Evaluation of amlodipine against strains of Candida spp. in planktonic cells, developing biofilms and mature biofilms.

Aim: To evaluate the antifungal activity of amlodipine against strains of Candida spp. and to its possible mechanism of action.Methods: Broth microdilution tests were used to determine the minimum inhibitory concentration, while the synergistic activity was evaluated by calculating the fractional inhibitory concentration index. The action of amlodipine against biofilms was determined using the MTT assay and its possible mechanism of action was investigated through flow cytometry tests.Results: Amlodipine showed MICs ranging from 62.5 to 250 µg/ml, in addition to action against pre-formed and forming biofilms, with reductions between 50 and 90%. Amlodipine increases the externalization of phosphatidylserine and reduces the cell viability of fungal cells, suggesting apoptosis.Conclusion: Amlodipine had good antifungal activity against planktonic cells and biofilms of Candida spp., by leading the cells to apoptosis.

Candida is a type of fungus that can cause diseases. This fungus became stronger over time and drugs can no longer kill them easily, so it is important to find new drugs. We decided to study whether amlodipine, a drug used for heart disease, has action against Candida. We discovered that amlodipine make fungi weaker. We still need to do more studies to find out if amlodipine can help prevent Candida diseases.

Unveiling novel insights: geraniol's enhanced anti-candida efficacy and mechanistic innovations against multidrug-resistant candida strains.

OBJECTIVES: This study addressed the need for new treatments for severe Candida infections, especially resistant strains. It evaluated the antifungal potential of geraniol alone and with fluconazole against various Candida spp., including resistant strains, and investigated geraniol's mechanism of action using flow cytometry. METHODS: The research assessed the inhibitory effects of geraniol on the growth of various Candida species at concentrations ranging from 110 to 883 µg/ml. The study also explored the potential synergistic effects when geraniol was combined with fluconazole. The mechanism of action was investigated through flow cytometry, with a particular emphasis on key enzymes associated with plasma membrane synthesis, membrane permeability changes, mitochondrial membrane depolarization, reactive oxygen species (ROS) induction, and genotoxicity. RESULTS: Geraniol demonstrated significant antifungal activity against different Candida species, inhibiting growth at concentrations within the range of 110 to 883 µg/ml. The mechanism of action appeared to be multifactorial. Geraniol was associated with the inhibition of crucial enzymes involved in plasma membrane synthesis, increased membrane permeability, induction of mitochondrial membrane depolarization, elevated ROS levels, and the presence of genotoxicity. These effects collectively contributed to cell apoptosis. CONCLUSIONS: Geraniol, alone and in combination with fluconazole, shows promise as a potential therapeutic option for Candida spp. INFECTIONS: Its diverse mechanism of action, impacting crucial cellular processes, highlights its potential as an effective antifungal agent. Further research into geraniol's therapeutic applications may aid in developing innovative strategies to address Candida infections, especially those resistant to current therapies.

Antifungal activity of tannic acid against Candida spp. and its mechanism of action.

The increase in fungal resistance is a major public health concern. In this context, Candida spp. is an important genus related to invasive diseases, especially in immunosuppressed patients. The relevance of alternative approaches to increasing fungal resistance stands out, in which products of natural origin demonstrate potential antifungal activity in vitro against Candida spp. In this sense, this work aimed to evaluate the in vitro activity of tannic acid against Candida spp. Minimum inhibitory concentration (MIC) was determined for tannic acid and the antifungals, and the checkerboard assay was performed to analyze the interactions between them. Furthermore, we evaluated the tannic acid antibiofilm activity and its possible mechanism of action. Tannic acid showed MIC ranging to 0.06 to 0.5 µg/ml and showed no loss of effectiveness when combined with antifungals. Also, is safe at the concentrations it exerts its antifungal activity in pre-formed biofilms, as demonstrated by IC50 in murine fibroblasts cells and the hemolytic assay. Additionally, its mechanisms of action can be related with induction of signals that lead to apoptosis in fungal cells.

Analysis of the anti-Candida activity of tricyclic antidepressants in association with amphotericin B and their antifungal mechanisms.

