Novel Dry Hyaluronic Acid-Vancomycin Complex Powder for Inhalation, Useful in Pulmonary Infections Associated with Cystic Fibrosis.

Polyelectrolyte-drug complexes are interesting alternatives to improve unfavorable drug properties. Vancomycin (VAN) is an antimicrobial used in the treatment of methicillin-resistant Staphylococcus aureus pulmonary infections in patients with cystic fibrosis. It is generally administered intravenously with a high incidence of adverse side effects, which could be reduced by intrapulmonary administration. Currently, there are no commercially available inhalable formulations containing VAN. Thus, the present work focuses on the preparation and characterization of an ionic complex between hyaluronic acid (HA) and VAN with potential use in inhalable formulations. A particulate-solid HA-VAN25 complex was obtained by spray drying from an aqueous dispersion. FTIR spectroscopy and thermal analysis confirmed the ionic interaction between HA and VAN, while an amorphous diffraction pattern was observed by X-ray. The powder density, geometric size and morphology showed the suitable aerosolization and aerodynamic performance of the powder, indicating its capability of reaching the deep lung. An in vitro extended-release profile of VAN from the complex was obtained, exceeding 24 h. Microbiological assays against methicillin-resistant and -sensitive reference strains of Staphylococcus aureus showed that VAN preserves its antibacterial efficacy. In conclusion, HA-VAN25 exhibited interesting properties for the development of inhalable formulations with potential efficacy and safety advantages over conventional treatment.

Synergistic bactericidal combinations between gentamicin and chitosan capped ZnO nanoparticles: A promising strategy for repositioning this first-line antibiotic.

Gentamicin (GEN), a widely used broad-spectrum antibiotic, faces challenges amid the global emergency of antimicrobial resistance. This study aimed to explore the synergistic effects of zinc oxide nanoparticles (ZnO NPs) in combination with GEN on the bactericidal activity against various bacterial strains. Results showed ZnO NPs with MICs ranging from 0.002 to 1.5 µg/mL, while the precursor salt displayed a MIC range of 48.75-1560 µg/mL. Chitosan (CS)-capped ZnO NPs exhibited even lower MICs than their uncapped counterparts, with the CS-capped synthesized ZnO NPs demonstrating the lowest values. Minimal bactericidal concentrations (MBC) aligned with MIC trends. Combinations of CS-capped synthesized ZnO NPs and GEN proved highly effective, inhibiting bacterial growth at significantly lower concentrations than GEN or ZnO NPs alone. This phenomenon may be attributed to the conformation of CS on the ZnO NPs' surface, enhancing the positive particle surface charge. This possibly facilitates a more effective interaction between ZnO NPs and microorganisms, leading to increased accumulation of zinc and GEN within bacterial cells and an overproduction of reactive oxygen species (ROS). It's crucial to note that, while this study did not specifically involve resistant strains, its primary focus remains on enhancing the overall antimicrobial activity of gentamicin. The research aims to contribute to addressing the global challenge of antimicrobial resistance, recognizing the urgent need for effective strategies to combat this critical issue. The findings, particularly the observed synergy between ZnO NPs and GEN, hold significant implications for repositioning the first-line antibiotic GEN.

Antibacterial Properties of Mesoporous Silica Nanoparticles Modified with Fluoroquinolones and Copper or Silver Species.

Antibiotic resistance is a global problem and bacterial biofilms contribute to its development. In this context, this study aimed to perform the synthesis and characterization of seven materials based on silica mesoporous nanoparticles functionalized with three types of fluoroquinolones, along with Cu2+ or Ag+ species to evaluate the antibacterial properties against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa, including clinical and multi-drug-resistant strains of S. aureus and P. aeruginosa. In addition, in order to obtain an effective material to promote wound healing, a well-known proliferative agent, phenytoin sodium, was adsorbed onto one of the silver-functionalized materials. Furthermore, biofilm studies and the generation of reactive oxygen species (ROS) were also carried out to determine the antibacterial potential of the synthesized materials. In this sense, the Cu2+ materials showed antibacterial activity against S. aureus and E. coli, potentially due to increased ROS generation (up to 3 times), whereas the Ag+ materials exhibited a broader spectrum of activity, even inhibiting clinical strains of MRSA and P. aeruginosa. In particular, the Ag+ material with phenytoin sodium showed the ability to reduce biofilm development by up to 55% and inhibit bacterial growth in a "wound-like medium" by up to 89.33%.

