Synergistic Antimicrobial Activity Research Articles

Enzyme-assisted polysaccharides extraction from Calocybe indica: Synergistic antibiofilm and oxidative stability of essential oil nanoemulsion

Recently, mushroom polysaccharides have been explored to attribute to vital biologically important functions, and several extraction techniques can be employed, therefore, polysaccharides were extracted from the edible mushroom Calocybe indica to explore its functionality. Multiple enzymes viz., cellulase, pectinase, and protease (1:1:1) at temperature 47 °C and pH 4.64 with an extraction time of 2 h yielded 7.24 % polysaccharide content. The thermograph curve of polysaccharides showed two-stage decomposition at a different temperature range and decomposition of polysaccharides initiated with an onset temperature of 226.77 °C and a maximum peak at 248.90 °C. Hydrodistillation processed Eucalyptus globulus leaf oil was characterized using the chromatography technique and eucalyptol, p-cymene, Γ-terpinene, 4-epi-cubebol, spathulenol, viridiflorol, and p-mentha-1,5-dien-8-ol was observed as major components. As well, we formulated nanoemulsion using mushroom polysaccharide and eucalyptus leaf oil with 140.8 nm and evaluated synergistic antimicrobial and antibiofilm activity. MIC and MBC values for Pseudomonas aeruginosa, E. coli, and S. typhi were 12.50–3.12 and 6.25–1.56, and for S. aureus were 6.25, 6.25, 3.12, and 3.12, 3.12, 1.56 and for C. albicans the values were 12.50, 12.50, 6.250 and 6.25, 6.25, and 3.12 μL/mL respectively. The polysaccharides, essential oil, and nanoemulsion showed remarkable antibiofilm activity against S. aureus with inhibition of 57.42 ± 0.19, 59.62 ± 0.15, and 69.34 ± 0.19 %, while E. coli showed the least antibiofilm activity. However, all three tested samples showed significant (p < 0.05) differences against tested pathogenic microorganisms with inhibition of biofilm formation. Therefore, it could be inferred that the synergistic properties of essential oils with mushroom polysaccharides are a promising strategy to enhance antimicrobial efficacy and control foodborne pathogens.

Characterization and genomic study of EJP2, a novel jumbo phage targeting antimicrobial resistant Escherichia coli.

The emergence of antimicrobial resistance (AMR) Escherichia coli has noticeably increased in recent years worldwide and causes serious public health concerns. As alternatives to antibiotics, bacteriophages are regarded as promising antimicrobial agents. In this study, we isolated and characterized a novel jumbo phage EJP2 that specifically targets AMR E. coli strains. EJP2 belonged to the Myoviridae family with an icosahedral head (120.9 ± 2.9 nm) and a non-contractile tail (111.1 ± 0.6 nm), and contained 349,185 bp double-stranded DNA genome with 540 putative ORFs, suggesting that EJP2 could be classified as jumbo phage. The functions of genes identified in EJP2 genome were mainly related to nucleotide metabolism, DNA replication, and recombination. Comparative genomic analysis revealed that EJP2 was categorized in the group of Rak2-related virus and presented low sequence similarity at the nucleotide and amino acid level compared to other E. coli jumbo phages. EJP2 had a broad host spectrum against AMR E. coli as well as pathogenic E. coli and recognized LPS as a receptor for infection. Moreover, EJP2 treatment could remove over 80% of AMR E. coli biofilms on 96-well polystyrene, and exhibit synergistic antimicrobial activity with cefotaxime against AMR E. coli. These results suggest that jumbo phage EJP2 could be used as a potential biocontrol agent to combat the AMR issue in food processing and clinical environments.

Drug-Free Antimicrobial Nanomotor for Precise Treatment of Multidrug-Resistant Bacterial Infections.

