In vitro antimicrobial, antibiofilm photodynamic activity, and molecular dynamic simulations of tetra-cationic porphyrinmembrane interactions against foodborne microorganisms.

This manuscript presents a new report on the in vitro antimicrobial photo-inactivation of foodborne microorganisms (Salmonella spp. and Listeria monocytogenes) using tetra-cationic porphyrins. Isomeric tetra-cationic porphyrins (3MeTPyP, 4MeTPyP, 3PtTPyP, and 4PtTPyP) were tested, and antimicrobial activity assays were performed at specific photosensitizer concentrations under dark and white-light LED irradiation conditions. Among the tested bacterial strains, 4MeTPyP exhibited the highest efficiency, inhibiting bacterial growth within just 60 min at low concentrations (17.5 µM). The minimal inhibitory concentration of 4MeTPyP increased when reactive oxygen species scavengers were present, indicating the significant involvement of singlet oxygen species in the photooxidation mechanism. Furthermore, the checkerboard assay testing the association of 4MeTPyP showed an indifferent effect. Atomic force microscopy analyses and dynamic simulations were conducted to enhance our understanding of the interaction between this porphyrin and the strain's membrane.

Chemical composition, antifungal activity, antibiofilm and citotoxicity of the essential oil of Citrus deliciosa tenore.

The leaves of Citrus deliciosa Tenore were collected in southern Brazil, dried, and subjected to the hydrodistillation process to obtain the essential oil. The extraction of essential oil yielded 0.97% ± 0.04. The chromatographic profile of this compound revealed 11 substances, being methyl N-methyl-anthranilate (75.1%), γ-terpinene (13.8%), and Limonene (7%) as major substances. The essential oil shows antifungal action against all tested yeasts, with promising action against Cryptococcus neoformans, Cryptococcus gattii, and Trichosporon asahii. This compound was also able to inhibit the biofilm production of Candida albicans, Candida glabrata, Candida parapsilosis, and T. asahii. The essential oil of tangerine showed weak antioxidant action. It did not show cytotoxicity in human mononuclear cells. It is hoped that these results may guide future studies for the production of formulations that can be used in the treatment of biofilms caused by yeasts, as well as in candidiasis, cryptococcosis, and/or trichosporonosis.

The First Report of In Vitro Antifungal and Antibiofilm Photodynamic Activity of Tetra-Cationic Porphyrins Containing Pt(II) Complexes against Candida albicans for Onychomycosis Treatment.

Onychomycosis is a prevalent nail fungal infection, and Candida albicans is one of the most common microorganisms associated with it. One alternative therapy to the conventional treatment of onychomycosis is antimicrobial photoinactivation. This study aimed to evaluate for the first time the in vitro activity of cationic porphyrins with platinum(II) complexes 4PtTPyP and 3PtTPyP against C. albicans. The minimum inhibitory concentration of porphyrins and reactive oxygen species was evaluated by broth microdilution. The yeast eradication time was evaluated using a time-kill assay, and a checkerboard assay assessed the synergism in combination with commercial treatments. In vitro biofilm formation and destruction were observed using the crystal violet technique. The morphology of the samples was evaluated by atomic force microscopy, and the MTT technique was used to evaluate the cytotoxicity of the studied porphyrins in keratinocyte and fibroblast cell lines. The porphyrin 3PtTPyP showed excellent in vitro antifungal activity against the tested C. albicans strains. After white-light irradiation, 3PtTPyP eradicated fungal growth in 30 and 60 min. The possible mechanism of action was mixed by ROS generation, and the combined treatment with commercial drugs was indifferent. The 3PtTPyP significantly reduced the preformed biofilm in vitro. Lastly, the atomic force microscopy showed cellular damage in the tested samples, and 3PtTPyP did not show cytotoxicity against the tested cell lines. We conclude that 3PtTPyP is an excellent photosensitizer with promising in vitro results against C. albicans strains.

Antimicrobial photodynamic in vitro inactivation of Enterococcus spp. and Staphylococcus spp. strains using tetra-cationic platinum(II) porphyrins.

