Synthesis of novel lignan-like compounds and their antimicrobial activity

Herein we report the preparation of 3,4-dibenzylfurans and some oxidized derivatives with lignan backbone. The compounds were prepared using the Friedel-Crafts reaction with BF₃ etherate as catalyst, demethylation with iodocyclohexane, acetylation and oxidation reactions. The antimicrobial activity was evaluated through their capacity to inhibit the growth of Gram positive and Gram negative bacteria, and of the yeast Candida albicans. Among ten products assayed four furans displayed a good antimicrobial activity against Staphylococcus aureus, S. epidermidis and C. albicans; on the contrary, none of the compounds were active against Pseudomonas aeruginosa. One of them inhibited the growth of S. aureus, S. epidermidis (biofilm producer strain) and C. albicans at 16 μg/mL, showing a bactericidal activity already after one hour of treatment. In summary, the results suggest a possible use of these derivatives for general disinfection practices or antimicrobial agents in cosmesis skin-care.     

Synthesis and Antibacterial Evaluation of Mannich Bases Derived from 1,2,4‐Triazole

The series of novel Mannich bases were synthesized and evaluated for their in vitro antibacterial activity against Gram‐positive and Gram‐negative bacterial strains. The results showed that all compounds were less active than the drugs used as reference, but some of them had moderate potency against Staphylococcus epidermidis ATCC 12228 and Bacillus subtilis ATCC 6633. The presence of a phenyl ring in the position 4 of piperazine seems to be necessary for antibacterial activity in this class of compounds.     

Synthesis,Antimicrobial Activity and Molecular Docking Study of Novel α‐(Diphenylphosphoryl)‐ and α‐(Diphenylphosphorothioyl)cycloalkanone Oximes

A series of novel α‐(diphenylphosphoryl)‐ and α‐(diphenylphosphorothioyl)cycloalkanone oximes have been synthesized in search for novel bioactive molecules. Their structures were characterized by various spectroscopic methods including IR, NMR (¹H, ³¹P, ¹³C), mass spectrometry and single crystal X‐ray diffraction. The newly synthesized phosphorus‐containing oximes were screened for their in vitro antimicrobial activity against Gram‐positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram‐negative bacteria (Escherichia coli and Salmonella typhimurium) and fungal strains (Candida albicans and Candida glabrata). The biological assays showed that all the studied compounds exhibited high antibacterial and antifungal activities at only 0.1–2.1 μg/mL. In silico molecular docking studies in FabH enzyme active site were performed in order to predict the possible interaction modes and binding energies of the drug candidates at the molecular level.     

Synthesis and Biological Evaluation of Novel Carbazole Hybrids as Promising Antimicrobial Agents

Two series of carbazole analogs of 8‐methoxy‐N‐substituted‐9H‐carbazole‐3‐carboxamides (series 1) and carbazolyl substituted rhodanines (series 2) were synthesized through facile synthetic routes. All the final compounds from these two series were evaluated for their preliminary in vitro antifungal and antibacterial activity against four fungal (Candida albicans, Cryptococcus neoformans, Cryptococcus tropicalis and Aspergillus niger) and four bacterial (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa) strains, respectively. Among the tested compounds, three compounds of series 1 displayed promising antifungal and antibacterial activity, especially against C. neoformans and S. aureus. In addition, one compound of series 1 displayed notable antimicrobial activity (MIC: 6.25 μg/mL) against clinical isolates of C. albicans and C. neoformans (MIC: 12.5 μg/mL). From the second series, four compounds exhibited significant antifungal and antibacterial activity, especially against C. neoformans and S. aureus. The most active compound of series 2 displayed a prominent antimicrobial activity against C. neoformans (MIC: 3.125 μg/mL) and S. aureus (MIC: 1.56 μg/mL), respectively.     

Biocidal and anti‐corrosive activities of benzoimidazol‐3‐ium cationic Schiff base surfactants