Candida species are among the priority pathogens in the area of research and development. Due to the problems associated with resistance to antifungals, new therapeutic alternatives are necessary. In this regard, drug repositioning has gained prominence. The objective of this study was to evaluate the activity of three tricyclic antidepressants (TCAs) - amitriptyline (AMT), nortriptyline (NOR) and clomipramine (CLO) - isolated or associated with antifungals against strains of Candida spp., as well as to analyze the possible mechanism of action. Among the methods used were broth microdilution tests, tolerance level assessment, checkerboard assays, flow cytometry and fluorescence microscopy. Furthermore, Candida cells were visualized after treatments by scanning electron microscopy (SEM). AMT presented MIC 50% in the range of 16 to 128 µg/mL, NOR from 8 to 128 µg/mL, and CLO from 8 to 64 µg/mL, with all three TCAs having a fungicidal inhibitory action profile. For these TCAs, there was synergism with amphotericin B (AMB) in 100% of the isolates. In association with fluconazole (FLC) and itraconazole (ITR), there were mostly indifferent interactions. TCAs isolated and associated with AMB reduced cell viability, promoted DNA fragmentation and damage, caused mitochondrial depolarization, externalization of phosphatidylserine, produced reactive oxygen species (ROS), decreased reduced glutathione (GSH) and increased carbonyl protein levels, causing morphological changes. The results suggest the antifungal mechanism of the TCAs works via the apoptotic pathway.

Anticandidal activity of Croton heliotropiifolius Kunth essential oil is enhanced by N-acetylcysteine and itraconazole.

Aim: Evaluate the anticandidal effect of Croton heliotropiifolius Kunth essential oil and its interaction with azoles and N-acetylcysteine (NAC) against planktonic cells and biofilms. Materials & methods: Broth microdilution and checkerboard methods were used to evaluate the individual and combined activity with fluconazole and itraconazole (ITRA). The antibiofilm effect of the oil was assessed in 96-well plates alone and combined with ITRA and NAC, and cytotoxicity determined by MTT. Results: The oil inhibited all Candida species growth. The activity was enhanced when associated with ITRA and NAC for planktonic cells and biofilms in formation. The effective concentrations were lower than the toxic ones to V79 cells. Conclusion: C. heliotropiifolius Kunth essential oil is an anticandidal alternative, and can be associated with ITRA and NAC.

Candida is a type of fungus that can cause disease in people. In recent years, the number of available drugs to treat this disease have declined. It is important to search for new drugs. Plants are often used to improve health, so we tested the essential oil of a plant called Croton heliotropiifolius to see if it could kill the fungus. We found that the essential oil could kill the fungus, and could be used with other drugs to improve their effects.

Ten-year follow-up after peri-implantitis treatment using resective surgery: A case report.

