Inhibition of the morphological transition of Candida spp. by riparins I-IV.

Candida spp. is an opportunistic pathogen capable of causing superficial to invasive infections. Morphological transition is one of the main virulence factors of this genus and, therefore, is an important variable to be considered in pharmacological interventions. Riparins I, II, III, and IV are alkamide-type alkaloids extracted from the unripe fruit of Aniba riparia, whose remarkable pharmacological properties were previously demonstrated. This work aimed to evaluate in silico and in vitro the inhibitory effects of Riparins on the morphological transition of Candida albicans, Candida tropicalis, and Candida krusei. Molecular docking was applied to analyze the inhibitory effects of riparins against proteins such as N-acetylglucosamine, CYP-51, and protein kinase A (PKA) using the Ramachandran plot. The ligands were prepared by MarvinSketch and Spartan software version 14.0, and MolDock Score and Rerank Score were used to analyze the affinity of the compounds. In vitro analyses were performed by culturing the strains in humid chambers in the presence of riparins or fluconazole (FCZ). The morphology was observed through optical microscopy, and the size of the hyphae was determined using the ToupView software. In silico analysis demonstrated that all riparins are likely to interact with the molecular targets: GlcNAc (>50%), PKA (>60%), and CYP-51 (>70%). Accordingly, in vitro analysis showed that these compounds significantly inhibited the morphological transition of all Candida strains. In conclusion, this study demonstrated that riparins inhibit Candida morphological transition and, therefore, can be used to overcome the pathogenicity of this genus.

Riparin II-type benzamides as novel antibiofilm agents against dermatophytes: chemical synthesis, in vitro, ex vivo and in silico evaluation.

BACKGROUND: The ability of dermatophytes to develop biofilms in host tissues confers physical and biochemical resistance to antifungal drugs. Therefore, research to find new compounds against dermatophyte biofilm is crucial. OBJECTIVES: To evaluate the antifungal activity of riparin II (RIP2), nor-riparin II (NOR2) and dinor-riparin II (DINOR2) against Trichophyton rubrum, Microsporum canis and Nannizzia gypsea strains. METHODS: Initially, we determined the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of benzamides. We evaluated the inhibitory effects on the development of dermatophyte biofilms using in vitro and ex vivo models. Finally, we built three-dimensional models of the sulphite pump Ssu1 to investigate the interactions with the benzamides by molecular docking. RESULTS: RIP2 showed a broad spectrum of activity against T. rubrum, M. canis and N. gypsea, whereas NOR2 and DINOR2 were more selective. Furthermore, the shortening of the carbon chain from RIP2 benzamide to NOR2 and DINOR2 homologs caused a decrease in the MIC values. The benzamides reduced biofilm production and viability in vitro (P < 0.05) at MIC. This result was similar ex vivo in human nail fragments tests, but NOR2 and DINOR2 showed significant results at 2xMIC (P < 0.05). We constructed a model of the Ssu1 protein for each dermatophyte with high similarity. Molecular docking showed that the benzamides obtained higher binding energy values than ciclopirox. CONCLUSIONS: Our study shows the antibiofilm potential for riparin II-type benzamides as new drugs targeting dermatophytes by inhibiting the Ssu1 protein.

Evaluation of antifungal activity, mechanisms of action and toxicological profile of the synthetic amide 2-chloro-N-phenylacetamide.

Aspergillus niger causes infections such as otitis and pulmonary aspergillosis in immunocompromised individuals. Treatment involves voriconazole or amphotericin B, and due to the increase in fungal resistance, the search for new compounds with antifungal activity has intensified. In the development of new drugs, cytotoxicity and genotoxicity assays are important, as they allow predicting possible damage that a molecule can cause, and in silico studies predict the pharmacokinetic properties. The aim of this study was to verify the antifungal activity and the mechanism of action of the synthetic amide 2-chloro-N-phenylacetamide against Aspergillus niger strains and toxicity. 2-Chloro-N-phenylacetamide showed antifungal activity against different strains of Aspergillus niger with minimum inhibitory concentrations between 32 and 256 µg/mL and minimum fungicides between 64 and 1024 µg/mL. The minimum inhibitory concentration of 2-chloro-N-phenylacetamide also inhibited conidia germination. When associated with amphotericin B or voriconazole, 2-chloro-N-phenylacetamide had antagonistic effects. Interaction with ergosterol in the plasma membrane is the probable mechanism of action.2-Chloro-N-phenylacetamide has favorable physicochemical parameters, good oral bioavailability and absorption in the gastrointestinal tract, crosses the blood-brain barrier and inhibits CYP1A2. At concentrations of 50 to 500 µg/mL, it has little hemolytic effect and a protective effect for type A and O red blood cells, and in the cells of the oral mucosa it promotes little genotoxic change. It is concluded that 2-chloro-N-phenylacetamide has promising antifungal potential, favorable pharmacokinetic profile for oral administration and low cytotoxic and genotoxic potential, being a promising candidate for in vivo toxicity studies.