Two series of cationic Schiff base surfactants, namely, 2‐(benzylideneamino)‐3‐(2‐oxo‐2‐alkoxyethyl)‐1,3‐benzoimidazol‐3‐ium bromide (I _A–D ) and 2‐[(4‐methoxybenzylidene) amino]‐3‐(2‐oxo‐2‐alkoxyethyl)‐1,3‐benzoimidazol‐3‐ium bromide (II _A–D ) were prepared. The chemical structures of the prepared Schiff bases were recognized by elemental analysis, FTIR, H NMR, C¹³‐NMR and GC/MS spectra. The surface activities of the synthesized Schiff base cationic surfactants showed their tendency towards adsorption at the air/water interface. The adsorption tendency was estimated from the values of surface tension and the depression of surface tension at the critical micelle concentration. The studied surfactants were evaluated as antimicrobial agents against pathogenic and sulfur‐reducing bacteria using inhibition zone diameters and minimum inhibition concentration values. The synthesized cationic benzoimidazolium Schiff base cationic surfactants showed good antimicrobial activities against the tested microorganisms including Gram positive, Gram negative as well as fungi. The synthesized compounds were tested for the activity as corrosion inhibitors against carbon steel corrosion in 0.5 M HCl at 200 and 400 ppm. The promising inhibition efficiency of these compounds against the sulfur‐reducing bacteria facilitates them to be applicable in the petroleum field as new categories of Sulfur Reducing Bacteria biocides. The inhibition efficiencies of the tested compounds showed good inhibition and protection of the carbon steel. The corrosion inhibition tendency correlated to the surface activity and chemical structure of the compounds.     

Synthesis and Antimicrobial Evaluation of Novel Chiral 2‐Amino‐4,5,6,7‐tetrahydrothieno[2,3‐c]pyridine Derivatives

New N‐substituted‐2‐amino‐4,5,6,7‐tetrahydrothieno[2,3‐c]pyridine derivatives were synthesized employing a convenient one‐pot three‐component method and their structures were characterized by ¹H‐NMR and single crystal X‐ray diffraction analysis. All the synthesized compounds were in vitro screened for antimicrobial activity against Gram‐positive (Sarcina lutea) and Gram‐negative bacteria (Escherichia coli). In this work, we introduced a chiral residue on the tetrahydropyridine nitrogen, the hitherto the less investigated position on this pharmacophore in order to explore the effect. The antibacterial results showed that the synthesized compounds were active only against Gram‐positive bacteria and the (R)‐enantiomers displayed a greater antimicrobial potency than their (S)‐counterparts. The structure–activity relationship here investigated may provide some interesting clues for future development of tetrahydrothienopyridine derivatives with higher antimicrobial activity.     

Synthesis and characterization of some hydroxypyridone derivatives and their evaluation as antimicrobial agents

The synthesis, in vitro antimicrobial activities of some novel hydroxy pyridines supported with various pharmacophores is described. Twenty-six out of the tested 58 compounds exhibited variable inhibitory effects on the growth of the tested Gram positive and Gram negative bacteria. The tested compounds revealed better activity against the Gram positive rather than the Gram negative strains. The synthesized hydroxypyridones have shown very significant inhibitory effect against Staphylococcus aureus and Bacillus subtilis. Twelve compounds namely; 5d, 5f, 6a, 6b, 8b, 18b, 18c, 19c, 21d, 22b, 22d and 23d were able to produce appreciable growth inhibitory activity against Candida albicans when compared to Clotrimazole. Among these, 22d proved to be the most potent antifungal agent.     

Antimicrobial activity studies on some piperidine and pyrrolidine substituted halogenobenzene derivatives

The in vitro antibacterial and antifungal activities of the compounds synthesised from some 1,2,3,5-tetrahalogeno benzenes in presence of sodium piperidide and sodium pyrrolidide (2,6-dipiperidino-1,4-dihalogenobenzenes; 2,6-dipyrrolidino-1,4-dibromobenzene; 2,4,6-tripyrrolidino chlorobenzene; and 1,3-dipyrrolidino benzene) were investigated. The in vitro antimicrobial activities were screened against the standard strains: Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 6633 as Gram positive, Yersinia enterocolitica ATCC 1501, Escherichia coli ATCC 11230 and Klebsiella pneumoniae as Gram negative, and Candida albicans as yeast-like fungus. Compounds (3, 5, 6, 7) inhibited the growth of all the test strains at MIC values of 32–512 μg/ml. None of the four compounds (1, 2, 4, 8) studied showed antimicrobial activity against any of the test strains within the MIC range 0.25–512 μg/ml.     