This manuscript presents the first report on antimicrobial photo-inactivation in vitro using tetra-cationic porphyrins with peripheral platinum(II) bipyridyl complexes against Gram-positive bacteria. Two isomeric tetra-cationic porphyrins (3TPyP and 4TPyP) were tested against clinically important bacterial species. The antimicrobial activity assays were performed at specific photosensitizer (PS) concentrations under dark and white-light LED irradiation conditions for 120 min. The porphyrin 3-PtTPyP was the most efficient PS against the bacteria tested, inhibiting bacterial growth in just 15 min and 30 min at low concentrations (3.75 and 0.45 µM). The minimal inhibitory concentration of the porphyrin increased in the presence of reactive oxygen species scavengers, indicating that singlet oxygen and radical species likely participated in the photo-oxidation mechanism. In addition, the checkerboard assay that tests the association of compounds, showed a synergistic effect, suggesting a potentiation of the antibacterial effect when porphyrin was tested in combination with ciprofloxacin and vancomycin. Thus, tetra-cationic porphyrins containing platinum(II) complexes are promising agents for microbial photo-inactivation as an alternative therapy against infections.

Antimicrobial activity of water-soluble tetra-cationic porphyrins on Pseudomonas aeruginosa.

This manuscript presents the cytotoxicity, antimicrobial activity, antibiofilm preliminary properties, and associated therapy with commercial drugs using water-soluble tetra-cationic porphyrins against Pseudomonas aeruginosa. Two commercial tetra-cationic porphyrins were tested against a standard strain of P. aeruginosa 01 (PA01) in antibacterial activity assays under dark conditions and irradiated with white light for 120 min. Porphyrin 4-H2TMePor showed better antimicrobial activity and was chosen for further tests. Increased minimum inhibitory concentration was observed in the presence of reactive oxygen species, suggesting that photooxidation was mediated by the singlet oxygen production. In the time-kill curve assay, 4-H2TMePor inhibited bacterial growth in 90 min of irradiation. The checkerboard assay revealed synergistic interactions. Biofilms of the standard PA01 strain and three clinical isolates were formed. The biofilm destruction assay was more efficient for PA01, significantly reducing the biofilm biomass formed compared to the positive control. The associated treatment to destroy the biofilm potentiated a significant decrease in the biofilm biomass compared to the positive control. The photosensitizer did not damage human keratinocytes or mouse fibroblasts in the cytotoxicity assays, demonstrating the safety of using 4-H2TMePor. Atomic force microscopy indicated lower adhesion force, higher cell wall deformation, and higher dissipation energy in the treated control compared to untreated PA01. Given our findings, it is evident that water-soluble tetra-cationic porphyrins have excellent antimicrobial and a preliminary antibiofilm activity against Gram-negative bacteria, proving to be a potential photosensitizer for clinical use.

Detection and characterization of Bacillus cereus isolated from the dialysis fluid.

In this study, B. cereus was detected in dialysis fluids within international parameters (ultrapure - maximum limit of 0.1 CFU/mL for heterotrophic bacteria count) by analyzing the pellet obtained through the centrifugation method. We also investigated the ability of the B. cereus isolate to form a biofilm at different temperatures, the production of virulence factors, and the susceptibility to commercial antimicrobial agents. This study demonstrated a high ability of B. cereus to persist in the hemodialysis system, which can be explained by its broad ability to produce a biofilm at 25 °C, its relevant production of virulence factors, such as ß-hemolysin, lecithinase and cereulide, and its important resistance pattern to antimicrobial drugs. In conclusion, these new findings expand the understanding that this microorganism should not be neglected and new methods for tracking it should be considered.

A novel nanotechnological mucoadhesive and fast-dissolving film for vaginal delivery of clotrimazole: design, characterization, and in vitro antifungal action.

