Antibacterial Research Articles

Synthesis and antibacterial potential of novel thymol derivatives against methicillin-resistant Staphylococcus aureus and P. aeruginosa pathogenic bacteria.

The increasing threat of antibiotic resistance has created an urgent need for new antibacterial agents, particularly plant-based natural compounds and their derivatives. Thymol, a natural monoterpenoid phenolic compound derived from Monarda citriodora, is known for its aromatic and therapeutic properties, including antibacterial activity. This study focuses on synthesizing dihydropyrimidinone and dihydropyridine derivatives of thymol and exploring their antibacterial properties. The synthesized compounds were tested for their in vitro antibacterial potential against pathogenic microorganisms, specifically Pseudomonas aeruginosa (Gram-negative) and methicillin-resistant Staphylococcus aureus (MRSA) (Gram-positive). Among the synthesized derivatives, compound 3i (ethyl 4-(4-hydroxy-5-isopropyl-2-methylphenyl)-2-imino-6-methyl-1,2,3,4-tetrahydropyrimidine-5-carboxylate) exhibited the most promising antibacterial activity, with minimum inhibitory concentration (MIC) values of 12.5µM against P. aeruginosa and 50.0µM against MRSA. Additionally, compound 3i demonstrated a synergistic effect when combined with vancomycin, enhancing its antibacterial efficacy. The optimum fractional inhibitory concentration index (FICI) observed was 0.10 and 0.5 for MRSA and P. aeruginosa, respectively, in combination with vancomycin. In silico analysis of the physiochemical properties of 3i indicated compliance with all drug-likeness rules. Furthermore, molecular docking studies revealed that compound 3i has a stronger binding affinity to the target protein than thymol, providing valuable insights into its potential mechanism of action.

Inhibitory effects of chlorhexidine-loaded calcium carbonate nanoparticles against dental implant infections

This study aimed to design sustained released biodegradable calcium carbonate nanoparticles loaded with chlorhexidine (CHX-loaded NPs) and to investigate the early osteogenic differentiation and antimicrobial effects on the important bacteria involved in infections of dental implants. The microemulsion method was used to prepare the calcium carbonate nanoparticles loaded with chlorhexidine. The prepared nanoparticles were characterized using conventional methods. The release pattern determination and the biodegradation test were performed for the prepared nanoparticles. For the early osteogenic differentiation test of the prepared nanoparticles, alkaline phosphatase (ALP) activity was detected in human dental pulp stem cells (HDPSCs). The antimicrobial effects of the nanoparticles were evaluated against Escherichia coli, Streptococcus mutans, Enterococcus faecalis, Staphylococcus aureus, and Pseudomonas aeruginosa. The sizes of free calcium carbonate nanoparticles and CHX-loaded NPs were 105 ± 1.63 and 118 ± 1.47 nm and their zeta potentials were − 27 and − 36, respectively. A 50% degradation of nanoparticles was achieved after 100 days. These nanoparticles showed a two-stage sustained release pattern in vitro. Microscopic images revealed that the morphology of free calcium carbonate nanoparticles primarily took on a spherical calcite form, while CHX-loaded NPs predominantly exhibited a cauliflower-like vaterite polymorph. The nanoparticles increased the activity of ALP in cells in two weeks significantly (p < 0.05). Antimicrobial and antibiofilm results showed an efficient effect of the prepared nanoparticle against the studied bacteria. Calcium carbonate nanoparticles are an efficient multifunctional vector for chlorhexidine and can be used as a bioactive antibacterial agent against various oral microorganisms to prevent implant infections.