Dual Anticancer and Antibacterial Properties of Silica-Based Theranostic Nanomaterials Functionalized with Coumarin343, Folic Acid and a Cytotoxic Organotin(IV) Metallodrug.

Five different silica nanoparticles functionalized with vitamin B12, a derivative of coumarin found in green plants and a minimum content of an organotin(IV) fragment (1-MSN-Sn, 2-MSN-Sn, 2-SBA-Sn, 2-FSPm-Sn and 2-FSPs-Sn), were identified as excellent anticancer agents against triple negative breast cancer, one of the most diagnosed and aggressive cancerous tumors, with very poor prognosis. Notably, compound 2-MSN-Sn shows selectivity for cancer cells and excellent luminescent properties detectable by imaging techniques once internalized. The same compound is also able to interact with and nearly eradicate biofilms of Staphylococcus aureus, the most common bacteria isolated from chronic wounds and burns, whose treatment is a clinical challenge. 2-MSN-Sn is efficiently internalized by bacteria in a biofilm state and destroys the latter through reactive oxygen species (ROS) generation. Its internalization by bacteria was also efficiently monitored by fluorescence imaging. Since silica nanoparticles are particularly suitable for oral or topical administration, and considering both its anticancer and antibacterial activity, 2-MSN-Sn represents a new dual-condition theranostic agent, based primarily on natural products or their derivatives and with only a minimum amount of a novel metallodrug.

Fungicidal and antibiofilm activities of gold nanoparticles on Candida tropicalis.

Aim: To investigate the antifungal activity of two different functionalized gold nanoparticles (AuNP), those stabilized with cetyltrimethylammonium bromide and those conjugated with cysteine, and their effects on the architecture of Candida tropicalis biofilms. Materials & methods: Biofilms were studied by crystal violet binding assay and scanning electron microscopy. We investigated the effects of AuNPs on reactive oxygen species, reactive nitrogen intermediates and enzymatic and nonenzymatic antioxidant defenses. Results/Conclusion: The fungicidal activity and cellular stress of both AuNPs affected biofilm growth through accumulation of reactive oxygen species and reactive nitrogen intermediates. However, cetyltrimethylammonium bromide-stabilized AuNPs revealed a higher redox imbalance. We correlated, for the first time, AuNP effects with the redox imbalance and alterations in the architecture of C. tropicalis biofilms.

Biofilms are at least 100­1000-times more resistant to the effects of antimicrobial agents compared with planktonic cells, and nanoparticles have emerged to provide new approaches to improve the safety and efficacy of antimicrobial therapy. The aim of this work was to investigate the antifungal activity with two different functionalized gold nanoparticles. A significant reduction of Candida tropicalis biofilms with alterations in surface topography and architecture was observed, and the oxidative and nitrosative stress affected the biofilms. To the best of our knowledge, this is the first study that attempts to correlate the antibiofilm effects of gold nanoparticles on the redox imbalance against biofilms. These compounds could be an alternative to fungal biofilms infections treatments, applied specifically in biological and medical fields.

Hybrid Nanosystems Based on Nicotinate-Functionalized Mesoporous Silica and Silver Chloride Nanoparticles Loaded with Phenytoin for Preventing Pseudomonas aeruginosa Biofilm Development.

Pseudomonas aeruginosa (PA) is one of the most common bacteria isolated from chronic wounds and burns. Its treatment is a challenge due to antimicrobial drug resistance and biofilm formation. In this context, this study aimed to perform the synthesis and full characterization of hybrid nanosystems based on mesoporous silica nanoparticles (MSNs) functionalized with a nicotinic ligand and silver chloride nanoparticles, both phenytoin sodium (Ph)-loaded and unloaded, to evaluate the antibacterial properties against three different strains of PA (including two clinical strains) in a planktonic state and as biofilms. Ph is a well-known proliferative agent, which was incorporated into the hybrid nanomaterials to obtain an effective material for tissue healing and prevention of infection caused by PA. The Ph-loaded materials promoted a quasi-complete inhibition of bacterial growth in wound-like medium and biofilm development, with values of 99% and 96%, respectively, with selectivity indices above the requirements for drugs to become promising agents for the topic preventive treatment of chronic wounds and burns.

