Antibacterial activity and mechanism of sanguinarine against Staphylococcus aureus by interfering with the permeability of the cell wall and membrane and inducing bacterial ROS production

Multi-enzymatic biomimetic cerium-based MOFs mediated precision chemodynamic synergistic antibacteria and tissue repair for MRSA-infected wounds

Antibiotic-resistant pathogens represent a significant global public health challenge, particularly in refractory infections associated with biofilms. Urgent development of innovative, safe, and therapeutically adaptive strategies to combat these resistant biofilms is essential. We present a novel biomimetic antibacterial system inspired by the multifunctional enzymatic properties of cerium-based metal-organic frameworks. This system utilizes the inherent oxidase and peroxidase activities of a nanozyme to generate reactive oxygen species (ROS) for bacterial eradication, while its phosphate-ester hydrolase activity disrupts bacterial genetic material and energy metabolism. By the reversible covalent binding between boronic acid groups and cis-diol groups on bacterial surfaces, combined with abundant cerium catalytic sites from the porous structure and the potent antibacterial effects of sanguinarine, we enhance targeted antibacterial activity. This system effectively penetrates extracellular polymeric substances (EPS) and demonstrates precise regulation of ROS, allowing for localized delivery of ROS and sanguinarine for biofilm eradication. Transcriptomic analyses indicate that this approach disrupts the cellular environment, impairs energy metabolism, inhibits bacterial attachment to EPS, and promotes biofilm dispersion by modulating drug resistance-related genes. In vivo experiments confirm that this nanocatalyst composite effectively treats biofilm-induced wounds with efficacy comparable to vancomycin, presenting a promising solution for managing chronic infections caused by antibiotic-resistant biofilms.

Phyto-molecules show potentials to combat drug-resistance in bacterial cell membranes

The global rise in antibiotic resistance and the emergence of infectious diseases have intensified the need for novel antimicrobial therapies. As a result, there is a growing demand to validate the ethnomedicinal claims that plant extracts possess antibacterial properties. This validation requires the characterization of specific phytoconstituents, including anti-infective compounds and antimicrobial peptides. This study explores the progress made in identifying and producing anti-infectives derived from plants, with a focus on their mechanisms of action, current applications, and future potentials. One key area of investigation is the therapeutic potential of phyto-molecules, that target bacterial cell membranes. These molecules which include phenols, alkaloids, terpenoids, saponins, and peptides, have shown significant ability to disrupt bacterial cell membranes through various molecular mechanisms. By impairing membrane integrity, inhibiting efflux pumps, and altering membrane permeability, phyto-molecules offer a novel strategy for combating drug-resistant bacterial strains. This disruption not only enhances the efficacy of conventional antibiotics but also provides standalone antimicrobial activity. In conclusion, phyto-molecules represent a promising solution to overcoming antibiotic resistance, with their ability to target structural and functional components of bacterial membranes offering new pathways for therapeutic development. However, further research is needed to assess the comparative effectiveness and safety of these plant-based molecules in relation to traditional membrane-disrupting antibiotics.

Synergistic inhibition of Pseudomonas aeruginosa by EGCG and I3A: preliminary mechanisms and application in fish meat preservation

Synergistic bacteriostatic action represents a potent strategy for combating microbial contamination in the food industry. This study investigated the synergistic bacteriostatic effect of epigallocatechin gallate (EGCG) and indole-3-carboxaldehyde (I3A). Results showed a pronounced synergistic action of EGCG and I3A against diverse food spoilage microorganisms, most notably Pseudomonas aeruginosa (P. aeruginosa), with a fractional inhibitory concentration index (FICI) of 0.25. Further research revealed that EGCG disrupted the cell wall and cell membrane of P. aeruginosa, while supplementing I3A significantly boosted the concentration of intracellular reactive oxygen species, thereby inflicting cellular damage. Moreover, the EGCG-I3A treatment inhibited the biofilm formation of P. aeruginosa in a dose-dependent manner, with the effectiveness increasing with the quantity of I3A added. Metabolomic study revealed a perturbation in glutathione and taurine metabolic pathways post synergistic treatment, compromising redox homeostasis. This synergistic treatment also downregulated uracil, proline, and glutamate metabolites, thereby suppressing Quorum Sensing (QS) and biofilm-associated expression within P. aeruginosa. Additionally, the combination significantly inhibited P. aeruginosa growth in fish meat. In essence, this study underscored the synergistic bacteriostatic efficacy of EGCG and I3A, highlighting its potential application in food preservation.

