Broad-spectrum Antibacterial Activity Research Articles

Highly Compressible, Superabsorbent, and Biocompatible Hybrid Cryogel Constructs Comprising Functionalized Chitosan and St. John's Wort Extract.

Biobased porous hydrogels enriched with phytocompounds-rich herbal extracts have aroused great interest in recent years, especially in healthcare. In this study, new macroporous hybrid cryogel constructs comprising thiourea-containing chitosan (CSTU) derivative and a Hypericum perforatum L. extract (HYPE), commonly known as St John's wort, were prepared by a facile one-pot ice-templating strategy. Benefiting from the strong interactions between the functional groups of the CSTU matrix and those of polyphenols in HYPE, the hybrid cryogels possess excellent liquid absorption capacity, mechanical resilience, antioxidant performance, and a broad spectrum of antibacterial activity simultaneously. Thus, owing to their design, the hybrid constructs exhibit an interconnected porous architecture with the ability to absorb over 33 and 136 times their dry weight, respectively, when contacted with a phosphate buffer solution (pH 7.4) and an acidic aqueous solution (pH 2). These cryogel constructs have extremely high compressive strengths ranging from 839 to 1045 kPa and withstand elevated strains of over 70% without developing fractures. Moreover, the water-swollen hybrid cryogels with the highest HYPE content revealed a complete and instant shape recovery after uniaxial compression. The incorporation of HYPE into CSTU cryogels enabled substantial improvement in scavenging reactive oxygen species and an expanded antibacterial spectrum toward multiple pathogens, including Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and fungi (Candida albicans). Cell viability experiments demonstrated the cytocompatibility of the 3D cryogel constructs, which did not induce changes in the fibroblast morphology. This work showcases a simple and effective strategy to immobilize HYPE extracts on CSTU 3D networks, allowing the development of novel multifunctional platforms with promising potential in hemostasis, wound dressing, and dermal regeneration scaffolds.

Organic nanoparticles incorporated starch/carboxymethylcellulose multifunctional coating film for efficient preservation of perishable products

Most of postharvest agricultural produces are perishable due to microorganisms infections and physiological change. Herein, one kind of multifunctional coating film of SC-ECCNPs was developed by incorporating organic nanoparticles of ECCNPs into starch/carboxymethylcellulose (SC) to prolong shelf life of food with excellent performances. The SC-ECCNPs coating was prepared with starch and sodium carboxymethylcellulose as film substrate (SC) to incorporate with organic nanoparticles of ECCNPs formed by integrating epigallocatechin-3-gallate (EGCG), cysteine (Cys), and cinnamaldehyde (CA). The incorporation of ECCNPs improves the UV-resistance and physical properties of SC-ECCNPs coating and also endows it with excellent antioxidative and broad-spectrum antibacterial activity. The application possibilities of SC-ECCNPs coating were explored with strawberries and oranges as samples, validating that the SC-ECCNPs coating can prolong the shelf life of fruits at room temperature. The biosafety of the coating was further confirmed with hemolysis and MTT experiments. The SC-ECCNPs coating film was prepared with natural substrates via a simple and green method. The investigation provides an instructive way for developing advanced packaging materials with high performances.

Ureido-Ionic Liquid Mediated Conductive Hydrogel: Superior Integrated Properties for Advanced Biosensing Applications.

Ionic conductive hydrogels (ICHs) have recently gained prominence in biosensing, indicating their potential to redefine future biomedical applications. However, the integration of these hydrogels into sensor technologies and their long-term efficacy in practical applications pose substantial challenges, including a synergy of features, such as mechanical adaptability, conductive sensitivity, self-adhesion, self-regeneration, and microbial resistance. To address these challenges, this study introduces a novel hydrogel system using an imidazolium salt with a ureido backbone (UL) as the primary monomer. Fabricated via a straightforward one-pot copolymerization process that includes betaine sulfonate methacrylate (SBMA) and acrylamide (AM), the hydrogel demonstrates multifunctional properties. The innovation of this hydrogel is attributed to its robust mechanical attributes, outstanding strain responsiveness, effective water retention, and advanced self-regenerative and healing capabilities, which collectively lead to its superior performance in various applications. Moreover, this hydrogel exhibited broad-spectrum antibacterial activity. Its potential for biomechanical monitoring, especially in tandem with contact and noncontact electrocardiogram (ECG) devices, represents a noteworthy advancement in precise real-time cardiac monitoring in clinical environments. In addition, the conductive properties of the hydrogel make it an ideal substrate for electrophoretic patches aimed at treating infected wounds and consequently enhancing the healing process.

