Antibacterial and antibiofilm activity of acetone leaf extracts of nine under-investigated south African Eugenia and Syzygium (Myrtaceae) species and their selectivity indices

Assessment of antibacterial activity, modes of action, and synergistic effects of Origanum vulgare hydroethanolic extract with antibiotics against avian pathogenic Escherichia coli

This study evaluates the antibacterial effectiveness of Origanum vulgare hydroethanolic extract, both independently and in combination with antibiotics, against Escherichia coli strains associated with avian colibacillosis-a significant concern for the poultry industry due to the rise of antibiotic-resistant E. coli. The urgent demand for new treatments is addressed by analyzing the extract's phytochemical makeup via High-Performance Liquid Chromatography (HPLC), which identified sixteen phenolic compounds. Antibacterial activity was determined through agar diffusion and the measurement of minimum inhibitory and bactericidal concentrations (MIC and MBC), showing moderate efficacy (MIC: 3.9 to 7.8 mg/mL, MBC: 31.2 to 62.4 mg/mL). Combining the extract with antibiotics like ampicillin and tetracycline amplified antibacterial activity, indicating a synergistic effect and highlighting the importance of combinatory treatments against resistant strains. Further analysis revealed the extract's mechanisms of action include disrupting bacterial cell membrane integrity and inhibiting ATPase/H+ proton pumps, essential for bacterial survival. Moreover, the extract effectively inhibited and eradicated biofilms, crucial for preventing bacterial colonization. Regarding cytotoxicity, the extract showed no hemolytic effect at 1 to 9 mg/mL concentrations. These results suggest Origanum vulgare extract, particularly when used with antibiotics, offers a promising strategy for managing avian colibacillosis, providing both direct antibacterial benefits and moderating antibiotic resistance, thus potentially reducing the economic impact of the disease on the poultry industry.

Antibacterial and Antibiofilm Properties of Native Australian Plant Endophytes against Wound-Infecting Bacteria

The wound management field faces significant challenges due to antimicrobial resistance (AMR) and the complexity of chronic wound care. Effective wound treatment requires antimicrobial dressings to prevent bacterial infections. However, the rise of AMR necessitates new antimicrobial agents for wound dressings, particularly for addressing bacterial pathogens like methicillin-resistant Staphylococcus aureus (MRSA). Endophytic fungi, known for producing diverse bioactive compounds, represent a promising source of such new agents. This study tested thirty-two endophytic fungi from thirteen distinct Australian native plants for their antibacterial activity against S. aureus. Ethyl acetate (EtOAc) extracts from fungal culture filtrates exhibited inhibitory effects against both methicillin-sensitive S. aureus ATCC 25923 (MIC = 78.1 µg/mL) and MRSA M180920 (MIC = 78.1 µg/mL). DNA sequence analysis was employed for fungal identification. The most active sample, EL 19 (Chaetomium globosum), was selected for further analysis, revealing that its EtOAc extracts reduced S. aureus ATCC 25923 biofilm formation by 55% and cell viability by 57% to 68% at 12 × MIC. Furthermore, cytotoxicity studies using the brine shrimp lethality test demonstrated low cytotoxicity up to 6 × MIC (25% mortality rate) with an LC50 value of 639.1 µg/mL. Finally, the most active sample was incorporated into polycaprolactone (PCL) fiber mats via electrospinning, with resultant inhibition of S. aureus species. This research underscores the potential of endophytic fungi from Australian plants as sources of substances effective against common wound pathogens. Further exploration of the responsible compounds and their mechanisms could facilitate the development of wound dressings effective against MRSA and innovative biofilm-resistant electrospun fibers, contributing to the global efforts to combat AMR.

Genomic Characterization of Bacillus pumilus Sonora, a Strain with Inhibitory Activity against Vibrio parahaemolyticus-AHPND and Probiotic Candidate for Shrimp Aquaculture

Acute hepatopancreatic necrosis disease, caused by Vibrio parahaemolyticus strains carrying the pirA and pirB toxin genes (VpAHPND), has been causing great economic losses in Asia and America in the shrimp farming industry. Numerous strains are resistant to antibiotics. However, supplementation with probiotic antagonists has become a more desirable treatment alternative. Fourteen strains of microorganisms were assessed for their potential to inhibit VpAHPND in vitro activity. The bacteria with the highest activity were challenged with VpAHPND-infected Pacific white shrimp Litopenaeus vannamei. Furthermore, the genomic characteristics of probiotic bacteria were explored by whole-genome sequencing. We identified the Sonora strain as Bacillus pumilus, which possesses positive proteolytic and cellulolytic activities that may improve shrimp nutrient uptake and digestion. Challenge trials showed a low cumulative mortality (11.1%). B. pumilus Son has a genome of 3,512,470 bp and 3734 coding sequences contained in 327 subsystems. Some of these genes are related to the biosynthesis of antimicrobial peptides (surfactins, fengycin, schizokinen, bacilibactin, and bacilysin), nitrogen and phosphorus metabolism, and stress response. Our in vitro and in vivo findings suggest that B. pumilus Sonora has potential as a functional probiotic.

Compound isolation through bioassay-guided fractionation of Tectona grandis leaf extract against Vibrio pathogens in shrimp

Tectona grandis Linn, commonly known as teak, is traditionally used to treat a range of diseases, including the common cold, headaches, bronchitis, scabies, diabetes, inflammation, and others. The present study was conducted with the purpose of isolating and identifying the active compounds in T. grandis leaf against a panel of Vibrio spp., which may induce vibriosis in shrimp, using bioassay-guided purification. The antimicrobial activity was assessed using the microdilution method, followed by the brine shrimp lethality assay to determine toxicity. Following an initial screening with a number of different solvents, it was established that the acetone extract was the most effective. The acetone extract was then exposed to silica gel chromatography followed by reversed-phase HPLC and further UHPLC-orbitrap-ion trap mass spectrometry to identify the active compounds. Three compounds called 1-hydroxy-2,6,8-trimethoxy-9,10-anthraquinone, deoxyanserinone B, and khatmiamycin were identified with substantial anti-microbial action against V. parahaemolyticus, V. alginolyticus, V. harveyi, V. anguillarum, and V. vulnificus. The IC50 values of the three compounds viz. 1-hydroxy-2,6,8-trimethoxy-9,10-anthraquinone, deoxyanserinone B, and khatmiamycin varied between 2 and 28, 7 and 38, and 7 and 56 μg/mL, respectively, which are as good as the standard antibiotics such as amoxicillin and others. The in vivo toxicity test revealed that the compounds were non-toxic to shrimp. The results of the study suggest that T. grandis leaf can be used as a source of bioactive compounds to treat Vibrio species in shrimp farming.

Phytochemical Profiling and Biological Activity of the Methanolic Extracts of Cirsium Monspessulanum (L.) Hill

The study of new plant species and the identification of their chemical composition may contribute to the discovery of a new breakthrough substances for pharmacotherapeutical applications. For the first time, we examined antioxidant and antimicrobial activity of 70 % v/v methanolic extracts from inflorescences and roots of Cirsium monspessulanum (L.) Hill. obtained by the ASE method. In the (2,2-diphenyl-1-picrylhydrazyl) DPPH analysis, tested extract of inflorescences showed antioxidant activity with an EC50=0.223±0.0479 mg/mL, and (Cupric Ion Reducting Antioxidant Capacity) CUPRAC test assessed the antiradical activity on 14.95±0.13 mgTE/g and for roots the values were EC50=0.307±0.0554 mg/mL and 11.18±0.49 mgTE/g, respectively. Furthermore, extract from the inflorescences possessed the highest antimicrobial activity against Staphylococcus aureus, Staphylococcus epidermidis and Micrococcus luteus with MIC=1.25 mg/mL for each. HPLC/ESI-QTOF-MS/MS method identified 7 phenolic acids and 14 flavonoids in inflorescences extract and only 7 phenolic acids in roots extract. To the best of our knowledge, this is the first qualitative analysis of Cirsium monspessulanum (L.) Hill. and all substances were described for the first time.

Antibacterial, Antibiofilm, and Antioxidant Activities of Aqueous Crude Gymnema inodorum Leaf Extract against Vancomycin-Resistant Enterococcus faecium

Vancomycin-resistant Enterococcus faecium (VREF) causes nosocomial infections with high mortality and morbidity rates. This study aimed to evaluate the antibacterial and antibiofilm activities of aqueous crude Gymnema inodorum leaf extract (GIE) against the VREF ATCC 700221 strain. The antimicrobial activity of GIE against VREF was performed using disk diffusion and broth microdilution. The antibiofilm activities were evaluated using the crystal violet staining assay. The antioxidant potential was evaluated. Preliminary screening of the antimicrobial activity of 50 and 100 µg/disk of GIE against VREF revealed inhibition zones of 8.33 ± 0.58 mm and 8.67 ± 0.29 mm, respectively. Additionally, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against VREF were 125 and ≥ 250 mg/mL, respectively. SEM analysis showed that treatment with GIE caused morphological changes, including incomplete cell division, damaged cell walls, and cell content leakage, suggesting a disruption of bacterial cells. GIE also inhibited and eradicated biofilms formed by VREF. The extract exhibited antioxidant activities in the DPPH and ABTS assays. While GIE shows potential as an antibacterial and antibiofilm agent, further studies are necessary to fully understand the underlying mechanisms and optimize its use for therapeutic applications.

Coptis rhizome extract influence on Streptococcus pneumoniae through autolysin activation

This study investigated the antibacterial properties of Coptis rhizome, a plant traditionally used for respiratory infections, against Streptoccus pneumonia (S. pneumoniae), for which there has been minimal empirical evidence of effectiveness. The study particularly examined autolysis, indirectly associated with antibacterial resistance, when using Coptis rhizome for bacterial infections. In our methodology, Coptis rhizome was processed with ethanol and distilled water to produce four different extracts: CRET30, CRET50, CRET70, and CRDW. The antibacterial activity of these extracts were tested through Minimum Inhibitory Concentration (MIC) assays, disk diffusion tests, and time-kill assays, targeting both standard (ATCC 49619) and resistant (ATCC 70067) strains. The study also evaluated the extracts' biofilm inhibition properties and monitored the expression of the lyt gene, integral to autolysis. The results prominently showed that the CRET70 extract demonstrated remarkable antibacterial strength. It achieved an MIC of 0.125 µg/mL against both tested S. pneumoniae strains. The disk diffusion assay recorded inhibition zones of 22.17 mm for ATCC 49619 and 17.20 mm for ATCC 70067. Impressively, CRET70 resulted in a 2-log decrease in bacterial numbers for both strains, showcasing its potent bactericidal capacity. The extract was also effective in inhibiting 77.40% of biofilm formation. Additionally, the significant overexpression of the lytA gene in the presence of CRET70 pointed to a potential mechanism of action for its antibacterial effects. The outcomes provided new perspectives on the use of Coptis rhizome in combating S. pneumoniae, especially significant in an era of escalating antibiotic resistance.