Pullulan (PUL) films containing pomegranate seed oil and Eudragit® RS100 nanocapsules loaded with clotrimazole (CTZ-NC-PUL) were developed to treat vulvovaginal candidiasis (VVC). Our findings showed that the nanocapsule average diameter was around 163 ± 4 nm, with polydispersity index values of up to 0.1 ± 0.01 and positively charged zeta potential (+ 43.5 ± 0.7 mV). The pH was in the acid range (5.14 ± 0.12) and encapsulation efficiency was around 99.6%; CTZ nanoencapsulation promoted higher homogeneity values for the film (91%), and the stability studies displayed no changes in the drug content after 120 days for the CTZ-NC-PUL under refrigerated conditions. All formulations were considered non-irritant, and CTZ-NC-PUL promoted a controlled release of the drug (60% in 24 h) compared to CTZ-PUL (100% in 8 h). The permeation results corroborate the drug release, where higher CTZ amounts were found in the mucosa and receptor medium for CTZ-PUL (21.02 and 4.46 µg/cm2). The films were fast dissolving (10 min), and CTZ-NC-PUL presented higher mucoadhesive properties; the antifungal activity against Candida albicans was maintained, and the in vitro efficacy of the film was proved. In conclusion, CTZ-NC-PUL formulation was considered promising and suitable for vaginal application against candida-related infections.

Antimycobacterial activity of Achyrocline flaccida (Asteraceae) aqueous extract from Southern Brazil.

Achyrocline flaccida aqueous extract was obtained by macerating wildflowers. The phytochemical profile present in the A. flaccida aqueous extract was elucidated by HPLC-ESI-MS/MS. Toxicity was evaluated in vitro by comet assay in peripheral blood mononuclear cells (PBMCs) and in vivo using Caenorhabditis elegans as a model. The antioxidant activity was also evaluated, and antimycobacterial activity was assessed by the broth microdilution method. The compounds present in the aqueous extract mainly belonged to the flavonoid class (89%). The concentrations that showed protective effects in C. elegans against oxidative stress and antimycobacterial activity had no toxic effects. The antimycobacterial activity test demonstrated that the concentration of 1,560 µg mL-1 inhibited the growth and eradication of the mycobacterial tested strains. Based on our findings, the A. flaccida aqueous extract presents a viable potential in developing new phytotherapeutic drugs against mycobacteria of clinical relevance.

Phytochemical characterization, genotoxicity, cytotoxicity, and antimicrobial activity of Gautheria procumbens essential oil.

This study investigated the chemical constituents of Gaultheria procumbens essential oil and is the first to relate cytogenotoxicity with oxidative metabolism and antimicrobial activity. Chromatographic analysis of the essential oil showed methyl salicylate (99.96%) and linalool (0.04%) as the major compounds. The essential oil showed no signs of cytogenotoxicity at different concentrations (1.82 to 58.34 mg mL-1). Furthermore, G. procumbens essential oil and methyl salicylate were used to evaluate the minimal inhibitory concentrations (MIC) and minimal microbicidal concentrations (MMC). The results showed efficacy against several microorganisms, including Aeromonas caviae, Candida albicans, and Mycobacterium fortuitum with MIC values ranging from 1.82 to 3.64 mg mL-1 and MMC values ranging from 3.64 to 12.67 mg mL-1, which were confirmed by time-kill kinetics. Based on our results, the essential oil is a promising alternative to developing future formulations to treat infections caused by microorganisms.

Detection and characterization of Bacillus cereus isolated from the dialysis fluid

ABSTRACT In this study, B. cereus was detected in dialysis fluids within international parameters (ultrapure - maximum limit of 0.1 CFU/mL for heterotrophic bacteria count) by analyzing the pellet obtained through the centrifugation method. We also investigated the ability of the B. cereus isolate to form a biofilm at different temperatures, the production of virulence factors, and the susceptibility to commercial antimicrobial agents. This study demonstrated a high ability of B. cereus to persist in the hemodialysis system, which can be explained by its broad ability to produce a biofilm at 25 °C, its relevant production of virulence factors, such as β-hemolysin, lecithinase and cereulide, and its important resistance pattern to antimicrobial drugs. In conclusion, these new findings expand the understanding that this microorganism should not be neglected and new methods for tracking it should be considered.