Recent Progress in Terrestrial Biota Derived Antibacterial Agents for Medical Applications

Conventional antibiotic and multidrug treatments are becoming less and less effective and the discovery of new effective and safe antibacterial agents is becoming a global priority. Returning to a natural antibacterial product is a relatively new current trend. Terrestrial biota is a rich source of biologically active substances whose antibacterial potential has not been fully utilized. The aim of this review is to present the current state-of-the-art terrestrial biota-derived antibacterial agents inspired by natural treatments. It summarizes the most important sources and newly identified or modified antibacterial agents and treatments from the last five years. It focuses on the significance of plant- animal- and bacteria-derived biologically active agents as powerful alternatives to antibiotics, as well as the advantages of utilizing natural antibacterial molecules alone or in combination with antibiotics. The main conclusion is that terrestrial biota-derived antibacterial products and substances open a variety of new ways for modern improved therapeutic strategies. New terrestrial sources of known antibacterial agents and new antibacterial agents from terrestrial biota were discovered during the last 5 years, which are under investigation together with some long-ago known but now experiencing their renaissance for the development of new medical treatments. The use of natural antibacterial peptides as well as combinational therapy by commercial antibiotics and natural products is outlined as the most promising method for treating bacterial infections. In vivo testing and clinical trials are necessary to reach clinical application.

Exploration of vanoxerine analogues as antibacterial agents.

Mycobacterium tuberculosis is a bacterial pathogen, responsible for approximately 1.3 million deaths in 2022 through tuberculosis infections. The complex treatment regimen required to treat tuberculosis and growing rates of drug resistance, necessitates the development of new anti-mycobacterial agents. One approach is to repurpose drugs from other clinical applications. Vanoxerine (GBR 12909) was previously shown to have anti-mycobacterial activity, through dissipating the membrane electric potential and hence, cellular energetics. Several vanoxerine analogues were synthesised in this study, which exhibited a range of activities against mycobacteria and enterococcus. All active analogues had similar impacts on the membrane electric potential and inhibition of ethidium bromide efflux. The most active compound displayed reduced inhibitory activity against the known human target of vanoxerine, the dopamine transporter. This work has identified a promising analogue, which could provide a starting point for further medicinal chemistry and drug development efforts to target mycobacteria.

ANTIBACTERIAL THERAPY IN SEPSIS PATIENTS

Today, sepsis, the cause of which is purulent-inflammatory processes of soft tissues, accounts for more than 45% of cases. In most multidisciplinary hospitals, the frequency of gram-positive and gram-negative sepsis is approximately the same. Antibacterial therapy (ABT) is the most important component of the complex therapy of sepsis, and early adequate empiric ABT leads to a decrease in mortality and the frequency of complications. ABT of sepsis at the beginning of treatment, in most cases, is empirical in nature, but it should be remembered that taking the material for microbiological research must be done before the start of antibacterial therapy! According to the principles adopted in the guideline "Sepsis - 3", the use of antibiotics for the treatment of sepsis is a necessary component, the effectiveness of which cannot be doubted. It should be remembered that a delay in the appointment of an antibacterial drug to patients with sepsis and septic shock for 1 hour leads to an increase in the risk of death of the patient by 7,6%. Empiric ABT should be initiated with a broad-spectrum regimen of one or more antibiotics in patients with sepsis or septic shock to cover all possible pathogens (including bacterial, possibly fungal, or viral). Empiric ABT should be narrowed after identification of the pathogen and determination of its sensitivity and/or when adequate clinical improvement is registered. There are no indications for long-term systemic antibacterial prophylaxis in patients with severe forms of inflammatory conditions of non-infectious origin (for example, severe pancreatitis, burns). Measurement of procalcitonin levels can be used to shorten the duration of antibacterial therapy in patients with sepsis. Rapid interpretation of the severity of the infectious process can be performed using ACCP/SCCM sepsis diagnostic criteria, organ dysfunction criteria (gSOFA, SOFA, MODS) or rapid procalcitonin test. Microbiological diagnosis of sepsis is the main factor in prescribing adequate ABT regimens. In the case when the same microorganism is released from the probable source of infection and from the peripheral blood, its etiological role in the development of sepsis should be considered as evidential. The standard for testing blood for sterility is the collection of material from two peripheral veins with an interval of up to 30 minutes, while blood from each vein must be collected in two vials. It is not permissible to take blood from the catheter! Building an ABT algorithm taking into account the etiology and characteristics of resistance of microorganisms to antibacterial drugs is the most optimal approach. Тoday, the optimal regimen of empiric ABT of sepsis with PON is carbapenems - as drugs that have the widest spectrum of action and to which the lowest level of resistance is observed among intra-hospital strains of gram(-) bacteria. In some cases, an alternative to carbapenems is cefepime, ceftaroline, protected by antipseudomonas β-lactams (cefaperazone/sulbactam, piperacillin/tazobactam) and "respiratory" fluoroquinolones. In cases of ineffectiveness of the indicated regimens of ABT, the feasibility of additional appointment of glycopeptides (vancomycin, teicoplanin or linezolid), as well as systemic antimycotics (fluconazole) should be evaluated. The latter should also be prescribed after 7-10 days after the start of ABT in a prophylactic dose of 150 mg per week.