Antibacterial and Antifungal Activities of Cimbopogon winterianus and Origanum syriacum Extracts and Essential Oils against Uropathogenic Bacteria and Foodborne Fungal Isolates

This study focused on testing the antibacterial and antifungal activity of Origanum syriacum (O. syriacum) and Cimbopogon winterianus (C. winterianus) extracts and their essential oils (EOs). The bacteria were isolated from urine samples and identified by a VITEK assay, and the fungi were isolated from spoiled food samples and further identified by MALDI-TOF. The susceptibility of the microbial isolates was assessed by determining the bacteriostatic and bactericidal/fungicidal effects by the minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) broth microdilution assay and time-kill test. The antibiofilm activities were assessed by the antibiofilm screening assays. The bacterial isolates included three Gram-negative isolates (Escherichia coli, Klebsiella pneumonia, and Citrobacter freundii) and two Gram-positive isolates (Staphylococcus aureus and Streptococcus intermedius). The fungal isolates included Candida albicans and Aspergillus niger. The O. syriacum and C. winterianus extracts exhibited bacteriostatic and fungistatic activities (MIC 1.25-2.5 mg/mL for the bacterial isolates and 2.5-5 mg/mL for the fungal isolates). However, their EOs exhibited bactericidal (MBC 5-20%) and fungicidal (MFC 1.25-10%) activities, meaning that the EOs had a better antimicrobial potential than the extracts. The antibiofilm activities of the mentioned extracts and their EOs were relatively weak. The O. syriacum extract inhibited S. aureus, S. intermedius, and K. pneumonia biofilms at a concentration of 0.3125 mg/mL and C. albicans and A. niger biofilms at 0.625 mg/mL. No antibiofilm activity was recorded for C. winterianus extract. In addition, the packaging of grapes with C. winterianus extract preserved them for about 40 days. The results reflect the significant antimicrobial activity of O. syriacum and C. winterianus extracts and their EOs, thus suggesting their potential in food packaging and preservation.

Unveiling the Multifaceted Capabilities of Endophytic Aspergillus flavus Isolated from Annona squamosa Fruit Peels against Staphylococcus Isolates and HCoV 229E-In Vitro and In Silico Investigations

Recently, there has been a surge towards searching for primitive treatment strategies to discover novel therapeutic approaches against multi-drug-resistant pathogens. Endophytes are considered unexplored yet perpetual sources of several secondary metabolites with therapeutic significance. This study aims to isolate and identify the endophytic fungi from Annona squamosa L. fruit peels using morphological, microscopical, and transcribed spacer (ITS-rDNA) sequence analysis; extract the fungus's secondary metabolites by ethyl acetate; investigate the chemical profile using UPLC/MS; and evaluate the potential antibacterial, antibiofilm, and antiviral activities. An endophytic fungus was isolated and identified as Aspergillus flavus L. from the fruit peels. The UPLC/MS revealed seven compounds with various chemical classes. The antimicrobial activity of the fungal ethyl acetate extract (FEA) was investigated against different Gram-positive and Gram-negative standard strains, in addition to resistant clinical isolates using the agar diffusion method. The CPE-inhibition assay was used to identify the potential antiviral activity of the crude fungal extract against low pathogenic human coronavirus (HCoV 229E). Selective Gram-positive antibacterial and antibiofilm activities were evident, demonstrating pronounced efficacy against both methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA). However, the extract exhibited very weak activity against Gram-negative bacterial strains. The ethyl acetate extract of Aspergillus flavus L exhibited an interesting antiviral activity with a half maximal inhibitory concentration (IC50) value of 27.2 µg/mL against HCoV 229E. Furthermore, in silico virtual molecular docking-coupled dynamics simulation highlighted the promising affinity of the identified metabolite, orienting towards three MRSA biotargets and HCoV 229E main protease as compared to reported reference inhibitors/substrates. Finally, ADME analysis was conducted to evaluate the potential oral bioavailability of the identified metabolites.

Magnetic separation, sunlight-driven photocatalytic activity, and antibacterial studies of Sm-doped Co0.33Mg0.33Ni0.33Fe2O4 nanoparticles

Magnetic nanoparticles have emerged as a promising tool for wastewater treatment due to their unique properties. In this regard, Co0.33Mg0.33Ni0.33SmxFe2-xO4 (0.00 ≤ x ≤ 0.08) nanoparticles were prepared to examine their magnetic separation efficiency (MSE), photocatalytic, antibacterial, and antibiofilm performances. Pure nanoparticles, having the highest saturation magnetization (Ms = 31.87 emu/g), exhibit the highest MSE, where 95.6% of nanoparticles were separated after 20 min of applying a magnetic field of 150 mT. The catalytic performance of the prepared samples is examined by the photodegradation of rhodamine B (RhB) dye exposed to direct sunlight radiation. Improved photocatalytic activity is exhibited by Co0.33Mg0.33Ni0.33Sm0.04Fe1.96O4 nanoparticles, labeled as Sm0.04, where the rate of the degradation reaction is enhanced by 4.1 times compared to pure nanoparticles. Rising the pH and reaction temperature improves the rate of the photodegradation reaction of RhB. The incorporation of 15 wt% reduced graphene oxide (rGO) with Sm0.04 enhanced the rate of the reaction by 1.7 and 2.4 times compared with pure Sm0.04 sample and rGO, respectively. The antibacterial and antibiofilm activities against Escherichia coli, Leclercia adecarboxylata, Staphylococcus aureus, and Enterococcus faecium are assessed by the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) broth microdilution, the agar well diffusion, the time-kill assays, the biofilm formation, and destruction assays. The bacteria used in these assessments are isolated from wastewater. The nanoparticles exhibit a bacteriostatic activity, with a better effect against the Gram-positive isolates. Co0.33Mg0.33Ni0.33SmxFe2O4 (x = 0.00) nanoparticles have the best effect. The effect is exerted after 2-3 h of incubation. Gram-positive biofilms are more sensitive to nanoparticles.

Evaluation of the Antioxidant, Cytotoxicity, Antibacterial, Anti-Motility, and Anti-Biofilm Effects of Myrothamnus flabellifolius Welw. Leaves and Stem Defatted Subfractions

The formation of biofilms underscores the challenge of treating bacterial infections. The study aimed to assess the antioxidant, cytotoxicity, antibacterial, anti-motility, and anti-biofilm effects of defatted fractions from Myrothamnus flabellifolius (resurrection plant). Antioxidant activity was assessed using DPPH radical scavenging and hydrogen peroxide assays. Cytotoxicity was screened using a brine shrimp lethality assay. Antibacterial activity was determined using the micro-dilution and growth curve assays. Antibiofilm potential was screened using the crystal violet and tetrazolium reduction assay. Liquid-liquid extraction of crude extracts concentrated polyphenols in the ethyl acetate and n-butanol fractions. Subsequently, these fractions had notable antioxidant activity and demonstrated broad-spectrum antibacterial activity against selected Gram-negative and Gram-positive bacteria and Mycobacterium smegmatis (MIC values < 630 μg/mL). Growth curves showed that the bacteriostatic inhibition by the ethyl acetate fractions was through the extension of the lag phase and/or suppression of the growth rate. The sub-inhibitory concentrations of the ethyl acetate fractions inhibited the swarming motility of Pseudomonas aeruginosa and Klebsiella pneumoniae by 100% and eradicated more than 50% of P. aeruginosa biofilm biomass. The polyphenolic content of M. flabellifolius plays an important role in its antibacterial, anti-motility, and antibiofilm activity, thus offering an additional strategy to treat biofilm-associated infections.

Investigation of phytochemical composition and bioactivity evaluation of extracts from Myrsine umbellata Mart

The objective of the study was to carry out phytochemical prospection through colorimetric tests to determine the groups of secondary metabolites and also to determine the total content of phenolic compounds (TPC) present in plant extracts methanol (ME), ethyl acetate (EAE), hexane (HE) and dichloromethane (DE) from the leaves of Myrsine umbellata, as well as to investigate the antimicrobial activity against twelve standard ATCC strains by the broth microdilution technique; the antioxidant potential by the DPPH method and the ABTS method and the antibiofilm potential on the biofilm biomass of standard bacteria by the crystal violet technique and tetrazolium salt reduction (MTT) assay. Phytochemical prospection detected the presence of saponins, steroids, alkaloids, anthocyanins, anthocyanidins, flavonoids, and tannins. The results of the quantitative phytochemical estimation revealed a higher content of total phenolics in DE (280.24 ± 0.037 µM GAE g ext. -1) followed by ME (159.01 ± 0.031 µM GAE g ext. -1). The ME showed the best biological activities when compared to the other extracts tested. We observed antimicrobial activity against Gram-positive Staphylococcus epidermidis strain (MIC 3.12 and MBC 6.25), antioxidant percentage of 92.58% against the DPPH radical and 420.31 µM Trolox g ext. -1 against the ABTS radical, finally showed antibiofilm action against Gram-positive strain Staphylococcus aureus, with eradication of the biomass in 92.58%. The results suggest that EM from M. umbellata represents an alternative source of plant bioactives for the development of natura products.

Anti-biofilm and anti-inflammatory active diterpene isolated from the fruit of Xylopia benthamii R.E.Fr

Xylopia benthamii (Annonaceae) is a plant with limited phytochemical and pharmacological evidence. Thus, using LC-MS/MS, we performed exploratory analyses of the fruit extract of X. benthamii, resulting in the tentative identification of alkaloids (1-7) and diterpenes (8-13). Through the application of chromatography techniques with the extract of X. benthamii, two kaurane diterpenes were isolated, xylopinic acid (9) and ent-15-oxo-kaur-16-en-19-oic acid (11). Their structures were established using spectroscopy (NMR 1D/2D) and mass spectrometry. The isolated compounds were submitted to anti-biofilm analysis against Acinetobacter baumannii, anti-neuroinflammatory and cytotoxic activity in BV-2 cells. Compound 11 (201.75 µM) inhibited 35% of bacterial biofilm formation and high anti-inflammatory activity in BV-2 (IC50 = 0.78 µM). In conclusion, the results demonstrated that compound 11 was characterized for the first time with pharmacological potential in the development of new alternatives for studies with neuroinflammatory diseases.