Disrupting cross-adaptation in high-risk MRSA: Sanguinarine as a multi-effective stress sensitizer for environmental and food safety

Methicillin-resistant Staphylococcus aureus (MRSA) represents a significant public health concern owing to its formidable antibiotic resistance and robust capacity for biofilm formation. The cross-adaptation mechanism enables MRSA to develop tolerance to environmental stressors such as antibiotics, acid, heat and osmotic pressure, leading to the persistence infections and environmental contamination. The cross-adaptation mechanism enables MRSA to develop tolerance to environmental stressors, such as antibiotics, acid, heat and osmotic pressure, leading to the persistence infections and environmental contamination. Here, we identified 261 strains of S. aureus and 9 high-risk MRSA from the environment of dairy farms and raw milk. The natural product Sanguinarine (SAN), derived from feed additives, exhibits effective anti-MRSA and anti-biofilm activity. Notably, SAN enhances the sensitivity of MRSA to antibiotics, acid, heat, and osmotic pressure by disrupting the cross-adaptation mechanism. Mechanistic investigations revealed that SAN significantly reduces the transcriptional level of type I (dnaK, groEL, etc.) and type III (clpB, clpP, etc.) heat stress response genes while markedly upregulating type II (σB) gene. Furthermore, SAN upregulates Na+/H+ antiporters activity, F0F1-ATPase activity and purine metabolism, while broadly downregulating DNA damage repair genes and disrupting ribosomal function. Additionally, SAN induces non-synonymous mutations in key stress response factors ClpB/L, leading to a loss of conformational homeostasis. SAN elicits a distinct stress response compared to environmental stressors, weakening MRSA's resilience and demonstrating promising capabilities for MRSA clearance and biofilm inhibition. Overall, SAN provides an effective strategy for the clearance of high-risk MRSA and the assurance of public health security.

Transcriptomic and metabolomic analysis of the antibacterial mechanism of sanguinarine against Enterobacter cloacae in vitro

BACKGROUND

Enterobacter cloacae (E. cloacae) is a notorious pathogen that poses serious threat to both human and animal health, causing severe gut infections and contributing to food spoilage. Traditional chemical treatment have led to increased drug resistance and environmental pollution. This study investigates the potential of Sanguinarine (SAN), a natural plant extract, as an alternative to chemical antibiotics.

RESULTS

In light of the escalating issue of antibiotic resistance, we examined the antibacterial efficacy and mechanisms of SAN against E. cloacae in vitro. Our findings revealed a minimum inhibitory concentration (MIC) of 100 µg/mL for SAN. Scanning electron microscopy (SEM) demonstrated substantial morphological disruptions in E. cloacae cells treated with SAN. Concurrently, a significant increase in absorbance at 260 nm suggested nucleic acid leakage, indicative of compromised cell membrane integrity. Comprehensive transcriptomic and metabolomic analyses revealed that SAN primarily disrupts amino acid synthesis and energy metabolism pathway in E. cloacae.

CONCLUSIONS

SAN exhibited potential antibacterial activity against E. cloacae, which can effectively inhibit its growth and disrupt its bacterial morphology and exert antibacterial effect through multiple pathways, and can be used as a potential substitute for antibiotics.

Bacterial responses to Ephedra aphylla stem extract and green-synthesized Ag-TiO2 and Ag-SeO2 core/shell nanocomposites: unveiling antimicrobial and antioxidant properties

This study reports an efficient and green protocol for the green synthesis of Ag-TiO2 and Ag-SeO2 nanocomposites using the extracted stems of Ephedra aphylla. Results of spectroscopic and analytical analyses confirmed the successful synthesis, stability, and crystalline nature of the nanomaterials. The phytochemical profile and antioxidant and antimicrobial activities of the E. aphylla extract and the nanocomposites were also studied. E. aphylla extract and both the nanomaterials exhibited significant levels of active phytochemical compounds. These compounds contributed to their potent antioxidant activity, with E. aphylla extract and Ag-TiO2 NC demonstrating the highest antioxidant activity. Besides, Ag-SeO2 NC displayed remarkable antibacterial properties against different pathogenic bacteria with 31.0 ± 1.27 mm against K. pneumonia, 31.0 ± 1.72 mm against S. aureus, and 44.0 ± 1.09 mm against B. subtilis, and antifungal properties against Candida glabrata and Aspergillus niger. The enhanced antimicrobial activity of Ag-SeO2 NC can be attributed to the synergistic effects of silver and selenium nanoparticles, which can disrupt cell membranes, induce oxidative stress, and interfere with essential cellular processes. The minimum inhibitory concentration values of Ag-SeO2 NC against S. aureus and K. pneumoniae were found to be 0.2956 mg mL-1 and 4.73 mg mL-1, respectively. The mechanism of action of Ag-SeO2 NC against both fungal strains was investigated using FTIR and HR-TEM analyses.

Targeting membrane integrity and imidazoleglycerol-phosphate dehydratase: Sanguinarine multifaceted approach against Staphylococcus aureus biofilms

BACKGROUND

Staphylococcus aureus is an opportunistic pathogen capable of readily forming biofilms, which can result in life-threatening infections involving different organs. Sanguinarine are benzo[c]phenanthridine alkaloids extracted from the Sanguinaria canadensis L. (Papaveraceae), which have a wide range of biological activities. Previous reports have shown that sanguinarine is able to induce an elevation of ROS to exert an anti-S. aureus effect. Nevertheless, the specific mechanism of action of sanguinarine against S. aureus biofilms remains unexplored.

