In vitro and in vivo anti-biofilm activity of pyran derivative against Staphylococcus aureus and Pseudomonas aeruginosa

Enhancing Titanium Disk Performance through In-Pack Cold Atmospheric Plasma Treatment

While titanium dental implants have already been clinically established, ongoing research is continuously being conducted to advance the fields of osseointegration and bacterial resistance, seeking further improvements in these areas. In this study, we introduce an innovative method for treating titanium surfaces within tightly sealed packaging. Specifically, titanium discs, enclosed in surgical-grade packaging, underwent treatment using cold atmospheric plasma (CAP). The surfaces were thoroughly characterized in terms of wettability, crystalline structure, and chemical composition. Hemocompatibility analyses were conducted using blood diluted in sodium citrate (1:9) exposed to titanium discs for 30 min inside a CO2 incubator at 37 °C. Subsequently, various blood parameters were evaluated, including prothrombin time (PT), activated partial thromboplastin time (APTT), and platelet adhesion. Microbiological analyses were also performed using Pseudomonas aeruginosa (ATCC 27853) for 4 h at 37 °C. The treatment with CAP Jet resulted in a reduction in contact angle without causing any changes in the crystalline structure. No statistically significant differences were observed in the blood parameters. The plasma-treated samples exhibited lower PT and APTT values compared to those of the control group. The surfaces treated with CAP Jet showed increased platelet activation, platelet density, and thrombus formation when compared with the untreated samples. Moreover, the treated surfaces demonstrated lower bacterial colony formation compared with other surfaces.

Role of small molecules and nanoparticles in effective inhibition of microbial biofilms: A ray of hope in combating microbial resistance

Microbial biofilms pose a severe threat to global health, as they are associated with deadly chronic infections and antibiotic resistance. To date, very few drugs are in clinical practice that specifically target microbial biofilms. Therefore, there is an urgent need for the development of novel therapeutic options targeting biofilm-related infections. In this review, we discuss nearly seventy-five different molecular scaffolds published over the last decade (2010-2023) which have exhibited their biofilm inhibition potential. For convenience, we have classified these into five different sub-groups based on their origin and design (excluding peptides as they are placed in between small molecules and biologics), namely, heterocycles; inorganic small molecules & metal complexes; small molecules decorated nanoparticles; small molecules derived from natural products (both plant and marine sources); and small molecules designed by in-silico approach. These antibiofilm agents are capable of disrupting microbial biofilms and can offer a promising avenue for future developments in human medicine. A hitherto review of this kind will lay a platform for the researchers to find new molecular entities to curb the serious menace of antimicrobial resistance especially caused by biofilms.

Antibiofilm Effects of Oleuropein against Staphylococcus aureus: An In Vitro Study

Staphylococcus aureus has posed a huge threat to human health and the economy. Oleuropein has antibacterial activities against various microorganisms but research on its effect on the S. aureus biofilm is limited. This research aimed to estimate the antibiofilm activities of oleuropein against S. aureus. The results suggest that the minimum inhibitory concentration of oleuropein against S. aureus ATCC 25923 was 3 mg/mL. The biomass of biofilms formed on the microplates and coverslips and the viability of bacteria were significantly reduced after the treatment with oleuropein. The scanning electron microscopy observation results indicated that the stacking thickness and density of the biofilm decreased when S. aureus was exposed to oleuropein. It had a bactericidal effect on biofilm bacteria and removed polysaccharides and proteins from mature biofilms. The effects of oleuropein on the biofilm could be explained by a reduction in bacterial secretion of extracellular polymeric substances and a change in bacterial surface hydrophobicity. Based on the above findings, oleuropein has the potential to be used against food pollution caused by S. aureus biofilms.