Investigation of mechanisms of action involved in the antidepressant-like effect of Trans,trans-farnesol in mice.

This study aimed to investigate, through in vivo and biochemical methodologies, the effect of trans,trans-farnesol (12.5, 25, 50 or 100 mg/kg, p.o.) acute administration, adopting different behavioral and neurochemical parameters associated with an acute induced-depression model in mice. The initial results showed that, the oral treatment with trans,trans-farnesol, at the dose of 100 mg/kg induced a possible antidepressant-like effect in animals subjected to forced swim test (FST) and reserpine-induced akinesia. In addition, it was observed that the compound in question has an effect size and properties similar to imipramine (prototype of tricyclic antidepressants), but devoid of proconvulsant adverse effect. In biochemical assays, the pretreatment with trans,trans-farnesol, at a dose of 100 mg/kg (p.o.), decreased the hippocampal concentration of thiobarbituric acid reactive substances (TBARS) and restored striatal levels of noradrenaline and serotonin in mice subjected to FST. Altogether, these results suggest that trans,trans-farnesol showed a significant antidepressant-like effect, which seems to be mediated by the antagonism of muscarinic cholinergic receptors, reduction of oxidative stress and the modulation of noradrenaline and serotonin content in the central nervous system.

Evaluation of the antibacterial and inhibitory activity of the MepA efflux pump of Staphylococcus aureus by riparins I, II, III, and IV.

The efflux pump mechanism contributes to the antibiotic resistance of widely distributed strains of Staphylococcus aureus. Therefore, in the present work, the ability of the riparins N-(4-methoxyphenethyl)benzamide (I), 2-hydroxy-N-[2-(4-methoxyphenyl)ethyl]benzamide (II), 2, 6-dihydroxy-N-[ 2-(4-methoxyphenyl)ethyl]benzamide (III), and 3,4,5-trimethoxy-N-[2-(4-methoxyphenethyl)benzamide (IV) as potential inhibitors of the MepA efflux pump in S. aureus K2068 (fluoroquinolone-resistant). In addition, we performed checkerboard assays to obtain more information about the activity of riparins as potential inhibitors of MepA efflux and also analyzed the ability of riparins to act on the permeability of the bacterial membrane of S. aureus by the fluorescence method with SYTOX Green. A molecular coupling assay was performed to characterize the interaction between riparins and MepA, and ADMET (absorption, distribution, metabolism, and excretion) properties were analyzed. We observed that I-IV riparins did not show direct antibacterial activity against S. aureus. However, combination assays with substrates of MepA, ciprofloxacin, and ethidium bromide (EtBr) revealed a potentiation of the efficacy of these substrates by reducing the minimum inhibitory concentration (MIC). Furthermore, increased EtBr fluorescence emission was observed for all riparins. The checkerboard assay showed synergism between riparins I, II, and III, ciprofloxacin, and EtBr. Furthermore, riparins III and IV exhibited permeability in the S. aureus membrane at a concentration of 200 µg/mL. Molecular docking showed that riparins I, II, and III bound in a different region from the binding site of chlorpromazine (standard pump inhibitor), indicating a possible synergistic effect with the reference inhibitor. In contrast, riparin IV binds in the same region as the chlorpromazine binding site. From the in silico ADMET prediction based on MPO, it could be concluded that the molecules of riparin I-IV present their physicochemical properties within the ideal pharmacological spectrum allowing their preparation as an oral drug. Furthermore, the prediction of cytotoxicity in liver cell lines showed a low cytotoxic effect for riparins I-IV.

Methyleugenol Has an Antidepressant Effect in a Neuroendocrine Model: In Silico and In Vivo Evidence.