From resistance to remedy: the role of clustered regularly interspaced short palindromic repeats system in combating antimicrobial resistance-a review.

The growing challenge of antimicrobial resistance (AMR) poses a significant and increasing risk to public health worldwide, necessitating innovative strategies to restore the efficacy of antibiotics. The precise genome-editing abilities of the CRISPR-Cas system have made it a potent instrument for directly targeting and eliminating antibiotic resistance genes. This review explored the mechanisms and applications of CRISPR-Cas systems in combating AMR. The latest developments in CRISPR technology have broadened its potential use, encompassing programmable antibacterial agents and improved diagnostic methods for antibiotic-resistant infections. Nevertheless, several challenges must be overcome for clinical success, including the survival of resistant bacteria, generation of anti-CRISPR proteins that reduce effectiveness, and genetic modifications that change target sequences. Additionally, the efficacy of CRISPR-Cas systems differs across bacterial species, making their universal application challenging. After overcoming these challenges, CRISPR-Cas has the potential to revolutionize AMR treatment, restore antibiotic efficacy, and reshape infection control.

Evidence of tosufloxacin deposition in the kidneys of a patient presenting with crystal nephropathy.

Tosufloxacin tosilate is classified as a new quinolone antibacterial agent, which has been reported to cause crystal nephropathy. However, the origin of these crystal deposits has not yet been elucidated. We encountered a case of renal failure that progressed slowly owing to crystal-forming interstitial nephritis after long-term exposure to tosufloxacin. Mass spectrometry of the renal specimens revealed that tosufloxacin was deposited in the kidneys. The patient's renal function improved slowly with the withdrawal of tosufloxacin and steroid therapy. This is the first case to demonstrate the presence of crystal deposits consisting of tosufloxacin.

Secondary Metabolites Screening Using GC-MS and In-Vitro Biological Assessment Against Human Pathogenic Bacterial Strains of Viola Indica

Viola indica, a medicinal herb with a long history of traditional use in treating various diseases. In this study we analyzed methanolic extract of Viola indica for metabolite composition using GC-MS, and antibacterial activity through disc diffusion method. In GC-MS analysis, we found total of 25 metabolites in which the major metabolites were 9,12-Octadecadienoic acid (Z,Z)- (20%; 20.34 min), followed by Stigmasterol, 22,23-dihydro- (16%; 26 min) and α-Amyrin (12.38%; 26.65 min) . In antibacterial activity viola indica methanolic extract showed significant antibacterial effects against all bacterial strains. The highest antibacterial activity was recorded against Bacillus subtilis (8.50±0.20 mm), followed by Klebsiella pneumoniae (8.10±0.25 mm) zone of inhibition, while the lowest was recorded against Staphylococcus aureus (2.10±0.30 mm). The result of this study suggests that viola indica has potent antibacterial metabolites with good potential as a natural alternative to synthetic antibacterial agents. However, this study also suggest that more instrumental and biological research is required to explore it’s in-depth phytochemistry, pharmacological potential and toxicological properties.

Synthesis and evaluation of antibacterial and antibiofilm agents based on phenylamino-substituted 1,4-benzoquinones.