Manufacturing heteronanostructures with specific physicochemical characteristics and tightly controllable designs is very appealing. Herein, we reported NIR-II light-driven dual plasmonic (AuNR-SiO2-Cu7S4) antimicrobial nanomotors with an intended Janus configuration through the overgrowth of copper-rich Cu7S4 nanocrystals at only one high-curvature site of Au nanorods (Au NRs). These nanomotors were applied for photoacoustic imaging (PAI)-guided synergistic photothermal and photocatalytic treatment of bacterial infections. Both the photothermal performance and photocatalytic activity of the nanomotors are dramatically improved owing to the strong plasmon coupling between Au NRs and the Cu7S4 component and enhanced energy transfer. The motion behavior of nanomotors promotes transdermal penetration and enhances the matter-bacteria interaction. More importantly, the directional navigation and synergistic antimicrobial activity of the nanomotors could be synchronously driven by NIR-II light. The marriage of active motion and enhanced antibacterial activity resulted in the expected good antibacterial effects in an abscess infection mouse model.

Synergistic Antimicrobial Activity of Magnetite and Vancomycin-Loaded Mesoporous Silica Embedded in Alginate Films

The aim of the present study was to obtain a hydrogel-based film as a carrier for the sustained and controlled release of vancomycin, an antibiotic commonly used in various types of infections. Considering the high-water solubility of vancomycin (>50 mg/mL) and the aqueous medium underlying the exudates, a prolonged release of vancomycin from an MCM-41 carrier was sought. The present work focused on the synthesis of malic acid coated magnetite (Fe3O4/malic) by co-precipitation, synthesis of MCM-41 by a sol-gel method and loading of MCM-41 with vancomycin, and their use in alginate films for wound dressing. The nanoparticles obtained were physically mixed and embedded in the alginate gel. Prior to incorporation, the nanoparticles were characterized by XRD, FT-IR and FT-Raman spectroscopy, TGA-DSC and DLS. The films were prepared by a simple casting method and were further cross-linked and examined for possible heterogeneities by means of FT-IR microscopy and SEM. The degree of swelling and the water vapor transmission rate were determined, considering their potential use as wound dressings. The obtained films show morpho-structural homogeneity, sustained release over 48 h and a strong synergistic enhancement of the antimicrobial activity as a consequence of the hybrid nature of these films. The antimicrobial efficacy was tested against S. aureus, two strains of E. faecalis (including vancomycin-resistant Enterococcus, VRE) and C. albicans. The incorporation of magnetite was also considered as an external triggering component in case the films were used as a magneto-responsive smart dressing to stimulate vancomycin diffusion.

Nanoencapsulation of Grapefruit Seed Extract and Cinnamon Oil for Oral Health: Preparation, In Vitro, and Clinical Antimicrobial Activities.

This study aimed to formulate mucoadhesive antimicrobial nanoparticles using natural antimicrobials and biopolymers for oral health and verify their antimicrobial activity in clinical studies. A combination of grapefruit seed extract and cinnamon oil (GCN) and chitosan/carrageenan (CS/CR) were selected as synergistic antimicrobial combinations and mucoadhesive wall materials for nanoparticles, respectively. GCN nanoparticles (NPs; size = 357 nm and polydispersity index = 0.188) prepared by ionic gelation between CS and CR exhibited synergistic antimicrobial activity between grapefruit seed extract and cinnamon oil and significantly higher antimicrobial activity against Streptococcus mutans and sobrinus than free GCN in a time-kill assay. The clinical antibacterial activity of GCN was significantly increased and sustained by nanoencapsulation in the mouth-rinse test and GCN NP-treated drinking yogurt. These results suggest that GCN-loaded CS/CR nanoencapsulation is a promising technique that can inhibit oral bacteria with or without the presence of other food ingredients.

Synergistic antimicrobial activity, MD simulation studies and crystal structure of natural alcohol motif containing novel substituted cinnamates

A series of natural alcohols motif containing novel substituted cinnamates were developed and screened against five bacterial strains namely, Enterococcus faecal (E. faecalis), Escherichia coli (E. coli), Bacillus subtilis (B. subtilis), Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella pneumonieae (K. pneumonieae). Among all cinnamates, YS17 was identified with 100% bacterial growth inhibition across the panel, except in E. faecalis with MIC values of 0.25 mg/mL against B. subtilis and P. aeruginosa whereas 0.125, 0.5 and 1 mg/mL against E. coli, K. pneumonieae and E. faecalis, respectively. The growth inhibitory property of YS17 was further validated by disk diffusion, synergistic study and in vitro toxicity assays. Interestingly, YS17 exhibits synergistic effect in combination with the standard drug Ampicillin (AMP). The single crystal structure analysis of YS4 and YS6 was also performed which reconfirmed their proposed structures. Molecular docking visualized significant non-covalent interactions between E. coli MetAP and YS17 and the structural and conformational changes were further analysed using MD simulation studies. Overall, the study provided a suitable core for further synthetic alterations for their optimization as an antibacterial agent. Communicated by Ramaswamy H. Sarma