Biologically synthesized silver nanoparticles, mediated by Bothriochloa laguroides, inhibit biofilm formation and eradicate mature biofilm of Yersinia enterocolitica and Staphylococcus aureus.

AIMS: To phytosynthesize silver nanoparticles (AgNPs) and determine their antibacterial and antibiofilm capacity against gram-positive and gram-negative bacterial strains. METHODS AND RESULTS: AgNPs were synthesized using Bothriochloa laguroides aqueous extract as reducing and stabilizing agent. After characterization, a phytochemical screening to the extract and the AgNPs was performed. Antibacterial activity, inhibition and eradication of biofilms against Staphylococcus aureus and Yersinia enterocolitica strains were tested. Spherical AgNPs with an average size of 8 nm were obtained. Tannins, flavonoids, carbohydrates, proanthocyanidins, anthocyanins and saponins were identified in aqueous extract; meanwhile, only carbohydrates were identified in AgNPs. The MIC and MBC were determined at pmol L-1  levels for all tested strains. Furthermore, AgNPs inhibited more than 90% of biofilms formation and eradicated more than 80% of mature biofilms at concentrations higher than MIC. CONCLUSIONS: The AgNPs obtained in this study inhibited planktonic and sessile growth, and eradicated mature biofilms of pathogenic bacterial strains at very low concentrations. SIGNIFICANCE AND IMPACT OF STUDY: The current study showed the promising potential of AgNPs as antibiofilm agents opening the way for the future development of a new class of antibacterial products.

Synergic activity of oligostyrylbenzenes with amphotericin B against Candida tropicalis biofilms.

Antimicrobial drug resistance is a serious challenge in clinical settings worldwide, with biofilm formation having been associated with this problem. In the present study, the synergism of oligostyrylbenzene (OSB) compounds in combination with amphotericin B (AmB) against Candida tropicalis biofilms was investigated. In addition, the toxicity in human blood cells was determined. Synergistic combinations of OSBs and AmB were evaluated to consider future effects of OSBs in vivo. The checkerboard microdilution method was used to study the interactions of one anionic (1) and two cationic (2 and 3) OSBs with AmB. We investigated the effects of OSBs on reactive oxygen species (ROS) and the levels of the reactive nitrogen intermediates (RNIs). The cellular stress affected biofilm growth through an accumulation of ROS and RNI, at synergistic concentrations of OSBs and AmB. Furthermore, significant surface topography differences were noted upon treatment with the OSB 2/AmB combination, using confocal laser scanning microscopy in conjunction with the image analysis software COMSTAT. The results revealed a low toxicity to leukocytes and red blood cells at synergistic combinations of cationic OSBs with AmB. These findings demonstrated the antibiofilm effects of OSBs and the synergism of AmB with cationic OSBs against biofilms of C. tropicalis for the first time.

Silver bionanoparticles toxicity in trophoblast is mediated by nitric oxide and glutathione pathways.

Silver bionanoparticles (AgNPs) biosynthesized by Pseudomonas aeruginosa culture supernatant have an important antibacterial activity mediated by ROS increase; however their toxicity in human cells is not known. Due to the high susceptibility of the developing tissues to xenobiotics, the aim of this study was to investigate the AgNPs effect on first trimester human trophoblasts. The HTR8/SVneo cell line was treated with AgNPs (0.3-1.5 pM), for 6 and 24 h. Cell viability, reactive nitrogen and oxygen species (RNS and ROS) production, nitric oxide synthase expression, antioxidant defenses and biomolecule damage were evaluated. The exposure to AgNPs produced changes in HTR8/SVneo cell morphology and decreased cell viability. Alterations in redox balance were observed, with an increase in ROS and RNS levels, and NOS2 protein expression. Superoxide dismutase and catalase augmented their activity accompanied with a decreased in glutathione content and glutathione S-transferase activity. Protein oxidation and genotoxic damage were observed at concentrations greater than 0.6 pM. The pre-incubation with l-NMMA, NAC, mannitol and peroxidase demonstrated that AgNPs-induced cytotoxicity was not mediated by HO and H2O2, but nitric oxide and glutathione pathways were implicated in cell death. Since reported AgNPs microbicidal mechanism is mediated by increasing ROS (mainly HO and H2O2) without an increase in RNS, this work indicates an interesting difference in the reactive species and oxidative pathways involved in AgNPs toxicity in eukaryotic and prokaryotic cells. Highlighting the importance of toxicity evaluation to determine the safety of AgNPs with pharmaceutical potential uses.