Antimicrobial peptide 2K4L inhibits the inflammatory response in macrophages and Caenorhabditis elegans and protects against LPS-induced septic shock in mice

2K4L is a rationally designed analog of the short α-helical peptide temporin-1CEc, a natural peptide isolated and purified from the skin secretions of the Chinese brown frog Rana chensinensis by substituting amino acid residues. 2K4L displayed improved and broad-spectrum antibacterial activity than temporin-1CEc in vitro. Here, the antibacterial and anti-inflammatory activities of 2K4L in macrophages, C. elegans and mice were investigated. The results demonstrated that 2K4L could enter THP-1 cells to kill a multidrug-resistant Acinetobacter baumannii strain (MRAB 0227) and a sensitive A. baumannii strain (AB 22933), as well as reduce proinflammatory responses induced by MRAB 0227 by inhibiting NF-κB signaling pathway. Similarly, 2K4L exhibited strong bactericidal activity against A. baumannii uptake into C. elegans, extending the lifespan and healthspan of the nematodes. Meanwhile, 2K4L alleviated the oxidative stress response by inhibiting the expression of core genes in the p38 MAPK/PMK-1 signaling pathway and downregulating the phosphorylation level of p38, thereby protecting the nematodes from damage by A. baumannii. Finally, in an LPS-induced septic model, 2K4L enhanced the survival of septic mice and decreased the production of proinflammatory cytokines by inhibiting the signaling protein expression of the MAPK and NF-κB signaling pathways and protecting LPS-induced septic mice from a lethal inflammatory response. In conclusion, 2K4L ameliorated LPS-induced inflammation both in vitro and in vivo.

Moringa oleifera seed methanol extract with consolidated antimicrobial, antioxidant, anti-inflammatory, and anticancer activities.

The wide biological activity of the Moringa oleifera represents a potential opportunity for developing selective cancer treatment drugs. The bioactive phytochemicals in Moringa seed extract (MSE) indicated large numbers of phytochemicals (21 compounds) with dominant abundance for cycloisolongifolene, 8,9-dehydro-9-vinyl, and chamazulene accounting for 12.7% and 12.19% of the total detected compounds. The MSE showed a potent anticancer effect toward Caco-2, MDA, and HepG-2 cells with half-maximal inhibitory concentration (IC50) values of 9.15±1.18, 4.85±0.11, and 7.36±0.22µg/mL, respectively, with higher safety (≥31-folds) toward normal human cells (IC50 of 150.7±11.11µg/mL). It appears that MSE stimulates selective-dose-dependent cell shrinkage, and nuclear condensation in the tumor cells, which finally induces the apoptosis pathway to increase its anticancer action. Additionally, MSE showed a potent capability to stimulate cell cycle arrest in both main checkpoint phases (G0/G1 and G2/M) of cell population growth. The apoptotic death stimulation was confirmed through upregulation of tumor protein p53 (p53) and cyclin-dependent kinase inhibitor p21 (p21) expression by more than three- to sixfold and downregulation of B-cell lymphoma 2 expression (threefold) in MSE-treated cells compared to 5-fluorouracil (5-FU)-treated tumor cells. Furthermore, the MSE revealed strong anti-inflammatory activity with significant antioxidant activity by lowering nitric oxide levels and enhancing the superoxide dismutase activity. On the other hand, the MSE revealed broad-spectrum antibacterial activity in a dose-dependent manner against Staphylococcus aureus minimum inhibitory concentration (MIC of 1.25mg/mL), followed by Salmonella typhimurium (MIC of 1.23mg/mL), whereas Escherichia coli was the least sensitive to MSE activity (MIC of 22.5mg/mL) with significant antibiofilm activity against sensitive pathogens.