Antimicrobial effects of essential oil vapors on Bacillus cereus on nutrient agar and iceberg lettuce

We investigated the antimicrobial effects of essential oil (EO) vapors individually and in combination against Bacillus cereus. In an initial study, EO vapors were generated from 95 commercially available EOs and their antimicrobial activities against B. cereus were tested. Five EO vapors (citronella, lemongrass, may chang, oregano, and thyme thymol) showed strong inhibitory activity. Next, we determined the minimal inhibitory concentrations (MICs) and minimal lethal concentrations (MLCs) of these EOs against B. cereus cultured on nutrient agar; values were 0.0781 μL/mL and >5 μL/mL, respectively. The synergistic antimicrobial activity of combinations between EO vapors on B. cereus were evaluated using a modified checkerboard assay. Oregano and thyme thymol EO vapors showed greatest synergism (fractional inhibitory concentration index: 0.5000 at a 1:1 vol ratio). Finally, we tested for antimicrobial properties of oregano and thyme thymol EO vapors against B. cereus on iceberg lettuce individually and in combination. The growth of B. cereus was inhibited by 0.0049–0.0098 μL/mL of EO vapors at concentrations 8- to 16-fold lower than that of MICs on nutrient agar. However, a combination of oregano and thyme thymol EO vapors did not have a synergistic lethal effect. Observations provide basic information for the development of decontamination treatments to inhibit the growth of B. cereus and perhaps other spore-forming bacteria on foods and food-contact surfaces using EO vapors.

Synergistic Antimicrobial Activity of Silver Nanoparticles with an Emergent Class of Azoimidazoles

The combination of two or more agents capable of acting in synergy has been reported as a valuable tool to fight against pathogens. Silver nanoparticles (AgNPs) present a strong antimicrobial action, although their cytotoxicity for healthy cells at active concentrations is a major concern. Azoimidazole moieties exhibit interesting bioactivities, including antimicrobial activity. In this work, a class of recently described azoimidazoles with strong antifungal activity was conjugated with citrate or polyvinylpyrrolidone-stabilized AgNPs. Proton nuclear magnetic resonance was used to confirm the purity of the compounds before further tests and atomic absorption spectroscopy to verify the concentration of silver in the prepared dispersions. Other analytical techniques elucidate the morphology and stability of AgNPs and corresponding conjugates, namely ultraviolet-visible spectrophotometry, scanning transmission electron microscopy and dynamic light scattering analysis. The synergistic antimicrobial activity of the conjugates was assessed through a checkerboard assay against yeasts (Candida albicans and Candida krusei) and bacteria (Staphylococcus aureus and Escherichia coli). The conjugates showed improved antimicrobial activity against all microorganisms, in particular towards bacteria, with concentrations below their individual minimal inhibitory concentration (MIC). Furthermore, some combinations were found to be non-cytotoxic towards human HaCaT cells.

Synergistic Antimicrobial Activity of Ceftriaxone and Polyalthia longifolia Methanol (MEPL) Leaf Extract against Methicillin-Resistant Staphylococcus aureus and Modulation of mecA Gene Presence.

Medicinal plants are an essential source of traditional curatives for numerous skin diseases. Polyalthia longifolia (Sonn.) Thwaites (Annonaceae family) is a medicinal plant used to cure skin illnesses. P. longifolia is usually applied in folkloric therapeutical systems to treat skin diseases. The methicillin-resistant Staphylococcus aureus (MRSA) bacteria is among the essential bacteria contributing to skin diseases. Hence, to verify the traditional medicinal claim of P. longifolia usage in skin disease treatment, the current research was performed to study the synergistic antibacterial activity of standardized Polyalthia longifolia methanol leaf extract (MEPL) against MRSA bacteria. The synergistic antimicrobial activity result of ceftriaxone, when mixed with MEPL, against MRSA was investigated by the disc diffusion method, broth microdilution method, checkerboard dilution test, and modulation of mecA gene expression by multiplex polymerase chain reaction (multiplex PCR). The MEPL extract exhibited good synergistic antimicrobial activity against MRSA. Using the checkerboard method, we confirmed the synergistic effect of MEPL from P. longifolia and ceftriaxone (2:1) for MRSA with a marked reduction of the MIC value of the ceftriaxone from 8000 µg/mL to 1000 µg/mL. Moreover, the combination of MEPL with ceftriaxone significantly (p < 0.05) inhibited the presence of the resistant mecA gene in the tested strain. The LC-ESI-MS/MS analysis identified compounds that were reported to exhibit antimicrobial activity. Conclusively, the MEPL extract, an important etiological agent for skin diseases, showed worthy synergistic antimicrobial action against MRSA bacteria, thus supporting the traditional use of P. longifolia.