BACKGROUND: Peri-implantitis poses significant challenges in clinical practice, necessitating effective therapeutic strategies. This case report presents a comprehensive treatment approach for managing peri-implantitis, focusing on resective surgery, including implantoplasty and long-term maintenance. METHODS: We describe the case of a 50-year-old female patient with peri-implantitis affecting a maxillary full-arch implant-supported rehabilitation. The treatment strategy involved resective surgery with implantoplasty, a new maxillary overdenture, and a regular maintenance care schedule of three to four visits per year. Clinical and radiographic assessments were performed over a 10-year follow-up period. RESULTS: Post-treatment, all maxillary implants demonstrated no probing depths exceeding 4 mm, absence of bleeding on probing or suppuration, minimal plaque accumulation, and no further bone loss. Resective surgery with implantoplasty seems to have effectively provided submucosal decontamination and created a supra-mucosal implant surface conducive to oral hygiene. Despite regular maintenance, some mandibular implants exhibited bone loss during the follow-up period and were managed using the same approach as for the maxillary implants. CONCLUSIONS: The comprehensive treatment approach yielded favorable long-term clinical and radiographic outcomes, underscoring the effectiveness of the combined strategies in managing peri-implantitis. Nevertheless, the potential for recurrence or the development of peri-implantitis in new implants, even after a decade of successful treatment and strict maintenance, highlights the importance of ongoing, diligent care and regular evaluations to promptly diagnose and address these issues. KEY POINTS: Why is this case new information? The long-term effectiveness of peri-implantitis treatments, particularly involving implantoplasty, remains under-documented. This case provides insights from a 10-year follow-up on the efficacy of a comprehensive approach for managing peri-implantitis. Furthermore, these findings illustrate the potential for new peri-implantitis to develop, regardless of sustained peri-implant health and rigorous maintenance. This finding highlights the critical role of continuous monitoring for the early diagnosis and treatment of new implants exhibiting peri-implantitis. What are the keys to the successful management of this case? The success of this case hinged on a comprehensive treatment approach that combines surgical intervention associated with implantoplasty to remove implant threads, thereby creating smoother surfaces, less retentive for plaque accumulation. A critical aspect of this approach was also the redesign of prosthetic components to improve hygiene accessibility, continuous monitoring, and consistent maintenance care. What are the primary limitations to success in this case? The primary challenge in achieving success in this case was the prevention of new implants with peri-implantitis, despite the patient's consistent adherence to the maintenance program. Moreover, a critical evaluation of implant characteristics, particularly their susceptibility to mechanical failures, is paramount when performing implantoplasty. Furthermore, aligning patient expectations with the realistic esthetic and functional outcomes of the treatment is often challenging. PLAIN LANGUAGE SUMMARY: Peri-implantitis, an inflammatory disease affecting dental implants, is quite challenging to treat. This case report describes how a 50-year-old woman with this condition was successfully treated and maintained over 10 years. The approach included a surgical method called resective surgery, which involved reshaping the bone defect (osteoplasty) and smoothing the implant surface (implantoplasty). Additionally, she was fitted with a new upper denture and had regular follow-up visits three to four times a year. After ten years, her upper implants were stable with no signs of infection or further bone loss, and they were easy to keep clean. Some of her lower implants did experience inflammation with progressive bone loss during this time, but they were managed using the same surgical procedure as for her upper implants. This 10-year case report highlights positive and stable clinical results after resective surgery for treating peri-implantitis and the importance of an interdisciplinary approach and regular check-ups for maintenance, early diagnosis, and management of peri-implantitis over the long term.

Mangiferin potentiates the activity of antifungal agents against fluconazole-resistant Candida spp.

Aim: To evaluate the antifungal activity of mangiferin against Candida spp. resistant to fluconazole.Materials & methods: The antifungal activity of mangiferin was assessed using broth microdilution and its interaction with azoles and amphotericin B was evaluated by checkerboard. The activity of mangiferin against Candida spp. biofilms was assessed using the MTT colorimetric assay and its possible mechanism of action was evaluated using flow cytometry.Results: Mangiferin showed activity against Candida albicans, Candida tropicalis and Candida parapsilosis resistant to fluconazole and showed synergism with azoles and amphotericin B. Mangiferin increased the activity of antifungals against Candida biofilms and caused depolarization of the mitochondrial membrane and externalization of phosphatidylserine, suggesting apoptosis.Conclusion: mangiferin combined with antifungals has potential against Candida spp.

Candida is a type of fungus that can make people ill. Over time, many species of Candida have found ways to resist the drugs used to kill them. It is important to find new drugs. We decided to see if a substance called mangiferin works against Candida. We found that mangiferin works against Candida and may help other drugs to work better. We still need to do more studies to find out whether mangiferin can help prevent diseases caused by Candida in the future.

Antifungal activity of propafenone on Candida spp. strains: interaction with antifungals and possible mechanism of action.