Quercetin's antibiofilm effectiveness against drug resistant Staphylococcus aureus and its validation by in silico modeling

Staphylococcus aureus is typically treated with antibiotics, however, due to its widespread and unselective usage, resistant strains of S. aureus have increased to a great extent. Treatment failure and recurring staphylococcal infections are also brought on by biofilm development, which boosts an organism's ability to withstand antibiotics and is thought to be a virulence factor in patients. The present study investigates the antibiofilm activity of naturally available polyphenol Quercetin against drug-resistant S. aureus. Micro dilution plating and tube adhesion methods were performed to evaluate the antibiofilm activity of quercetin against S. aureus. Quercetin treatment resulted in remarkably reduction of biofilm in S. aureus cells. Further we performed a study to investigate binding efficacies of quercetin with genes icaB and icaC from ica locus involved in biofilm formation. 3D structure of icaB, icaC and quercetin were retrieved from Protein data bank and PubChem chemical compound database, respectively. All computational simulation were carried out using AutoDock Vina and AutoDockTools (ADT) v 1.5.4. In silico study demonstrated a strong complex formation, large binding constants (Kb) and low free binding energy (ΔG) between quercetin and icaB (Kb = 1.63 × 10-5, ΔG = -7.2 k cal/mol) and icaC (Kb = 1.98 × 10-6, ΔG = -8.7 kcal/mol). This in silico analysis indicates that quercetin is capable of targeting icaB and icaC proteins which are essential for biofilm formation in S. aureus. Our study highlighted the antibiofilm activity of quercetin against drug resistant pathogen S.aureus.

Anti Gram-Positive Bacteria Activity of Synthetic Quaternary Ammonium Lipid and Its Precursor Phosphonium Salt

Organic ammonium and phosphonium salts exert excellent antimicrobial effects by interacting lethally with bacterial membranes. Particularly, quaternary ammonium lipids have demonstrated efficiency both as gene vectors and antibacterial agents. Here, aiming at finding new antibacterial devices belonging to both classes, we prepared a water-soluble quaternary ammonium lipid (6) and a phosphonium salt (1) by designing a synthetic path where 1 would be an intermediate to achieve 6. All synthesized compounds were characterized by Fourier-transform infrared spectroscopy and Nuclear Magnetic Resonance. Additionally, potentiometric titrations of NH3+ groups 1 and 6 were performed to further confirm their structure by determining their experimental molecular weight. The antibacterial activities of 1 and 6 were assessed first against a selection of multi-drug-resistant clinical isolates of both Gram-positive and Gram-negative species, observing remarkable antibacterial activity of both compounds against Gram-positive isolates of Enterococcus and Staphylococcus genus. Further investigations on a wider variety of strains of these species confirmed the remarkable antibacterial effects of 1 and 6 (MICs = 4-16 and 4-64 µg/mL, respectively), while 24 h-time-killing experiments carried out with 1 on different S. aureus isolates evidenced a bacteriostatic behavior. Moreover, both compounds 1 and 6, at the lower MIC concentration, did not show significant cytotoxic effects when exposed to HepG2 human hepatic cell lines, paving the way for their potential clinical application.

Elimination of detached Listeria monocytogenes from the biofilm on stainless steel surfaces during milk and cheese processing using natural plant extracts

Bacterial cells can form biofilm on food contact surfaces, becoming a source of food contamination with profound health implications. The current study aimed to determine some Egyptian medicinal plants antibacterial and antibiofilm effects against foodborne bacterial strains in milk plants. Results indicated that four ethanolic plant extracts, Cinnamon (Cinnamomum verum), Chamomile (Matricaria chamomilla), Marigold (Calendula officinalis), and Sage (Salvia officinalis), had antibacterial (12.0-26.5 mm of inhibition zone diameter) and antibiofilm (10-99%) activities against Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes and Salmonella Typhimurium. The tested extracts had minimum inhibitory concentration values between 0.14 and 2.50 mg/ml and minimum bactericidal concentration values between 0.14 and 12.50 mg/ml. L. monocytogenes was more sensitive for all tested ethanolic extracts; Sage and Cinnamon showed a bacteriocidal effect, while Chamomile and Marigold were bacteriostatic. The ethanolic extracts mixture from Chamomile, Sage, and Cinnamon was chosen for its antibiofilm activity against L. monocytogenes using L-optimal mixture design. Gas chromatography and mass spectrometry analysis showed that this mixture contained 12 chemical compounds, where 2-Propenal,3-phenyl- had the maximum area % (34.82%). At concentrations up to 500 µg/ml, it had no cytotoxicity in the normal Vero cell line, and the IC50 value was 671.76 ± 9.03 µg/ml. Also, this mixture showed the most significant antibacterial effect against detached L. monocytogenes cells from formed biofilm in stainless steel milk tanks. At the same time, white soft cheese fortified with this mixture was significantly accepted overall for the panelist (92.2 ± 2.7) than other cheese samples, including the control group.

A promising antifungal lipopeptide from Bacillus subtilis: its characterization and insight into the mode of action

Emerging resistance of fungal pathogens and challenges faced in drug development have prompted renewed investigations into novel antifungal lipopeptides. The antifungal lipopeptide AF3 reported here is a natural lipopeptide isolated and purified from Bacillus subtilis. The AF3 lipopeptide's secondary structure, functional groups, and the presence of amino acid residues typical of lipopeptides were determined by circular dichroism, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. The lipopeptide's low minimum inhibitory concentrations (MICs) of 4-8 mg/L against several fungal strains demonstrate its strong antifungal activity. Biocompatibility assays showed that ~ 80% of mammalian cells remained viable at a 2 × MIC concentration of AF3. The treated Candida albicans cells examined by scanning electron microscopy, transmission electron microscopy, and atomic force microscopy clearly showed ultrastructural alterations such as the loss of the cell shape and cell membrane integrity. The antifungal effect of AF3 resulted in membrane permeabilization facilitating the uptake of the fluorescent dyes-acridine orange (AO)/propidium iodide (PI) and FUN-1. Using 1,6-diphenyl-1,3,5-hexatriene (DPH) and 4-(2-[6-(dioctylamino)-2-naphthalenyl] ethenyl)-1-(3-sulfopropyl) pyridinium inner salt (di-8-ANEPPS), we observed that the binding of AF3 to the membrane bilayer results in membrane disruption and depolarization. Flow cytometry analyses revealed a direct correlation between lipopeptide activity, membrane permeabilization (~ 75% PI uptake), and reduced cell viability. An increase in 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescence demonstrates endogenous reactive oxygen species production. Lipopeptide treatment appears to induce late-stage apoptosis and alterations to nuclear morphology, suggesting that AF3-induced membrane damage may lead to a cellular stress response. Taken together, this study illustrates antifungal lipopeptide's potential as an antifungal drug candidate. KEY POINTS: • The studied lipopeptide variant AF3 displayed potent antifungal activity against C. albicans • Its biological activity was stable to proteolysis • Analytical studies demonstrated that the lipopeptide is essentially membranotropic and able to cause membrane dysfunction, elevated ROS levels, apoptosis, and DNA damage.

Chemical profiling and dermatological and anti-aging properties of Syzygium jambos L. (Alston): evidence from molecular docking, molecular dynamics, and in vitro experiments

The phytoconstituents of the aqueous extract from Syzygium jambos L. (Alston) leaves were defined using HPLC-PDA-MS/MS and the antioxidant, anti-aging, antibacterial, and anti-biofilm activities of the extract were in silico and in vitro investigated. The antioxidant activities were performed using in vitro DPPH and FRAP assays as well as H2-DCFDA assay in HaCaT cells in which oxidative stress was induced by UVA radiation. Anti-aging activity was tested in vitro, using aging-related enzymes. The antibacterial, anti-biofilm and inhibitory effects on bacterial mobilities (swarming and swimming) were assessed against Pseudomonas aeruginosa. Results showed that S. jambos aqueous extract contained 28 phytochemicals belonging to different metabolite classes, mainly phenolic acids, gallic acid derivatives, flavonoids, and ellagitannins. Mineral content analysis showed that S. jambos leaves contained moderate amounts of nitrogen, potassium, manganese, magnesium, and zinc, relatively low amounts of phosphorus and copper, and high concentration of calcium and iron. The extract displayed strong antioxidant activities in vitro and inhibited UVA-induced oxidative stress in HaCaT cells. Docking the major compounds identified in the extract into the four main protein targets involved in skin aging revealed an appreciable inhibitory potential of these compounds against tyrosinase, elastase, hyaluronidase, and collagenase enzymes. Moreover, molecular dynamic simulations were adopted to confirm the binding affinity of some selected compounds towards the target enzymes. The extract exhibited pronounced in vitro anti-aging effects, compared to kojic acid and quercetin (the reference compounds). It also inhibited the growth of P. aeruginosa, counteracted its ability to form biofilm, and impeded its swarming and swimming mobilities. Altogether, these findings strongly propose S. jambos leaves as a promising source of bioactive metabolites for the development of natural cosmeceutical and dermatological agents.

Evaluating Antibiofilm, Cytotoxic and Apoptotic Activities of Scutellaria brevibracteata subsp. brevibracteata Essential Oil

Essential oils have many important biological properties, including antibacterial and antibiofilm activities. These unique properties make, essential oils good alternatives to synthetic chemical drugs, which have many side effects. In this study, we aimed to determine the chemical composition and biological activity of the essential oil obtained from Scutellaria brevibracteata subsp. brevibracteata. Specifically, its antibiofilm activity against Pseudomonas aeruginosa PAO1 and Staphylococcus aureus ATCC 29213 biofilms using XTT assay. Cytotoxic and apoptotic properties of the essential oil were investigated in human lung cancer cells (A540 and H1299) using MTT assay, Annexin V-FITC and propidium iodide staining and q-PCR. Thirty-two different compounds were identified from the essential oil, of which elemol (20.42 %), γ-eudesmol (20.12 %) and β-eudesmol (14.85 %) were the main components. The essential oil was more effective against P. aeruginosa PAO1 biofilm (79 %) than S. aureus ATCC 29213 biofilm (27 %). The specific activity of the essential oil against P. aeruginosa biofilm may be related to its high terpene contents. In addition, the essential oil showed high cytotoxic activity towards A549 (IC50 9.09 μg/ml) and H1299 (IC50 55.04 μg/ml) cell lines, inducing apoptosis in these cancer cells. These results demonstrate the antibiofilm and anticancer activities of S. brevibracteata subsp. brevibracteata essential oil.