Major depressive disorder is a severe mood disorder characterized by different emotions and feelings. This study investigated the antidepressant activity of the phenylpropanoid methyleugenol (ME) in adult female mice exposed to a stress model induced by dexamethasone. The animals were randomly divided into groups containing eight animals and were pre-administered with dexamethasone (64 µg/kg subcutaneously). After 165 and 180 min, they were treated with ME (25, 50 and 100 mg/kg intraperitoneally) or imipramine (10 mg/kg intraperitoneally) after 45 min and 30 min, respectively; they were then submitted to tests which were filmed. The videos were analyzed blindly. In the tail suspension test, ME (50 mg/kg) increased latency and reduced immobility time. In the splash test, ME (50 mg/kg) decreased grooming latency and increased grooming time. In the open field, there was no statistical difference for the ME groups regarding the number of crosses, and ME (50 mg/kg) increased the number of rearing and time spent in the center. Regarding in silico studies, ME interacted with dopaminergic D1 and α1 adrenergic pathway receptors and with tryptophan hydroxylase inhibitor. In the in vivo evaluation of the pathways of action, the antidepressant potential of ME (50 mg/kg) was reversed by SCH23390 (4 mg/kg intraperitoneally) dopaminergic D1 receptor, Prazosin (1 mg/kg intraperitoneally) α1 adrenergic receptor, and PCPA (4 mg/kg intraperitoneally) tryptophan hydroxylase inhibitor. Our findings indicate that ME did not alter with the locomotor activity of the animals and shows antidepressant activity in female mice with the participation of the D1, α1 and serotonergic systems.

Study on Morphological Changes and Interference in the Development of Aedes aegypti Caused by Some Essential Oil Constituents.

Dengue, Chikungunya and Zika are arboviruses, transmitted by the mosquito Aedes aegypti, that cause high mortality and serious health consequences in human populations. Efforts to control Ae. aegypti are important for preventing outbreaks of these diseases. Essential oil constituents are known to exhibit many activities, such as their use as larvicides. Given their potential, the present study aimed to characterize the larvicidal effect of dihydrojasmone, p-cymene, carvacrol, thymol, farnesol and nerolidol on the larvae of Ae. aegypti and their interference over the morphology of the mosquitos. The essential oil constituents were dissolved in dimethylsulfoxide at concentrations of 1-100 µg/mL and were applied in the breeding environment of third-stage larvae. The larvae from bioassays were fixed, dehydrated and embedded. Ultrathin sections were contrasted using 5% uranyl acetate and 1% lead citrate for observation through transmission electron microscopy. The oil with the highest larvicidal efficiency was found to be nerolidol, followed by farnesol, p-cymene, carvacrol, thymol and dihydrojasmone, with an LC50 of 11, 21, 23, 40, 45 and 66 µg/mL, respectively. The treated Ae. aegypti larvae caused alteration to the tegument or internal portions of larvae. The present study demonstrated which of these oils-dihydrojasmone, farnesol, thymol, p-cymene, carvacrol and nerolidol-have effective larvicidal activity.

In vitro inhibition and eradication of multidrug-resistant Acinetobacter baumannii biofilms by riparin III and colistin combination.

Acinetobacter baumannii, a prominent emerging pathogen, is responsible for persistent and recurrent healthcare-associated infections (HAIs). Its bacterial resistance and virulence factors, such as biofilm formation, contribute to its survival in hospital environments. Combination therapy has proven to be an effective approach for controlling these infections; however, antimicrobial resistance and compound toxicity can hinder antimicrobial efficacy. Numerous in vitro studies have demonstrated the synergistic effect of antimicrobials and natural products against multidrug-resistant (MDR) A. baumannii biofilm. Riparin III, a natural alkamide derived from Aniba riparia (Nees) Mez., possesses various biological activities, including significant antimicrobial potential. Nonetheless, no reports are available on the use of this compound in conjunction with conventional antimicrobials. Hence, this study aimed to investigate the inhibition and eradication of A. baumannii MDR biofilm by combining riparin III and colistin, along with potential ultrastructural changes observed in vitro. Clinical isolates of A. baumannii, known for their robust biofilm production, were inhibited, or eradicated in the presence of the riparin III/colistin combination. Furthermore, the combination resulted in several ultrastructural alterations within the biofilm, such as elongated cells and coccus morphology, partial or complete disruption of the biofilm's extracellular matrix, and cells exhibiting cytoplasmic material extravasation. At the synergistic concentrations, the riparin III/colistin combination exhibited a low hemolytic percentage, ranging from 5.74% to 6.19%, exerting inhibitory and eradicating effects on the A. baumannii biofilm, accompanied by notable ultrastructural changes. These findings suggest its potential as a promising alternative for therapeutic purposes.