Aim: This work describes the synthesis and antimicrobial evaluation of 6-aminated 1,4-benzoquinones (6-AQs) against seven resistant pathogens.Materials & methods: The 6-AQs, synthesized via a Michael addition reaction between bromoquinone and p-substituted anilines, were assessed for their antimicrobial activity through both in vitro and in silico analyses.Results: Bromoquinone and 6-AQs with electron-withdrawing groups demonstrated activity against Pseudomonas aeruginosa, with minimum inhibitory concentrations ranging from 16 to 128μg/ml, comparable to standard antimicrobials. Two derivatives exhibited minimum inhibitory concentrations values against methicillin-resistant Staphylococcus aureus ranging from 64 to 128μg/ml. These compounds demonstrated both bacteriostatic and bactericidal effects, and antibiofilm features.Conclusion: The 6-AQs 19g and 19f showed a promising antimicrobial profile, indicating their potential as new therapeutic options.

Azithromycin induces liver injury in mice by targeting the AMPK/Nrf2 pathway

Background Azithromycin is an antibacterial and anti-inflammatory drug widely used for the treatment of various diseases, including those caused by atypical pathogens, bacterial or viral infections, chronic sinusitis, and bronchial asthma, particularly in pediatric patients. However, concerns have emerged regarding its hepatotoxicity and its precise mechanism of action remains unclear. Objective To investigate the molecular mechanisms responsible for azithromycin-induced acute liver injury to advance our understanding of the progression and pathogenesis of antibiotic-induced liver damage, and to improve prevention and treatment strategies. Materials and methods C57BL/6 mice, Nrf2-/- mice, and primary hepatocytes were used. Primary hepatocytes from mice were isolated using a two-step perfusion method and cultured in vitro via the ‘sandwich’ culture model. Results The exposure to azithromycin resulted in increased apoptosis and reactive oxygen species (ROS) levels. In mouse models, intraperitoneal administration of azithromycin at varying concentrations and time points substantially induced hepatic disarray, swelling, and dysfunction. Azithromycin markedly upregulated the mRNA and protein levels of phosphorylated adenosine-activated protein kinase (AMPK) while downregulating nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase 1 (HO-1), and NADPH: quinone oxidoreductase 1 (NQO-1). Moreover, HO-1 and NQO-1 protein levels remained largely unaffected in primary hepatocytes co-cultured with azithromycin in Nrf2-/- mice. Conclusions Our findings suggest that azithromycin-induced acute liver injury is mediated by suppression of Nrf2 activation and ROS production. This sheds light on the potential mechanisms involved in azithromycin-induced liver damage, underscoring the importance of exploring targeted interventions to mitigate the hepatotoxic effects.

Signaling Molecules in Pseudomonas aeruginosa Response to Antibiotics at Sub-Inhibitory Concentrations

Signaling Molecules are N-acylhomoserine lactones (AHLs) that form the Pseudomonas aeruginosa cell information system which determines gene expressions in a population dependent manner called quorum sensing (QS). Signal molecules, which are chemically varied, control genes expressions to antibiotics resistance, pathogenicity, motility, biofilm development, bioluminescence, secondary metabolite production, and plasmid transfer. This research was aimed to identify the signaling molecules in Pseudomonas aeruginosa response to antibiotics at sub-inhibitory concentrations. One hundred and fifty (150) clinical swab specimens were collected from urinary catheter wound and ear infection of patients and the swabs inoculated using standard microbiology method. The isolates were characterized based on the bacteriological methods such as morphology and biochemical tests. The isolates were further confirmed by species specific PCR by amplification of 16S rRNA and the amplicons were analyzed by gel electrophoresis; and further genomic sequencing was done and blast with NCBI database mining. Disc diffusion method was applied for the antibiotics susceptibility pattern. The isolates cell suspensions were analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). The result of the isolation showed 22(59.46%) from wound infections, 12(32.43%) from ear infections and 3(8.11%) from urinary catheter. The isolates were Gram negative, produced β-hemolysis on blood agar and the morphology is small pigmented circular in form. The isolates showed positive result to catalase, oxidase, citrate, nitrate and indole tests. The amplification of 16S rRNA gene region resulted in the band size of 1500bp PCR product and the BLAST analysis gave 99% similarity. The resistant antibiotics susceptibility showed that Pseudomonas aeruginosa is multidrug resistant bacteria. The GC-MS results obtained from urinary catheter isolates showed four (4) signaling molecules such as N-Octanoyl-L-homoserine Lactone, N-Decanoyl-DL-Homoserine Lactone, N-Dodecanoyl-DL-Homoserine Lactone and N-Tetradecanoyl-L-Homoserine Lactone. Three (3) signaling molecules such as N-Octanoyl-L-homoserine Lactone, N-Decanoyl-DL-Homoserine Lactone and N-Tetradecanoyl-L-Homoserine Lactone were obtained from wound isolates. N-Tetradecanoyl-L-Homoserine Lactone was the only signaling molecule obtained from ear isolates. Further research should be done to develop rapid tests that could be possible to detect acyl homoserine specific to Pseudomonsa aeruginosa present to human samples and deliver results in real time. Signaling molecules inhibitors (SMI) are possible potential therapeutics that could produce the subsequent class of antibacterial drugs. The fundamental role of each signal molecule in the production of biofilms and virulent factors should also be investigated, as well as whether Pseudomonas aeruginosa needs one or more signaling molecules to form quorum sensing. Identification of the signals molecules (AHLs) of P. aeruginosa and developing signaling molecules inhibitors (SMI) can have an important prognostic, diagnostic and therapeutic value in human medicine for the treatment of P. aeruginosa infections.