Interaction of a novel antimicrobial peptide isolated from the venom of solitary bee Colletes daviesanus with phospholipid vesicles and Escherichia coli cells

The peptide named codesane (COD), consisting of 18 amino acid residues and isolated from the venom of wild bee Colletes daviesanus (Hymenoptera : Colletidae), falls into the category of cationic α‐helical amphipathic antimicrobial peptides. In our investigations, synthetic COD exhibited antimicrobial activity against Gram‐positive and Gram‐negative bacteria and Candida albicans but also noticeable hemolytic activity. COD and its analogs (collectively referred to as CODs) were studied for the mechanism of their action. The interaction of CODs with liposomes led to significant leakage of calcein entrapped in bacterial membrane‐mimicking large unilamellar vesicles made preferentially from anionic phospholipids while no calcein leakage was observed from zwitterionic liposomes mimicking membranes of erythrocytes. The preference of CODs for anionic phospholipids was also established by the blue shift in the tryptophan emission spectra maxima when the interactions of tryptophan‐containing COD analogs with liposomes were examined. Those results were in agreement with the antimicrobial and hemolytic activities of CODs. Moreover, we found that the studied peptides permeated both the outer and inner cytoplasmic membranes of Escherichia coli. This was determined by measuring changes in the fluorescence of probe N‐phenyl‐1‐naphthylamine and detecting cytoplasmic β‐galactosidase released during the interaction of peptides with E. coli cells. Transmission electron microscopy revealed that treatment of E. coli with one of the COD analogs caused leakage of bacterial content mainly from the septal areas of the cells. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.     

Antimicrobial and antiadhesive properties of a biosurfactant isolated from Lactobacillus paracasei ssp. paracasei A20

Aims: The aim of this study was to determine the antimicrobial and antiadhesive properties of a biosurfactant isolated from Lactobacillus paracasei ssp. paracasei A20 against several micro‐organisms, including Gram‐positive and Gram‐negative bacteria, yeasts and filamentous fungi. Methods and Results: Antimicrobial and antiadhesive activities were determined using the microdilution method in 96‐well culture plates. The biosurfactant showed antimicrobial activity against all the micro‐organisms assayed, and for twelve of the eighteen micro‐organisms (including the pathogenic Candida albicans, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus agalactiae), the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were achieved for biosurfactant concentrations between 25 and 50 mg ml^?1. Furthermore, the biosurfactant showed antiadhesive activity against most of the micro‐organisms evaluated. Conclusions: As far as we know, this is the first compilation of data on antimicrobial and antiadhesive activities of biosurfactants obtained from lactobacilli against such a broad group of micro‐organisms. Although the antiadhesive activity of biosurfactants isolated from lactic acid bacteria has been widely reported, their antimicrobial activity is quite unusual and has been described only in a few strains. Significance and Impact of the Study: The results obtained in this study regarding the antimicrobial and antiadhesive properties of this biosurfactant opens future prospects for its use against micro‐organisms responsible for diseases and infections in the urinary, vaginal and gastrointestinal tracts, as well as in the skin, making it a suitable alternative to conventional antibiotics.     

Antibacterial activity of naringin derivatives against pathogenic strains

Aims: To study the antimicrobial activity of naringin (NAR), a flavonoid extracted from citrus industry waste, and NAR derivatives [naringenin (NGE), prunin and alkyl prunin esters] against pathogenic bacteria such as L. monocytogenes, E. coli O157:H7 and S. aureus. The relationship between the structure of the chemical compounds and their antagonistic effect was also analysed. Methods and Results: The agar dilution technique and direct contact assaying were applied. NGE, prunin and NAR showed no antimicrobial activity at a concentration of 0·25 mmol l^?1. Similarly, fatty acids with a chain length between C2 and C18 showed no antimicrobial activity at the same concentration. However, prunin‐6″‐O‐acyl esters presented high antibacterial activity, mainly against Gram‐positive strains. This activity increased with increasing chain length (up to 10–12 carbon atoms). Alkyl prunin esters with 10–12 carbon atoms diminished viability of L. monocytogenes by about 3 log orders and S. aureus by 6 log orders after 2 h of contact at 37°C and at a concentration of 0·25 mmol l^?1. The compounds examined were not effective against any of the Gram‐negative strains assayed, even at the highest concentration. Conclusions: Addition of sugars to the aglycone did not enhance its antimicrobial activity. Attachment of a saturated aliphatic chain with 10–12 carbon atoms to the A ring of the flavonoid (or to sugars attached to this ring), seems to be the most promising modification. In conclusion, alkyl prunin esters with a chain length of C10–C12 have promising features as antimicrobial agents because of their high antilisterial and antistaphylococcal activity. Significance and Impact of the Study: This study shows that it is possible to obtain NAR derivatives with important antimicrobial activity, especially against Gram‐positive pathogenic bacteria. It also provides guidelines on the structural modifications in similar molecules to enhance the antimicrobial activity.     