A comparative analysis of the antimicrobial efficacy of different concentrations of silver nanoparticles and chlorhexidine against Enterococcus faecalis - In vitro study

Introduction: Root canal irrigants combat endodontic microbial flora, effectively targeting resilient microbes like Enterococcus faecalis, which persist despite treatment. Chlorhexidine (CHX), as an irrigant, boasts broad-spectrum antibacterial activity, notable substantivity in dentine, and favorable biocompatibility. In the realm of nanotechnology, the use of silver nanoparticle (AgNP) solutions appears promising, given their strong antibacterial and antimicrobial properties. Objective: The objective of the study was to compare the antimicrobial effectiveness of varying concentrations (1%, 0.75%, and 0.5%) of AgNPs and 2% CHX against E. faecalis. Materials and Methods: Four irrigant solutions, including 1%, 0.75%, and 0.5% AgNPs and 2% CHX with gentamicin as the control, will be assessed. The ATCC 29212 strain of E. faecalis will be cultivated at 37°C on brain–heart infusion Broth plates. After 48 h, the bacterial population will be quantified by counting colony-forming units on agar plates. Each irrigant will be applied to the plates, and the resulting bacterial inhibition zone will be measured. Results: Our study demonstrates the antimicrobial effects of 1%, 0.75%, and 0.5% AgNPs and 2% CHX against E. faecalis. While 2% CHX exhibited superior activity, AgNPs at various concentrations also displayed inhibitory effects against E. faecalis. Conclusion: In conclusion, this study highlights the antimicrobial properties of 1%, 0.75%, and 0.5% AgNPs and 2% CHX against E. faecalis. The results indicate that 2% CHX exhibits superior activity, while AgNPs at various concentrations also demonstrate inhibitory zones against E. faecalis.

Modulating the morphology and protonation degree of chitosan coatings for enabling controlled fabric functionalization

Chitosan (CS), a versatile biopolymer known for its diverse bioactivity, is commonly used as a coating or finishing agent to enhance fabric performance and broaden their applications. However, conventional methods for introducing CS coating layer on the fabrics often relies on using composition to control their functionality, limiting the ability to tailor properties for specific needs. In this study, we introduce an innovative coating platform utilizing drying, ionic gelation, or a combination of both to control the morphology and amino-protonation degree of CS. This approach allows the development of three distinct functional CS coatings from the same material composition. The method is effectively applied to cotton and polylactic acid (PLA)-based non-woven fabrics, preserving the permeability, breathability, and mechanical properties of the substrates. By varying processing conditions, it is found that CS coatings can impart distinct functions to the fabrics upon their morphology, such as attaining high degree of hydrophobicity (with a water contact angle reaching 129°), broad-spectrum antibacterial activity (>99.99 %) for the sample prepared by combined drying and ionic gelation methods. Additionally, our CS-coated fabrics can exhibit good biocompatibility, as demonstrated by cytocompatibility and histocompatibility evaluations, while excellent anti-adhesive properties and healing performance in infected wound models in rats can be obtained with the presence of CS microsphere. Our methods are straightforward and potentially scalable, enabling modular control over the functionality of CS-coated fabrics to meet diverse requirements. This work offers a promising strategy for modifying fabric properties with CS coatings, making it suitable for various applications such as facial masks, dressings, and antibacterial textiles.

TC-14, a cathelicidin-derived antimicrobial peptide with broad-spectrum antibacterial activity and high safety profile

TC-14, a cathelicidin-derived antimicrobial peptide with broad-spectrum antibacterial activity and high safety profile

The therapeutic potential of indole hybrids, dimers, and trimers against drug-resistant ESKAPE pathogens.

Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter (ESKAPE) species as causative agents are characterized by increased levels of resistance towardmultiple classes of first-line as well as last-resort antibiotics and represent serious global health concerns, creating a critical need for the development of novel antibacterials with therapeutic potential against drug-resistant ESKAPE species. Indole derivatives with structural and mechanistic diversity demonstrated broad-spectrum antibacterial activity against various clinically important pathogens including drug-resistant ESKAPE. Moreover, several indole-based agents that are exemplified by creatmycin have already been used in clinics or under clinical trials for the treatment of bacterial infections, demonstrating that indole derivatives hold great promise for the development of novel antibacterials. This review is an endeavor to highlight the current scenario of indole hybrids, dimers, and trimers with therapeutic potential against drug-resistant ESKAPE pathogens, covering articles published from 2020 to the present, to open new avenues for the exploration of novel antidrug-resistant ESKAPE candidates.