Antibacterial Capabilities of Metallic Nanoparticles and Influencing Factors

ABSTRACTThe increase of antibiotic resistance in bacteria has become a major concern for successful diagnosis and treatment of infectious diseases. Over the past few decades, significant progress has been achieved on the development of nanotechnology‐based medicines for combating multidrug resistance in microorganisms. Among these, metallic nanoparticles (MNPs) hold great promise in addressing this challenge due to their broad‐spectrum and robust antimicrobial properties. This review illustrates the antibacterial activities of MNPs and further elucidates how different factors including synthesis method, size, shape, surface charge, pH, dose, type of capping or stabilizing agents of MNPs, and Gram‐type of the bacteria, impact their antibacterial activities, which are expected to promote the future development of more potent MNP‐based antibacterial agents.

Modern approaches to the eradication of &lt;i&gt;Helicobacter pylori&lt;/i&gt;: a spectrum of perspectives

Helicobacter pylori is one of the most widespread infections, affecting approximately 50% of the global population, with the Russian Federation ranking among the regions with a relatively high prevalence. Eradication therapy remains the primary strategy, not only for the treatment and prevention of gastrointestinal diseases but also for reducing the risk of stomach cancer, highlighting the medical and social impact of this infection. A key factor contributing to the reduced effectiveness of eradication therapy is the microorganism’s primary or secondary resistance to antibacterial drugs, a problem recognized worldwide. It is widely acknowledged that national treatment regimens for Helicobacter pylori infection must be adapted based on systematic antimicrobial sensitivity testing to curb the rise of global antibiotic resistance. Despite decades of research and clinical practice, identifying the most effective, safe, and straightforward therapy remains a significant challenge for clinicians. This review provides a comparative analysis of current treatment recommendations for Helicobacter pylori infection, as presented by various national and regional gastroenterological societies, including those relevant in the Russian Federation.

Experimental and real-life effectiveness of the herbal drug Sinupret® extract in the treatment of acute rhinosinusitis in the context of the strategy for the rational use of antibacterial drugs