PURPOSE

The objective of this study was to elucidate the target site of sanguinarine in S. aureus, as well as to investigate its mechanism of antimicrobial action and its interference with biofilm formation. Additionally, the study aimed to provide further evidence supporting the use of sanguinarine as an alternative to traditional antibiotics.

METHODS

Initially, we assessed the in vitro anti-S. aureus properties of sanguinarine through a series of methodologies, including MIC assays, time-dependent assays, and resistance development studies. Secondly, we explored the antimicrobial mechanism of sanguinarine using TEM, membrane permeability assays, and membrane fluidity assays. Subsequently, the mechanism by which sanguinarine interferes with S. aureus biofilm formation was preliminarily analyzed in vitro. Additionally, the interaction between sanguinarine and imidazoleglycerol-phosphate dehydratase (IGPD) was investigated using bio-layer interferometry assays, circular dichroism spectroscopy, molecular docking, and site-directed mutagenesis to further elucidate the role of sanguinarine in biofilm disruption. Finally, the therapeutic efficacy of sanguinarine was evaluated in vivo using mouse models of biofilm and bacteremia.

RESULTS

Herein, sanguinarine demonstrated notable antimicrobial properties and interfering effects on biofilm formation. Mechanistic investigations revealed that sanguinarine exerts its antimicrobial action by dissipating the proton motive force in bacteria and compromising the integrity and functionality of the cytoplasmic membrane. Furthermore, sanguinarine was found to regulate IGPD expression and inhibit L-histidine synthesis, thereby interfering S. aureus biofilm formation. Consequently, due to its polypharmacological effect, sanguinarine significantly reduced the S. aureus load in mouse organs and the formation of biofilm on the surface of implants in vivo without any resistance.

CONCLUSIONS

In this study, we demonstrated that sanguinarine can exert antibacterial and interfere with biofilm formation by disrupting the cell membrane of S. aureus and targeting IGPD. These findings suggest that sanguinarine holds potential for further development as a novel antibiotic to combat biofilm-associated infections.

The effect and mechanism of sanguinarine against PCV2 based on the analysis of network pharmacology and TMT quantitative proteomics

Porcine circovirus type 2 (PCV2) is highly prevalent in nature and serves as the primary pathogen responsible for porcine circovirus-associated disease (PCVD/PCVAD), posing a significant threat to pig production. Currently, vaccination alone could not provide the complete protection for PCV2 infection. The active ingredients of traditional Chinese medicine have shown a positive effect in combating viral infections. This study employed tandem mass tag (TMT) labeled proteomic analyses and network pharmacology to examine the effect and mechanism of sanguinarine against PCV2. IFIH1, IFITM1, p38α, and JNK were identified as the key targets of sanguinarine against PCV2 based on proteomics and network pharmacology. Using PCV2-infected PK-15 cells, it was discovered that sanguinarine inhibited the expression of the PCV2 CAP gene by upregulating IFIH1, thereby promoting STAT1 phosphorylation and activating MAVS expression. This, in turn, facilitated IRF3 phosphorylation, leading to increase IFITM1 expression. Simultaneously, sanguinarine suppressed the expression of the PCV2 CAP gene by inhibiting the expression of p38α, JNK, and p-JNK protein. In conclusion, the results of this study suggest that sanguinarine exerts anti-PCV2 effects through different targets and pathways, which lays the foundation for the subsequent development of new anti-PCV2 veterinary drugs.

Thermosensitive-based synergistic antibacterial effects of novel LL37@ZPF-2 loaded poloxamer hydrogel for infected skin wound healing

Trauma healing is the process of healing after the body has been subjected to an external force and the skin and other tissues have become dissected or defective, showing the synergistic effect of various processes. Therefore, the investigation of innovative wound dressings has significant research and clinical implications. In this study, we constructed a zinc based metal-organic framework (MOF) and loaded with antimicrobial peptide LL37 to prepare LL37@ZPF-2 (ZPF = zeolite pyrimidine backbone), which was subsequently integrated with Poloxamer 407 to fabricate LL37@ZPF-2 thermosensitive hydrogel. Our study showed that in-situ packaging method can achieve encapsulation rate of 98 % and 15 % of drug loading for LL37. LL37@ZPF-2 demonstrated a higher inhibitory potency against S.aureus compared to E.coli. The Poloxamer 407-gel exhibits thermo-responsive sol-to-gel phase transition behaviors with a phase transition temperature (Tsol/gel) of ∼ 28.01℃, making it an appropriate material for wound healing. The composite hydrogel has excellent biocompatibility and hemocompatibility. A full-thickness skin defect model was built to confirm that LL37@ZPF-2 thermosensitive hydrogel dressing could inhibit bacterial growth, reduce the risk of wound infection, and stimulate angiogenesis and collagen deposition, resulting in a wound healing rate of 94.4 % on day 7 and complete healing on day 10. Our findings demonstrate that the novel thermosensitive LL37@ZPF-2 hydrogel confers good antibacterial activity, promoting cell migration and infected-wound healing properties, providing a promising platform for wound healing.