In vitro and ex vivo antibiofilm activity of riparin 1, and its nor and dinor homologs, against dermatophytes.

Dermatophytosis is one of the most frequent superficial mycoses in the world. They are mainly caused by the dermatophytes Trichophyton rubrum and Microsporum canis. Biofilm production is an essential factor in the pathogenesis of dermatophytes; it confers drug resistance and significantly impairs antifungal effectiveness. Therefore, we evaluated the antibiofilm activity of an alkamide-type alkaloid called riparin 1 (RIP1) against clinically relevant dermatophytes. We also produced synthetic nor (NOR1) and dinor (DINOR1) homologs for pharmacological evaluation, with a 61-70% yield. We used in vitro (96-well polystyrene plates) and ex vivo (hair fragments) models to verify the effects of these compounds on the formation and viability of biofilms. RIP1 and NOR1 showed antifungal activity against strains of T. rubrum and M. canis, but DINOR1 showed no significant antifungal activity against the dermatophytes. Furthermore, RIP1 and NOR1 significantly reduced the viability of biofilms in vitro and ex vivo (P < 0.05). RIP1 was more potent than NOR1, possibly due to the distance between the p-methoxyphenyl and the phenylamide moieties in these compounds. Due to the significant antifungal and antibiofilm activities observed for RIP1 and NOR1, we suggest that they could be useful in the treatment of dermatophytosis.

Antifungal effect of the liposome encapsulation of the Trans- Caryophylene and its association with fluconazole.

Trans-Caryophyllene (TC), a sesquiterpene, with proven biological activities, which in this work was tested alone, encapsulated in liposomes and associated with Fluconazole in vitro in an attempt to enhance the effect of the drug. Liposomes were characterized from vesicle size, polydispersity index, and Zeta potential, and imaging by scanning electron microscopy. Antifungal assays were performed against Candida albicans, Candida tropicalis and Candida krusei by microdilution to determine the IC50 values and the viability curve. The Minimum Fungicidal Concentration (MFC) was performed by subcultivation in solid medium and the inhibitory effect of the association of TC and Fluconazole and tests to verify morphological changes was performed in micro-cultivation chambers based on concentrations on microdilution plates. The corresponding IC50 data of the substances ranged from 34.4 to 65249 µg/mL, considerably high values compared to the control (Fluconazole). The MFC of all compounds showing fungistatic effect. The performance of the compounds on the cell viability curve was similar in all tested strains, as they showed no antifungal potential when compared to the control (FCZ), when associated with FCZ they showed no significant antifungal activity. The free and liposomal TC also managed to restrict 100% of the fungal dimorphism, in both concentrations, against C. albicans, and against C. tropicalis the isolated TC did not show a significant inhibitory effect; however, against the C. krusei strain inhibited 100% in filamentous growth in both concentrations, which is statistically relevant. The liposomes were homogeneous, with vesicles with diameters of 185.46 nm for the control and 143.8 nm for the liposomal TC, and a surface charge potential of - 42.6 mV. By scanning microscopy, the spherical shapes of the vesicles were verified.

Antifungal and Antibiofilm Activity of Riparin III against Dermatophytes.

The ability of dermatophytes to develop biofilms is possibly involved in therapeutic failure because biofilms impair drug effectiveness in the infected tissues. Research to find new drugs with antibiofilm activity against dermatophytes is crucial. In this way, riparins, a class of alkaloids that contain an amide group, are promising antifungal compounds. In this study, we evaluated the antifungal and antibiofilm activity of riparin III (RIP3) against Trichophyton rubrum, Microsporum canis, and Nannizzia gypsea strains. We used ciclopirox (CPX) as a positive control. The effects of RIP3 on fungal growth were evaluated by the microdilution technique. The quantification of the biofilm biomass in vitro was assessed by crystal violet, and the biofilm viability was assessed by quantifying the CFU number. The ex vivo model was performed on human nail fragments, which were evaluated by visualization under light microscopy and by quantifying the CFU number (viability). Finally, we evaluated whether RIP3 inhibits sulfite production in T. rubrum. RIP3 inhibited the growth of T. rubrum and M. canis from 128 mg/L and N. gypsea from 256 mg/L. The results showed that RIP3 is a fungicide. Regarding antibiofilm activity, RIP3 inhibited biofilm formation and viability in vitro and ex vivo. Moreover, RIP3 inhibited the secretion of sulfite significantly and was more potent than CPX. In conclusion, the results indicate that RIP3 is a promising antifungal agent against biofilms of dermatophytes and might inhibit sulfite secretion, one relevant virulence factor.