Chemical Composition and Antimicrobial Potential of a Plant-Based Substance for the Treatment of Seborrheic Dermatitis

Seborrheic dermatitis (SD) is the most prevalent dermatological disease, occurring in up to 50% of newborns, children, and adults around the world. The antibacterial and antifungal resistance contributed to the search for new natural substances and the development of a novel substance based on Melaleuca alternifolia (M. alternifolia) leaf oil (TTO), 1,8-cineole (eucalyptol), and α-(-)-bisabolol. Thus, this work aimed to determine the chemical composition of the novel plant-based substance and to evaluate its antimicrobial activity against standard microorganisms involved in the pathogenesis of SD. Moreover, the chemical composition of the substance was analyzed by gas chromatography coupled with mass spectrometry (GC/MS). Staphylococcus epidermidis (S. epidermidis), Staphylococcus aureus (S. aureus), Micrococcus luteus (M. luteus), and Candida albicans (C. albicans) were used for antimicrobial and antifungal assays by means of the broth microdilution method to determine the minimal inhibitory concentration (MIC). Finally, the substance's ability to inhibit Malassezia furfur (M. furfur) was evaluated. Eighteen compounds from different chemical groups were identified by GC/MS. The major biologically active compounds of the substance were terpinen-4-ol (20.88%), 1,8-cineole (22.28%), (-)-α-bisabolol (25.73%), and o-cymene (8.16%). The results showed that the substance has a synergistic antimicrobial and antifungal activity, while S. epidermidis and C. albicans strains were the most susceptible. Furthermore, the substance inhibited M. furfur, which is a main pathogen involved in the pathogenesis of SD and clinical manifestations. It can be concluded that the novel plant-based substance has a promising potential against M. furfur and scalp commensal bacteria and may be helpful for the development of new drugs for treatment of dandruff and SD.

Antimicrobial and cytotoxic synergism of biocides and quorum-sensing inhibitors against uropathogenic Escherichiacoli

Uropathogenic Escherichia coli (UPEC) are a primary cause of catheter-associated urinary tract infections (CAUTIs), often forming mature recalcitrant biofilms on the catheter surface. Anti-infective catheter coatings containing single biocides have been developed but display limited antimicrobial activity due to the selection of biocide-resistant bacterial populations. Furthermore, biocides often display cytotoxicity at concentrations required to eradicate biofilms, limiting their antiseptic potential. Quorum-sensing inhibitors (QSIs) provide a novel anti-infective approach to disrupt biofilm formation on the catheter surface and help prevent CAUTIs. To evaluate the combinatorial impact of biocides and QSIs at bacteriostatic, bactericidal and biofilm eradication concentrations in parallel to assessing cytotoxicity in a bladder smooth muscle (BSM) cell line. Checkerboard assays were performed to determine fractional inhibitory, bactericidal, and biofilm eradication concentrations of test combinations in UPEC and combined cytotoxic effects in BSM cells. Synergistic antimicrobial activity was observed between polyhexamethylene biguanide, benzalkonium chloride or silver nitrate in combination with either cinnamaldehyde or furanone-C30 against UPEC biofilms. However, furanone-C30 was cytotoxic at concentrations below those required even for bacteriostatic activity. A dose-dependent cytotoxicity profile was observed for cinnamaldehyde when in combination with BAC, PHMB or silver nitrate. Both PHMB and silver nitrate displayed combined bacteriostatic and bactericidal activity below the half-maximum inhibitory concentration (IC50). Triclosan in combination with both QSIs displayed antagonistic activity in both UPEC and BSM cells. PHMB and silver in combination with cinnamaldehyde display synergistic antimicrobial activity in UPEC at non-cytotoxic concentrations, suggesting potential as anti-infective catheter-coating agents.