Introduction. The development of new antifungal drugs has become a global priority, given the increasing cases of fungal diseases together with the rising resistance to available antifungal drugs. In this scenario, drug repositioning has emerged as an alternative for such development, with advantages such as reduced research time and costs.Gap statement. Propafenone is an antiarrhythmic drug whose antifungal activity is poorly described, being a good candidate for further study.Aim. This study aims to evaluate propafenone activity against different species of Candida spp. to evaluate its combination with standard antifungals, as well as its possible action mechanism.Methodology. To this end, we carried out tests against strains of Candida albicans, Candida auris, Candida parapsilosis, Candida tropicalis, Candida glabrata and Candida krusei based on the evaluation of the MIC, minimum fungicidal concentration and tolerance level, along with checkerboard and flow cytometry tests with clinical strains and cell structure analysis by scanning electron microscopy (SEM).Results. The results showed that propafenone has a 50% MIC ranging from 32 to 256 µg ml-1, with fungicidal activity and positive interactions with itraconazole in 83.3% of the strains evaluated. The effects of the treatments observed by SEM were extensive damage to the cell structure, while flow cytometry revealed the apoptotic potential of propafenone against Candida spp.Conclusion. Taken together, these results indicate that propafenone has the potential for repositioning as an antifungal drug.

Antibiofilm activity of promethazine against ESBL-producing strains of Escherichia coli in urinary catheters.

The bacterium Escherichia coli is one of the main causes of urinary tract infections. The formation of bacterial biofilms, especially associated with the use of urinary catheters, contributes to the establishment of recurrent infections and the development of resistance to treatment. Strains of E. coli that produce extended-spectrum beta-lactamases (ESBL) have a greater ability to form biofilms. In addition, there is a lack of drugs available in the market with antibiofilm activity. Promethazine (PMZ) is an antihistamine known to have antimicrobial activity against different pathogens, including in the form of biofilms, but there are still few studies of its activity against ESBL E. coli biofilms. The aim of this study was to evaluate the antimicrobial activity of PMZ against ESBL E. coli biofilms, as well as to assess the application of this drug as a biofilm prevention agent in urinary catheters. To this end, the minimum inhibitory concentration and minimum bactericidal concentration of PMZ in ESBL E. coli strains were determined using the broth microdilution assay and tolerance level measurement. The activity of PMZ against the cell viability of the in vitro biofilm formation of ESBL E. coli was analyzed by the MTT colorimetric assay and its ability to prevent biofilm formation when impregnated in a urinary catheter was investigated by counting colony-forming units (CFU) and confirmed by scanning electron microscopy (SEM). PMZ showed bactericidal activity and significantly reduced (p < 0.05) the viability of the biofilm being formed by ESBL E. coli at concentrations of 256 and 512 µg/ml, as well as preventing the formation of biofilm on urinary catheters at concentrations starting at 512 µg/ml by reducing the number of CFUs, as also observed by SEM. Thus, PMZ is a promising candidate to prevent the formation of ESBL E. coli biofilms on abiotic surfaces.

Digital three-dimensional assessment of free gingival graft remodeling over 12 months.

OBJECTIVE: To digitally evaluate the three-dimensional (3D) remodelling of FGG used to treat RT2 gingival recessions and lack of keratinized tissue on mandibular incisor teeth. METHODS: Data from 45 patients included in a previous multicentric RCT were analyzed. Silicone impressions were taken before (baseline) and 3, 6 and 12 months after standardized FGG placement. Casts were scanned and images were superimposed, using digital software, to obtain measurements of estimated soft tissue thickness (eTT; 1, 3, and 5 mm apical to baseline gingival margin). In addition, soft tissue volume (STV) and creeping attachment (CA) were assessed. RESULTS: All patients exhibited postoperative eTT and STV increases, at all time points. The greatest mean thickness gain was observed at eTT3 (1.0 ± 0.4 mm) at 12 months. At 12 months, STV was 52.3 ± 21.1 mm3, without relevant changes compared to the 3- and 6-month follow-up. CA, which was observed as early as six months postoperatively, was evident in ∼85 % of teeth at 12 months. CONCLUSIONS: Application of FGG was an effective phenotype modification therapy, as shown by the significantly increased tissue thickness postoperatively. Despite the use of FGG technique not aiming for root coverage, digital 3D assessment documented the early and frequent postoperative occurrence of CA, which helped improve recession treatment outcomes. CLINICAL SIGNIFICANCE: The use of 3D assessment methodology allows precise identification of the tissue gain obtained with FGG, which, regardless of technique, results in predictable phenotype modification and frequent occurrence of creeping attachment.