Modifications on amphiphilicity and cationicity of unnatural amino acid containing peptides for the improvement of antimicrobial activity against pathogenic bacteria

The widespread natural sources‐derived cationic peptides have been reported to reveal bacterial killing and/or growth‐inhibiting properties. Correspondingly, a number of artificial peptides have been designed to understand antibacterial mechanism of the cationic peptides. These peptides are expected to be an alternative antibiotic against drug‐resistant pathogenic bacteria because major antimicrobial mechanism of cationic peptides involves bacterial membrane disorder, although those availabilities have not been well evaluated. In this study, cationic peptides containing Aib were prepared to evaluate the availability as an antimicrobial agent, especially against representative pathogenic bacteria. Among them, BRBA20, consisting of five repeated Aib‐Arg‐Aib‐Ala sequences, showed strong antibacterial activity against both Gram‐negative and Gram‐positive bacteria, including methicillin‐resistant Staphylococcus aureus. Additionally, growth of Serratia marcescens and multidrug‐resistant Pseudomonas aeruginosa, known as proteases‐secreting pathogenic bacteria, were also completely inhibited by BRBA20 under 20 µg/ml peptide concentrations. Our results suggested availabilities of Aib‐derived amphiphilicity and protease resistance in the design of artificial antimicrobial peptides. Comparing BRBA20 with BKBA20, it was also concluded that Arg residue is the preferred cationic source than Lys for antimicrobial action of amphiphilic helices. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

Antimicrobial potential of polyphenols extracted from almond skins

Aims: To evaluate the antimicrobial properties of flavonoid‐rich fractions derived from natural and blanched almond skins, the latter being a by‐product from the almond processing industry. Methods and Results: Almond skin extracts were tested against Gram‐negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, Serratia marcescens), Gram‐positive bacteria (Listeria monocytogenes, Enterococcus hirae, Staphylococcus aureus, Enterococcus durans) and the yeast Candida albicans. Almond skin fractions were found to have antimicrobial activity against L. monocytogenes and Staph. aureus in the range 250–500 μg ml^?1, natural skins showing antimicrobial potential against the Gram‐negative Salm. enterica. The interactions between three almond skin flavonoids were also evaluated with isobolograms. Conclusions: Pairwise combinations of protocatechuic acid, naringenin and epicatechin showed both synergistic and indifferent interactions against Salm. enterica and Staph. aureus. Antagonism was observed against L. monocytogenes with all combinations tested. Further studies need to be performed to understand the mechanisms responsible for these interactions. Significance and Impact of the Study: Almond skins are a potential source of natural antimicrobials.     

In vitro activity of novel in silico‐developed antimicrobial peptides against a panel of bacterial pathogens

Antimicrobial‐peptide‐based therapies could represent a reliable alternative to overcome antibiotic resistance, as they offer potential advantages such as rapid microbicidal activity and multiple activities against a broad spectrum of bacterial pathogens. Three synthetic antimicrobial peptides (AMPs), AMP72, AMP126, and also AMP2041, designed by using ad hoc screening software developed in house, were synthesized and tested against nine reference strains. The peptides showed a partial β‐sheet structure in 10‐mM phosphate buffer. Low cytolytic activity towards both human cell lines (epithelial, endothelial, and fibroblast) and sheep erythrocytes was observed for all peptides. The antimicrobial activity was dose dependent with a minimum bactericidal concentration (MBC) ranging from 0.17 to 10.12 μM (0.4–18.5 µg/ml) for Gram‐negative and 0.94 to 20.65 μM (1.72‐46.5 µg/ml) for Gram‐positive bacteria. Interestingly, in high‐salt environment, the antibacterial activity was generally maintained for Gram‐negative bacteria. All peptides achieved complete bacterial killing in 20 min or less against Gram‐negative bacteria. A linear time‐dependent membrane permeabilization was observed for the tested peptides at 12.5 µg/ml. In a medium containing Mg²⁺ and Ca²⁺, the peptide combination with EDTA restores the antimicrobial activity particularly for AMP2041. Moreover, in combination with anti‐infective agents (quinolones or aminoglycosides) known to bind divalent cation, AMP126 and AMP2041 showed additive activity in comparison with colistin. Our results suggest the following: (i) there is excellent activity against Gram‐negative bacteria, (ii) there is low cytolytic activity, (iii) the presence of a chelating agent restores the antimicrobial activity in a medium containing Mg²⁺ and Ca²⁺, and (iv) the MBC value of the combination AMPs–conventional antibiotics was lower than the MBC of single agents alone. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