Aim. To substantiate the clinical and experimental effectiveness of the herbal medicine Sinupret® extract for acute rhinosinusitis (ARS), with an emphasis on the strategy of rational use of antibiotics. Materials and methods. A meta-analysis of clinical studies ARhiSi-1 (EudraCT No. 2008-002794-13) and ARhiSi-2 (EudraCT No. 2009-016682-28), which included 676 patients, was performed. The main focus was on reducing Symptom Severity Scale (SSS) scores and improving Sinus Osteopathy Test (SNOT-20) scores with Sinupret® extract. In addition, a retrospective cohort study involving 203,382 patients was conducted to compare the real-world effectiveness of Sinupret® extract in reducing ARS-related side effects with antibiotics and other conventional treatments. Results. The use of the drug Sinupret® extract contributed to the improvement of symptoms of ARS, which was reflected in a decrease in the average score on the CVS by 1.9 points (p0.0001) and an improvement in the quality of life (QoL) of patients according to the SNOT-2 test, by 3.5 points (p=0.001) compared to placebo. In patients with moderate and severe symptoms, the effect of Sinupret® extract was even more significant (PVS -2.3 points; p0.0001; SNOT-20 -4.9 points; p=0.0158). Moreover, the use of the drug Sinupret® extract showed equal or greater effectiveness in reducing the risk of adverse outcomes associated with ARS, such as prescription of antibiotics, prolongation of illness by ≥7 days or the need to visit a doctor, especially compared with antibiotics. Conclusion. Sinupret® extract is a safe and effective treatment for ARS, which may help reduce the overuse of antibiotics.

One-pot synthesis of monodisperse silver-lignin particles: Enhanced antibacterial agents against antibiotic-resistant bacteria

Lignin-based supports for metal nanoparticles (NPs) have attracted significant attention due to their abundant functional groups that facilitate NPs loading. However, many studies involve a two-step process: fabricating lignin particles and then reducing metal ions to NPs using physical energy consumption or chemical reduction. A one-step in-situ reduction method for NP synthesis on carrier surfaces, eliminating energy consumption, is needed for environmentally friendly and sustainable approach. Herein, we demonstrate that poly-l-lysine (PL) controls the self-assembly kinetics of kraft lignin (KL), and reduces silver ion (Ag+) to silver nanoparticles (AgNPs), forming highly monodisperse, co-self-assembled PL-KL particles (Ag@PL-KLPs) without chemical reducing agents or energy consumption. PL facilitated rapid KL desolvation, promoting intermolecular interactions and silver ion adsorption, followed by an efficient, separate nucleation and growth process yielded Ag@PL-KLPs approximately 270 nm in size with a narrow distribution. Notably, Ag@PL-KLPs exhibited enhanced bacteriostatic and bactericidal properties against antibiotic-resistant bacteria (ARB), including both Gram-negative and Gram-positive strains, at concentrations of 250 μg/mL. Leveraging biomass-derived lignin and this cost-effective, one-step green synthesis approach offers a sustainable method for avoiding antibiotic overuse and environmental contamination.

The Antibacterial Activities and Effects of Baicalin on Ampicillin Resistance of MRSA and Stenotrophomonas maltophilia.

The development of novel antibacterial agents from plant sources is emerging as a successful strategy to combat antibiotic resistance in pathogens. In this study, we systemically investigated the antibacterial activity and underlying mechanisms of baicalin against methicillin-resistant Staphylococcus aureus (MRSA) and Stenotrophomonas maltophilia. Our results showed that baicalin effectively restrained bacterial proliferation, compromised the integrity of cellular membranes, increased membrane permeability, and triggered oxidative stress within bacteria. Transcriptome profiling revealed that baicalin disrupted numerous biological pathways related to antibiotic resistance, biofilm formation, cellular membrane permeability, bacterial virulence, and so on. Furthermore, baicalin demonstrated a synergistic antibacterial effect when combined with ampicillin against both MRSA and S. maltophilia. In conclusion, baicalin proves to be a potent antibacterial agent with significant potential for addressing the challenge of antibiotic resistance in pathogens.

In vitro antibacterial activity of essential oils from Cymbopogon flexuosus and Cymbopogon winterianus

The objective of the study was to identify and quantify chemical compounds present in the essential oils of C. flexuosus and C. winterianus and evaluate their antibacterial action on Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. This is an in vitro experimental study using essential oils of Cymbopogon flexuosus and Cymbopogon winterianus. The gram-negative strains E. coli (ATCC 25922) and P. aeruginosa (ATCC 27853) and Staphylococcus aureus (ATCC 25923) were used as a Gram-positive strain for the analysis of the antibacterial properties of essential oil. Oil analyzes were carried out using gas chromatography coupled to mass spectrometry (GC/MS). The antibacterial activity of lemongrass (Cymbopogon flexuosus) and citronella (Cymbopogom winterianus) essential oils against bacteria of pathological relevance was confirmed, denoting the potential of using plant essential oils as antibacterial agents, an important alternative considering the emergence of antibiotic resistance.