Molecular docking, quorum quenching effect, antibiofilm activity and safety profile of silver-complexed sulfonamide on Pseudomonas aeruginosa.

Microbial infections caused by sessile microorganisms are known to be a more challenging issue than infections caused by the same microorganisms in the planktonic state. Pseudomonas aeruginosa is an opportunistic pathogen and biofilm-forming agent. This species presents intense cellular communication mediated by signaling molecules. This process is known as quorum sensing (QS) and induces the transcription of specific genes that favors cell density growth and three-dimensional bacterial grouping. In this context, the discovery of compounds capable of inhibiting the action of the QS signaling molecules seems to be a promising strategy against biofilms. This work aimed to evaluate the anti-biofilm action and the in vitro safety profile of a sulfamethoxazole-Ag complex. The results obtained indicate potential anti-biofilm activity through QS inhibition. In silico tests showed that the compound acts on the las and pqs systems, which are the main regulators of biofilm formation in P. aeruginosa. Additionally, the molecule proved to be safe for human peripheral blood mononuclear cells.

Investigation of the triplet excited state and application of cationic meso-tetra(cisplatin)porphyrins in antimicrobial photodynamic therapy.

In this manuscript, we report, the photophysical study of triplet excited states and antimicrobial photoinactivation of positively charged tetra-cisplatin porphyrin derivatives against Gram + and Gram ‒ bacterial strains. Isomeric cisplatin-porphyrins were used and applied in aPDT assays in the bacilli Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa (Gram negative) and a cocci Staphylococcus aureus (Gram positive) strains. The results show that compound substituted at meta position (3-cis-PtTPyP) is the more efficient photosensitizer against bacteria culture. In this way, tetra-cationic porphyrins containing cisplatin derivatives might be promising aPDT agents with potential applications in clinical infections.

Sulfonamides complexed with metals as mycobacterial biofilms inhibitors.

Rapidly growing mycobacteria (RGM) are found in non-sterile water and often associated with severe post-surgical infections and affect immunocompromised patients. In addition, RGM can prevent the host's immune response and have the ability to adhere to and form biofilms on biological and synthetic substrates, making pharmacological treatment difficult because conventional antimicrobials are ineffective against biofilms. Thus, there is an urgent need for new antimicrobial compounds that can overcome these problems. In this context, sulfonamides complexed with Au, Cd, Ag, Cu, and Hg have shown excellent activity against various microorganisms. Considering the importance of combating RGM-associated infections, this study aimed to evaluate the activity of sulfonamide metal complexes against RGM biofilm. The sulfonamides were tested individually for their ability to inhibit mycobacterial formation and destroy the preformed biofilm of standard RGM strains, such as Mycobacterium abscessus, M. fortuitum, and M. massiliense. All sulfonamides complexed with metals could reduce, at subinhibitory concentrations, the adhesion and biofilm formation of three RGM species in polystyrene tubes. It is plausible that the anti-biofilm capacity of the compounds is due to the inhibition of c-di-GMP synthesis, which is an important signal for RGM biofilm formation. Hence, the impacts and scientific contribution of this study are based on the discovery of a potential new therapeutic option against RGM-associated biofilm infections. Sulfonamides complexed with metals have proven to be a useful and promising tool to reduce microbial adhesion on inert surfaces, stimulating the improvement of methodologies to insert compounds as new antibacterial and coating agents for medical and hospital materials.

Nanobiopesticides: development and inseticidal activity of nanoemulsions containing lemongrass or eucalyptus oils.

The bioinsecticides, like essential oils, are a promising alternative in pest control. However, these oils have some limitations, such as instability and low solubility. These limitations can be circumvented through nanotechnology, with the nanoemulsification of these compounds. Therefore, the objective of this study was to prepare, characterize and explore the insecticidal activity against adult flies of nanoemulsions containing essential oil of lemongrass or eucalyptus. The nanoemulsions were prepared by the high-energy method and presented droplet size smaller than 125 nm, with polydispersity index of 0.2, pH acid and spherical morphology. The insecticidal activity was evaluated by the Topical Application Method and Exposure Impregnated Paper Exposure, where it was possible to demonstrate a potential insecticidal effect of lemongrass oil in the concentrations of 10, 30 and 50 µL/mL against Musca domestica and Lucilia cuprina and the potentiation of this effect when nanoemulsified this oil against L. cuprina.

