RESUMEN

Helicobacter pylori is a bacterium that is present in the stomach of about 50% of the global population and is associated with several gastric disorders, including cancer. Natural products with antimicrobial activity have been tested against H. pylori, among them Trichilia catigua (catuaba), which is widely distributed in Brazil. This study aimed to evaluate extracts of T. catigua bark against H. pylori via determination of the minimum inhibitory and bactericidal concentrations (MIC and MBC); evaluation of virulence factors by real-time PCR, synergism with standard antimicrobials and morphology by scanning electron microscopy and simulations of the mechanism of action by molecular docking. The ethyl acetate fraction provided the best results, with an MIC50 of 250 µg/mL and a 42.34% reduction in urease activity, along with reduced expression of the CagA and VacA genes, which encode for the main virulence factors. This fraction presented synergistic activity with clarithromycin, reducing the MIC of the drug by four-fold. Docking simulations suggested that the extracts inhibit fatty acid synthesis by the FAS-II system, causing damage to the cell membrane. Therefore, T. catigua extracts have potential as an adjuvant to treatment and are promising for the development of new anti-H. pylori drugs.

Asunto(s)

Antibacterianos , Proteínas Bacterianas , Helicobacter pylori , Pruebas de Sensibilidad Microbiana , Simulación del Acoplamiento Molecular , Corteza de la Planta , Extractos Vegetales , Helicobacter pylori/efectos de los fármacos , Antibacterianos/farmacología , Antibacterianos/química , Extractos Vegetales/farmacología , Extractos Vegetales/química , Corteza de la Planta/química , Brasil , Factores de Virulencia , Meliaceae/química , Claritromicina/farmacología , Ureasa , Sinergismo Farmacológico , Antígenos Bacterianos

RESUMEN

The treatment of skin and soft tissue infections (SSTIs) can be challenging due to bacterial resistance, particularly from strains like MRSA and biofilm formation. However, combining conventional antibiotics with natural products shows promise in treating SSTIs. The objective of this study is to develop a nanoemulsion-based hydrogel containing Protium spruceanum extract and mupirocin and evaluate its potential for the treatment of SSTIs. The nanoemulsion was obtained by phase inversion and subsequently characterized. The antibacterial activity was evaluated in vitro against S. aureus MRSA, including the synergism of the combination, changes in membrane permeability using flow cytometry, and the anti-biofilm effect. In addition, the irritative potential was evaluated by the HET-CAM assay. The combination exhibited synergistic antibacterial activity against S. aureus and MRSA due to the extract enhancing membrane permeability. The hydrogel demonstrated suitable physicochemical properties, inhibited biofilm formation, and exhibited low irritation. The formulation was nanometric (176.0 ± 1.656 nm) and monodisperse (polydispersity index 0.286 ± 0.011). It exhibited a controlled release profile at 48 h and high encapsulation efficacy (94.29 ± 4.54% for quercitrin and 94.20 ± 5.44% for mupirocin). Therefore, these findings suggest that the hydrogel developed could be a safe and effective option for treating SSTIs.

RESUMEN

The antifungal activity of palindromic peptide RWQWRWQWR and its derivatives was evaluated against clinical isolates of Candida albicans and C. auris. Also, Bidens pilosa ethanolic extracts of leaves and stem were evaluated. Furthermore, combinations of peptide, extract, and/or fluconazole (FLC) were evaluated. The cytotoxicity of peptides and extracts in erythrocytes and fibroblasts was determined. The original palindromic peptide, some derivative peptides, and the ethanolic extract of leaves of B. pilosa exhibited the highest activity in some of the strains evaluated. Synergy was obtained between the peptide and the FLC against C. auris 435. The combination of the extract and the original palindromic peptide against C. albicans SC5314, C. auris 435, and C. auris 537 decreased the minimal inhibitory concentrations (MICs) by a factor of between 4 and 16. These mixtures induced changes in cell morphology, such as deformations on the cell surface. The results suggest that the combination of RWQWRWQWR and B. pilosa extract is an alternative for enhancing antifungal activity and decreasing cytotoxicity and costs and should be considered to be a promising strategy for treating diseases caused by Candida spp.

RESUMEN

Aim: To evaluate the antibacterial and synergistic effect of a new 8-hydroxyquinoline derivative (PH176) against MRSA. Materials & methods: PH176 activity was determined by broth microdilution against 38 Staphylococcus aureus clinical isolates. The antibacterial and synergistic effects with oxacillin and nitroxoline were evaluated by time-kill assays to five MRSA isolates. Toxicity was evaluated by in vitro and ex vivo models. Results: The MIC50 and MIC90 of PH176 were 16 and 32 µg/ml, respectively. The PH176 and nitroxoline led to a reduction in colony count for four isolates and the combination of PH176 and oxacillin acted synergically for three isolates. Furthermore, PH176 was determined to be noncytotoxic/nonirritant. Conclusion: These results demonstrate that PH176 has revealed promising results to be a potential candidate to treat MRSA infections.