Antimicrobial activity,bactericidal mechanism and LPS‐neutralizing activity of the cell‐penetrating peptide pVEC and its analogs

pVEC is a cell‐penetrating peptide derived from the murine vascular endothelial‐cadherin protein. To evaluate the potential of pVEC as antimicrobial peptide (AMP), we synthesized pVEC and its analogs with Trp and Arg/Lys substitution, and their antimicrobial and lipopolysaccharide (LPS)‐neutralizing activities were investigated. pVEC and its analogs displayed a potent antimicrobial activity (minimal inhibitory concentration: 4–16 μM) against Gram‐positive and Gram‐negative bacteria but no or less hemolytic activity (less than 10% hemolysis) even at a concentration of 200 μM. These peptides induced a near‐complete membrane depolarization (more than 80%) at 4 μM against Staphylococcus aureus and a significant dye leakage (35–70%) from bacterial membrane‐mimicking liposome at a concentration as low as 1 μM. The fluorescence profiles of pVEC and its analogs in dye leakage from liposome and membrane depolarization were similar to those of a frog‐derived AMP, magainin 2. These results suggest that pVEC and its analogs kill bacteria by forming a pore or ion channel in the cytoplasmic membrane. pVEC and its analogs significantly inhibited nitric oxide production or tumor necrosis factor‐α release in LPS‐stimulated mouse macrophage RAW264.7 cells at 10 to 50 μM, in which RAW264.7 were not damaged. Taken together, our results suggest that pVEC and its analogs with potent antimicrobial and LPS‐neutralizing activities can serve as AMPs for the treatment of microbial infection and sepsis. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.     

Biological activity of roots and aerial parts of Zinnia peruviana on pathogenic micro-organisms in planktonic state and biofilm forming

Microbial resistance to antibiotics affects the control of clinical infections and is a growing concern in global public health. One important mechanism whereby micro-organisms acquire resistance is biofilm formation. This context has led to the investigation of new antimicrobial substances from plants popularly used in folk medicine. In this work, we studied the antimicrobial and antibiofilm activity of Zinnia peruviana roots, ziniolide (major root metabolite) and aerial parts against Staphylococcus aureus, Staphylococcus epidermidis, Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. The minimum inhibitory and minimum microbicidal concentration and inhibition of biofilm production was determined. All Z. peruviana extracts showed antimicrobial activity, but that corresponding to the roots was the most active one. The best inhibitory and microbicidal activity was detected against Gram-positive bacteria (0·039–0·078 mg ml⁻¹). The acetonic extract from Z. peruviana leaves showed moderate activity against Gram-positive bacteria (0·625 mg ml⁻¹). Acetonic extract of Z. peruviana flowers showed weak activity (1·25–5 mg ml⁻¹). All the extracts tested showed inhibition of biofilm formation, as well as the ziniolide, however, roots and flowers extracts showed higher antibiofilm activity particularly against Staphylococcus, Listeria and Candida. The extracts tested may be a promising natural alternative for the control of microbial infections.     

Additivity and synergy between an antimicrobial peptide and inhibitory ions

Recently we described the pH dependence of activity for a family of cationic antimicrobial peptides (CAMPs) selected from a combinatorial library. In the current work we report on the effects of toxic ions (Cu²⁺, Zn²⁺, and F⁻) and the chelator EDTA on the activity profiles of one member of this family, the 12-residue cationic antimicrobial peptide *ARVA, against a panel of microorganisms. All four ions exhibited either synergy or additivity with *ARVA for all organisms tested with the exception of *ARVA combined with NaF against Candida albicans which exhibited indifference. CuCl₂ and ZnCl₂ exhibited synergy with *ARVA against both the Gram negative Pseudomonas aeruginosa and the Gram positive Staphylococcus aureus as well as strong additivity against Escherichia coli at submillimolar concentrations. The chelator EDTA was synergistic with *ARVA against the two Gram negative organisms but showed only simple additivity with S. aureus and C. albicans despite their much lower MICs with EDTA. This effect may be related to the known differences in the divalent ion binding properties of the Gram negative LPS layer as compared to the peptidoglycan layer of the Gram positive organism. Unlike the other ions, NaF showed only additivity or indifference when combined with *ARVA and required much higher concentrations for activity. The yeast C. albicans did not show synergy or strong additivity with any of the inhibitory compounds tested. The effects of toxic ions and chelators observed here have important implications for applications using CAMPs and for the design of novel formulations involving CAMPs. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova.     