Transforming microbial pigment into therapeutic revelation: extraction and characterization of pyocyanin from Pseudomonas aeruginosa and its therapeutic potential as an antibacterial and anticancer agent

BackgroundThe objectives of the current study were to extract pyocyanin from Pseudomonas aeruginosa clinical isolates, characterize its chemical nature, and assess its biological activity against different bacteria and cancer cells. Due to its diverse bioactive properties, pyocyanin, being one of the virulence factors of P. aeruginosa, holds a promising, safe, and available therapeutic potential.Methods30 clinical P. aeruginosa isolates were collected from different sources of infections and identified by routine methods, the VITEK 2 compact system, and 16 S rRNA. The phenazine-modifying genes (phzM, phzS) were identified using polymerase chain reaction (PCR). Pyocyanin chemical characterization included UV-Vis spectrophotometry, Fourier Transform Infra-Red spectroscopy (FTIR), Gas Chromatography-Mass Spectrometry (GC-MS), and Liquid Chromatography-Mass Spectrometry (LC-MS). The biological activity of pyocyanin was explored by determining the MIC values against different clinical bacterial strains and assessing its anticancer activity against A549, MDA-MB-231, and Caco-2 cancer cell lines using cytotoxicity, wound healing and colony forming assays.ResultsAll identified isolates harboured at least one of the phzM or phzS genes. The co-presence of both genes was demonstrated in 13 isolates. The UV-VIS absorbance peaks were maxima at 215, 265, 385, and 520 nm. FTIR could identify the characteristic pyocyanin functional groups, whereas both GC-MS and LC-MS elucidated the chemical formula C11H18N2O2, with a molecular weight 210. The quadri-technical analytical approaches confirmed the chemical nature of the extracted pyocyanin. The extract showed broad-spectrum antibacterial activity, with the greatest activity against Bacillus, Staphylococcus, and Streptococcus species (MICs 31.25–125 µg/mL), followed by E. coli isolates (MICs 250–1000 µg/mL). Regarding the anticancer activity, the pyocyanin extract showed IC50 values against A549, MDA-MB-231, and Caco-2 cancer cell lines of 130, 105, and 187.9 µg/mL, respectively. Furthermore, pyocyanin has markedly suppressed colony formation and migratory abilities in these cells.ConclusionsThe extracted pyocyanin has demonstrated to be a potentially effective candidate against various bacterial infections and cancers. Hence, the current findings could contribute to producing this natural compound easily through an affordable method. Nonetheless, future studies are required to investigate pyocyanin’s effects in vivo and analyse the results of combining it with other traditional antibiotics or anticancer drugs.

NewIndole Alkaloidsfrom the Fungus Talaromyces assiutensis JTY2.

Three new indole alkaloids, named talatensindoidsA-C (1-3), together with two known biogenetically related indole alkaloids tryptamine (4) and L-tryptophan (5) were isolated from the Talaromyces assiutensisJTY2 based on the guidance of OSMAC approach.The structures of these indole alkaloidswere determined by comprehensive spectroscopic analyses.The absolute configuration of 3was confirmed by X-ray crystallographic analysis. Compound 1representthe rare example of a chlorine-substitutedindolealkaloidfrom natural products. The inhibitory activityof compounds1-5against twophytopathogenic fungiand three phytopathogenic bacteriawas evaluated.Compound1exhibited broad spectrumantibacterial activities.

Screening and evaluation of antibacterial active strains of Actinomycetes isolated from Northern Indian soil for biofilm inhibition against selected ESKAPE pathogens

AbstractThe growing problem of antimicrobial resistance (AMR) globally has warranted the search for new and alternate anti-infective strategies. This study aimed to isolate and screen soil Actinomycetes from three different locations in Northern India for their broad-spectrum antibacterial and antibiofilm activity against certain drug-resistant bacteria from ESKAPE group. A total of 110 isolates of Actinomycetes were screened for antibacterial activity using overlay and agar-well diffusion assay against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Ninety-five isolates showed antibacterial activity against one or more test bacteria. These isolates were tentatively identified as members of genus Streptomyces. Five isolates (IMA13, IMA25, IMA43, IMA46, and IMA47) demonstrated broad-spectrum activity against test pathogens and were subjected to production of secondary metabolites in liquid medium. Ethyl acetate fraction of culture filtrate showed MIC in the range of 64–512 µg/ml against test bacteria. The most active isolate, IMA-46, was identified by 16srRNA gene sequence analysis as Streptomyces rameus. Further, ethyl acetate fraction from S. rameus-IMA46 was used to inhibit biofilm formation at sub-MIC values. A significant level (50% to 92%) of biofilm inhibition was recorded against test pathogens. Light microscopy and SEM analysis revealed the biofilm structural changes, reduction in cell aggregation and EPS production. LC/MS analysis of the active extract of S. rameus IMA46 showed the presence of many biologically active compounds, including tetracycline and doxycycline. The present study highlights the potential of soil Actinomycetes in production of broad-spectrum anti-infective compounds in combating growing problem of AMR.