Natural nanogels crosslinked with S-benzyl-L-cysteine exhibit potent antibacterial activity

Biofilm-forming bacteria E. coli and P. aeruginosa have both exhibited resistance against multiple antibiotics in clinical settings. To find a solution, researchers have turned to antibacterial structurally modified from natural materials that are harmless to the human body. Among these is DNA, a natural polymer composed of deoxyribose that when treated with HCl exposes its aldehyde groups and produces DNA-HCl. Here, we crosslinked these aldehyde groups with the primary amines in S-benzyl-L-cysteine (SBLC) using a Schiff reaction to obtain DNA-HCl-SBLC. We additionally treated alginate acid (AA) with EDAC, obtaining AA-EDAC, and substituting it with SBLC to produce AA-SBLC. We incorporated the above reactions with an emulsification process to produce nanogels (NGs) that were verified to be spherical and possessing benzene rings successfully grafted onto DNA-HCl and AA-EDAC. These natural NGs were proven to be negatively charged through zeta potential analysis and presented low cytotoxicity toward normal cells in cell organoid viability assays. These SBLC-modified polymers provided better inhibition of bacterial growth than those without modification. Moreover, after incubation with SBLC-modified NGs, bacteria expressed intracellular recA or pvdA in a dose-dependent manner, which was consistent with SEM data from damaged bacteria. Out of four tested NGs, DNA-HCl-SBLC NGs suppressed P. aeruginosa-induced sepsis most effectively and extended the lifespan of C. elegans. This study provides an alternative clinical solution to antibiotics-resistant biofilm strains.

Magnolia officinalis L. bark extract and respiratory diseases: From traditional Chinese medicine to western medicine via network target

The understanding of the use of Magnolia officinalis L. (Magnoliaceae) as a possible dietary supplement for supporting the treatment of airway pathologies might be of clinical interest. Two commercially available bark extracts (M. officinalis extract [MOE]) were characterized by quantitation in honokiol and magnolol content by means of high-performance liquid chromatography with UV detection. MOE effects, as well as those of the reference compounds per se, on some targets connected to airway pathologies (antibacterial- and lung and trachea relaxing- activities) were investigated. Results showed that MOE possessed interesting antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus pneumoniae. This was accompanied by a spasmolytic and antispasmodic activity, possibly owing to its ability to concurrently modulate different targets such as H₁ -, β₂ - and muscarinic receptors and l-type calcium channels involved in bronchodilation. All these effects were directly related to the MOE content in honokiol and magnolol. In conclusion, the properties of MOE highlighted here strongly encourage its application as dietary supplement in the treatment of airway diseases.

Polyketides as Secondary Metabolites from the Genus Aspergillus

Polyketides are an important class of structurally diverse natural products derived from a precursor molecule consisting of a chain of alternating ketone and methylene groups. These compounds have attracted the worldwide attention of pharmaceutical researchers since they are endowed with a wide array of biological properties. As one of the most common filamentous fungi in nature, Aspergillus spp. is well known as an excellent producer of polyketide compounds with therapeutic potential. By extensive literature search and data analysis, this review comprehensively summarizes Aspergillus-derived polyketides for the first time, regarding their occurrences, chemical structures and bioactivities as well as biosynthetic logics.

In vitro visualization and quantitative characterization of Pseudomonas aeruginosa biofilm growth dynamics on polyether ether ketone

Prevention and treatment of orthopedic device-related infection (ODRI) is complicated by the formation of bacterial biofilms. Biofilm formation involves dynamic production of macromolecules that contribute to the structure of the biofilm over time. Limitations to clinically relevant and translational biofilm visualization and measurement hamper advances in this area of research. In this paper, we present a multimodal methodology for improved characterization of Pseudomonas aeruginosa grown on polyether ether ketone (PEEK) as a model for ODRI. PEEK discs were inoculated with P. aeruginosa, incubated for 4-48 h time intervals, and fixed with 10% neutral-buffered formalin. Samples were stained with fluorescent dyes to measure biofilm components, imaged with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), and quantified. We were able to visualize and quantify P. aeruginosa biofilm growth on PEEK implants over 48 h. Based on imaging data, we propose a generalized growth cycle that can inform orthopedic diagnostic and treatment for this pathogen on PEEK. These results demonstrate the potential of using a combined CLSM and SEM approach for determining biofilm structure, composition, post-adherence development on orthopedic materials. This model may be used for quantitative biofilm analysis for other pathogens and other materials of orthopedic relevance for translational study of ODRI.