Naphthoquinones inhibit formation and viability of Yersinia enterocolitica biofilm.

The capacity of different naphthoquinones to inhibit and eradicate Yersinia enterocolitica biofilm was investigated and possible mechanisms of action were evaluated. Inhibition of biofilm formation and cell viability, quorum sensing (QS) inhibition and oxidative stress generation of 23 naphthoquinones were assayed against Yersinia enterocolitica. The best anti-biofilm agents at 100 µmol l-1 were compounds 3, 11 and 13, which showed biofilm inhibition higher than 75%. Compound 3 was the most effective against biofilm forming capacity of Y. enterocolitica WAP 314 with a minimum biofilm inhibitory concentration (MBIC) of 25 µmol l-1; while against Y. enterocolitica CLC001, the lowest MBIC was 6.1 µmol l-1 for compound 11. Acyl-homoserine lactones production was decreased with compound 13. We showed that the oxidative stress influence biofilm growth, by means of ROS and RNI increment. All treatments increased ROS and RNI values in the biofilm of both strains; while in planktonic cells, the increase was lesser. Additionally, Y. enterocolitica WAP 314 biofilm treated with compounds 11 and 13 showed above 80% of SOD consumption. In Y. enterocolitica CLC001 biofilm all compounds induced above 90% of SOD consumption. The SOD activity was higher in biofilm than in planktonic cells. In conclusion, this is the first study to demonstrate that naphthoquinones are able to inhibit biofilm formation of Y. enterocolitica without critical disturbing its planktonic growth. Naphthoquinones as anti-biofilm agents might potentially be useful in the treatment of biofilm-associated infections in the future.

Novel antifungal activity of oligostyrylbenzenes compounds on Candida tropicalis biofilms.

As sessile cells of fungal biofilms are at least 500-fold more resistant to antifungal drugs than their planktonic counterparts, there is a requirement for new antifungal agents. Olygostyrylbenzenes (OSBs) are the first generation of poly(phenylene)vinylene dendrimers with a gram-positive antibacterial activity. Thus, this study aimed to investigate the antifungal activity of four OSBs (1, 2, 3, and 4) on planktonic cells and biofilms of Candida tropicalis. The minimum inhibitory concentration (MIC) for the planktonic population and the sessile minimum inhibitory concentrations (SMIC) were determined. Biofilm eradication was studied by crystal violet stain and light microscopy (LM), and confocal laser scanning microscopy (CLSM) was also utilized in conjunction with the image analysis software COMSTAT. Although all the OSBs studied had antifungal activity, the cationic OSBs were more effective than the anionic ones. A significant reduction of biofilms was observed at MIC and supraMIC50 (50 times higher than MIC) for compound 2, and at supraMIC50 with compound 3. Alterations in surface topography and the three-dimensional architecture of the biofilms were evident with LM and CLSM. The LM analysis revealed that the C. tropicalis strain produced a striking biofilm with oval blastospores, pseudohyphae, and true hyphae. CLSM images showed that a decrease occurred in the thickness of the mature biofilms treated with the OSBs at the most effective concentration for each one. The results obtained by microscopy were supported by those of the COMSTAT program. Our results revealed an antibiofilm activity, with compound 2 being a potential candidate for the treatment of C. tropicalis infections. LAY SUMMARY: This study aimed to investigate the antifungal activity of four OSBs (1, 2, 3, and 4) on planktonic cells and biofilms of Candida tropicalis. Our results revealed an antibiofilm activity, with compound 2 being a potential candidate for the treatment of C. tropicalis infections.