Antibacterial potential and synergistic interaction between natural polyphenolic extracts and synthetic antibiotic on clinical isolates

Emergence of antimicrobial resistance complicates treatment of infections by antibiotics. This has driven research on novel and combination antibacterial therapies. The present study evaluated synergistic antimicrobial activity of plant extracts and cefixime in resistant clinical isolates. Preliminary susceptibility profiling of antibiotics and antibacterial activity of extracts was done by disc diffusion and microbroth dilution assays. Checker-board, time-kill kinetics and protein content studies were performed to validate synergistic antibacterial activity. Results showed noteworthy quantities of gallic acid (0.24–19.7 µg/mg), quercetin (1.57–18.44 µg/mg) and cinnamic acid (0.02–5.93 µg/mg) in extracts of plants assessed by reverse-phase high performance liquid chromatography (RP-HPLC). Gram-positive (4/6) and Gram-negative (13/16) clinical isolates were intermediately susceptible or resistant to cefixime, which was used for synergistic studies. EA and M extracts of plants exhibited total synergy, partial synergy and indifferent characteristics whereas aqueous extracts did not show synergistic patterns. Time-kill kinetic studies showed that synergism was both time and concentration-dependent (2–8-fold decrease in concentration). Bacterial isolates treated with combinations at fractional inhibitory concentration index (FICI) showed significantly reduced bacterial growth, as well as protein content (5–62 %) as compared to extracts/cefixime alone treated isolates. This study acknowledges the selected crude extracts as adjuvants to antibiotics to treat resistant bacterial infections.

Evaluation of the Synergistic Antimicrobial Activity of Amikacin with Norfloxacin against Pseudomonas aeruginosa Isolated from Buffaloes Clinical Mastitis

Evaluation of the Synergistic Antimicrobial Activity of Amikacin with Norfloxacin against Pseudomonas aeruginosa Isolated from Buffaloes Clinical Mastitis

Synergistic photoinactivation of Escherichia coli and Listeria innocua by curcumin and lauric arginate ethyl ester micelles

This study evaluated the changes in dispersibility in the aqueous phase, chemical stability, and antimicrobial activity of curcumin after being encapsulated in a lauric arginate ethyl ester (LAE) micelle. Stock curcumin-LAE solutions were prepared by titrating curcumin dissolved in ethanol into LAE aqueous solutions (pH 3.5). The LAE in the stock solutions inhibited the crystallization and prevented the chemical degradation of curcumin during storage at 20 °C. The antimicrobial activity of the curcumin-LAE solutions against Escherichia coli (E. coli) and Listeria innocua (L. innocua) cocktails was assessed by exposing the sample to UV-A light (λ = 365 nm) for 5 min. For samples with both LAE and curcumin at pH 3.5 during irradiation, synergistic antimicrobial activity was observed. The release of protein or nucleic acid from the cells indicated an increase in its membrane permeability after treatments which was due to LAE-facilitated interaction between the photosensitizer and the membrane. LAE could inactivate both bacteria within 10 min without UV-A light irradiation, only at pH 7, which shows that LAE's antimicrobial efficacy depends on the pH. Therefore, microbial inactivation by two mechanisms, photosensitization and permeability operating simultaneously, produced a curcumin-LAE solution that could inactivate bacteria at a broad pH range.

Ethylated analogue of Zingerone: A new and eco-respectful preservative in cosmetics.