Sanguinarine chloride hydrate mitigates colitis symptoms in mice through the regulation of the intestinal microbiome and metabolism of short-chain fatty acids

Sanguinarine constitutes the main components of Macleaya cordata, and exhibits diverse biological and pharmacological activities. This study investigated the effects of sanguinarine chloride hydrate (SGCH) on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) mice. Five groups were designed to investigate the effects of SGCH on the pathological symptoms, the mRNA expression levels of inflammatory cytokines, colonic mucosal barrier damage, microbiota composition, and SCFAs metabolism in UC mice. The administration of SGCH in DSS-induced UC mice resulted in the amelioration of pathological symptoms, as evidenced by an increase in body weight, a decrease in disease activity index score, elongation of colon length, reduction in spleen index, and improvement in colon injury. SGCH can regulate the expression of inflammatory cytokines (IL-6, TNF-α, IL-1β and IL-10) and tight junction proteins (ZO-1 and Occludin) associated with UC. SGCH exhibited a significant decrease in NF-κB P65 mRNA expression levels, accompanied by a significantly reduced protein level of NF-κB P-P65/P65. Further studies revealed SGCH effectively reversed the decrease in intestinal microbiota diversity induced by UC, thereby promoting the growth of beneficial bacteria such as Akkermansia, Alistipes, and norank_o_Clostridia_UCG-014. Correlation analysis demonstrated a positive association between butanoic acid, propanoic acid, isobutyric acid, isovaleric acid, valeric acid, hexanoic acid with Colidextribacter, while Coriobacteriaceae_UCG-002 exhibited a negative correlation with butanoic acid, acetic acid and propanoic acid. In conclusion, the administration of SGCH can ameliorate clinical symptoms in UC mice, regulate the expression of inflammatory cytokines and tight junction proteins, modulate intestinal microbiota metabolism and SCFAs production.

Preparation and Antibacterial Activity Evaluation of Daphnetin-Loaded Poloxamers/Polyvinylpyrrolidone Thermosensitive Hydrogels

Antibiotic misuse and bacterial resistance are pressing issues threatening public health. Natural plant extracts with bactericidal properties offer potential alternatives to reduce or replace antibiotic use. This study aims to develop a thermosensitive hydrogel containing daphnetin (DAP-TG) using poloxamers 407 (P407), polyvinylpyrrolidone (PVP), and poloxamers 188 (P188). We systematically evaluated the gel's antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), as well as its antibacterial mechanisms. By examining the gelation temperature and time, degradation time, and in vitro release performance of DAP-TG, we produced a sustained-release DAP-TG with a rapid phase transition at (31.6 ± 0.1) °C. Its structure was characterized through Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The results indicated that the DAP thermosensitive hydrogel was formed and presented a 3D network spatial structure. The biocompatibility of DAP-TG was explored through the hemolysis test and cytotoxicity test. The results indicated that DAP-TG possessed excellent biocompatibility. The antibacterial efficacy of DAP-TG against E. coli and S. aureus was assessed using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), growth curve, and inhibition zone tests. Results showed that DAP-TG exhibited excellent antibacterial activity against both E. coli and S. aureus, with MIC values of 1.28 and 0.32 mg/mL. The antibacterial mechanism of DAP-TG was preliminarily explored through the investigation of bacterial cell content leakage, AKP leakage, membrane permeability, SEM, ROS production, and biofilm inhibition activity. DAP-TG induced irreversible damage to the cell membranes of E. coli and S. aureus, resulting in enhanced permeability, elevated ROS levels, and inhibited biofilm formation. Our study indicates that DAP-TG exhibits effective sustained-release and antibacterial properties against E. coli and S. aureus in vitro, making it a promising candidate for antibacterial applications in food and pharmaceutical products.

Synergistic Effects and Mechanisms of Action of Rutin with Conventional Antibiotics Against Escherichia coli

Rutin is a widely known plant secondary metabolite that exhibits multiple physiological functions. The present study focused on screening for synergistic antibacterial combinations containing rutin, and further explored the mechanisms behind this synergy. In vitro antibacterial test results of rutin showed that the ranges of minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) are 0.125-1 and 0.125-2 mg/mL, respectively. However, rutin and amikacin have a significant synergistic effect, with a fractional inhibitory concentration index (FICI) range of 0.1875-0.5. The time bactericidal curve proved that the combination of rutin and amikacin inhibited bacterial growth within 8 h. Scanning electron microscopy (SEM) revealed that a low-dose combination treatment could disrupt the cell membrane of Escherichia coli (E. coli). A comprehensive analysis using alkaline phosphatase (AKP), K+, and a protein leakage assay revealed that co-treatment destroyed the cell membrane of E. coli, resulting in the significant leakage of AKP, intracellular K+, and proteins. Moreover, confocal laser scanning microscopy (CLSM) and red-green cell ratio analysis indicated severe damage to the E. coli cell membrane following the co-treatment of rutin and amikacin. This study indicates the remarkable potential of strategically selecting antibacterial agents with maximum synergistic effect, which could significantly control antibiotic resistance.