Oxidative Imbalance in Candida tropicalis Biofilms and Its Relation With Persister Cells.

BACKGROUND: Persister cells (PCs) make up a small fraction of microbial population, can survive lethal concentrations of antimicrobial agents. In recent years, Candida tropicalis has emerged as being a frequent fungal agent of medical devices subject to biofilm infections. However, PCs are still poorly understood. OBJECTIVES: This study aimed to investigate the relation of PCs on the redox status in C. tropicalis biofilms exposed to high doses of Amphotericin B (AmB), and alterations in surface topography and the architecture of biofilms. METHODS: We used an experimental model of two different C. tropicalis biofilms exposed to AmB at supra minimum inhibitory concentration (SMIC80), and the intra- and extracellular reactive oxygen species (iROS and eROS), reactive nitrogen species (RNS) and oxidative stress response were studied. Light microscopy (LM) and confocal laser scanning microscopy (CLSM) were also used in conjunction with the image analysis software COMSTAT. RESULTS: We demonstrated that biofilms derived from the PC fraction (B2) showed a higher capacity to respond to the stress generated upon AmB treatment, compared with biofilms obtained from planktonic cells. In B2, a lower ROS and RNS accumulation was observed in concordance with higher activation of the antioxidant systems, resulting in an oxidative imbalance of a smaller magnitude compared to B1. LM analysis revealed that the AmB treatment provoked a marked decrease of biomass, showing a loss of cellular aggrupation, with the presence of mostly yeast cells. Moreover, significant structural changes in the biofilm architecture were noted between both biofilms by CLSM-COMSTAT analysis. For B1, the quantitative parameters bio-volume, average micro-colony volume, surface to bio-volume ratio and surface coverage showed reductions upon AmB treatment, whereas increases were observed in roughness coefficient and average diffusion distance. In addition, untreated B2 was substantially smaller than B1, with less biomass and thickness values. The analysis of the above-mentioned parameters also showed changes in B2 upon AmB exposure. CONCLUSION: To our knowledge, this is the first study that has attempted to correlate PCs of Candida biofilms with alterations in the prooxidant-antioxidant balance and the architecture of the biofilms. The finding of regular and PCs with different cellular stress status may help to solve the puzzle of biofilm resistance, with redox imbalance possibly being an important factor.

Copper-functionalized nanostructured silica-based systems: Study of the antimicrobial applications and ROS generation against gram positive and gram negative bacteria.

A series of copper-functionalized SBA-15 (Santa Barbara Amorphous) materials containing the ligands triethoxysilylpropylmaleamic acid (maleamic) or triethoxy-3-(2-imidazolin-1-yl)propylsilane (imidazoline) have been prepared. The nanostructured silica-based systems SBA-maleamic, SBA-imidazoline, SBA-maleamic-Cu and SBA-imidazoline-Cu were characterized by several methods observing that the functionalization took place mainly inside the pores of the mesoporous system. The antimicrobial behaviour of the synthesized materials against Staphylococcus aureus and Escherichia coli was tested observing a very potent activity of the copper-functionalized systems (minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for SBA-maleamic-Cu of ca. 31.25 µg/mL, which correspond with ca. 1.13 µg/mL of Cu). A study of the oxidative stress promoted by the synthesized materials showed that the SBA-maleamic-Cu and the SBA-imidazoline-Cu were able to increase the reactive oxygen species (ROS) production in S. aureus by 427% and 373%, respectively, while this increase was slightly lower in E. coli (387 and 324%, respectively). Furthermore, an electrochemical study was carried out in order to determine if these materials interact with lysine or alanine to validate a potential antimicrobial mechanism based on the inhibition of the synthesis of the peptidoglycan of the bacterial wall. Finally, these studies were also performed to determine the potential interaction of the copper-containing materials with glutathione in order to assess if they are able to perturb the metabolism of this tripeptide.

Biogenic nanoparticles: Synthesis, stability and biocompatibility mediated by proteins of Pseudomonas aeruginosa.