Evaluation of Antibiofilm and Antiquorum Sensing Activities of Fucoidan Characterized from Padina boryana against Nosocomial Pathogens

Modern functional chemicals that can be employed in biotechnology, pharmaceutics, and food science are a sustainable source to be found in seaweeds. The bioactivity of the majority of these marine compounds has received scant research. Fucoidan is a highly sulfated polysaccharide with a range of bioactivities, including an antipathogenic effect. There is still much to learn about the relationship between fucoidan structure and its function in pathogen infections. By employing microwave and probe sonication to create crude fucoidan, DEAE-cellulose anion-exchange chromatography was used to further purify the substance. Purified fucoidan was structurally characterized using UV-Visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and NMR analysis. The results of the structural analysis demonstrate that sulfates and hydroxyl groups are present in the isolated fucoidan. There are fucose residues, according to the NMR data. The present study investigates the bioactivity of fucoidan, a polysaccharide derived from the brown algae Padina boryana, as a potent weapon against the known nosocomial diseases Proteus vulgaris and Salmonella enterica. Fluorescence microscopy was used to show that fucoidan antibiofilm action is totally effective against Proteus vulgaris and Salmonella enterica biofilm formations as well as planktonic cell growths at dosages over 25 g/mL. Here, using in vitro investigations of the possible inactivation of molecules that are regulated by acyl-homoserine lactone (AHL) in both bacterial species, we explore the antiquarum sensing and antibiofilm capabilities of fucoidan. According to the present study, extracted fucoidan from Padina boryana can be used to generate antibacterial compounds and operate as a quorum-sensing inhibitor to combat side effects and antibiotic resistance.

Transcriptional Profiling of the Effect of Coleus amboinicus L. Essential Oil against Salmonella Typhimurium Biofilm Formation

Salmonella enterica serovar Typhimurium cause infections primarily through foodborne transmission and remains a significant public health concern. The biofilm formation of this bacteria also contributes to their multidrug-resistant nature. Essential oils from medicinal plants are considered potential alternatives to conventional antibiotics. Therefore, this study assessed the antimicrobial and antibiofilm activities of Coleus amboinicus essential oil (EO-CA) against S. Typhimurium ATCC 14028. Seventeen chemical compounds of EO-CA were identified, and carvacrol (38.26%) was found to be the main constituent. The minimum inhibitory concentration (MIC) of EO-CA for S. Typhimurium planktonic growth was 1024 µg/mL while the minimum bactericidal concentration was 1024 µg/mL. EO-CA at sub-MIC (≥1/16× MIC) exhibited antibiofilm activity against the prebiofilm formation of S. Typhimurium at 24 h. Furthermore, EO-CA (≥1/4× MIC) inhibited postbiofilm formation at 24 and 48 h (p < 0.05). Transcriptional profiling revealed that the EO-CA-treated group at 1/2× MIC had 375 differentially expressed genes (DEGs), 106 of which were upregulated and 269 were downregulated. Five significantly downregulated virulent DEGs responsible for motility (flhD, fljB, and fimD), curli fimbriae (csgD), and invasion (hilA) were screened via quantitative reverse transcription PCR (qRT-PCR). This study suggests the potential of EO-CA as an effective antimicrobial agent for combating planktonic and biofilm formation of Salmonella.

Some novel bioactivities of Virgibacillus halodenitrificans carotenoids, isolated from Wadi El-Natrun lakes

Carotenoids come in second among the most frequent natural pigments and are utilized in medications, nutraceuticals, cosmetics, food pigments, and feed supplements. Based on recent complementary work, Virgibacillus was announced for the first time as a member of Wadi El-Natrun salt and soda lakes microbiota, identified as Virgibacillus halodenitrificans, and named V. halodenitrificans DASH; hence, this work aimed to investigate several in vitro medicinal bioactivities of V. halodenitrificans DASH carotenoids. The carotenoid methanolic extract showed antioxidant activity based on diphenylpicrylhydrazyl (DPPH) scavenging capacity with a half-maximal concentration (IC50) of 1.6 mg/mL as well as nitric oxide (NO) scavenging action expressed by an IC50 of 46.4 µg/mL. The extract showed considerable inhibitory activity for alpha-amylase (α-amylase) and alpha-glucosidase (α-glucosidase) enzymes (IC50 of 100 and 173.4 μg/mL, respectively). Moreover, the extract displayed selective anticancer activity against Caco-2 (IC50 = 138.96 µg/mL) and HepG-2 cell lines (IC50 = 31.25 µg/mL), representing colorectal adenocarcinoma and hepatoblastoma. Likewise, the extract showed 98.9 % clearance for human hepatitis C virus (HCV) using reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), HCV-NS5B polymerase activity inhibition (IC50 = 27.4 µg/mL), and selective inhibitory activity against human coronavirus (HCoV 229E) using the plaque reduction assay (IC50 = 53.5 µg/mL). As far as we can tell, the anticancer, antiviral, and antidiabetic attributes of Virgibacillus carotenoids are, de novo, reported in this work which accordingly invokes further exploration of the other medicinal, biotechnological, and industrial applications of Virgibacillus and haloalkaliphilic bacteria carotenoids.

Extracts of Selected South African Medicinal Plants Mitigate Virulence Factors in Multidrug-Resistant Strains of Klebsiella pneumoniae

The emergence of multidrug-resistant (MDR) Klebsiella pneumoniae remains a global health threat due to its alarming rates of becoming resistant to antibiotics. Therefore, identifying plant-based treatment options to target this pathogen's virulence factors is a priority. This study examined the antivirulence activities of twelve plant extracts obtained from three South African medicinal plants (Lippia javanica, Carpobrotus dimidiatus, and Helichrysum populifolium) against carbapenem-resistant (CBR) and extended-spectrum beta-lactamase (ESBL) positive K. pneumoniae strains. The plant extracts (ethyl acetate, dichloromethane, methanol, and water) were validated for their inhibitory activities against bacterial growth and virulence factors such as biofilm formation, exopolysaccharide (EPS) production, curli expression, and hypermucoviscosity. The potent extract on K. pneumoniae biofilm was observed with a scanning electron microscope (SEM), while exopolysaccharide topography and surface parameters were observed using atomic force microscopy (AFM). Chemical profiling of the potent extract in vitro was analysed using liquid chromatography-mass spectrometry (LC-MS). Results revealed a noteworthy minimum inhibitory concentration (MIC) value for the C. dimidiatus dichloromethane extract at 0.78 mg/mL on CBR- K. pneumoniae. L. javanica (ethyl acetate) showed the highest cell attachment inhibition (67.25%) for CBR- K. pneumoniae. SEM correlated the in-vitro findings, evidenced by a significant alteration of the biofilm architecture. The highest EPS reduction of 34.18% was also noted for L. javanica (ethyl acetate) and correlated by noticeable changes observed using AFM. L. javanica (ethyl acetate) further reduced hypermucoviscosity to the least length mucoid string (1 mm-2 mm) at 1.00 mg/mL on both strains. C. dimidiatus (aqueous) showed biofilm inhibition of 45.91% for the ESBL-positive K. pneumoniae and inhibited curli expression at 0.50 mg/mL in both K. pneumoniae strains as observed for H. populifolium (aqueous) extract. Chemical profiling of L. javanica (ethyl acetate), C. dimidiatus (aqueous), and H. populifolium (aqueous) identified diterpene (10.29%), hydroxy-dimethoxyflavone (10.24%), and 4,5-dicaffeoylquinic acid (13.41%), respectively, as dominant compounds. Overall, the ethyl acetate extract of L. javanica revealed potent antivirulence properties against the studied MDR K. pneumoniae strains. Hence, it is a promising medicinal plant that can be investigated further to develop alternative therapy for managing K. pneumoniae-associated infections.

Essential Oil from Tagetes minuta Has Antiquorum Sensing and Antibiofilm Potential against Pseudomonas aeruginosa Strain PAO1

Biofilms are complex communities of microorganisms that are enclosed in a matrix that shows increased resistance to antimicrobial and immunological encounters. Mostly, the traditional methods to control biofilm are exhausted; therefore, the aim is to evaluate the potential of essential oil (EO) from Tagetes minuta to encounter biofilm and other related virulence factors. The EO of T. minuta was extracted through steam-distillation, analyzed on gas chromatography-mass spectrometry, and the biofilm inhibition assays were performed with various concentrations of EO. Mainly the EO from T. minuta contains cis-β-ocimene (29.1%), trans-tagetenone (23.1%), and cis-tagetenone (17.7%). The virulence factors were monitored while applying different concentrations of EO and it was recorded that the EO from T. minuta significantly inhibited the virulence factors linked with quorum sensing (QS), such as pyocyanin production, protease production, and swarming motility. Biofilm formation is one of the most important virulence factors associated with the QS pathway and was inhibited up to 79% in the presence of EO. Antibacterial activity against the PAO1 of EO was not so promising particularly and it has high MIC (325 μg/mL) and MBC (5000 μg/mL). EO is quite efficient to inhibit biofilm in a very small concentration of 20 μg/mL, which confirms that the biofilm inhibition by EO is not by killing bacterial cells but by inhibiting the QS pathway. The study on PAO1 constructs carrying various QS reported genes confirmed that the EO interferes with the QS pathway that ultimately controls various virulence factors caused by PAO1.

Autoinducers modulation as a potential anti-virulence target of bacteria by phenolic compounds

OBJECTIVE

The goal of this study was to determine the effects of phenolic extracts from grape (GrPE), pomegranate (PoPE), and persimmon (PePE) by-products on bacterial virulence activities such as biofilms, motility, energy-dependent efflux pumps, and β-lactamase activity, which are modulated primarily by quorum sensing (QS), defining their potential applications.

METHOD

The microdilution method was used to determine the minimum inhibitory concentration (MIC) and sub-inhibitory concentrations (SICs) of the extracts against reference pathogenic bacteria. The antibacterial mode of action was determined by labelling bacterial cells in in vivo cell-tracking experiments.