This article describes the eco-design of a new preservative in cosmetics based on bio-inspiration of natural extracts from traditional medicines. In order to reach the multiple specification targets, various structures have been synthesized and evaluated to select the one demonstrating broad antimicrobial spectrum with favorable environmental profile and application potential to a wide variety of formulas. In order to evaluate the antimicrobial activity of the synthesized structures, the method of the challenge test consisting in an artificial contamination of the sample with collection microbial strains and evaluation of the number of revivable microorganisms was used to select the most promising candidate. Validation of its antimicrobial potential was later confirmed on Gram positive and Gram negative bacteria, yeast and mold with measurement of its Minimum Inhibitory Concentration (MIC) in comparison with known preservatives. Environmental impact assessment of the selected candidate was achieved with the help of ready biodegradability and aquatic ecotoxicity tests performed according to appropriate Organization tes a strfor Economic Co-operation and Development (OECD) and European Union (EU) guidelinesy. Bio-inspired from turmeric and ginger extracts, an ethylated analog of Zingerone (EZ) with the chemical name 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one demonstrates the strongest activity on Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans. Moreover, EZ shows a solubility in water two times higher than that of Zingerone thus increasing its interest as a potential preservative. Finally, its assessment of ready biodegradability and aquatic ecotoxicity in OECD-EU tests with a favorable environmental profile confirms its unique interest and fully justifies its use in cosmetic formulas as an eco-respectful preservative. Bio-inspiration based on technologies without noteworthy side effects but also on eco-design, particularly through the use of measures of potential environmental impact very upstream of a development, are two fundamental elements for the launching of new eco-friendly cosmetic ingredients. This approach has thus validated the strong potential of EZ as a preservative of eco-respectful formulas. The selection of EZ is also a very good example of the achievement of two key objectives targeted by cosmetic companies for the development of a novel active ingredient: environmental performance and technical performance.

Synergistic Potentiation of Antimicrobial and Antibiofilm Activities of Penicillin and Bacitracin by Octyl Gallate, a Food-Grade Antioxidant, in Staphylococcus epidermidis.

Staphylococcus epidermidis is a major nosocomial pathogen that frequently forms biofilms on indwelling medical devices. This study aimed to investigate the synergistic antimicrobial and antibiofilm activities of octyl gallate (OG) in combination with penicillin and bacitracin against S. epidermidis. Antimicrobial synergy was assessed by conducting checkerboard titration assays, and antibiofilm activity was determined with biofilm assays and fluorescence microscopy analysis. The presence of 8 µg/mL of OG increased both the bacteriostatic and bactericidal activities of penicillin and bacitracin against S. epidermidis. It lowered the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of penicillin by eight-fold and those of bacitracin by four-fold. Moreover, when used with penicillin or bacitracin, OG significantly decreased the level of biofilm production by preventing microcolony formation. Furthermore, OG significantly permeabilized the bacterial cell wall, which may explain its antimicrobial synergy with penicillin and bacitracin. Together, these results demonstrate that OG, a food-grade antioxidant, can be potentially used as a drug potentiator to enhance the antimicrobial and antibiofilm activities of penicillin and bacitracin against S. epidermidis.

Synergistic antimicrobial effects of Dryopteris erythrosora extract and mild heat treatment against Staphylococcus aureus

Control of pathogenic bacteria using natural plant extracts has potential in preventing the emergence of microbial resistance. Also, they are attractive alternatives to antibiotics—particularly in the food industry—because they are safer and more environmentally friendly. Among them, Dryopteris erythrosora (DEE) is rich in flavonoids that have biological functions, including antioxidant activities, but few have been done on their antibacterial activity research. We investigated the synergistic antimicrobial activity of DEE and mild heat against Staphylococcus aureus. The minimum inhibitory concentration (MIC) of DEE against S. aureus was 0.125 mg/mL. The viable S. aureus cell count was reduced by 5.04 log CFU/mL after a DEE and mild heat combinational treatment of 20 min while DEE or mild heat treatments alone produced no inhibition. Propidium iodide fluorescence and scanning electron microscopy analyses revealed that this synergistic antimicrobial effect may be the result of enhanced cell membrane damage. Antimicrobial efficiency was confirmed on stainless steel surfaces: an approximate 6 log reduction was achieved using the combinational treatment. However, DEE or mild heat treatments resulted in less than a 1.5 log reduction. In conclusion, our data showed the potential of DEE with mild heat as an effective disinfection strategy in the food industry.