The development of environmental friendly new procedures for the synthesis of metallic nanoparticles is one of the main objectives of nanotechnology. Plants, algae, fungi and bacteria for the production of nanomaterials are viable alternatives due to their low cost, the absence of toxic waste production and their highly energy efficiency. It is also known that biosynthesized silver nanoparticles (AgNPs) show higher biocompatibility compared to the chemically-synthesized ones. In previous results, biosynthesized AgNPs were obtained from the supernatant of Pseudomonas aeruginosa, and they showed a bigger antimicrobial activity against different bacterial species compared to the chemically-synthesized ones. The aim of this work was to analyze the capping of biosynthesized AgNPs using techniques such as transmission electron microscopy (TEM), infrared spectroscopy (IR), and protein identification through mass spectrometry (MS) in order to identify the compounds responsible for their formation, stability and biocompatibility. The TEM images showed that AgNPs were surrounded by an irregular coverage. The IR spectrum showed that this coverage was composed of carbohydrates and/or proteins. Different proteins were identified in the capping associated to biosynthesized AgNPs. Some proteins seem to be important for their formation (Alkyl hydroperoxide reductase and Azurin) and stabilization (Outer membrane protein OprG and Glycine zipper 2 T M domain-containing protein). The proteins identified with the capability to interact with some biomolecules can be responsible for the biocompatibility and may be responsible for the bigger antimicrobial activity than AgNPs have previously shown. These results are pioneers in the identification of proteins in the capping of biosynthesized AgNPs.

Preparation and Study of the Antibacterial Applications and Oxidative Stress Induction of Copper Maleamate-Functionalized Mesoporous Silica Nanoparticles.

Mesoporous silica nanoparticles (MSNs) are an interesting class of nanomaterials with potential applications in different therapeutic areas and that have been extensively used as drug carriers in different fields of medicine. The present work is focused on the synthesis of MSNs containing a maleamato ligand (MSN-maleamic) and the subsequent coordination of copper(II) ions (MSN-maleamic-Cu) for the exploration of their potential application as antibacterial agents. The Cu-containing nanomaterials have been characterized by different techniques and the preliminary antibacterial effect of the supported maleamato-copper(II) complexes has been tested against two types of bacteria (Gram positive and Gram negative) in different assays to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The biological results showed a moderate antibacterial activity against Escherichia coli which motivated a more detailed study of the antibacterial mechanism of action of the synthesized maleamate-containing nanosystems and whose findings showed oxidative stress generation in bacterial cells. All the prepared nanomaterials were also tested as catalysts in the "solvent free" selective oxidation of benzyl alcohol, to observe if there is a potential correlation between the catalytic oxidation capacity of the materials and the observed oxidative stress in bacteria. This may help in the future, for a more accurate rational design of antibacterial nanosystems, based on their observed catalytic oxidation activity.

Promising Chitosan-Coated Alginate-Tween 80 Nanoparticles as Rifampicin Coadministered Ascorbic Acid Delivery Carrier Against Mycobacterium tuberculosis.

The aim of this study was to design a nanocarrier system for inhalation delivery of rifampicin (RIF) in combination with ascorbic acid (ASC), namely constituted of sodium alginate coated with chitosan and Tween 80 (RIF/ASC NPs) as a platform for the treatment of pulmonary tuberculosis infection. A Box-Behnken experimental design and response surface methodology (RSM) were applied to elucidate and evaluate the effects of several factors on the nanoparticle properties. On the other hand, it was found that RIF/ASC NPs were less cytotoxic than the free RIF, showing a significantly improved activity against nine clinical strains of Mycobacterium tuberculosis (M. tb) in comparison with the free drug. RIF/ASC NPs had an average particle size of 324.0 ± 40.7 nm, a polydispersity index of 0.226 ± 0.030, and a zeta potential of - 28.52 ± 0.47 mV and the surface was hydrophilic. The addition of sucrose (1% w/v) to the nanosuspension resulted in the formation of a solid pellet easily redispersible after lyophilization. RIF/ASC NPs were found to be stable at different physiological pH values. In summary, findings of this work highlight the potential of the RIF/ASC NP-based formulation development herein to deliver RIF in combination with ASC through pulmonary route by exploring a non-invasive route of administration of this antibiotic, increasing the local drug concentrations in lung tissues, the primary infection site, as well as reducing the risk of systemic toxicity and hence improving the patient compliance.