Evaluation of the antibacterial activity of hecogenin acetate and its inhibitory potential of NorA and MepA efflux pumps from Staphylococcus aureus.

Antimicrobial drugs are of great importance in the control of bacterial infections. Its indiscriminate use contributes to the consolidation of bacterial resistance. Its applicability is due to its secondary metabolites, such as saponins, which are compounds with relevant antibacterial action. Hecogenin acetate is a saponin present in plants of the agave genus with analgesic, antioxidant, antinociceptive, cardioactive, anticancer, antifungal and antimicrobial activity. The present work aimed to identify the antibacterial activity of hecogenin acetate against strains of E. coli, P. aeruginosa and S. aureus and to investigate the NorA and MepA efflux pump inhibitory activity of S. aureus strains. The Minimum Inhibitory Concentration was evaluated by broth microdilution. The Antibiotic Activity Modifier effect and the assessment of efflux pump inhibition were evaluated by microdilution with sub-inhibitory concentrations. Hecogenin acetate showed minimal inhibitory concentration without significant relevance. In the evaluation of the potentiating activity of the antibiotic action, a greater antagonistic behavior is noticed. In the analyzes performed with the efflux pump, it was noticed that the hecogenin acetate does not interfere in the efflux pump mechanism of the analyzed bacteria.

Milonine attenuates the lipopolysaccharide-induced acute lung injury in mice by modulating the Akt/NF-κB signaling pathways.

Acute lung injury is an inflammation that triggers acute respiratory distress syndrome with perialveolar neutrophil infiltration, alveolar-capillary barrier damage, and lung edema. Activation of the toll-like receptor 4 complex (TLR4/MD2) and its downstream signaling pathways are responsible for the cytokine storm and cause alveolar damage. Due to the complexity of this pulmonary inflammation, a defined pharmacotherapy has not been established. Thus, this study evaluated the anti-inflammatory potential of milonine, an alkaloid of Cissampelos sympodialis Eichl, in an experimental model of lung inflammation. BALB/c mice were lipopolysaccharide-challenged and treated with milonine at 2.0 mg/kg. Twenty-four hours later, the bronchoalveolar fluid, peripheral blood, and lungs were collected for cellular and molecular analysis. The milonine treatment decreased the cell migration (mainly neutrophils) to the alveoli, the pulmonary edema, and the cytokine levels (IL-1ß, IL-6, TNF-α). The systemic IL-6 level was also reduced. The milonine docking analysis demonstrated hydrophobic interaction at TLR4/MD2 groove with Ile124 and Phe126 amino acids. Indeed, the alkaloid downregulated the kinase-Akt and NF-κB through TLR4/MD2. Therefore, milonine is an effective inflammatory modulator being a potential molecule for the treatment of lung inflammation.

Potentiation of Antibiotic Action and Efflux Pump Inhibitory Effect on Staphylococcus aureus Strains by Solasodine.

A worrisome fact is the increase in microbial resistance, which has as its main cause the indiscriminate use of antibiotics. Scientific studies have investigated bioactive compounds such as steroidal sapogenins, in the perspective of new beneficial alternatives for the control of bacterial resistance. Therefore, the objective of this work was to verify the antibacterial activity as well as the modifying action of antibiotics associated with solasodine and its ability to inhibit the efflux pump mechanism in strains of Staphylococcus aureus. Tests were performed to verify the minimum inhibitory concentration (MIC). In addition, the action-modifying potential of antibiotics and the inhibitory capacity of the efflux pump NorA and MepA through synergistic effects on the antibiotic and ethidium bromide were evaluated. Solasodine showed significant results for the standard bacteria with an MIC of 512 µg/mL, and when associated with the antibiotics gentamicin and nofloxacin for the multidrug-resistant bacteria S. aureus 10, Escherichia coli 06, and Pseudomonas aeruginosa 24, it showed a 50% reduction in MIC. The association of solasodine with the antibiotic ciprofloxacin against S. aureus K2068 (MepA) showed synergism, with a reduction in the MIC of the antibiotic from 64 µg/mL to 40 µg/mL, and also a reduction in the MIC when the antibiotic was used in conjunction with the efflux pump inhibitors. Solasodine may be acting on the mechanism of action of the antibiotic, as it has shown a potentiating effect when associated with antibiotics, inducing a reduction in the MIC against Gram-positive and Gram-negative bacteria. Therefore, this study demonstrated significant results for the potentiating action of solasodine when associated with antibiotics of clinical importance.