Antibacterial Activity and Antifungal Activity of Monomeric Alkaloids

Scientists are becoming alarmed by the rise in drug-resistant bacterial and fungal strains, which makes it more costly, time-consuming, and difficult to create new antimicrobials from unique chemical entities. Chemicals with pharmacological qualities, such as antibacterial and antifungal elements, can be found in plants. Alkaloids are a class of chemical compounds found in nature that mostly consist of basic nitrogen atoms. Biomedical science relies heavily on alkaloid compounds. Based on 241 papers published in peer-reviewed scientific publications within the last ten years (2014-2024), we examined 248 natural or synthesized monomeric alkaloids that have antifungal and antibacterial activity against Gram-positive and Gram-negative microorganisms. Based on their chemical structure, the chosen alkaloids were divided into four groups: polyamine alkaloids, alkaloids with nitrogen in the side chain, alkaloids with nitrogen heterocycles, and pseudoalkaloids. With MIC values of less than 1 µg/mL, compounds 91, 124, 125, 136-138, 163, 164, 191, 193, 195, 205 and 206 shown strong antibacterial activity. However, with MIC values of below 1 µg/mL, compounds 124, 125, 163, 164, 207, and 224 demonstrated strong antifungal activity. Given the rise in antibiotic resistance, these alkaloids are highly significant in regard to their potential to create novel antimicrobial drugs.

Biochemistry and Future Perspectives of Antibiotic Resistance: An Eye on Active Natural Products

Antibiotic resistance poses a serious threat to the current healthcare system, negatively impacting the effectiveness of many antimicrobial treatments. The situation is exacerbated by the widespread overuse and abuse of available antibiotics, accelerating the evolution of resistance. Thus, there is an urgent need for novel approaches to therapy to overcome established resistance mechanisms. Plants produce molecules capable of inhibiting bacterial growth in various ways, offering promising paths for the development of alternative antibiotic medicine. This review emphasizes the necessity of research efforts on plant-derived chemicals in the hopes of finding and creating novel drugs that can successfully target resistant bacterial populations. Investigating these natural chemicals allows us to improve our knowledge of novel antimicrobial pathways and also expands our antibacterial repertoire with novel molecules. Simultaneously, it is still necessary to utilize present antibiotics sparingly; prudent prescribing practices must be encouraged to extend the effectiveness of current medications. The combination of innovative drug research and responsible drug usage offers an integrated strategy for managing the antibiotic resistance challenge.

Design, synthesis of griseofamine A derivatives and development of potent antibacterial agents against MRSA

The prevalence of methicillin-resistant Staphylococcus aureus (MRSA), one of the most important multidrug-resistant bacteria in clinic, has become a serious global health issue. In this study, we designed and synthesized a series of griseofamine A derivatives and evaluated their antibacterial profiles. In vitro assays found that compound 9o10 showed a remarkable improvement of antibacterial activity toward MRSA (MIC = 0.0625 μg/mL), compared with griseofamine A (MIC = 8 μg/mL) and vancomycin (MIC = 0.5 μg/mL) with low hemolysis and cytotoxicity. Its rapid bactericidal property was also confirmed by time-kill curve assay. Furthermore, compound 9o10 displayed weak drug resistance frequency. In in vivo experiment, compound 9o10 exhibited more potent antibacterial efficacy than vancomycin and excellent biosafety (LD50 > 2 g/kg). Preliminary mechanism study revealed compound 9o10 might involve antibacterial mechanisms contributing to membrane damage. Taken together, compound 9o10 possessed excellent inhibitory activity against MRSA in vitro and in vivo with low toxicity and drug resistance frequency, making it a promising hit compound for further development against MRSA infections.

Preparation of sanguinarine/glabridin loaded antifungal double-layer nanoemulsion edible coating using arabic gum/WPI for forest frog's oviduct oil preservation

Forest frog's oviduct oil (FFOO) is highly susceptible to microbial spoilage during storage, which causes serious safety concerns and economic losses. However, little information is available regarding the preservation of it up to now. The aim of this research is to understand the dominant microbial community of FFOO spoilage, and based on this, develop a kind of edible nanoemulsion coating for preserving FFOO. Microbial metagenomic analysis indicated that the Aspergillus genus increased significantly during storage. In the present study, gum arabic and whey protein isolate were chosen as the coating matrix, the natural compounds sanguinarine and glabridin were selected as antimicrobial agents to prepare double-layer nanoemulsion edible coating. When the ratio of sanguinarine and glabridin in the nanoemulsion was 1:3, it exhibited strongest storage stability and antifungal activity. The mycelial inhibition rate of 1:3 nanoemulsion against dominant microbial community (Aspergillus niger and Aspergillus glaucus) reached 88.89 ± 1.37 % and 89.68 ± 1.37 %, respectively. The experimental results indicated that the edible nanoemulsion coating not only had outstanding antifungal activity, but also had excellent fresh-keeping effect on FFOO. This nanoemulsion coating could be a promising and potential candidate for food preservation.