RESULTS

Antibiograms showed that PoPE inhibited bacteria at lower concentrations, and PePE had a stronger effect against Klebsiella pneumoniae. Both extracts caused significant cell membrane damage (CMD), whereas GrPE did not. At SICs, all extracts showed anti-QS activity, especially PePE, which inhibited violacein and pyocyanin production at 1/128 × MIC. Additionally, QS autoinducers found in Chromobacterium violaceum and Pseudomonas aeruginosa were modulated by the extracts; PePE showed the highest modulation. Antibiofilm assays revealed that GrPE, at MIC and 2 × MIC, acted as a potent antibiofilm agent against biofilms of Pseudomonas putida, Bacillus cereus, and Staphylococcus aureus, which was related to disruption of swarming motility by GrPE. All extracts, especially PoPE, exerted a potent effect against the activation of efflux pumps of P. aeruginosa as well as β-lactamase activity in K. pneumoniae.

CONCLUSION

Results suggest that the anti-virulence potential of the extracts may be related to their effect as extracellular autoinducer modulators. This study allowed to define potential applications of these extracts.

Comparative Study of Cytotoxicity and Antioxidant, Anti-Aging and Antibacterial Properties of Unfermented and Fermented Extract of Cornus mas L

Due to the high demand for products that can help treat various skin conditions, the interest in plant extracts, which are a valuable source of phytochemicals, is constantly growing. In this work, the properties of extracts and ferments from Cornus mas L. and their potential use in cosmetic products were compared. For this purpose, their composition, antioxidant properties and cytotoxicity against skin cells, keratinocytes and fibroblasts were assessed in vitro. In addition, the ability to inhibit the activity of collagenase and elastase was compared, which enabled the assessment of their potential to inhibit skin aging. Microbiological analyses carried out on different bacterial strains were made in order to compare their antibacterial properties. The conducted analyses showed that both dogwood extract and ferment have antioxidant and anti-aging properties. In addition, they can have a positive effect on the viability of keratinocytes and fibroblasts and inhibit the proliferation of various pathogenic bacteria, which indicates their great potential as ingredients in skin care preparations. The stronger activity of the ferment compared to the extract indicates the legitimacy of carrying out the fermentation process of plant raw materials using kombucha in order to obtain valuable products for the cosmetics industry.

Evaluation of anti-quorum sensing and antibiofilm effects of secondary metabolites from Gambeya lacourtiana (De Wild) Aubr. & Pellegr against selected pathogens

BACKGROUND

Microbial infections cause serious health problems especially with the rising antibiotic resistance which accounts for about 700,000 human deaths annually. Antibiotics which target bacterial death encounter microbial resistance with time, hence, there is an urgent need for the search of antimicrobial substances which target disruption of virulence factors such as biofilm and quorum sensing (QS) with selective pressure on the pathogens so as to avoid resistance.

METHODS

Natural products are suitable leads for antimicrobial drugs that can inhibit bacterial biofilms and QS. Twenty compounds isolated from the medicinal plant Gambeya lacourtiana were evaluated for their antibiofilm and anti-quorum sensing effects against selected pathogenic bacteria.

RESULTS

Most of the compounds inhibited violacein production in Chromobacterium violaceum CV12472 and the most active compound, Epicatechin had 100% inhibition at MIC (Minimal Inhibitory Concentration) and was the only compound to inhibit violacein production at MIC/8 with percentage inhibition of 17.2 ± 0.9%. Since the bacteria C. violaceum produces violacein while growing, the inhibition of the production of this pigment reflects the inhibition of signal production. Equally, some compounds inhibited violacein production by C. violaceum CV026 in the midst of an externally supplied acylhomoserine lactone, indicating that they disrupted signal molecule reception. Most of the compounds exhibited biofilm inhibition on Staphyloccocus aureus, Escherichia coli and Candida albicans and it was observed that the Gram-positive bacteria biofilm was most susceptible. The triterpenoids bearing carboxylic acid group, the ceramide and epicatechin were the most active compounds compared to others.

CONCLUSION

Since some of the compounds disrupted QS mediated processes in bacteria, it indicates that this plant is a source of antibiotics drugs that can reduce microbial resistance.

Agonistic antibacterial potential of Loigolactobacillus coryniformis BCH-4 metabolites against selected human pathogenic bacteria: An in vitro and in silico approach

Lactic acid bacteria are known to produce numerous antibacterial metabolites that are active against various pathogenic microbes. In this study, bioactive metabolites from the cell free supernatant of Loigolactobacillus coryniformis BCH-4 were obtained by liquid-liquid extraction, using ethyl acetate, followed by fractionation, using silica gel column chromatography. The collected F23 fraction effectively inhibited the growth of pathogenic bacteria (Escherichia coli, Bacillus cereus, and Staphylococcus aureus) by observing the minimum inhibitory concentration (MIC) and minimum bactericidal concentrations (MBC). The evaluated values of MIC were 15.6 ± 0.34, 3.9 ± 0.59, and 31.2 ± 0.67 μg/mL and MBC were 15.6 ± 0.98, 7.8 ± 0.45, and 62.5 ± 0.23 μg/mL respectively, against the above-mentioned pathogenic bacteria. The concentration of F23 fraction was varying from 1000 to 1.9 μg/mL. Furthermore, the fraction also exhibited sustainable biofilm inhibition. Using the Electrospray Ionization Mass Spectrometry (ESI-MS/MS), the metabolites present in the bioactive fraction (F23), were identified as phthalic acid, myristic acid, mangiferin, 16-hydroxylpalmatic acid, apigenin, and oleandomycin. By using in silico approach, docking analysis showed good interaction of identified metabolites and receptor proteins of pathogenic bacteria. The present study suggested Loigolactobacillus coryniformis BCH-4, as a promising source of natural bioactive metabolites which may receive great benefit as potential sources of drugs in the pharmacological sector.

Invasive Alien Species as a Potential Source of Phytopharmaceuticals: Phenolic Composition and Antimicrobial and Cytotoxic Activity of Robinia pseudoacacia L. Leaf and Flower Extracts

Black locust (Robinia pseudoacacia L.), an invasive tree in Europe, commonly known for its negative impact on biodiversity, is a rich source of phenolic compounds recognized in traditional medicine. Since the metabolite profile depends on the environment and climate, this study aimed to provide the first LC-MS phytochemical screening of the black locust from the Istria region (Croatia). The compounds were extracted from leaves and flowers with 70% ethanol and 80% methanol. Total phenolics (TP) and flavonoids (TF), as well as antioxidant capacity (AC) measured by ABTS (17.49-146.41 mg TE/g DW), DPPH (24.67-118.49 mg TE/g DW), and FRAP (7.38-77.53 mg TE/g DW) assays, were higher in leaf than in flower extracts. Higher TP and total non-flavonoid (TNF) values were displayed in ethanolic than in methanolic extracts. In total, 64 compounds were identified, of which flavonols (20) and hydroxycinnamic acid derivatives (15) were the most represented. Flavanols such as catechin dominated in leaf extracts, followed by flavonols, with kaempferol glucuronyl rhamnosyl hexosides as the main compound, respectively. Flower extracts had the highest share of flavones, followed by ellagitannins, with luteolin dirhamnosyl hexosides and vescalagin, respectively, being predominant. The extracts had good quorum sensing, biofilm formation prevention, and eradicating capacity. The results provided new insights into the phytochemical properties of R. pseudoacacia as the first step toward its potential pharmaceutical use.

Deciphering the antimicrobial, antibiofilm and membrane stabilizing synergism of Mikania scandens (L.) Willd. leaves and stems substantiation through in vitro and in silico studies

Considering the traditional application of Mikania scandens (L.) Willd. against wounds and itching. Leaves (MSL) and stems (MSS) were sequentially extracted using solvents petroleum-ether, carbon-tetrachloride, chloroform, ethyl-acetate and ethanol. Disk-diffusion assay revealed the ethyl acetate MSL and MSS extracts were the prominent against ten bacteria, five carbapenem-resistant bacteria and one fungal strains. Subsequent quantitative antimicrobial analysis specified MSL extractives more potent over MSS with lower 1500 and 3500µg/ml MIC and MBC value in both gram-negative and positive bacteria. These sturdiest ethyl-acetate MSL extractives antimicrobial efficiency also fostered fungicidal activity having lower 100µg/ml MFC. Whereat, almost homologous 160-180 min timing noted liken to standard ciprofloxacin susceptibility in both strains, 75% biofilm inhibition at 2×MIC concentration along with 92±0.2% membrane stabilizing activities over synthetic counterparts prospected in preceding standard extractives. Computational molecular docking of MSL compounds supported this findings therefore forego this valuable synergistic insight as antimicrobial agents to efficiently eradicate human infections.

Effects of Piper betle Extracts against Biofilm Formation by Methicillin-Resistant Staphylococcus pseudintermedius Isolated from Dogs

Emergence of methicillin-resistant Staphylococcus pseudintermedius (MRSP) isolated from dogs with cutaneous and wound infections has significantly impacted veterinary medicine. This study aimed to isolate S. pseudintermedius from canine pyoderma and investigate the effects of ethanolic extracts of Piper betle (PB), P. sarmentosum (PS), and P. nigrum (PN) on the bacterial growth and biofilm formation of S. pseudintermedius and MRSP. Of the isolated 152 isolates, 53 were identified as S. pseudintermedius using polymerase chain reaction, and 10 isolates (6.58%) were identified as MRSP based on the presence of mecA. Based on phenotype, 90% of MRSPs were multidrug-resistant. All MRSP had moderate (10%, 1/10) and strong (90%, 9/10) biofilm production ability. PB extracts were the most effective in inhibiting planktonic cells, and the minimum inhibitory concentration at which ≥50% of the isolates were inhibited (MIC₅₀) was 256 µg/mL (256-1024 µg/mL) for S. pseudintermedius isolates and 512 µg/mL (256-1024 µg/mL) for MRSP isolates. The MIC₉₀ for S. pseudintermedius and MRSP was 512 µg/mL. In XTT assay, PB at 4× MIC showed an inhibition rate of 39.66-68.90% and 45.58-59.13% for S. pseudintermedius and MRSP, respectively, in inhibiting biofilm formation. For PB at 8× MIC, the inhibition rates for S. pseudintermedius and MRSP were 50.74-81.66% and 59.57-78.33%, respectively. Further, 18 compounds were identified in PB using gas chromatography-mass spectrometry, and hydroxychavicol (36.02%) was the major constituent. These results indicated that PB could inhibit bacteria growth of and biofilm formation by S. pseudintermedius and MRSP isolated from canine pyoderma in a concentration-dependent manner. Therefore, PB is a potential candidate for the treatment of MRSP infection and biofilm formation in veterinary medicine.