Management of an extensive soft tissue deficiency prior to immediate implant in the aesthetic zone: a 4-year follow-up.

Soft tissue deficiency in a tooth extraction site in the aesthetic area is a common and challenging clinical situation. This case report demonstrates the successful treatment of extensive gingival recession and buccal bone dehiscence associated with a hopeless tooth. Initially, a connective tissue graft was used to cover the root and thicken the soft tissue. After 2 months, the tooth was extracted, an implant was immediately placed, and a temporary restoration was installed. After 3 months, the soft tissue exhibited a natural and harmonious architecture. A custom zirconia abutment and crown were then fabricated and placed. At the 4-year follow-up, the peri-implant tissue displayed satisfactory aesthetics, with a well-structured buccal bone plate and healthy peri-implant indicators. This two-stage approach, addressing gingival recession first and proceeding with immediate implant placement after soft tissue healing, proved to be a safe and effective method with stable long-term results.

Biosurfactant complexed with arginine has antibiofilm activity against methicillin-resistant Staphylococcus aureus.

Aim: The present study investigated the antimicrobial effectiveness of a rhamnolipid complexed with arginine (RLMIX_Arg) against planktonic cells and biofilms of methicillin-resistant Staphylococcus aureus (MRSA). Methodology: Susceptibility testing was performed using the Clinical & Laboratory Standards Institute protocol: M07-A10, checkerboard test, biofilm in plates and catheters and flow cytometry were used. Result: RLMIX_Arg has bactericidal and synergistic activity with oxacillin. RLMIX_Arg inhibits the formation of MRSA biofilms on plates at sub-inhibitory concentrations and has antibiofilm action against MRSA in peripheral venous catheters. Catheters impregnated with RLMIX_Arg reduce the formation of MRSA biofilms. Conclusion: RLMIX_Arg exhibits potential for application in preventing infections related to methicillin-resistant S. aureus biofilms.

[Box: see text].

Antimicrobial potential of a biosurfactant gel for the prevention of mixed biofilms formed by fluconazole-resistant C. albicans and methicillin-resistant S. aureus in catheters.

Dual-species biofilms formed by Candida albicans and Staphylococcus aureus have high virulence and drug resistance. In this context, biosurfactants produced by Pseudomonas aeruginosa have been widely studied, of which a new derivative (RLmix_Arg) stands out for possible application in formulations. The objective of this study was to evaluate the antibiofilm activity of RLmix_Arg, both alone and incorporated in a gel prepared with Pluronic F-127, against dual-species biofilms of fluconazole-resistant C. albicans (FRCA) and methicillin-resistant S. aureus (MRSA) in impregnated catheters. Broth microdilution tests, MTT reduction assays of mature biofilms, impregnation of RLmix_Arg and its gel in peripheral venous catheters, durability tests and scanning electron microscopy (SEM) were performed. RLmix_Arg showed antimicrobial activity against Candida spp. and S. aureus, by reducing the cell viability of mixed biofilms of FRCA and MRSA, and preventing their formation in a peripheral venous catheter. The incorporation of this biosurfactant in the Pluronic F-127 gel considerably enhanced its antibiofilm activity. Thus, RLmix_Arg has potential application in gels for impregnation in peripheral venous catheters, helping to prevent development of dual-species biofilms of FRCA and MRSA.

Promising activity of etomidate against mixed biofilms of fluconazole-resistant Candida albicans and methicillin-resistant Staphylococcus aureus.

Introduction. Candida albicans and Staphylococcus aureus are recognized for their development of resistance and biofilm formation. New therapeutic alternatives are necessary in this context.Hypothesis. Etomidate shows potential application in catheters against mixed biofilms of fluconazole-resistant C. albicans and methicillin-resistant S. aureus (MRSA).Aim. The present study aimed to evaluate the activity of etomidate against mixed biofilms of fluconazole-resistant C. albicans and MRSA.Methodology. The action of etomidate against mature biofilms was verified through the evaluation of biomass and cell viability, and its ability to prevent biofilm formation in peripheral venous catheters was determined based on counts of colony forming units (c.f.u.) and confirmed by morphological analysis through scanning electron microscopy (SEM).Results. Etomidate generated a reduction (P<0.05) in biomass and cell viability starting from a concentration of 250 µg ml-1. In addition, it showed significant ability to prevent the formation of mixed biofilms in a peripheral venous catheter, as shown by a reduction in c.f.u. SEM revealed that treatment with etomidate caused substantial damage to the fungal cells.Conclusion. The results showed the potential of etomidate against polymicrobial biofilms of fluconazole-resistant C. albicans and MRSA.