Antibacterial activity and mechanism of Stevia extract against antibiotic-resistant Escherichia coli by interfering with the permeability of the cell wall and the membrane

Natural plant-derived compounds with broad-spectrum antimicrobial activity have become an effective strategy against multidrug-resistant bacteria. The present study was designed to compare the antibacterial activity of six chlorogenic acid (CA) isomers extracted from stevia and investigated the underlying antibacterial mechanisms involved. The results indicated that isochlorogenic acid C (ICAC) exhibited the strongest antibacterial activity against the tested bacteria, especially E. coli, at a 2 mg/mL minimum inhibitory concentration (MIC) and 8 mg/mL minimum bactericidal concentration (MBC). At the MBC, ICAC inhibited 72.66% of the clinical multidrug-resistant strains. Scanning electron microscopy (SEM) revealed that ICAC induced considerable morphological alterations in E. coli ATCC25922 and C4E2. The significant increase in the activity of extracellular alkaline phosphatase (AKP) indicated that ICAC damages the permeability of the bacterial cell wall. Additionally, the intracellular membrane (IM) permeability and the content of lipopolysaccharide (LPS), a main component of the outer membrane (OM), were determined. The significant decrease in LPS content and increased leakage of intracellular proteins and K+ from E. coli indicated that ICAC could induce the exfoliation of OM and disrupt IM permeability, resulting in the loss of barrier function. The uptake of propidium iodide (PI), a compromised cell membrane nucleic acid stain, and confocal laser scanning microscopy (CLSM) further demonstrated that ICAC disrupted IM integrity. Moreover, the bactericidal effect and damage to bacterial microstructural function occurred in a dose-dependent manner. These data demonstrate that ICAC has excellent antibacterial activity and is a promising approach for overcoming the antibiotic resistance of pathogenic bacteria.

6-Methoxyldihydrochelerythrine Chloride Inhibiting Intra and Extracellular Drug-Resistant Bacteria

Vancomycin-resistant enterococcus (VRE) is a major nosocomial pathogen that exhibits enhanced infectivity due to its robust virulence and biofilm-forming capabilities. In this study, 6-methoxyldihydrochelerythrine chloride (6-MDC) inhibited the growth of exponential-phase VRE and restored VRE's sensitivity to vancomycin. 6-MDC predominantly suppressed the de novo biosynthetic pathway of pyrimidine and purine in VRE by the RNA-Seq analysis, resulting in obstructed DNA synthesis, which subsequently weakened bacterial virulence and impeded intracellular survival. Furthermore, 6-MDC inhibited biofilm formation, eradicated established biofilms, reduced virulence, and enhanced the host immune response to prevent intracellular survival and replication of VRE. Finally, 6-MDC reduced the VRE load in peritoneal fluid and cells significantly in a murine peritoneal infection model. This paper provides insight into the potential antimicrobial target of benzophenanthridine alkaloids for the first time.

Mechanism of antibacterial phytoconstituents: an updated review

The increase of multiple drug resistance bacteria significantly diminishes the effectiveness of antibiotic armory and subsequently exaggerates the level of therapeutic failure. Phytoconstituents are exceptional substitutes for resistance-modifying vehicles. The plants appear to be a deep well for the discovery of novel antibacterial compounds. This is owing to the numerous enticing characteristics of plants, they are easily accessible and inexpensive, extracts or chemicals derived from plants typically have significant levels of action against infections, and they rarely cause serious adverse effects. The enormous selection of phytochemicals offers very distinct chemical structures that may provide both novel mechanisms of antimicrobial activity and deliver us with different targets in the interior of the bacterial cell. They can directly affect bacteria or act together with the crucial events of pathogenicity, in this manner decreasing the aptitude of bacteria to create resistance. Abundant phytoconstituents demonstrate various mechanisms of action toward multi drug resistance bacteria. Overall, this comprehensive review will provide insights into the potential of phytoconstituents as alternative treatments for bacterial infections, particularly those caused by multi drug resistance strains. By examining the current state of research in this area, the review will shed light on potential future directions for the development of new antimicrobial therapies.

Antibacterial activity and mechanism of chelerythrine against Streptococcus agalactiae