Microwave-assisted synthesis of novel [1,4] oxazine derivatives as potent anti-bacterial and antioxidant agents

Microwave-assisted synthesis of novel [1,4] oxazine derivatives as potent anti-bacterial and antioxidant agents

HPLC analysis and antimicrobial activity of Vitex altissima leaves extracts

The exploration of ethnomedicinal plants for phytochemical and pharmacological properties is crucial for developing novel therapeutics for chronic diseases. Vitex altissima, known as the Peacock chaste tree, is a significant member of the Verbenaceae family, is widely utilized in traditional medicine. This study investigates the phytochemical composition and antibacterial properties of V. altissima, a plant recognized for its medicinal use by various indigenous communities, including the Malayali tribes of Servarayan hills. The study involved extracting phytochemicals from the leaves of V. altissima using hexane, ethyl acetate and methanol through soxhlet extraction. The extracts were analyzed for secondary metabolites, including carbohydrates, proteins, amino acids, steroids, glycosides, alkaloids, tannins, phenolics, flavonoids, terpenoids, saponins, anthraquinones, oils and resins, diterpenes, phlobatannins and coumarins. Quantitative assessments of phenolic compounds, flavonoids and alkaloids were performed. Column chromatography was employed to fractionate the methanolic extract, resulting in 12 distinct fractions. These fractions were screened for antibacterial activity against E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Streptococcus mutans and Staphylococcus aureus using the agar well diffusion method. The minimal inhibitory concentration (MIC) was determined through a 2-fold serial dilution technique. High-performance liquid chromatography (HPLC) was utilized to identify the polyphenolic compounds responsible for antibacterial activity. Phytochemical screening revealed a diverse array of bioactive compounds in the extracts, with methanol extracts showing the highest total phenolic content (218 ± 7.21 mg GAE/g of extract) and significant antibacterial activity. The ethyl acetate extract exhibited the highest total flavonoid content (40.67 ± 6.65 mg QE/g of extract). Among the fractions, the column fraction from the chloroform-methanol gradient (VACF) demonstrated superior antimicrobial activity, particularly against S. mutans and P. aureginosa. The MIC values for VACF were 427 µg/mL for P. aeruginosa and 400 µg/mL for S. aureus, indicating potent antibacterial properties. HPLC analysis identified key polyphenolic compounds, including p-coumaric acid, ferulic acid and elagic acid, as the primary contributors to the antibacterial activity. The presence of these compounds aligns with the observed antimicrobial efficacy and highlights the potential of V. altissima extracts as a source of natural antibacterial agents.

Preparation of pectin/carboxymethyl cellulose composite films via high-pressure processing and enhancement of antimicrobial packaging

This study investigated the impact of high-pressure processing (HPP) treatment on the structure and physicochemical properties of pectin (PEC)/carboxymethyl cellulose (CMC) composite films, along with the development of new active films incorporating emodin as an antibacterial agent. The results showed that 500 MPa/20 min HPP treatment significantly improved the tensile strength (from 45.91 ± 4.63 MPa to 52.24 ± 4.87 MPa) and elongation at the break (from 5.00 ± 1.44 % to 11.72 ± 2.97 %) of the films. It also improved the film's thermal stability and had no significant effect on its thermal degradability. Moreover, emodin was incorporated into the PEC/CMC film-forming solution and subjected to 500 MPa/20 min HPP treatment to investigate the structure, functional properties, optical properties, and antibacterial activity of the film. The emodin caused the film structural alteration, but significantly improved the water vapor barrier properties. It also reduced the film brightness and light transmission. The antibacterial assessment demonstrated that the film's antibacterial activity was correlated positively with increasing emodin content, and the number of viable cells of Staphylococcus aureus decreased by 1.29 log10 CFU/mL, 1.70 log10 CFU/mL, and 1.80 log10 CFU/mL with different levels of EM antimicrobial films after 12 h.