Assessing the impact of two forms of PACAP-38 (pituitary adenylate cyclase-activating polypeptide) on Nile tilapia (Oreochromis niloticus) immune response following challenge with Flavobacterium columnare

Antimicrobial peptides have been isolated from various organisms and play an essential role in defense against infections. They are small peptides (less than 60 amino acids) with broad-spectrum antibacterial activity. In teleosts, pituitary adenylate cyclase-activating polypeptide (PACAP) has been demonstrated to have direct antimicrobial activity against several aquatic pathogens, including those from the genus Flavobacterium. Our goal was to examine the impacts of PACAP and route of administration on the immune response of Nile tilapia (Oreochromis niloticus). Over the course of four studies, tilapia (416.1±116.7 g) randomly assigned to replicate tanks were administered with either PACAP-38 or a modified form of PACAP-38 via intraperitoneal (i.p.) injection, bath, nares flush, or gill flush, and compared to PBS controls. In the first two studies, following individual treatments, tilapia underwent a bath exposure (40 L tank for 45 min) to F. columnare (isolate ALG-00-530; at 2.1×108 CFU/ml) or sham exposure without the addition of the bacterial culture. Fish were sampled before exposure, 48 h after stimulation, at 1 day after the onset of mortality in exposed tanks, and resolution of mortality. Tilapia that received i.p. injection of PACAP-38 showed significantly lower mortality from F. columnare (10%) than those receiving PBS i.p. (25%). However, bath immersion of fish, both with and without F. columnare, resulted in significant mortality due to secondary infections with Edwardsiella tarda. Administration of modified PACAP-38 via nares/gill flush, or i.p. injection did not, however, result in significantly fewer mortalities compared to sham/PBS. Furthermore, the same modified form of PACAP-38 also induced inflammatory gene expression in the spleen, and eosinophilic granule cell aggregation in the nares, following flushing. The data from the first study suggest that PACAP-38 induces protection against infection and stress mainly through a reduction of inflammatory-il1β expression. Moreover, data analysis of spleen samples from these two studies also indicates that PACAP-38 might have more anti-inflammatory impacts than its modified form. In the fourth trial, after exposing tilapia to low temperature (15-17°C) for 30 minutes (cold stress), the PACAP-38 treated group had significantly lower cortisol levels compared to both PBS injected group and the negative control. Due to the observed impacts of PACAP-38 treatment on the immunophysiology of Nile tilapia, its potential for therapeutic use should be further investigated.

New Series of Ni(II), Cu(II), Zr(IV), Ag(I), and Cd(II) Complexes of Trimethoprim and Diamine Ligands: Synthesis, Characterization, and Biological Studies

New compounds series of [M(TMP)(en)]X·nH2O and [M(TMP)(PD)]X·nH2O, where M = Ni2+, Cu2+, Zr4+, Ag+, Cd2+, TMP = trimethoprim, en = ethylenediamine, PD = o-phenylene and X= Cl− or NO3−, were prepared. The compounds were characterized using techniques including melting points, conductance, elemental analysis, FTIR, NMR, and mass spectroscopy. FTIR spectra indicated TMP acted like a bi-dentate ligand, combining via the nitrogen atoms of azomethine and pyrimidine amino groups. Diamine ligands (en or o-PD) are coordinated via two nitrogen atoms. Prepared compounds showed monomeric behavior and adopted a 6-coordinate octahedral geometry based on magnetic susceptibility and UV spectra. Conductivity measurements revealed Zr(IV) compounds were 1:2 conductive, while Ag+ and Cd2+ were 1:1 conductive; Ni2+ and Cu2+ compounds were non-conductive. Antibacterial tests on compounds and ligands against Bacillus subtilis and Staphylococcus aureus demonstrated broad-spectrum antibacterial activity. The mixed metal compounds revealed an observable tendency of antibacterial activity in the order Zr > Cd = Ag > Cu, making Zr(IV) compounds the most biologically active among them against S. aureus (Gram-positive) while the same compounds showed less antibacterial activity against B. subtilis (Gram-negative) than the free ligand.