Streptococcus agalactiae (S.agalactiae), also known as group B Streptococcus (GBS), is a highly infectious pathogen. Prolonged antibiotic usage leads to significant issues of antibiotic residue and resistance. Chelerythrine (CHE) is a naturally occurring benzophenidine alkaloid and chelerythrine chloride (CHEC) is its hydrochloride form with diverse biological and pharmacological activities. However, the antibacterial mechanism of CHEC against GBS remains unclear. Thus, this study aims to investigate the in vitro antibacterial activity of CHEC on GBS and elucidate its underlying mechanism. The antibacterial effect of CHEC on GBS was assessed using inhibitory zone, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays, as well as by constructing a time-kill curve. The antibacterial mechanism of CHEC was investigated through techniques such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM), measurement of alkaline phosphatase (AKP) activity, determination of Na+ K+, Ca2+ Mg2+-adenosine triphosphate (ATP) activity, observation of membrane permeability, and analysis of intracellular reactive oxygen species (ROS) and mRNA expression levels of key virulence genes. The results demonstrated that the inhibition zone diameters of CHEC against GBS were 14.32 mm, 12.67 mm, and 10.76 mm at concentrations of 2 mg/mL, 1 mg/mL, and 0.5 mg/mL, respectively. The MIC and MBC values were determined as 256 μg/mL and 512 μg/mL correspondingly. In the time-kill curve, 8 × MIC, 4 × MIC and 2 × MIC CHEC could completely kill GBS within 24 h. SEM and TEM analyses revealed significant morphological alterations in GBS cells treated with CHEC including shrinkage, collapse, and leakage of cellular fluids. Furthermore, the antibacterial mechanism underlying CHEC's efficacy against GBS was attributed to its disruption of cell wall integrity as well as membrane permeability resulting in extracellular release of intracellular ATP, AKP, Na+ K+, Ca2+ Mg2+. Additionally CHEC could increase the ROS production leading to oxidative damage and downregulating mRNA expression levels of key virulence genes in GBS cells. In conclusion, CHEC holds potential as an antimicrobial agent against GBS and further investigations are necessary to elucidate additional molecular mechanisms.

Zwitterion-Modified MXene Quantum Dot as a Nanocarrier for Traditional Chinese Medicine Sanguinarine Delivery and Its Application for Photothermal-Chemotherapy Synergistic Antibacterial and Wound Healing

The nanomaterialization of traditional Chinese medicine (TCM) has aroused widespread interest among researchers. Sanguinarine (SAN) is a kind of TCM with good antibacterial properties, which has important applications in anti-infection of wounds. Additionally, the combination of photothermal therapy and chemotherapy can overcome bacterial resistance, further improving bactericidal and wound healing efficiency. In this paper, we prepared an antibacterial agent by loading SAN on the zwitterion-modified MXene quantum dot nanocarrier (SAN@AHEP@Ta4C3), realizing pH/NIR controlled drug release and photothermal/chemotherapy synergistic antibacterial and wound healing. The particle size of SAN@AHEP@Ta4C3 is about 120 nm, and it has a good water solubility and stability. In addition, it also has excellent photothermal conversion performance (η = 39.2%), which can effectively convert light energy into heat energy under near-infrared (NIR) laser irradiation, further promoting drug release and achieving bactericidal effects by synergistic chemotherapy and photothermal therapy. The in vitro and in vivo experiments show that SAN@AHEP@Ta4C3 exhibits an excellent antibacterial effect against Staphylococcus aureus and Escherichia coli, and it can effectively promote the wound healing of mice. Moreover, the SAN@AHEP@Ta4C3 also has good biocompatibility and has no side effects on normal tissue and organs. This work introduces a multifunctional antibacterial agent based on TCM and hot-spot material MXene, which will have considerable application prospects in biomedical fields.

Antifungal Activity and Putative Mechanism of HWY-289, a Semisynthetic Protoberberine Derivative, against Botrytis cinerea

The emergence of resistant pathogens has increased the demand for alternative fungicides. The use of natural products as chemical scaffolds is a potential method for developing fungicides. HWY-289, a semisynthetic protoberberine derivative, demonstrated broad-spectrum and potent activities against phytopathogenic fungi, particularly Botrytis cinerea (with EC50 values of 1.34 μg/mL). SEM and TEM imaging indicated that HWY-289 altered the morphology of the mycelium and the internal structure of cells. Transcriptomics revealed that it could break down cellular walls through amino acid sugar and nucleotide sugar metabolism. In addition, it substantially decreased chitinase activity and chitin synthase gene (BcCHSV) expression by 53.03 and 82.18% at 1.5 μg/mL, respectively. Moreover, this impacted the permeability and integrity of cell membranes. Finally, HWY-289 also hindered energy metabolism, resulting in a significant reduction of ATP content, ATPase activities, and key enzyme activities in the TCA cycle. Therefore, HWY-289 may be a potential candidate for the development of plant fungicides.

Bioactivity and mechanism of action of sanguinarine and its derivatives in the past 10 years

Sanguinarine is a quaternary ammonium benzophenanthine alkaloid found in traditional herbs such as Chelidonium, Corydalis, Sanguinarum, and Borovula. It has been proven to possess broad-spectrum biological activities, such as antitumor, anti-inflammatory, antiosteoporosis, neuroprotective, and antipathogenic microorganism activities. In this paper, recent progress on the biological activity and mechanism of action of sanguinarine and its derivatives over the past ten years is reviewed. The results showed that the biological activities of hematarginine and its derivatives are related mainly to the JAK/STAT, PI3K/Akt/mTOR, NF-κB, TGF-β, MAPK and Wnt/β-catenin signaling pathways. The limitations of using sanguinarine in clinical application are also discussed, and the research prospects of this subject are outlined. In general, sanguinarine, a natural medicine, has many pharmacological effects, but its toxicity and safety in clinical application still need to be further studied. This review provides useful information for the development of sanguinarine-based bioactive agents.