Asunto(s)

Staphylococcus aureus Resistente a Meticilina , Antibacterianos/farmacología , Sinergismo Farmacológico , Pruebas de Sensibilidad Microbiana , Oxiquinolina/farmacología

RESUMEN

The essential oil (EO), the methanolic (MeOH), and the 70% ethanolic (70% EtOH) extracts obtained from the aerial parts of Ocimum campechianum Mill. (Ecuador) were chemically characterized through gas-chromatography coupled to mass spectrometry detector (GC-MS), high-performance liquid chromatography coupled to diode array-mass spectrometry detectors (HPLC-DAD-MS) and studied for their in vitro biological activity. The radical scavenger activity, performed by spectrophotometric 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, highlighted significant IC50 values for the EO, extracts and their main constituents (eugenol and rosmarinic acid). EO (and eugenol) showed noteworthy activity against Pseudomonas syringae pv. syringae and a moderate effect against clinical Candida strains, with possible synergism in association to fluconazole against the latter microorganisms. The extracts and pure molecules exhibited weak cytotoxic activity against the HaCat cell line and no mutagenicity against Salmonella typhimurium TA98 and TA100 strains, giving indication of safety. Instead, EO showed a weak activity against adenocarcinomic human alveolar basal epithelial cells (A549). The above-mentioned evidence leads us to suggest a potential use of the crude drug, extracts, and EO in cosmetic formulation and food supplements as antioxidant agents. In addition, EO may also have a possible application in plant protection and anti-Candida formulations.

Asunto(s)

Cinamatos/farmacología , Depsidos/farmacología , Eugenol/farmacología , Ocimum/química , Extractos Vegetales/química , Extractos Vegetales/farmacología , Células A549 , Antibacterianos/farmacología , Antioxidantes/farmacología , Benzotiazoles/química , Compuestos de Bifenilo/química , Candida/efectos de los fármacos , Muerte Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Sinergismo Farmacológico , Ecuador , Fluconazol/farmacología , Humanos , Concentración 50 Inhibidora , Pruebas de Sensibilidad Microbiana , Mutagénesis , Aceites Volátiles/análisis , Picratos/química , Ácidos Sulfónicos/química , Ácido Rosmarínico

RESUMEN

Anaerobic digestion of microalgal biomass for biogas production may be limited due to the cell wall resulting in an inefficient bioconversion. Enzymatic pretreatments are applied for inducing cell damage/lysis and organic matter solubilisation and this way increasing biogas production. We evaluated enzymatic pretreatments in different conditions for comparing in relation to cell wall rupture, increase of soluble material and increase in biogas production through anaerobic digestion performance in BMP assay. Chlorella sorokiniana cultures were subjected to three different enzymatic pretreatments, each under four different conditions of enzyme/substrate ratio, pH and application time. The results showed increases over 21% in biogas productions for all enzymatic pretreatments. Enzymatic pretreatment was effective at damaging microalgae cell wall, releasing organic compounds and increasing the rate and final methane yield in BMP tests. We observed a synergistic activity between the mixtures enzymes, which would depend on operational conditions used for each pretreatment.

Asunto(s)

Biomasa , Biotecnología/métodos , Pared Celular/metabolismo , Celulasa/metabolismo , Chlorella/citología , Metano/biosíntesis , Microalgas/citología , Anaerobiosis , Chlorella/metabolismo , Microalgas/metabolismo , Solubilidad

RESUMEN

In the search for new antimicrobial molecules, antimicrobial peptides (AMPs) offer a viable alternative to conventional antibiotics, as they physically disrupt the bacterial membranes, leading to membrane disruption and eventually cell death. In particular, the group of linear α-helical cationic peptides has attracted increasing research and clinical interest. The AMP P5 has been previously designed as a cationic linear α-helical sequence, being its antimicrobial and hemolytic properties also evaluated. In this work, we analyzed the feasibility of using P5 against a carbapenem-resistant clinical isolate of Pseudomonas aeruginosa, one of the most common and risky pathogens in clinical practice. After antimicrobial activity confirmation in in vitro studies, synergistic activity of P5 with meropenem was evaluated, showing that P5 displayed significant synergistic activity in a time kill curve assay. The ability of P5 to permeabilize the outer membrane of P. aeruginosa can explain the obtained results. Finally, the antibiofilm activity was investigated by viability analysis (MTT assay), crystal violet and confocal imaging, with P5 displaying mild biofilm inhibition in the range of concentrations tested. Regarding biofilm disruption activity, P5 showed a higher efficacy, interfering with biofilm structure and promoting bacterial cell death. Atomic force microscope images further demonstrated the peptide potential in P. aeruginosa biofilm eradication, confirming the promising application of P5 in multi-resistant infections therapeutics.