Synergistic activity of pomegranate rind extract and Zn (II) against Candida albicans under planktonic and biofilm conditions, and a mechanistic insight based upon intracellular ROS induction

Candida albicans (C. albicans) is an opportunistic pathogen, which causes superficial infection and can lead to mortal systemic infections, especially in immunocompromised patients. The incidence of C. albicans infections is increasing and there are a limited number of antifungal drugs used in treatment. Therefore, there is an urgent need for new and alternative antifungal drugs. Pomegranate rind extract (PRE) is known for its broad-spectrum antimicrobial activities, including against C. albicans and recently, PRE and Zn (II) have been shown to induce synergistic antimicrobial activity against various microbes. In this study, the inhibitory activities of PRE, Zn (II) and PRE in combination with Zn (II) were evaluated against C. albicans. Antifungal activities of PRE and Zn (II) were evaluated using conventional microdilution methods and the interaction between these compounds was assessed by in vitro checkerboard and time kill assays in planktonic cultures. The anti-biofilm activities of PRE, Zn (II) and PRE in combination with Zn (II) were assessed using confocal laser scanning microscopy, with quantitative analysis of biofilm biomass and mean thickness analysed using COMSTAT2 analysis. In addition, antimicrobial interactions between PRE and Zn (II) were assayed in terms reactive oxygen species (ROS) production by C. albicans. PRE and Zn (II) showed a potent antifungal activity against C. albicans, with MIC values of 4 mg/mL and 1.8 mg/mL, respectively. PRE and Zn (II) in combination exerted a synergistic antifungal effect, as confirmed by the checkerboard and time kill assays. PRE, Zn (II) and PRE and Zn (II) in combination gave rise to significant reductions in biofilm biomass, although only PRE caused a significant reduction in mean biofilm thickness. The PRE and Zn (II) in combination caused the highest levels of ROS production by C. albicans, in both planktonic and biofilm forms. The induction of excess ROS accumulation in C. albicans may help explain the synergistic activity of PRE and Zn (II) in combination against C. albicans in both planktonic and biofilm forms. Moreover, the data support the potential of the PRE and Zn (II) combination as a novel potential anti-Candida therapeutic system.

The design and evaluation of the antimicrobial activity of a novel conjugated penta-ultrashort antimicrobial peptide in combination with conventional antibiotics against sensitive and resistant strains of S. aureus and E. coli.

Antimicrobial resistance still constitutes a major health concern to the global human population. The development of new classes of antimicrobial agents is urgently needed to thwart the continuous emergence of highly resistant microbial pathogens. In this study, we have rationally designed a novel conjugated ultrashort antimicrobial peptide. The peptide named naprolyginine was challenged against representative strains of wild-type and multidrug-resistant bacteria individually or in combination with individual antibiotics by employing standard antimicrobial and checkerboard assays. Our results displayed that the peptide exhibits potent synergistic antimicrobial activity against resistant strains of gram-positive and gram-negative bacteria when combined with individual antibiotics. Additionally, the peptide was evaluated for its hemolytic activity against human red blood cells and displayed negligible toxicity. Naprolyginine could prove to be a promising candidate for antimicrobial drug development.

Synthesis and Overall Migration Study of Chitosan‐Encapsulated ZnO‐Based ESO Bionanocomposite with Synergistic Antimicrobial Activity for Packaging Purpose.

AbstractCurrent report deals with the successful synthesis and characterization of bionanocomposites from Epoxidized soybean oil matrix reinforced with Chitosan (CS) encapsulated ZnO nanoparticle in different compositions by using simple sonication method. Then they are pressed by using a mold for fabrication of nanocomposite. The properties like mechanical, thermal, water absorption tendency, biodegradability, water contact angle characteristics and antibacterial activity of the cured bionanocomposites have been performed. The cured bionanocomposites demonstrated significant improvement in all of the above properties due to the nanofiller reinforcement. This nanocomposite confirmed a progress in the mechanical properties with good temperature forbearance due to this reinforcement. For determination of the presence of functional groups as well as surface morphology of the prepared bionanocomposite, it was characterized by FTIR and SEM. FTIR analysis proved the presence of strong hydrogen bonding among the polar groups of the bioresin and the hydroxyl groups of the synthesized nanoparticle. Again the study of overall migration tendency with enhanced biodegradability and antibacterial activity, the nanocomposite has proved its candidature for food packaging applications. This novel bionanocomposite is biodegradable, recyclable and can strongly establish its potentiality for multiple applications in different fields with various atmospheric conditions at a particular concentration of the CS encapsulated ZnO nanofiller.