Evaluating Biofilm Inhibitory Potential in Fish Pathogen, Aeromonas hydrophila by Agricultural Waste Extracts and Assessment of Aerolysin Inhibitors Using In Silico Approach

Aeromonas hydrophila, an opportunistic bacteria, causes several devastating diseases in humans and animals, particularly aquatic species. Antibiotics have been constrained by the rise of antibiotic resistance caused by drug overuse. Therefore, new strategies are required to prevent appropriate antibiotic inability from antibiotic-resistant strains. Aerolysin is essential for A. hydrophila pathogenesis and has been proposed as a potential target for inventing drugs with anti-virulence properties. It is a unique method of disease prevention in fish to block the quorum-sensing mechanism of A. hydrophila. In SEM analysis, the crude solvent extracts of both groundnut shells and black gram pods exhibited a reduction of aerolysin formation and biofilm matrix formation by blocking the QS in A. hydrophila. Morphological changes were identified in the extracts treated bacterial cells. Furthermore, in previous studies, 34 ligands were identified with potential antibacterial metabolites from agricultural wastes, groundnut shells, and black gram pods using a literature survey. Twelve potent metabolites showed interactions between aerolysin and metabolites during molecular docking analysis, in that H-Pyran-4-one-2,3 dihydro-3,5 dihydroxy-6-methyl (-5.3 kcal/mol) and 2-Hexyldecanoic acid (-5.2 kcal/mol) showed promising results with potential hydrogen bond interactions with aerolysin. These metabolites showed a better binding affinity with aerolysin for 100 ns in molecular simulation dynamics. These findings point to a novel strategy for developing drugs using metabolites from agricultural wastes that may be feasible pharmacological solutions for treating A. hydrophila infections for the betterment of aquaculture.

Influence of Lanthanum Doping on the Photocatalytic and Antibacterial Capacities of Mg0.33Ni0.33Co0.33Fe2O4 Nanoparticles

The increase in environmental pollution, especially water pollution, has intensified the requirement for new strategies for the treatment of water sources. Furthermore, the improved properties of nano-ferrites permit their usage in wastewater treatment. In this regard, novel Mg0.33Ni0.33Co0.33LaxFe2−xO4 nanoparticles (NPs), where 0.00≤x≤0.08, were synthesized to test their photocatalytic, antibacterial and antibiofilm activities. The structural and optical properties of the prepared NPs were investigated by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), UV-Vis spectroscopy and photoluminescence (PL) analysis. As La content increases, the bandgap energy increases, whereas the particle size decreases. The photocatalytic activity of the prepared NPs is evaluated by the degradation of methylene blue (MB) dye under sunlight irradiation. Superior activity is exhibited by Mg0.33Ni0.33Co0.33La0.01Fe1.99O4 NPs. The influence of catalyst dosage, pH, temperature and addition of graphene (Gr) on the photodegradation reaction was studied. Increasing the pH and temperature improved the rate of the photodegradation reaction. The antibacterial and antibiofilm activities of the NPs were assessed against Escherichia coli, Leclercia adecarboxylata, Staphylococcus aureus and Enterococcus faecium. Mg0.33Ni0.33Co0.33Fe2O4 NPs inhibited bacterial growth. They had bacteriostatic activity on all isolates, with a greater effect on Gram-positive bacteria. All tested nano-ferrites had significant antibiofilm activities against some biofilms.

Antibacterial, Anti-Biofilm and Pro-Migratory Effects of Double Layered Hydrogels Packaged with Lactoferrin-DsiRNA-Silver Nanoparticles for Chronic Wound Therapy

Antimicrobial resistance and biofilm formation in diabetic foot infections worsened during the COVID-19 pandemic, resulting in more severe infections and increased amputations. Therefore, this study aimed to develop a dressing that could effectively aid in the wound healing process and prevent bacterial infections by exerting both antibacterial and anti-biofilm effects. Silver nanoparticles (AgNPs) and lactoferrin (LTF) have been investigated as alternative antimicrobial and anti-biofilm agents, respectively, while dicer-substrate short interfering RNA (DsiRNA) has also been studied for its wound healing effect in diabetic wounds. In this study, AgNPs were complexed with LTF and DsiRNA via simple complexation before packaging in gelatin hydrogels. The formed hydrogels exhibited 1668% maximum swellability, with a 46.67 ± 10.33 µm average pore size. The hydrogels demonstrated positive antibacterial and anti-biofilm effects toward the selected Gram-positive and Gram-negative bacteria. The hydrogel containing AgLTF at 125 µg/mL was also non-cytotoxic on HaCaT cells for up to 72 h of incubation. The hydrogels containing DsiRNA and LTF demonstrated superior pro-migratory effects compared to the control group. In conclusion, the AgLTF-DsiRNA-loaded hydrogel possessed antibacterial, anti-biofilm, and pro-migratory activities. These findings provide a further understanding and knowledge on forming multipronged AgNPs consisting of DsiRNA and LTF for chronic wound therapy.

Phytochemical Screening, Antibacterial, Antifungal, Anti-Biofilm and Antioxidant Activity of Azadiracta Indica A. Juss. Flowers

The present study involves investigation of Azadiracta Indica flowers with respect to its pharmacognostic properties, phytochemical screening, and its application as anti-oxidant, anti-biofilm, and anti-microbial agent. The Pharmacognostic characteristics were evaluated with respect to moisture content, total ash content, acid, and water-soluble ash content, swelling index, foaming index, and metal content. The macro and micronutrient content of the crude drug was estimated by AAS and Flame photometric methods and it gives the quantitative estimation of minerals, where calcium is present in abundance (88.64 mg/L). Soxhlet extraction was carried out in the increasing order of polarity of the solvent viz Petroleum Ether (PE), Acetone (AC), and Hydroalcohol (20 %) (HA) to extract the bioactive compounds. The characterization of the bioactive compounds of all the three extract have been carried out using gcms and lcms. The presence of 13 major compounds have been identified in PE extract and 8 compounds in AC extract using gcms studies. The HA extract is found to contain polyphenols, flavanoids, and glycosides. The antioxidant activity of the extracts was evaluated by DPPH, FRAP, and Phosphomolybdenum assay. This reveals that HA extract shows good scavenging activity than PE and AC extracts which is well correlated with the bioactive compounds, especially phenols which are present as a major component in the extract. The anti-microbial activity was investigated via Agar well diffusion method for all the extracts. Among all the extracts HA extract shows good antibacterial activity with MIC of 25 μg/mL and AC extract shows good anti-fungal activity with MIC of 25 μg/mL. The antibiofilm assay confirms that the HA extract shows good biofilm inhibition about 94 % among other extracts when tested on human pathogens. The results confirm that the HA extract of A. Indica flowers will be an excellent source of natural anti-oxidant and also antimicrobial agents. This paves the way for its potential uses in herbal product formulation.

Beyond the Risk of Biofilms: An Up-and-Coming Battleground of Bacterial Life and Potential Antibiofilm Agents

Microbial pathogens and their virulence factors like biofilms are one of the major factors which influence the disease process and its outcomes. Biofilms are a complex microbial network that is produced by bacteria on any devices and/or biotic surfaces to escape harsh environmental conditions and antimicrobial effects. Due to the natural protective nature of biofilms and the associated multidrug resistance issues, researchers evaluated several natural anti-biofilm agents, including bacteriophages and their derivatives, honey, plant extracts, and surfactants for better destruction of biofilm and planktonic cells. This review discusses some of these natural agents that are being put into practice to prevent biofilm formation. In addition, we highlight bacterial biofilm formation and the mechanism of resistance to antibiotics.

Synergistic Antifungal Interactions between Antibiotic Amphotericin B and Selected 1,3,4-thiadiazole Derivatives, Determined by Microbiological, Cytochemical, and Molecular Spectroscopic Studies

In recent years, drug-resistant and multidrug-resistant fungal strains have been more frequently isolated in clinical practice. This phenomenon is responsible for difficulties in the treatment of infections. Therefore, the development of new antifungal drugs is an extremely important challenge. Combinations of selected 1,3,4-thiadiazole derivatives with amphotericin B showing strong synergic antifungal interactions are promising candidates for such formulas. In the study, microbiological, cytochemical, and molecular spectroscopy methods were used to investigate the antifungal synergy mechanisms associated with the aforementioned combinations. The present results indicate that two derivatives, i.e., C1 and NTBD, demonstrate strong synergistic interactions with AmB against some Candida species. The ATR-FTIR analysis showed that yeasts treated with the C1 + AmB and NTBD + AmB compositions, compared with those treated with single compounds, exhibited more pronounced abnormalities in the biomolecular content, suggesting that the main mechanism of the synergistic antifungal activity of the compounds is related to a disturbance in cell wall integrity. The analysis of the electron absorption and fluorescence spectra revealed that the biophysical mechanism underlying the observed synergy is associated with disaggregation of AmB molecules induced by the 1,3,4-thiadiazole derivatives. Such observations suggest the possibility of the successful application of thiadiazole derivatives combined with AmB in the therapy of fungal infections.

Antifouling activity of isonitrosoacetanilides against microfouling and macrofouling

Biofouling is responsible for structural and economic damage to man-made surfaces. Antifouling paints with biocides have been applied to structures to avoid organism adhesion; however, they have high toxicity and are not able to prevent all biofouling processes, necessitating the periodic mechanical removal of organisms and paint reapplication. Thus, there is an urgent demand for novel, effective, and environmentally friendly antifouling alternatives. As isonitrosoacetanilide is the precursor for many compounds with antibacterial activity, we believe that it could have antifouling activity against microfouling and, consequently, against macrofouling. The aim of this work was to investigate the antifouling potential of six isonitrosoacetanilide compounds and their toxicity. The compounds were employed at different concentrations (0.625-1.25-2.5-5-10 µg mL^-1) in this study. The biofilm and planktonic bacteria inhibition and biofilm eradication potential were evaluated by crystal violet assay, while Amphibalus amphitrite barnacle settlement was evaluated by cyprid settlement assay. Toxicity evaluation (LC₅₀ and EC₅₀) was performed with A. amphitrite nauplii II and cyprid larvae. At least one of the tested concentrations of 4-Br-INA, 4-CH₃-INA, and 2-Br-INA compounds showed nontoxic antifouling activity against microfouling (antibiofilm) and macrofouling (antisettlement). However, only 4-CH₃-INA and 2-Br-INA also showed biofilm eradication potential. These compounds with antibiofilm activity and nontoxic effects could be combined with acrylic base paint resin or added directly into commercial paints in place of toxicant biocides to cover artificial structures as friendly antifouling agents.