Bioactive Compounds from Plant Origin as Natural Antimicrobial Agents for the Treatment of Wound Infections

The rising prevalence of drug-resistant bacteria underscores the need to search for innovative and nature-based solutions. One of the approaches may be the use of plants that constitute a rich source of miscellaneous compounds with a wide range of biological properties. This review explores the antimicrobial activity of seven bioactives and their possible molecular mechanisms of action. Special attention was focused on the antibacterial properties of berberine, catechin, chelerythrine, cinnamaldehyde, ellagic acid, proanthocyanidin, and sanguinarine against Staphylococcus aureus, Enterococcus spp., Klebsiella pneumoniae, Acinetobacter baumannii, Escherichia coli, Serratia marcescens and Pseudomonas aeruginosa. The growing interest in novel therapeutic strategies based on new plant-derived formulations was confirmed by the growing number of articles. Natural products are one of the most promising and intensively examined agents to combat the consequences of the overuse and misuse of classical antibiotics.

Studies on the Inhibition Mechanism of Linalyl Alcohol against the Spoilage Microorganism Brochothrix thermosphacta

The aim of this study was to investigate the bacterial inhibitory ability and mechanism of action of linalyl alcohol against B. thermosphacta. Linalyl alcohol causes the leakage of intracellular material by disrupting the cell wall and exposing the hydrophobic phospholipid bilayer, which binds to bacterial membrane proteins and alters their structure. In addition, linalyl alcohol causes cell membrane damage by affecting fatty acids and proteins in the cell membrane. By inhibiting the synthesis of macromolecular proteins, the normal physiological functions of the bacteria are altered. Linalyl alcohol binds to DNA in both grooved and embedded modes, affecting the normal functioning of B. thermosphacta, as demonstrated through a DNA interaction analysis.

The antibacterial activity of berberine against Cutibacterium acnes: its therapeutic potential in inflammatory acne

Cutibacterium acnes (C. acnes) is a major pathogen implicated in the evolution of acne inflammation. Inhibition of C. acnes-induced inflammation is a prospective acne therapy strategy. Berberine (BBR), a safe and effective natural ingredient, has been proven to exhibit powerful antimicrobial and anti-inflammatory properties. However, the antimicrobial effect of BBR against C. acnes and its role in C. acnes-mediated inflammatory acne have not been explored. The objective of this investigation was to assess the antibacterial activity of BBR against C. acnes and its inhibitory effect on the inflammatory response. The results of in vitro experiments showed that BBR exhibited significant inhibition zones against four C. acnes strains, with the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) in the range of 6.25-12.5 μg/mL and 12.5-25 μg/mL, respectively. On the bacterial growth curve, the BBR-treated C. acnes exhibited obvious growth inhibition. Transmission electron microscopy (TEM) images indicated that BBR treatment resulted in significant morphological changes in C. acnes. High-content imaging analysis further confirmed that BBR could effectively inhibit the proliferation of C. acnes. The disruption of cell wall and cell membrane structure by BBR treatment was preliminary confirmed according to the leakage of cellular contents such as potassium (K+), magnesium (Mg2+), and alkaline phosphatase (AKP). Furthermore, we found that BBR could reduce the transcript levels of genes associated with peptidoglycan synthesis (murC, murD, mraY, and murG). Meanwhile, we investigated the modulatory ability of BBR on C. acnes-induced skin inflammation in mice. The results showed that BBR effectively reduced the number of C. acnes colonized in mice's ears, thereby alleviating ear swelling and erythema and significantly decreasing ear thickness and weight. In addition, BBR significantly decreased the levels of pro-inflammatory cytokines IL-6, IL-1β, and TNF-α in auricular tissues. These results suggest that BBR has the potential to treat inflammatory acne induced by C. acnes.

A CuS@g-C3N4 heterojunction endows scaffold with synergetic antibacterial effect

Graphitic carbon nitride (g-C3N4) had aroused tremendous attention in photodynamic antibacterial therapy due to its excellent energy band structure and appealing optical performance. Nevertheless, the superfast electron-hole recombination and dense biofilm formation abated its photodynamic antibacterial effect. To this end, a nanoheterojunction was synthesized via in-situ growing copper sulfide (CuS) on g-C3N4 (CuS@g-C3N4). On the one hand, CuS could form Fermi level difference with g-C3N4 to accelerate carrier transfer and thus facilitate electron-hole separation. On the other hand, CuS could respond near-infrared light to generate localized thermal to disrupt biofilm. Then the CuS@g-C3N4 nanoparticle was introduced into the poly-l-lactide (PLLA) scaffold. The photoelectrochemistry results demonstrated that the electron-hole separation efficiency was apparently enhanced and thereby brought an approximate sevenfold increase in reactive oxygen species (ROS) production. The thermal imaging indicated that the scaffold possesses a superior photothermal effect, which effectively eradicated the biofilm by disrupting its extracellular DNA and thereby facilitated to the entry of ROS. The entered ROS could effectively kill the bacteria by causing protein, K+, and nucleic acid leakage and glutathione consumption. As a consequence, the scaffold displayed an antibacterial rate of 97.2% and 98.5% against E. coli and S. aureus, respectively.