Asunto(s)

Antibacterianos/farmacología , Péptidos Catiónicos Antimicrobianos/farmacología , Biopelículas/efectos de los fármacos , Carbapenémicos/farmacología , Pseudomonas aeruginosa/efectos de los fármacos , Farmacorresistencia Bacteriana

RESUMEN

ABSTRACT Hypericum species, Hypericaceae, are recognized as a source of therapeutical agents. Purified fractions and isolated compounds have been shown antimicrobial activity. As the indiscriminate use of antifungals and the increase of infections caused by emerging species are leading to the search of new alternative treatments, the aim of this study was to continue the study with Hypericum carinatum Griseb. lipophilic fraction, rich in phloroglucinol derivatives, investigating the effect of its association with fluconazole against emerging yeasts (Candida krusei, C. famata, C. parapsilosis and Cryptococcus neoformans). The synergistic activity between H. carinatum lipophilic fraction and fluconazole was assessed by two methodologies for multiple dose–response analysis: checkerboard and isobologram. Regarding synergistic experiments, the effect of the association was higher than the effect of fluconazole alone against Candida krusei and C. famata isolates (MIC fluconazole decreased about eight and four folds, respectively), suggesting that, somehow, H. carinatum lipophilic fraction compounds are facilitating the action of this drug. On the other hand, when tested against Cryptococcus neoformans and C. parapsilosis, fluconazole showed better results than the association. Thus, against Candida krusei and C. famata, the lipophilic fraction of H. carinatum was able to reduce the MIC values of fluconazole and could be considered as a potential alternative to be used against emerging yeast species.

RESUMEN

BACKGROUND: Candida tropicalis is increasingly becoming among the most commonly isolated pathogens causing fungal infections with an important biofilm-forming capacity. PURPOSE: This study addresses the antifungal effect of rubiadin (AQ1) and rubiadin 1-methyl ether (AQ2), two photosensitizing anthraquinones (AQs) isolated from Heterophyllaea pustulata, against C. tropicalis biofilms, by studying the cellular stress and antioxidant response in two experimental conditions: darkness and irradiation. The combination with Amphotericin B (AmB) was assayed to evaluate the synergic effect. STUDY DESIGN/METHODS: Biofilms of clinical isolates and reference strain of Candida tropicalis were treated with AQs (AQ1 or AQ2) and/or AmB, and the biofilms depletion was studied by crystal violet and confocal scanning laser microscopy (CSLM). The oxidant metabolites production and the response of antioxidant defense system were also evaluated under dark and irradiation conditions, being the light a trigger for photo-activation of the AQs. The Reactive Oxygen Species (ROS) were detected by the reduction of Nitro Blue Tetrazolium test, and Reactive Nitrogen Intermediates (RNI) by the Griess assay. ROS accumulation was also detected inside biofilms by using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) probe, which was visualized by CSLM. Superoxide dismutase (SOD) activity and the total antioxidant capacity of biofilms were measured by spectrophotometric methods. The minimun inhibitory concentration for sessile cells (SMIC) was determined for each AQs and AmB. The fractional inhibitory concentration index (FICI) was calculated for the combinations of each AQ with AmB by the checkerboard microdilution method. RESULTS: Biofilm reduction of both strains was more effective with AQ1 than with AQ2. The antifungal effect was mediated by an oxidative and nitrosative stress under irradiation, with a significant accumulation of endogenous ROS detected by CSLM and an increase in the SOD activity. Thus, the prooxidant-antioxidant balance was altered especially by AQ1. The best synergic combination with AmB was also obtained with AQ1 (80.5%) (FICI=0.74). CONCLUSION: Under irradiation, the oxidative stress was the predominant effect, altering the prooxidant-antioxidant balance, which may be the cause of the irreversible cell injury in the biofilm. Our results showed synergism of these natural AQs with AmB. Therefore, the photosensitizing AQ1 could be an alternative for the Candida infections treatment, which deserves further investigation.

Asunto(s)

Antraquinonas/farmacología , Antifúngicos/farmacología , Biopelículas/efectos de los fármacos , Candida tropicalis/efectos de los fármacos , Anfotericina B/farmacología , Antraquinonas/química , Antraquinonas/efectos de la radiación , Antioxidantes/metabolismo , Candida tropicalis/fisiología , Luz , Pruebas de Sensibilidad Microbiana , Estrés Oxidativo/efectos de los fármacos , Especies de Nitrógeno Reactivo/metabolismo , Superóxido Dismutasa/metabolismo

RESUMEN

Boa constrictor is widely used in traditional communities in many different folk remedies and products derived from it are sold in public markets throughout northeastern Brazil and as its body fat has many different therapeutic indications as a folk remedy. The present work evaluates the antibacterial activity of the body fat from the snake Boa constrictor when employed either alone or in combination with antibiotics and discusses the ecological implications of the use of this traditional remedy. Oil (OBC) was extracted from body fat located in the ventral region of B. constrictor using hexane as a solvent. The antibacterial activity of OBC was tested against standard as well as multi-resistant lines, either alone and in combination with antibiotics. OBC did not demonstrate any relevant antibacterial activity against standard or multidrug-resistant bacterial strains. OBC showed synergistic activity when combined with the aminoglycoside antibiotics. Our results indicate that the body fat of Boa constrictor does not possess bactericidal activity, from the clinical point of view, but when combined with an antibiotic, the fat demonstrated a significant synergistic activity.