The anti-platelet drug ticlopidine inhibits FapC fibrillation and biofilm production: Highlighting its antibiotic activity

Multidrug resistance of bacteria and persistent infections related to biofilms, as well as the low availability of new antibacterial drugs, make it urgent to develop new antibiotics. Here, we evaluate the antibacterial and anti-biofilm properties of ticlopidine (TP), an anti-platelet aggregation drug, TP showed antibacterial activity against both gram-positive (MRSA) and gram-negative (E. coli, and P. aeruginosa) bacteria over a long treatment period. TP significantly reduced the survival of gram-negative bacteria in human blood though impact on gram-positives was more limited. TP may cause death in MRSA by inhibiting staphyloxanthin pigment synthesis, leading to oxidative stress, while scanning electron microscopy imaging indicate a loss of membrane integrity, damage, and consequent death due to lysis in gram-negative bacteria. TP showed good anti-biofilm activity against P. aeruginosa and MRSA, and a stronger biofilm degradation activity on P. aeruginosa compared to MRSA. Measuring fluorescence of the amyloid-reporter Thioflavin T (ThT) in biofilm implicated inhibition of amyloid formation as part of TP activity. This was confirmed by assays on the purified protein in P. aeruginosa, FapC, whose fibrillation kinetics was inhibited by TP. TP prolonged the lag phase of aggregation and reduced the subsequent growth rate and prolonging the lag phase to very long times provides ample opportunity to exert TP's antibacterial effect. We conclude that TP shows activity as an antibiotic against both gram-positive and gram-negative bacteria thanks to a broad range of activities, targeting bacterial metabolic processes, cellular structures and the biofilm matrix.

Cytotoxicity and antimicrobial activity of isolated compounds from Monsonia angustifolia and Dodonaea angustifolia

ETHNOPHARMACOLOGICAL RELEVANCE

Monsonia angustifolia is traditionally used to treat anthrax, heartburn, diarrhea, eye infections and hemorrhoids. Dodonaea angustifolia is frequently used as a treatment for dental pain, microbial infections and jungle fever. The two plant species were selected due to the presence of secondary metabolites such as coumarins, flavonoids, terpenoids, saponins and polyphenolics from the crude extracts, which exhibit pharmacological significance. The pure isolated compounds from the crude extracts are known for their diverse structures and interesting pharmacophores.

AIM

To isolate and identify antibacterial and antifungal chemical constituents from Monsonia angustifolia and Dodonaea angustifolia plant extracts and evaluate the cytotoxicity of pure compounds from the crude extracts.

MATERIALS AND METHODS

Extractives from M. angustifolia and D. angustifolia plants were isolated using chromatographic techniques and structures were elucidated based on NMR, IR and MS spectroscopic techniques. A microplate serial dilution method was used to evaluate the antibacterial activity of extracts and pure compounds against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and antifungal activity against Candida albicans and Cryptococcus neoformans. The cytotoxicity was determined using the 3-(4, 5-dimethylthiazol)-2, 5-diphenyl tetrazolium bromide (MTT) assay.

RESULTS

The dichloromethane, ethyl acetate and methanol crude extracts from the plants exhibited significant inhibition of microbial growth. The phytochemical investigation of these active crude extracts led to the isolation of five pure active compounds, 5-methoxyjusticidin A (1), cis-phytyl diterpenoidal fatty acid ester (2), stigmasterol (3), β-sitosterol (4) and 5-hydroxy-7,4'-dimethoxyflavone (5). Stigmasterol (3) showed good antifungal activity against Cryptococcus neoformans with a minimum inhibition concentration (MIC) of 25 μg/mL and Candida albicans (MIC = 50 μg/mL).

CONCLUSION

Compounds (1-5) isolated from Monsonia angustifolia and Dodonaea angustifolia showed antibacterial and antifungal activities and were non-toxic against Madin-Darby canine kidney (MDCK) cells and VERO monkey kidney (VERO) cells.

Phytochemical Analysis and Demonstration of Antioxidant, Antibacterial, and Antibiofilm Activities of Ethnomedicinal Plants of North East India

Ethnomedicinal plants are a rich reservoir of active compounds with potent pharmacological properties. Therefore, plants could serve as a source for the discovery of active antimicrobial and antioxidant agents and are focused because of their low toxicity, economic viability, easy availability, etc. In this regard, phytochemical analyses, viz. β-carotene, total sugar, reducing sugar, vitamin C, total carotenoids, protein, total phenolic content (TPC), and total flavonoid content (TFC) of 20 ethnomedicinal plants of North East India (NEI) were evaluated in this study. The antibacterial activity against human pathogens and antioxidant potential of plant extracts was also demonstrated. The minimum inhibitory concentration (MIC₈₀), minimum bactericidal concentration (MBC), and total antibacterial activity (TAA) of the active extracts were evaluated against Pseudomonas aeruginosa and Chromobacterium violaceum. The active extracts were also examined for antibiofilm as well as anti-pyocyanin activities against P. aeruginosa and anti-QS activity against C. violaceum at sub-MICs. The study demonstrated variable concentration of phytochemicals of the extracts, viz. β-carotene (0.29-8.91 mg g^-1), total sugar (2.92-30.6 mM), reducing sugar (0.44-14.5 mM), vitamin C (8.41-31.3 mg g^-1), total carotenoids (14.9-267.0 mg g^-1), protein (5.65-283 mg g^-1), TPC (5.32-31.0 mg GAE/g DW), and TFC (1.74-68.2 mg QE/g DW). The plant extracts also exhibited potent antioxidant and antibacterial activities against both Gram-positive and Gram-negative bacteria. Some of the extracts also demonstrated significant biofilm inhibition and eradication, anti-pyocyanin, and anti-QS activities at sub-MICs. The selected ethnomedicinal plants are rich in phytochemicals and demonstrated potent antioxidant, antibacterial, and antibiofilm activities, thus could serve as the important source of novel antioxidant and antimicrobial agents.

Antimicrobial Peptides with Rigid Linkers against Gram-Negative Bacteria by Targeting Lipopolysaccharide

A series of hybrid peptides were designed by connecting an antimicrobial peptide Ce(1-8) with a lipopolysaccharide (LPS)-targeting peptide Lf(28-34) via different linkers. Antimicrobial experimental results indicated that linkers play an essential role in the anti-Gram-negative bacterial activity of the hybrid peptides. Among these hybrid peptides, peptide CL5 with dipeptide rigid linker LP exhibited excellent activity and selectivity against Gram-negative bacteria. The minimum inhibitory concentrations of CL5 against the tested Gram-negative bacteria were 4-32 μM, while the toxicity toward HEK-293 cells was relatively low. It was found that the interactions of the peptides with LPS were crucial for peptide activity against Gram-negative bacteria. Antimicrobial mechanistic studies showed that peptide CL5 contributed to the death of Gram-negative bacterial cells by disrupting the integrity of the bacterial membranes. This study revealed the importance of linker selection in the design of hybrid peptides and provides the basis for the further development of antimicrobial peptides.

Multidirectional Characterization of Phytochemical Profile and Health-Promoting Effects of Ziziphora bungeana Juz. Extracts

Ziziphora species (Lamiaceae) have been used in traditional medicine as sedatives, antiseptics, carminatives, or expectorants. Despite their common applications in phytotherapy, there is still lack of evidence about the composition of their extracts and its impact on biological properties of the plants. The aim of this study was to evaluate the content of Ziziphora bungeana, a less studied species growing in Kazakhstan, using HPLC-ESI-QTOF-MS/MS instrumentation and to determine its antimicrobial, antioxidant, and cytotoxic activity together with inhibitory properties against tyrosinase and toxicity in erythrocyte lysis assay. Extracts from Z. bungeana were found to be sources of flavonoids, phenolic acids, organic acids, and terpenes that determined their antiradical activity. The minimum inhibitory concentrations of extracts were lower for Gram-positive bacteria (1.25-10 mg/mL) than for Gram-negative bacteria and fungi (5-20 mg/mL). The EC₅₀ value calculated for antiradical activity ranged between 15.00 ± 1.06 µg/mL and 13.21 ± 3.24 µg/mL for ABTS and DPPH assays, respectively. Z. bungeana extracts were found to decrease the activity of tyrosinase by 50% (at 200 µg/mL) similarly to kojic acid and were slightly cytotoxic for human melanoma A375 cell line (at 200 µg/mL) with no effect on HaCaT keratinocytes. In the end, Z. bungeana did not reveal toxic effects in hemolytic assay as compared to the positive control Triton X-100. The performed tests show potential application of the plant in the treatment of infectious diseases, disorders caused by free radicals, and skin problems.

Investigating the antimicrobial activity of essential oils against pathogens isolated from sewage sludge of southern Lebanese villages

Introduction

Due to the high load of pathogens in sewage, seeking for effective treatments became a priority. In this regard, testing the sensitivity of microorganisms isolated from sewage against essential oils (EOs) is suggested. In Lebanon, little evidence supports bacteria isolated from sewage reveals a sensitivity to EOs. Due to this fact, the present investigation aims at determining the sensitivity of microbes isolated from sewage sludge to three EOs: lettuce, coconut, and almond.

Methods

Bacterial isolates were identified by VITEK screening. Yeast was identified by germ tube assay. The chemical components of the oils were identified by gas chromatography - mass spectrometry (GC-MS). Susceptibility of the microbial isolates was assessed by the agar well diffusion assay. Bacteriostatic and bactericidal effects of EOs were detected by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) broth microdilution assay. The activity of EOs on biofilms was detected by antibiofilm screening.

Results

The identified microorganisms include Gram-negative isolates (Escherichia coli, Citrobacter freundii, Citrobacter braakii, Leclercia adecarboxylata, and Stenotrophomonas maltophilia), Gram-positive isolates (Enterococcus faecium, Streptococcus intermedius, Staphylococcus aureus, Staphylococcus capitis, and Staphylococcus haemolyticus), and Candida albicans. Thirty oils' chemical components were identified. Among the antibiotics, doxycycline exhibited the best inhibitory effect. The three EOs were effective against bacterial isolates and yeast at concentrations ranging between 3.125% and 50%. They exhibited a bacteriostatic activity. Lettuce and coconut oils were effective against biofilm formation and the three oils were effective on pre-formed biofilms.