Evaluation of Progesterone Receptor Antagonist and Maxi-K Channel Agonist as Neuroprotective in Feeney's Weight Drop Model of TBI.

Background: Neuroprotection in traumatic brain injury (TBI) is an unmet medical need. Objective: We evaluated two agents, aglepristone (progesterone receptor antagonist) and N-salicyloyltryptamine (STP) (activator of Maxi-K channel in GH3 cells), for neuroprotection in Feeney's weight drop model of TBI. Material and Methods: Forty-eight male Wistar rats were divided into six groups (n = 8 per group). A battery of six neurobehavioral tests was evaluated at the end of the first week (EO1W), second week (EO2W), and third week (EO3W). In addition, histopathological and immunohistochemistry (BAX, Bcl-2, and M30 Cytodeath) tests were performed at EO3W. Results: Aglepristone at 10 mg/kg showed significant neuroprotection compared to control as assessed by Rota-rod test at EO1W, VEFP right paw and 28-point neurobehavioral test at EO2W, MWM test at EO3W, and positive histopathological and IHC findings. Aglepristone at 20 mg/kg showed negative results as assessed by BAX expression, downregulation of Bcl-2, and positive M30 Cytodeath, thereby suggesting toxicity at higher doses. STP 100 mg/kg showed modest neuroprotective activity but failed to show a dose-response relationship at a dose of 50 mg/kg. Conclusion: The study shows that progesterone receptor antagonists have neuroprotection at lower doses and toxicity at higher doses.

Possible mechanisms involved in the neuroprotective effect of Trans,trans-farnesol on pilocarpine-induced seizures in mice.

This study aimed to investigate, through in vivo and in vitro methodologies, the effect of acute trans,trans-farnesol (12.5, 25, 50 or 100 mg/kg, p.o.) administration on behavioral and neurochemical parameters associated with pilocarpine-induced epileptic seizure (300 mg/kg, i.p.) in mice. The initial results showed that the compound in question presents no anxiolytic-like or myorelaxant effects, despite reducing locomotor activity in the animals at all doses tested. In addition, the lowest dose increased the latency to onset of the first epileptic seizure, and the time to death. In addition to decreasing the mortality percentage in mice submitted to the pilocarpine model. In this same model, pretreatment with the lowest dose of the compound decreased the hippocampal concentrations of thiobarbituric acid and nitrite, and partially restored striatal concentrations of noradrenaline, dopamine, and serotonin. Taken together, the results suggest that trans,trans-farnesol presents a central depressant effect which contributes to its antiepileptic action which, in turn, seems to be mediated by the antagonism of muscarinic cholinergic receptors, reduction of oxidative stress. and modulation of noradrenaline, dopamine and serotonin concentrations in the central nervous system.

Avaliação da citotoxicidade em hemácias de humanos do extrato etanólico de Praxelis clematidea (Griseb.)

Introdução: Espécies da família Asteraceae são conhecidas por apresentarem propriedades aromática, cosmética e terapêutica; tendo diversas pesquisas que evidenciou potencial medicinal dessa família. Dentre as espécies de Asteraceae, está Praxelis clematidea, que é rica em substâncias químicas como flavonoides, terpenóides e esteroides, as quais podem desempenhar uma série de atividades biológicas. Objetivo: Verificar o potencial tóxico do extrato etanólico das folhas de P. clematidea frente à células sanguíneas humanas, afim de determinar a toxicidade teórica dessa espécie. Métodos: Para a realização do teste de atividade citotóxica foram preparadas suspensões sanguíneas dos tipos A, B e O, que posteriormente foram misturadas a concentrações distintas do extrato etanólico por 1 (uma) hora. A hemólise foi quantificada por espectrofotometria em comprimento de onda de 540 nm. Resultados: O extrato etanólico das folhas de P. clematidea em diferentes concentrações apresentou baixa citoxicidade contra os eritrócitos humanos in vitro, enfatizando o produto como uma possível opção viável para a indústria de medicamentos fitoterápicos. No entanto, é importante elucidar que mais estudos in vivo precisam ser realizados para confirmar esse perfil toxicológico do extrato.