Biosynthesized silver nanoparticles: Decoding their mechanism of action in Staphylococcus aureus and Escherichia coli.

The oxidative stress generation in bacteria by the presence of antibiotics (in this case silver nanoparticles (AgNPs)) is already widely known. Previously, we demonstrated that AgNPs generate oxidative stress in Staphylococcus aureus and Escherichia coli mediated by the increase of reactive oxygen species (ROS). In this work we are demonstrating the consequences of the oxidative stress by the presence of AgNPs; these bacterial strains increased the levels of oxidized proteins and lipids. In addition, it was possible to determine which reactive oxygen species are mainly responsible for the oxidative damage to macromolecules. Also, we found that the bacterial DNA was fragmented and the membrane potential was modified. This increase in the levels of ROS found in both, S. aureus and E. coli, was associated with the oxidation of different types of important macromolecules for the normal functioning of cell, so the oxidative stress would be one of the mechanisms by which the AgNPs would exert their toxicity in both strains, one Gram positive and the other Gram negative of great clinical relevance.

Flavonoids as protective agents against oxidative stress induced by gentamicin in systemic circulation. Potent protective activity and microbial synergism of luteolin.

The flavonoids effect on gentamicin (GEN)-induced oxidative stress (OS) in systemic circulation was evaluated in terms of reactive oxygen species (ROS) production, enzymatic antioxidant defenses superoxide dismutase (SOD) and catalase (CAT), and lipid peroxidation (LP) in vitro on human leukocytes and in vivo on rat whole blood. The inhibitory activity of ROS was ATS < QTS < isovitexin < vitexin < luteolin. Luteolin, the most active, showed more inhibition in ROS production than vitamin C (reference inhibitor) in mononuclear cells and a slightly lower protective behavior compared to this inhibitor in polymorphonuclear cells. In both cellular systems, luteolin tends to level SOD and CAT activities modified by GEN, reaching basal values and preventing LP. In Wistar rats, GEN plus luteolin can suppress ROS generation, collaborate with SOD and CAT and diminish LP produced by GEN at therapeutic doses. Finally, luteolin and antibiotic association was evaluated on the antimicrobial activity in S. aureus and E. coli showing a synergism between GEN and luteolin on S. aureus ATCC and an additive effect on E. coli ATCC. Therefore, simultaneous administration of luteolin and GEN could represent a potential therapeutic option capable of protecting the host against OS induced by GEN in the systemic circulation while enhancing the antibacterial activity of GEN.

Intra- and Extracellular Biosynthesis and Characterization of Iron Nanoparticles from Prokaryotic Microorganisms with Anticoagulant Activity.

BACKGROUND: The use of microorganisms for the synthesis of nanoparticles (NPs) is relatively new in basic research and technology areas. PURPOSE: This work was conducted to optimized the biosynthesis of iron NPs intra- and extracellular by Escherichia coli or Pseudomonas aeruginosa and to evaluate their anticoagulant activity. STUDY DESIGN/METHODS: The structures and properties of the iron NPs were investigated by Ultraviolet-visible (UV-vis) spectroscopy, Zeta potential, Dynamic light scattering (DLS), Field emission scanning electron microscope (FESEM)/ Energy dispersive X-ray (EDX) and transmission electron microscopy (TEM). Anticoagulant activity was determined by conducting trials of Thrombin Time (TT), Activated Partial Prothrombin Time (APTT) and Prothrombin Time (PT). RESULTS: UV-vis spectrum of the aqueous medium containing iron NPs showed a peak at 275 nm. The forming of iron NPs was confirmed by FESEM/ EDX, and TEM. The morphology was spherical shapes mostly with low polydispersity and the average particle diameter was 23 ± 1 nm. Iron NPs showed anticoagulant activity by the activation of extrinsic pathway. CONCLUSION: The eco-friendly process of biosynthesis of iron NPs employing prokaryotic microorganisms presents a good anticoagulant activity. This could be explored as promising candidates for a variety of biomedical and pharmaceutical applications.