Membrane-targeting, ultrashort lipopeptide acts as an antibiotic adjuvant and sensitizes MDR gram-negative pathogens toward narrow-spectrum antibiotics

Globally, infections due to multi-drug resistant (MDR) Gram-negative bacterial (GNB) pathogens are on the rise, negatively impacting morbidity and mortality, necessitating urgent treatment alternatives. Herein, we report a detailed bio-evaluation of an ultrashort, cationic lipopeptide ‘SVAP9I’ that demonstrated potent antibiotic activity and acted as an adjuvant to potentiate existing antibiotic classes towards GNBs. Newly synthesized lipopeptides were screened against ESKAPE pathogens and cytotoxicity assays were performed to evaluate the selectivity index (SI). SVAP9I exhibited broad-spectrum antibacterial activity against critical MDR-GNB pathogens including members of Enterobacteriaceae (MIC 4–8 mg/L), with a favorable CC50 value of ≥100 mg/L and no detectable resistance even after 50th serial passage. It demonstrated fast concentration-dependent bactericidal action as determined via time-kill analysis and also retained full potency against polymyxin B-resistant E. coli, indicating distinct mode of action. SVAP9I targeted E. coli's outer and inner membranes by binding to LPS and phospholipids such as cardiolipin and phosphatidylglycerol. Membrane damage resulted in ROS generation, depleted intracellular ATP concentration and a concomitant increase in extracellular ATP. Checkerboard assays showed SVAP9I's synergism with narrow-spectrum antibiotics like vancomycin, fusidic acid and rifampicin, potentiating their efficacy against MDR-GNB pathogens, including carbapenem-resistant Acinetobacter baumannii (CRAB), a WHO critical priority pathogen. In a murine neutropenic thigh infection model, SVAP9I and rifampicin synergized to express excellent antibacterial efficacy against MDR-CRAB outcompeting polymyxin B. Taken together, SVAP9I's distinct membrane-targeting broad-spectrum action, lack of resistance and strong in vitro andin vivopotency in synergism with narrow spectrum antibiotics like rifampicin suggests its potential as a novel antibiotic adjuvant for the treatment of serious MDR-GNB infections.

The Ocular Chloramphenicol Story

Chloramphenicol eye drops and ointment are the most used ocular antibiotic worldwide. Chloramphenicol was discovered in 1947 and was only the third antibiotic to successfully be produced and only the first antibiotic suitable for large-scale commercial production. By the 1950s, the drug had been developed into drop and ointment forms. The broad spectrum of anti-bacterial activity of Chloramphenicol led to widespread use. Ocular Chloramphenicol remains an important weapon in the ophthalmic armamentarium despite emergence of evidence of possible side effects in the 1970s. This is a short review of the remarkable story of the discovery, development and tribulations of ocular Chloramphenicol. Keywords: History; Chloramphenicol Abbreviations: FDA: Food and Drug Administration

Characterization of antibiofilm compound from marine sponge Stylissa carteri.