Achyrocline flaccida essential oil from Brazil: phytochemical composition, genotoxicity, protective effects on Caenorhabditis elegans, and antimycobacterial activity.

Achyrocline flaccida (Weinm) DC. essential oil was obtained by hydrodistillation of wild flowers from southern Brazil. We explored, for the first time, the phytochemical composition, toxicity, resistance to oxidative stress in Caenorhabditis elegans, and antimycobacterial activities of A. flaccida essential oil. Twenty-four compounds were identified by GC-FID-MS and the major constituents identified were α-pinene (41.10%) and caryophyllene (30.52%). The essential oil showed no signs of genotoxicity in the comet assay and presented relevant antioxidant capacity since it prevented ROS production in the C. elegans model. Furthermore, the minimal inhibitory concentrations (MIC) results showed that M. abscessus, M. massiliense, and M. fortuitum had their growth inhibited by A. flaccida essential oil. Therefore, the essential oil of this plant is a promising alternative in the search for new compounds capable of decreasing oxidative stress and treating mycobacteriosis.

Investigation of isomeric tetra-cationic porphyrin activity with peripheral [Pd(bpy)Cl]+ units by antimicrobial photodynamic therapy.

In this work, we report the antimicrobial photoinactivation using tetra-cationic porphyrins with peripheral palladium(II) complexes against bacterial strains. Two different isomeric Pd(II)-porphyrins were used and applied in PDI experiments in the strains Gram negative bacilli Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa and a Gram positive cocci Staphylococcus aureus. All experiments are conducted with adequate concentration (without aggregation) of photosensitizer under white-light irradiation over 2 h . We showed that the most effective PS caused a significative reduction in the concentration of viable bacteria. The present results show that porphyrin with positively charge at meta position (3-PtTPyP) are more efficient photosensitizer against bacteria strains. In this way, tetra-cationic porphyrins might be promising antibacterial PDI agents with potential applications in clinical cases.

Antimicrobial and antileukemic effects: in vitro activity of Calyptranthes grandifolia aqueous leaf extract.

Natural products are still a promising source of bioactive molecules. Food and Drug Administration data showed that approximately 49% of the approved molecules originate naturally or chemically-resemble these substances, of which more than 70% are being used in anticancer therapy. It is noteworthy that at present there are no scientific studies to prove the effectiveness and safety of a number of plants used in folk medicine such as in the case of Calyptranthes grandifolia O. Berg (Myrtaceae) originally from South America. The aim of the present study was to determine the biological potential and toxicological effects of the aqueous leaf extract of C. grandifolia. The main detected phytoconstituents were condensed tannins and flavonoids and a high quantity of polyphenols. Regarding the antimicrobial potential, the extract exerted inhibitory activity against Pseudomonas aeruginosa. The results also revealed the extract induced DNA damage in a concentration-dependent manner in RAW 264.7 cells. In addition, C. grandifolia produced cytotoxicity in leukemia cell lines (HL60 and Kasumi-1) without affecting isolated human lymphocytes but significantly inhibited JAK3 and p38α enzyme activity. Taken together, these findings add important information on the biological and toxicological effects of C. grandifolia, indicating that aqueous extract may be a source of natural antimicrobial and antileukemic constituents.

Toxicological evaluation of naringin-loaded nanocapsules in vitro and in vivo.