SUMMARY Introduction: Species of the Asteraceae family are known to have aromatic, cosmetic and therapeutic properties; having several researches that evidenced medicinal potential of this family. Among the species of Asteraceae, there is Praxelis clematidea, which is rich in chemical substances such as flavonoids, terpenoids and steroids, which can perform a series of biological activities. Aim: To verify the toxic potential of the ethanolic extract of P. clematidea leaves against human blood cells, in order to determine the theoretical toxicity of this species. Method: For the performance of the cytotoxic activity test, blood suspensions of types A, B and O were prepared, which were subsequently mixed at different concentrations of the ethanolic extract for 1 (one) hour. Hemolysis was quantified by spectrophotometry at a wavelength of 540 nm. Results: The ethanolic extract of P. clematidea leaves in different concentrations showed low cytotoxicity against human erythrocytes in vitro, emphasizing the product as a possible viable option for the herbal medicine industry. However, it is important to clarify that more in vivo studies need to be carried out to confirm this toxicological profile of the extract.

Introducción: Se sabe que las especies de la familia Asteraceae tienen propiedades aromáticas, cosméticas y terapéuticas; habiendo varias investigaciones que evidenciaron el potencial medicinal de esta familia. Entre las especies de Asteraceae, se encuentra Praxelis clematidea, que es rica en sustancias químicas como flavonoides, terpenoides y esteroides, que pueden realizar una serie de actividades biológicas. Objetivo: Verificar el potencial tóxico del extracto etanólico de hojas de P. clematidea contra las células sanguíneas humanas, con el fin de determinar la toxicidad teórica de esta especie. Metodos: Para realizar la prueba de actividad citotóxica se prepararon suspensiones de sangre de los tipos A, B y O, que luego se mezclaron a diferentes concentraciones del extracto etanólico durante 1 (una) hora. La hemólisis se cuantificó mediante espectrofotometría a una longitud de onda de 540 nm. Resultados: El extracto etanólico de hojas de P. clematidea a diferentes concentraciones mostró baja citotoxicidad contra eritrocitos humanos in vitro, destacando el producto como una posible opción viable para la industria de la fitoterapia. Sin embargo, es importante aclarar que es necesario realizar más estudios in vivo para confirmar este perfil toxicológico del extracto.

Is IFN expression by NK cells a hallmark of severe COVID-19?

Natural Killer cells (NK) are crucial in host defense against viruses. There are many unanswered questions about the immune system in COVID-19, especially the mechanisms that contribute to the development of mild or severe forms of the disease. Although NK cells may have an essential role in the pathogenesis of COVID-19, the mechanisms involved in this process are not yet fully elucidated. Here, we demonstrate that CD3-CD56+ NK cells frequency in the volunteers who recovered from mild COVID-19 (Mild CoV) presented a significant increase compared to the healthy control (HC) and individuals recovering from severe COVID-19 (Severe CoV) groups. Furthermore, distinct IFN profiles in recovered COVID-19 patients with mild or severe clinical forms of the disease were observed in the total NK cells (CD3-CD56+). In the first group, NK cells express increased levels of IFN-α compared to the severe CoV, while higher production of IFN-γ in severe CoV was found. Moreover, NK cells in mild CoV express more cytolytic granules depicted by granzyme B and perforin. Compared to HC, PBMCs from mild CoV presented higher Ki-67 and TIM-3 production after Pool CoV-2 and Pool Spike CoV-2 peptides stimulus. In addition, non-stimulated PBMCs in the mild CoV group had higher NK TIM-3+ frequency than severe CoV. In the mild CoV group, Pool Spike CoV-2 and Pool CoV-2 peptides stimuli elicited higher granzyme B and perforin coexpression and IFN-α production by PBMCs. However, in severe CoV, Pool Spike CoV-2 reduced the coexpression of granzyme B, perforin, and CD107a suggesting a decrease in the cytotoxic activity of NK cells. Therefore, our study shows that NK cells may have a crucial role in COVID-19 with the involvement of IFN-α and cytotoxic properties that aid in developing qualified immune responses. Furthermore, the data suggest that higher amounts of IFN-γ may be linked to the severity of this disease.