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.

Analysis of possible pathways on the mechanism of action of minocycline and doxycycline against strains of Candida spp. resistant to fluconazole.

Species of the genus Candida, characterized as commensals of the human microbiota, are opportunistic pathogens capable of generating various types of infections with high associated costs. Considering the limited pharmacological arsenal and the emergence of antifungal-resistant strains, the repositioning of drugs is a strategy used to search for new therapeutic alternatives, in which minocycline and doxycycline have been evaluated as potential candidates. Thus, the objective was to evaluate the in vitro antifungal activity of two tetracyclines, minocycline and doxycycline, and their possible mechanism of action against fluconazole-resistant strains of Candida spp. The sensitivity test for antimicrobials was performed using the broth microdilution technique, and the pharmacological interaction with fluconazole was also analysed using the checkerboard method. To analyse the possible mechanisms of action, flow cytometry assays were performed. The minimum inhibitory concentration obtained was 4-427 µg ml-1 for minocycline and 128-512 µg ml-1 for doxycycline, and mostly indifferent and additive interactions with fluconazole were observed. These tetracyclines were found to promote cellular alterations that generated death by apoptosis, with concentration-dependent reactive oxygen species production and reduced cell viability. Therefore, minocycline and doxycycline present themselves as promising study molecules against Candida spp.

Antifungal activity of selective serotonin reuptake inhibitors against Cryptococcus spp. and their possible mechanism of action.

Fungal infections caused by Cryptococcus spp. pose a threat to health, especially in immunocompromised individuals. The available arsenal of drugs against cryptococcosis is limited, due to their toxicity and/or lack of accessibility in low-income countries, requiring more therapeutic alternatives. Selective serotonin reuptake inhibitors (SSRIs), through drug repositioning, are a promising alternative to broaden the range of new antifungals against Cryptococcus spp. This study evaluates the antifungal activity of three SSRIs, sertraline, paroxetine, and fluoxetine, against Cryptococcus spp. strains, as well as assesses their possible mechanism of action. Seven strains of Cryptococcus spp. were used. Sensitivity to SSRIs, fluconazole, and itraconazole was evaluated using the broth microdilution assay. The interactions resulting from combinations of SSRIs and azoles were investigated using the checkerboard assay. The possible action mechanism of SSRIs against Cryptococcus spp. was evaluated through flow cytometry assays. The SSRIs exhibited in vitro antifungal activity against Cryptococcus spp. strains, with minimum inhibitory concentrations ranging from 2 to 32 µg/mL, and had synergistic and additive interactions with azoles. The mechanism of action of SSRIs against Cryptococcus spp. involved damage to the mitochondrial membrane and increasing the production of reactive oxygen species, resulting in loss of cellular viability and apoptotic cell death. Fluoxetine also was able to cause significant damage to yeast DNA. These findings demonstrate the in vitro antifungal potential of SSRIs against Cryptococcus spp. strains.

Antibacterial activity of menadione alone and in combination with oxacillin against methicillin-resistant Staphylococcus aureus and its impact on biofilms.