Pyrancoumarin derivative LP4C targeting of pyrimidine de novo synthesis pathway inhibits MRSA biofilm and virulence

Staphylococcus aureus poses a serious public health threat because of its multidrug resistance and biofilm formation ability. Hence, developing novel anti-biofilm agents and finding targets are needed to mitigate the proliferation of drug-resistant pathogens. In our previous study, we showed that the pyrancoumarin derivative 2-amino-4-(2,6-dichlorophenyl)-3-cyano-5-oxo-4H, 5H- pyrano [3,2c] chromene (LP4C) can destroy the biofilm of methicillin-resistant S. aureus (MRSA) in vitro and in vivo. Here, we further explored the possible mechanism of LP4C as a potential anti-biofilm drug. We found that LP4C inhibits the expression of enzymes involved in the de novo pyrimidine pathway and attenuates the virulence of MRSA USA300 strain without affecting the agr or luxS quorum sensing system. The molecular docking results indicated that LP4C forms interactions with the key amino acid residues of pyrR protein, which functions as the important regulator of bacterial pyrimidine synthesis. These findings reveal that pyrancoumarin derivative LP4C inhibits MRSA biofilm formation and targeting pyrimidine de novo synthesis pathway.

Bacterial virulence factors: a target for heterocyclic compounds to combat bacterial resistance

Antibiotic resistance is one of the most important challenges of the 21st century. However, the growing understanding of bacterial pathogenesis and cell-to-cell communication has revealed many potential strategies for the discovery of drugs that can be used for the treatment of bacterial infections. Interfering with bacterial virulence and/or quorum sensing could be a particularly interesting approach, because it is believed to exert less selective pressure on the bacterial resistance than with traditional strategies, geared toward killing bacteria or preventing their growth. Here, we discuss the mechanism of bacterial virulence, presenting promising strategies and recently synthesized heterocyclic compounds to combat future bacterial infections.

Hybrid hydrogels for bacteriocin delivery to infected wounds

Superficial infections in chronic wounds can prevent the wound healing process by the development of persistent infections and drug-resistant biofilms. Topically applied antimicrobial formulations with stabilized and controlled release offer significant benefits for the effective treatment of wound infections. Bacteriocins are the antimicrobial peptides (AMPs) produced by bacteria that are viable alternatives to antibiotics owing to their natural origin and low propensity for resistance development. Herein, we developed a hybrid hydrogel composed of Pluronic F127 (PF127), ethylenediaminetetraacetic acid (EDTA) loaded liposomes, glutathione (GSH), and the bacteriocin Garvicin KS (GarKS) referred to as "GarKS gel". The GarKS gel exhibited suitable viscosity and rheological properties along with controlled release behavior (up to 9 days) for effective peptide delivery following topical application. Potent in vitro antibacterial and anti-biofilm effects of GarKS gel were evident against the Gram-positive bacterium Staphylococcus aureus. The in vivo treatment of methicillin resistant S. aureus (MRSA) infected mouse wounds suggested potent antibacterial effects of the GarKS gel following multiple applications of once-a-day application for three consecutive days. Altogether, these results provide proof-of-concept for the successful development of AMP loaded topical formulation for effective treatment of wound infections.

Recent Applications of Heteropolyacids and Related Compounds in Heterocycle Synthesis. Contributions between 2010 and 2020

Over the past two decades, polyoxometalates (POM) have received considerable attention as solid catalysts, due to their unique physicochemical characteristics, since, first, they have very strong Bronsted acidity, approaching the region of a superacid, and second, they are efficient oxidizers that exhibit rapid redox transformations under fairly mild conditions. Their structural mobility is also highlighted, since they are complex molecules that can be modified by changing their structure or the elements that compose them to model their size, charge density, redox potentials, acidity, and solubility. Finally, they can be used in substoichiometric amounts and reused without an appreciable loss of catalytic activity, all of which postulate them as versatile, economic and ecological catalysts. Therefore, in 2009, we wrote a review article highlighting the great variety of organic reactions, mainly in the area of the synthesis of bioactive heterocycles in which they can be used, and this new review completes that article with the contributions made in the same area for the period 2010 to 2020. The synthesized heterocycles to be covered include pyrimidines, pyridines, pyrroles, indoles, chromenes, xanthenes, pyrans, azlactones, azoles, diazines, azepines, flavones, and formylchromones, among others.