Naringin is a flavonoid widely known for its pharmacological properties, such as: anti-inflammatory and antioxidant ones, being an ally to avoid oxidative damage. Although naringin is an active easily found in citrus fruits, it has low bioavailability, biodistribution and also undergoes biotransformation in naringenin, limiting the described effects. The use of nanocapsules as drug carriers may increase solubility, improve biodistribution, impede the biotransformation thereof, and thus could improve the performance of naringin for use in treating neurological diseases. Therefore, the objective of this work is to produce a nanocapsule containing naringin, validate an analytical method by RP-HPLC to determination of the drug in nanoparticle and evaluate the toxicity. To that end, the blank nanocapsules (NB, without the drug) or naringin-loaded nanocapsules (NN) at the concentration of 2 mg/mL were prepared by interfacial deposition of the preformed polymer and the quantification of naringin by HPLC. Toxicity of the formulations was evaluated in vitro in rat hippocampal slices and in vivo models with C. elegans and Danio rerio (zebrafish). The analytical parameters evaluated (linearity, limit of detection and quantification, specificity, precision, accuracy and robustness) indicated adequate method to assay of naringin in nanocapsules by HPLC. There was no indication of toxicity by the nanocapsules in the evaluated biological assays.

Diphenyl Diselenide and Clotrimazole Co-loaded into Eudragit® RS 100 Nanocapsules Formulation Has Superior Antioxidant Potential and Promising Anti-candida Activity

Abstract In the current study, nanocapsules (NC) formulations containing a co-load of clotrimazole (C), a highly prescribed antifungal drug, and diphenyl diselenide [(PhSe)2], an organoselenium compound with a promising scope of pharmacological actions, were prepared. Formulations were characterized as well as the potential toxicity, antioxidant action, and antifungal effect were assessed using in vitro techniques. The NCs were prepared employing Eudragit® RS 100 as polymeric wall and medium chain triglycerides or virgin coconut oil (CO) as core. All NC suspensions had pH around acid range, compound content close to theoretical value (1 mg/mL/drug), average diameter in nanometric range, positive values of zeta potential as well as high encapsulation efficacy and mucoadhesive property. Physicochemical stability was performed over a 30-day period and showed no modification in the aforementioned parameters to all samples. Preliminary screening of toxicological potential performed by the hen's egg test chorioallantoic membrane technique classified the formulations as non-irritant. The DPPH radical assay revealed that nanoencapsulated compounds had superior antioxidant action in comparison to their free forms (concentration range tested 1.0-25.0 µg/mL). Importantly, the formulation composed of CO and containing C and (PhSe)2 showed the highest antioxidant potential and was selected for further investigation regarding antifungal effect against some Candida spp strains. Results of in vitro antifungal assay demonstrated that the C and (PhSe)2 co-encapsulation had a minimum inhibitory concentration (MIC) values around 60. Thus, our study supplies additional data about advantages achieved by encapsulating active compounds.

Anti-biofilm and anti-inflammatory effect of a herbal nanoparticle mouthwash: a randomized crossover trial.

Laboratory evidence has demonstrated the antimicrobial effect of Melaleuca alternifolia (MEL) against oral microorganisms. This randomized, double-blind, crossover clinical trial, compared the anti-biofilm and anti-inflammatory effects of MEL nanoparticles with 0.12% chlorhexidine gluconate (CHX) on biofilm-free (BF) and biofilm-covered (BC) surfaces. Before each experimental period, the participants refrained from all oral hygiene practices for 72 hours. The 60 participants were randomly assigned to professional prophylaxis in two quadrants (Q1-Q3 or Q2-Q4), and rinsed with MEL or CHX for four days. The Quigley & Hein plaque index (QHPI), gingival crevicular fluid (GCF) volume, and participants' perceptions were assessed. CHX showed significantly lower mean QHPI on BF (2.65 ± 0.34 vs. 3.34 ± 0.33, p < 0.05) and BC surfaces (2.84 ± 0.37 vs. 3.37 ± 0.33, p < 0.05). Intragroup comparisons indicated reductions in GCF in all the groups, with significant differences only for CHX on BF surfaces (p < 0.05). Intergroup comparisons revealed no significant differences (p > 0.05). Based on individual perceptions, CHX had better taste and biofilm control, but resulted in a greater change in taste. Nevertheless, MEL demonstrated anti-inflammatory effects similar to those of CHX. Further clinical trials testing different protocols, concentrations and follow-up periods are required to establish its clinical application.