Conclusions

The results reflected the significant antimicrobial and antibiofilm activities of the oils, thus suggesting their potential antimicrobial applications.

A Self-Forming Hydrogel from a Bactericidal Copolymer: Synthesis, Characterization, Biological Evaluations and Perspective Applications

Objects touched by patients and healthcare workers in hospitals may harbor pathogens, including multi-drug resistant (MDR) staphylococci, enterococci (VRE), Escherichia coli, Acinetobacter, and Pseudomonas species. Medical devices contaminated by these pathogens may also act as a source of severe and difficult-to-treat human infections, thus becoming a critical public health concern requiring urgent resolutions. To this end, we recently reported the bactericidal effects of a cationic copolymer (CP1). Here, aiming at developing a bactericidal formulation possibly to be used either for surfaces disinfection or to treat skin infections, CP1 was formulated as a hydrogel (CP1_1.1-Hgel). Importantly, even if not cross-linked, CP1 formed the gel upon simple dispersion in water, without requiring gelling agents or other additives which could be skin-incompatible or interfere with CP1 bactericidal effects in possible future topical applications. CP1_1.1-Hgel was characterized by attenuated-total-reflectance Fourier transform infrared (ATR-FTIR) and UV-Vis spectroscopy, as well as optic and scanning electron microscopy (OM and SEM) to investigate its chemical structure and morphology. Its stability was assessed by monitoring its inversion properties over time at room temperature, while its mechanical characteristics were assessed by rheological experiments. Dose-dependent cytotoxicity studies performed on human fibroblasts for 24 h with gel samples obtained by diluting CP_1.1-Hgel at properly selected concentrations established that the 3D network formation did not significantly affect the cytotoxic profile of CP1. Also, microbiologic investigations carried out on two-fold serial dilutions of CP1-gel confirmed the minimum inhibitory concentrations (MICs) previously reported for the not formulated CP1.Selectivity indices values up to 12 were estimated by the values of LD₅₀ and MICs determined here on gel samples.

Mutual Jellification of Two Bactericidal Cationic Polymers: Synthesis and Physicochemical Characterization of a New Two-Component Hydrogel

Here, a new two-component hydrogel (CP1OP2-Hgel) was developed, simply by dispersing in water two cationic bactericidal polymers (CP1 and OP2) effective against several multidrug-resistant (MDR) clinical isolates of the most relevant Gram-positive and Gram-negative species. Interestingly, while OP2 acts only as an antibacterial ingredient when in gel, CP1 works as both an antibacterial and a gelling agent. To verify whether it would be worthwhile to use CP1 and OP2 as bioactive ingredients of a new hydrogel supposed for a future treatment of skin infections, dose-dependent cytotoxicity studies with CP1 and OP2 were performed on human fibroblasts for 24 h, before preparing the formulation. Although a significant cytotoxicity at concentrations > 2 µM was evidenced for both polymers, selectivity indices (SIs) over 12 (CP1) and up to six (OP2) were determined, due to the powerful antibacterial properties of the two polymers, thus supporting the rationale for their formulation as a hydrogel. The chemical structure and morphology of CP1OP2-Hgel were investigated by PCA-assisted attenuated total reflectance (ATR) Fourier-transform infrared (FTIR) analysis and scanning electron microscopy (SEM), while its rheological properties were assessed by determining its dynamic viscosity. The cumulative weight loss and swelling percentage curves, the porosity, and the maximum swelling capability of CP1OP2-Hgel were also determined and reported. Overall, due to the potent bactericidal effects of CP1 and OP2 and their favorable selectivity indices against several MDR pathogens, good rheological properties, high porosity, and strong swelling capability, CP1OP2-Hgel may, in the future, become a new weapon for treating severe nosocomial skin infections or infected chronic wounds. Further investigations in this sense are currently being carried out.

Antibacterial and Antibiofilm Activity of Juglone Derivatives against Enterococcus faecalis: An In Silico and In Vitro Approach

Enterococcus faecalis is a Gram-positive bacterium that is normally found in the gastrointestinal tract of humans and animals. E. faecalis is an opportunistic pathogen that causes a number of invasive and noninvasive infections. The emergence of multidrug resistance and biofilm formation by the bacterium have rendered the treatment of E. faecalis infections very difficult. Due its high rate of resistance and biofilm formation, there are very few options of treatment. Therefore, the current study was designed to evaluate the antibacterial and biofilm activities of juglone derivatives such as 2-methoxy-6-acetyl-7-methyljuglone and 2-ethoxy-6-acetyl-7-methyljuglone against multidrug-resistant (MDR) and biofilm-producing strains of E. faecalis. Agar well diffusion and broth microdilution methods were used to determine the antibacterial activities. Biofilm attachment and preformed biofilm inhibition were determined using crystal violet staining assay. Both juglone derivatives displayed promising antibacterial and antibiofilm activities against E. faecalis. Among these compounds, 2-ethoxy-6-acetyl-7-methyljuglone possessed better inhibitory activity with minimum inhibitory concentration (MIC) of $9.7\pm 3\mu \text{M}$ as compared to 2-methoxy-6-acetyl-7-methyljuglone (MIC, $19.5\pm 2\mu \text{M}$ ). Additionally, 2-ethoxy-6-acetyl-7-methyljuglone also showed stronger antibiofilm activity than 2-methoxy-6-acetyl-7-methyljuglone. Furthermore, both the ligand molecules were docked into the binding site of the enterococcal surface protein, and the results revealed that both the molecules are actively binding in the target site. Based on these findings, juglone derivatives may be considered useful for the treatment of E. faecalis infections; however, further studies are required to elucidate the mechanism of action.

Secondary Metabolite Profile and Pharmacological Opportunities of Lettuce Plants following Selenium and Sulfur Enhancement

Selenium (Se) is an essential trace nutrient for humans and animals owing to its role in redox regulation, thyroid hormone control factors, immunity, inflammatory reactions, brain activities, and carbohydrate regulation. It is also important to support muscle development, as well as for reproductive and cardiovascular well-being. Furthermore, sulfur is known to be a healing element, due to the remarkable function of specialized and secondary S-containing compounds. The scope of the current study was to determine the impact of Se and S enrichment on the secondary metabolite accumulation and antibacterial and NO inhibition activities in green and red leaf lettuce (V1 and V2, respectively). The plants were grown in a hydroponic system supplied with different S concentrations (S0: 0, S1: 1 mM and S2: 1.5 mM K₂SO₄) via the nutrient solution and foliar-applied varying levels of Se (0, 0.2 and 2.6 µM). Electrospray ionization-quadrupole time-of-flight mass spectrometry (ESI-QTOF/MS) combined with ultra-performance liquid chromatography (UPLC) was used to identify the secondary metabolites in green and red lettuce. The results indicated that extracts of the biofortified lettuce were not cytotoxic to Vero kidney cells at the highest concentration tested of 1 mg/mL. The ESI/MS of the tentatively identified metabolites showed that the response values of 5-O-caffeoylquinic acid, cyanidin 3-O-galactoside, quercetin 3-O-(6''-acetyl-glucoside) and quercetin 3-O-malonylglucoside were induced synergistically under higher Se and S levels in red lettuce plants. The acetone extract of red lettuce had antibacterial activity against Pseudomonas aeruginosa, with a minimum inhibitory concentration (MIC) of 0.156 and 0.625 μg/mL under S2/Se1 and S2/Se2 treatments, respectively. As with antibacterial activity, the acetone extract of green (V1) lettuce treated with adequate (S1) and higher S (S2) under Se-limiting conditions showed the ability to inhibit nitric oxide (NO) release from macrophages. NO production by macrophages was inhibited by 50% at respective concentrations of 106.1 ± 2.4 and 101.0 ± 0.6 μg/mL with no toxic effect on the cells, in response to S1 and S2, respectively, under Se-deficient conditions (Se0). Furthermore, the red cultivar (V2) exhibited the same effect as the green cultivar (V1) regarding NO inhibition, with IC₅₀ = 113.0 ± 4.2 μg/mL, in response to S1/Se2 treatments. Collectively, the promising NO inhibitory effect and antibacterial activity of red lettuce under the above-mentioned conditions might be attributed to the production of flavonoid glycosides and phenylpropanoic acid esters under the same condition. To the best of our knowledge, this is the first report to show the novel approach of the NO inhibitory effect of Se and S enrichment in food crops, as an indicator for the potential of Se and S as natural anti-inflammatory agents.

Anti-Biofilm, Antibacterial, and Anti-Quorum Sensing Activities of Selected South African Plants Traditionally Used to Treat Diarrhoea

The development of resistance of microorganisms to conventional antibiotics is a major global health concern; hence, there is an increasing interest in medicinal plants as a therapeutic option. This study aimed to evaluate the antibacterial, anti-biofilm, and anti-quorum activities of crude extracts prepared using various solvents of nine indigenous South African plants used locally for the treatment of diarrhoea. The minimum inhibitory concentration (MIC) was determined using the broth microdilution method and the crystal violet assay was used to test the anti-biofilm activity of the extracts against a panel of bacteria. Anti-quorum sensing activity of the extracts was assessed via inhibition of violacein production in Chromobacterium violaceum ATCC 12472. Preliminary screening of extracts against E. coli ATCC 25922 revealed that the acetone extracts had significant activity, with MIC values ranging from 0.04 to 0.63 mg/mL. Further screening against a panel of bacterial pathogens showed that the acetone extract of Bauhinia bowkeri was the most active with MIC of 0.01 mg/mL against Salmonella enteritidis, followed by Searsia lancea with MIC of 0.03 mg/mL against Bacillus cereus. All the plant extracts prevented the attachment of biofilms by more than 50% against at least one of the tested bacteria. However, only the mature biofilm of B. cereus was susceptible to the extracts, with 98.22% eradication by Searsia pendulina extract. The minimum quorum sensing inhibitory concentration of the extracts ranged from 0.08 to 0.32 mg/mL with S. lancea having the most significant activity. The extract of S. lancea had the best violacein production inhibitory activity with IC₅₀ value of 0.17 mg/mL. Overall, the results obtained indicate that acetone extracts of S. leptodictya, S. lancea, S. batophylla, S. pendulina, B. galpinii, and B. bowkeri possess antibacterial and anti-biofilm activities and can modulate quorum sensing through the inhibition of violacein production. Therefore, these results signify the potential of the selected plant extracts in treating diarrhoea through inhibition of bacterial growth, biofilm formation inhibition, and quorum sensing antagonism, supporting their medicinal use.