Anticonvulsant Activity of trans-Anethole in Mice.

Epilepsy is a chronic neurological disorder affecting 1-2% of world population, and one-third of patients are refractory to pharmacological treatment. This fact has stimulated research for new antiepileptic drugs and natural products have been an important source. trans-Anethole (TAN) is a phenylpropanoid, component of some essential oils, extracted from plants, and its effects have been little studied. Therefore, this study is aimed at investigating the TAN effect in classic seizure models and evaluate the electroencephalographic (EEG) profile of animals treated with this substance. For this, Swiss male mice (Mus musculus) were used, and the lethal dose was evaluated and subsequently submitted to the test maximal electroshock (MES), the pentylenetetrazole- (PTZ) induced seizure test, and the EEG profile. Initially, the LD50 for TAN was estimated in 1000 mg/kg (i.p.) dose and there was no sign of acute toxicity or death. In the MES test, TAN 300, i.p. (12.00 ± 2.9 s) and 400 mg/kg, i.p. (9.00 ± 4.4 s) doses was able to decrease tonic seizures duration induced by electric discharge (0.5 mA, 150 pulses/s, for 0.5 s). In the PTZ test (75 mg/kg, i.p.), TAN 400 mg/kg, i.p. increased the latency to myoclonic jerks (80.0 (56.0-134.0)), the latency totonic-clonic seizures (900.0 (861.0-900.0) and decrease seizure duration (0.0 (0.0-10.0)). No deaths were found in this groups compared to vehicle. EEG analysis showed an amplitude decrease of waves (ratio of baseline) in TAN 300 (1.82 ± 0.23) and 400 mg/kg (1.06 ± 0.16) groups. In this way, TAN at 400 mg/kg was able to inhibit and/or attenuate seizures by increasing the time for the onset of spasms and convulsions, as reducing the duration of seizures. The EEG profile corroborate with this results showing a reduction in the amplitude of waves compared to the PTZ group. Thus, TAN showed an anticonvulsant effect in all experimental models performed, behavioral and electroencephalographic.

A Betulinic Acid Derivative, BA5, Induces G0/G1 Cell Arrest, Apoptosis Like-Death, and Morphological Alterations in Leishmania sp.

Leishmaniasis are endemic diseases caused by different species of intracellular parasites of the genus Leishmania. Due to the high toxicity and drug resistance of current antileishmanial drugs, it is necessary to identify new and more effective drugs. Previously, we investigated the immunomodulatory and anti-Trypanosoma cruzi action of BA5, a derivative of betulinic acid. In the present study, we investigated the in vitro activity of BA5 against different species of Leishmania and their action mechanism. BA5 exhibited low cytotoxicity against macrophages and inhibited the proliferation of promastigote forms of Leishmania amazonensis (IC50 = 4.5 ± 1.1 µM), Leishmania major (IC50 = 3.0 ± 0.8 µM), Leishmania braziliensis (IC50 = 0.9 ± 1.1 µM) and Leishmania infantum (IC50 = 0.15 ± 0.05 µM). Incubation with BA5 reduced the percentage of Leishmania amazonensis-infected macrophages and the number of intracellular parasites (IC50 = 4.1 ± 0.7 µM). To understand the mechanism of action underlying BA5 antileishmanial activity (incubation at IC50/2, IC50 or 2xIC50 values of the drug), we investigated ultrastructural changes by scanning electron microscopy and evaluated cell cycle, membrane mitochondrial potential, and cell death against promastigote forms of Leishmania amazonensis by flow cytometry. Promastigotes incubated with BA5 presented membrane blebbing, flagella damage, increased size, and body deformation. Flow cytometry analysis showed that parasite death is mainly caused by apoptosis-like death, arrested cell cycle in G0/G1 phase and did not alter the membrane mitochondrial potential of Leishmania amazonensis. Surprisingly, the combination of BA5 and amphotericin B, an assay used to determine the degree of drug interaction, revealed synergistic effects (CI = 0.15 ± 0.09) on promastigotes forms of Leishmania amazonensis. In conclusion, BA5 compound is an effective and selective antileishmanial agent.