The fouling phenomenon grabbed global attention and caused huge economic losses specifically in marine-related industries. Sessile behavior exposed the sponge to the risk of fouling. However, their bodies remained free from foulers, which were attributed to the chemical defense system. The objectives of this study were to determine the antibiofilm activity of the marine sponge, Stylissa carteri, and to characterize the isolated compound involved. The antibiofilm activity of S. carteri methanolic crude extract (MCE) and fractions was tested against biofilm-producing bacteria, Pseudomonas aeruginosa, using two different modes of crystal violet biofilm assays: preventive and detachment. Besides that, the disc-diffusion test was conducted to screen the antibacterial activity against gram-positive and gram-negative bacteria while a cytotoxicity assay was conducted on the HepG2 cell line. Bioassay-guided fractionation was carried out using vacuum liquid chromatography (VLC) and solid phase extraction using a C18 Sep-Pak Cartridge. The crystal compound was isolated and characterized through thin-layer chromatography (TLC), Fourier transform infrared (FTIR) spectroscopy, liquid chromatography-mass spectrometry (LCMS), and nuclear magnetic resonance (NMR) spectroscopy. The S. carteri MCE showed a promising result with a half-maximal inhibitory concentration (IC50) of 20.22μg/mL in the preventive assay, while no IC50 was determined in the detachment assay since all inhibitions < 50%. The S. carteri MCE exhibited broad-spectrum antibacterial activity and displayed a non-cytotoxic effect. Fraction 4 from MCE of S. carteri (IC50 = 2.40μg/mL) reduced the biofilm in the preventive assay at all concentrations and exhibited no antibacterial activity indicating the independence of antibiofilm from antibacterial properties. Based on the data obtained, an alkaloid named debromohymenialdisine (DBH) was identified from Fraction 4 of S. carteri MCE. In conclusion, S. carteri was able to reduce the establishment of the biofilm formed by P. aeruginosa and could serve as a prominent source of natural antifouling agents.

Michael Addition Reaction between Dehydroalanines and Phosphites Enabled the Introduction of Phosphonates into Oligopeptides.

A method for introducing a range of phosphonates into oligopeptides through a Michael addition reaction between dehydroalanine and phosphite is presented. The method offers a mild, cheap, and straightforward approach to peptide phosphorylation that has potential applications in chemical biology and medicinal chemistry. Moreover, the introduction of a phosphonate group into short antibacterial peptides is described to demonstrate its utility, leading to the discovery of phosphonated antibacterial peptides with potent broad-spectrum antibacterial activity.

Heterologous expression of frog antimicrobial peptide Odorranain-C1 in Pichia pastoris: Biological characteristics and its application in food preservation

To reduce food spoilage and deterioration caused by microbial contamination, antimicrobial peptides (AMPs) have gradually gained attention as a biological preservative. Odorranain-C1 is an α-helical cationic antimicrobial peptide extracted from the skin of frogs with broad-spectrum antimicrobial activity. In this study, we achieved the expression of Odorranain-C1 in Pichia pastoris (P. pastoris) (also known as Komagataella phaffii) by employing DNA recombination technology. The recombinant Odorranain-C1 showed broad-spectrum antibacterial activity and displayed a minimum inhibitory concentration within the range of 8–12 μg.mL-1. Meanwhile, Odorranain-C1 exhibited superior stability and lower hemolytic activity. Mechanistically, Odorranain-C1 disrupted the bacterial membrane's integrity, ultimately causing membrane rupture and subsequent cell death. In tilapia fillets preservation, Odorranain-C1 inhibited the total colony growth and pH variations, while also reducing the production of total volatile basic nitrogen (TVB-N) and thiobarbituric acid (TBA). In conclusion, these studies demonstrated the efficient recombinant expression of Odorranain-C1 in P. pastoris, highlighting its promising utilization in food preservation.

Dental Caries Management with Antibacterial Silver-Doped Prussian Blue Hydrogel by the Combined Effects of Photothermal Response and Ion Discharge.

Caries is a destructive condition caused by bacterial infection that affects the hard tissues of the teeth, significantly reducing the quality of life for individuals. Photothermal therapy (PTT) offers a noninvasive and painless treatment for caries, but the use of unsafe laser irradiance limits its application. To address this challenge, we prepared nanoparticles of silver ion-doped Prussian blue (AgPB), which was encased within cationic guar gum (CG) to form the antibacterial PTT hydrogel CG-AgPB with a photothermal conversion efficiency of 34.4%. When exposed to an 808 nm laser at a power density of 0.4 W/cm2, the hydrogel readily reached a temperature of over 50 °C in just 3 min, synchronized by the discharge of Ag+ ions from the interstitial sites of AgPB crystals, resulting in broad-spectrum and synergistic antibacterial activities (>99%) against individual oral pathogens (Streptococcus sanguinis, Streptococcus mutans, and Streptococcus sobrinus) and pathogen-induced biofilms. In vivo, CG-AgPB-mediated PTT demonstrated a capability to profoundly reduce the terminal number of cariogenic bacteria to below 1% in a rat model of caries. Given the outstanding biocompatibility, injectability, and flushability, this CG-AgPB hydrogel may hold promise as a next-generation oral hygiene adjunct for caries management in a clinical setting.