Introduction. Antibiotic resistance is a major threat to public health, particularly with methicillin-resistant Staphylococcus aureus (MRSA) being a leading cause of antimicrobial resistance. To combat this problem, drug repurposing offers a promising solution for the discovery of new antibacterial agents.Hypothesis. Menadione exhibits antibacterial activity against methicillin-sensitive and methicillin-resistant S. aureus strains, both alone and in combination with oxacillin. Its primary mechanism of action involves inducing oxidative stress.Methodology. Sensitivity assays were performed using broth microdilution. The interaction between menadione, oxacillin, and antioxidants was assessed using checkerboard technique. Mechanism of action was evaluated using flow cytometry, fluorescence microscopy, and in silico analysis.Aim. The aim of this study was to evaluate the in vitro antibacterial potential of menadione against planktonic and biofilm forms of methicillin-sensitive and resistant S. aureus strains. It also examined its role as a modulator of oxacillin activity and investigated the mechanism of action involved in its activity.Results. Menadione showed antibacterial activity against planktonic cells at concentrations ranging from 2 to 32 µg ml-1, with bacteriostatic action. When combined with oxacillin, it exhibited an additive and synergistic effect against the tested strains. Menadione also demonstrated antibiofilm activity at subinhibitory concentrations and effectively combated biofilms with reduced sensitivity to oxacillin alone. Its mechanism of action involves the production of reactive oxygen species (ROS) and DNA damage. It also showed interactions with important targets, such as DNA gyrase and dehydroesqualene synthase. The presence of ascorbic acid reversed its effects.Conclusion. Menadione exhibited antibacterial and antibiofilm activity against MRSA strains, suggesting its potential as an adjunct in the treatment of S. aureus infections. The main mechanism of action involves the production of ROS, which subsequently leads to DNA damage. Additionally, the activity of menadione can be complemented by its interaction with important virulence targets.

Preparation and characterization of porous membranes of glucomannan and silver decorated cellulose nanocrystals for application as biomaterial.

Bacterial infection usually represents a threat in medical wound care, due to the increase in treatment complexity and the risk of antibiotic resistance. For presenting interesting characteristics for the use as biomaterial, natural polymers have been explored for this application. Among them, a promising candidate is the konjac glucomannan (KGM) with outstanding biocompatibility and biodegradability but lack of antibacterial activity. In this study, KGM was combined with silver decorated cellulose nanocrystals (CNC-Ag) to prepare membranes by using a recent reported casting-freezing method. The results highlight the potential anti-adhesive activity of the new materials against Staphylococcus aureus upon contact, without the burst release of silver nanoparticles. Furthermore, the incorporation of CNC enhanced the thermal stability of these membranes while preserving the favorable mechanical properties of the KGM-based material. These findings highlight a straightforward approach to enhance the antibacterial properties of natural polymers, which can be effectively useful in medical devices like wound dressings that typically lack such properties.

Automated, High-Throughput Screening of Hybrid Elastin-like Polypeptide/Polysaccharide Multilayer Film Deposition.

The self-assembled layer-by-layer technique has attracted a great deal of attention as a method for engineering bio-functional surfaces under mild chemical conditions. The production of multilayer films, starting from newly designed building blocks, may be laborious, considering the inherent limitations for anticipating how minimal changes in the macromolecular composition may impact both film deposition and performance. This paper presents an automated, high-throughput approach to depositing polyelectrolyte multilayers (PEMs) in multiwell plates, enabling the screening of nearly 100 film formulations in the same process. This high-throughput layer-by-layer (HT-LbL) method runs in an affordable, fully commercial platform using Python-coded routines that can be easily adapted for the materials science lab settings. The HT-LbL system was validated by investigating the deposition of polysaccharide-based films in multiwell plates, probing the absorbance signal of ionically stained polyelectrolyte multilayers (PEMs) prepared in one single batch. The HT-LbL method was also used to investigate the deposition of PEMs with a small library of genetically engineered elastin-like polypeptides (ELPs) with different levels of ionizable and hydrophobic amino acid residues. The deposition of ELP/chitosan films was assessed based on the signal of fluorescently labeled species (chitosan or ELP-mCherry), demonstrating that both electrostatic and hydrophobic residues are essential for film buildup. The growth and surface properties of ELP-mCherry/chitosan films also seemed susceptible to the assembly pH, forming a higher film growth and a rougher and more hydrophobic surface for both polyelectrolytes deposited under a low ionization degree. Overall, this study illustrates the challenge of predicting the growth and properties of multilayer films and how the HT-LbL can accelerate the development of multilayer films that demand high levels of testing and optimization.