation of glutathione-dependent enzymes.

Troxerutin is a natural flavonoid present abundantly in tea, coffee, olives, wheat, and a variety of fruits and vegetables. Due to its diverse pharmacological properties, this flavonoid has aroused interest for treatment of various diseases, and consequently prompted investigation into its toxicological characteristics. The aim of this study was to evaluate the genotoxic and mutagenic effects and chemoprotective activity attributed to troxerutin using human peripheral blood leukocytes (PBLs) through several well-established experimental protocols based upon different parameters. Data demonstrated that troxerutin (100 to 1000 µM) induced no marked cytotoxic effect on PBLs after 24 hr, and did not produce strand breaks and mutagenicity. Regarding chemoprevention, this flavonoid attenuated cytotoxicity, genotoxicity, and mutagenicity initiated by hydrogen peroxide (H2O2) in human PBLs. Further, troxerutin demonstrated no marked cytotoxic effect on PBLs and exerted a protective effect against oxidative stress induced by H2O2 through modulation of GSH-dependent enzymes.

Etomidate is devoid of genotoxicty and mutagenicity in human lymphocytes and in the Salmonella typhimurium/microsomal activation test.

No carcinogenesis or mutagenesis studies have been carried out with etomidate. The current study showed that etomidate has weak cytotoxic potential after 48 h exposure in human lymphocytes and has no hemolytic activity. The weak cytotoxicity seems to be related with redox imbalance of etomidate (40.9 and 81.9 µM) treated lymphocytes. At both etomidate concentrations, a slight decrease of the levels of GSH intracellular content and a significant increase in the amount of carbonylated proteins were observed after 48 h. The contribution of oxidative stress to genetic toxicity was only perceived when the enzyme Fpg was applied in the comet assay. Etomidate (40.9 and 81.9 µM) is a weak generator of oxidative DNA damage in lymphocytes. These damages to DNA probably were repaired, since no DNA strand breaks were detected in the standard alkaline comet assay (in the presence or absence of hepatic S9 microsomal fraction) without Fpg. Also, no micronucleated lymphocytes or carrying chromosomal aberrations were observed. Finally, etomidate (2046.8 and 4093.5 µM) was not mutagenic in the Salmonella/microsome mutagenicity assay, which used four Salmonella typhimurium strains (TA97a, TA98, TA100, and TA102) to detect frameshift and base-substitution mutations. In summary, etomidate is a weak oxidative DNA damaging anesthetic and is devoid of mutagenic properties in eukaryotic and prokaryotic models.

Virtual screening based on molecular docking of possible inhibitors of Covid-19 main protease.

Coronavirus (COVID-19) is an enveloped RNA virus that is diversely found in humans and that has now been declared a global pandemic by the World Health Organization. Thus, there is an urgent need to develop effective therapies and vaccines against this disease. In this context, this study aimed to evaluate in silico the molecular interactions of drugs with therapeutic indications for treatment of COVID-19 (Azithromycin, Baricitinib and Hydroxychloroquine) and drugs with similar structures (Chloroquine, Quinacrine and Ruxolitinib) in docking models from the SARS-CoV-2 main protease (M-pro) protein. The results showed that all inhibitors bound to the same enzyme site, more specifically in domain III of the SARS-CoV-2 main protease. Therefore, this study allows proposing the use of baricitinib and quinacrine, in combination with azithromycin; however, these computer simulations are just an initial step for conceiving new projects for the development of antiviral molecules.

Gum arabic and red propolis protecteting colorectal preneoplastic lesions in a rat model of azoxymethane1.

PURPOSE: To evaluate red propolis, gum arabic and L-lysine activity on colorectal preneoplastic lesions induced by azoxymethane (AOM). METHODS: The study featured 4 control groups (I-IV) and 4 experimental groups (V-VIII), totaling 48 rats. Once a week for 2 weeks, animals on control groups received saline, while animals in experimental groups received azoxymethane (15 mg/kg i.p.). The follow up along 16 weeks included daily oral gavage to administer water (I and V), L-lysine (150 mg/kg)(II and VI), própolis (100mg/5ml/kg)(III and VII), or gum arabic (5ml/kg)(IV and VIII). Was performed surgery on the animals in the end of this time in order to collect blood for biological assays (TBARS, GSH), followed by their sacrifice to tissue extract. RESULTS: Oxidative stress (TBARS) and the number of aberrant crypt foci (ACF) in distal colon were lower using própolis (p<0.01 for both parameters). Gum arabic reduced preneoplastic lesions (ACF ≤ 4 crypts) on distal colon and on the entire colon (p<0.05). CONCLUSIONS: Red propolis reduced AOM-induced oxidative stress (TBARS) and total number of ACF in the distal colon. L-lysine neither protected against nor enhanced AOM-induced ACF. Gum arabic reduced the number of ACF.

Is chronic use of hydroxyurea safe for patients with sickle cell anemia? An account of genotoxicity and mutagenicity.

Sickle cell anemia (SCA) is a hereditary hematological disease that is characterized by a point mutation in the beta globin S gene and has no specific treatment; hydroxyurea (HU) is the only therapeutic agent used in clinical practice. In the present study, we evaluated the deoxyribonucleic acid (DNA) damage index (DI) and chromosomal damage in leukocytes of adult patients with SCA with and without HU. The DI was assessed by the comet assay and chromosomal damage by the leukocyte micronucleus test of adult patients treated with HU (SCA-HU) and without the use of HU (SCA-NoHU). This is a cross-sectional study with 77 patients with SCA who attended a referral hospital in Fortaleza, Brazil. The control group (CG) consisted of 58 reportedly healthy individuals. The comparisons of means were performed by analysis of variance and Tukey's post-test. Values of P < 0.05 were considered statistically significant. SCA-NoHU patients had statistically higher DI values and a statistically significantly higher frequency of micronuclei compared to the CG. In addition, HU treatment accentuated DNA lesions by significantly increasing both parameters in treated patients (SCA-HU). HU potentiates DNA damage and the occurrence of chromosomal damage, which may promote genomic instability, mutation occurrence, and carcinogenesis. Studies are needed to evaluate the involved pathways, repair mechanisms, and the clinical impact that such damage can cause. Environ. Mol. Mutagen. 60:302-304, 2019. © 2018 Wiley Periodicals, Inc.