Biogenic selenium nanoparticles: characterization,antimicrobial activity and effects on human dendritic cells and fibroblasts

Tailored nanoparticles offer a novel approach to fight antibiotic‐resistant microorganisms. We analysed biogenic selenium nanoparticles (SeNPs) of bacterial origin to determine their antimicrobial activity against selected pathogens in their planktonic and biofilm states. SeNPs synthesized by Gram‐negative Stenotrophomonas maltophilia [Sm‐SeNPs(?)] and Gram‐positive Bacillus mycoides [Bm‐SeNPs(+)] were active at low minimum inhibitory concentrations against a number of clinical isolates of Pseudomonas aeruginosa but did not inhibit clinical isolates of the yeast species Candida albicans and C. parapsilosis. However, the SeNPs were able to inhibit biofilm formation and also to disaggregate the mature glycocalyx in both P. aeruginosa and Candida spp. The Sm‐SeNPs(?) and Bm‐SeNPs(+) both achieved much stronger antimicrobial effects than synthetic selenium nanoparticles (Ch‐SeNPs). Dendritic cells and fibroblasts exposed to Sm‐SeNPs(?), Bm‐SeNPs(+) and Ch‐SeNPs did not show any loss of cell viability, any increase in the release of reactive oxygen species or any significant increase in the secretion of pro‐inflammatory and immunostimulatory cytokines. Biogenic SeNPs therefore appear to be reliable candidates for safe medical applications, alone or in association with traditional antibiotics, to inhibit the growth of clinical isolates of P. aeruginosa or to facilitate the penetration of P. aeruginosa and Candida spp. biofilms by antimicrobial agents.     

Anti‐biofilm activity of ultrashort cinnamic acid peptide derivatives against medical device‐related pathogens

The threat of antimicrobial resistance has placed increasing emphasis on the development of innovative approaches to eradicate multidrug‐resistant pathogens. Biofilm‐forming microorganisms, for example, Staphylococcus epidermidis and Staphylococcus aureus, are responsible for increased incidence of biomaterial infection, extended hospital stays and patient morbidity and mortality. This paper highlights the potential of ultrashort tetra‐peptide conjugated to hydrophobic cinnamic acid derivatives. These peptidomimetic molecules demonstrate selective and highly potent activity against resistant biofilm forms of Gram‐positive medical device‐related pathogens. 3‐(4‐Hydroxyphenyl)propionic)‐Orn‐Orn‐Trp‐Trp‐NH₂ displays particular promise with minimum biofilm eradication concentration (MBEC) values of 125 µg/ml against methicillin sensitive (ATCC 29213) and resistant (ATCC 43300) S. aureus and activity shown against biofilm forms of Escherichia coli (MBEC: 1000 µg/ml). Kill kinetics confirms complete eradication of established 24‐h biofilms at MBEC with 6‐h exposure. Reduced cell cytotoxicity, relative to Gram‐positive pathogens, was proven via tissue culture (HaCaT) and haemolysis assays (equine erythrocytes). Existing in nature as part of the immune response, antimicrobial peptides display great promise for exploitation by the pharmaceutical industry in order to increase the library of available therapeutic molecules. Ultrashort variants are particularly promising for translation as clinical therapeutics as they are more cost‐effective, easier to synthesise and can be tailored to specific functional requirements based on the primary sequence allowing factors such as spectrum of activity to be varied. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.     

Copper Oxide Nanomaterials Derived from Zanthoxylum armatum DC. and Berberis lycium Royle Plant Species: Characterization,Assessment of Free Radical Scavenging and Antibacterial Activity

Copper oxide nanomaterials were synthesized by a facile sustainable biological method using two plant species (Zanthoxylum armatum DC. and Berberis lycium Royle ). The formation of materials was confirmed by FT‐IR, ATR, UV‐visible, XRD, TEM, SEM, EDX, TGA and PL. The antibacterial activity was evaluated by agar well diffusion method to ascertain the efficacy of plant species extract and extract derived copper oxide nanomaterials against six Gram‐positive bacteria namely Staphylococcus aureus, Streptococcus mutans, Streptococcus pyogenes, Corynebacterium diphtheriae, Corynebacterium xerosis, Bacillus cereus and four Gram‐negative bacteria such as Klebsiella pneumonia, Escherichia coli, Pseudomonas aeruginosa and Proteus vulgaris against the standard drug, Ciprofloxacin for Gram‐positive and Gentamicin for Gram‐negative bacteria, respectively. In both cases, copper oxide nanomaterials were found to be sensitive in all the bacterial species. Sensitivity of copper oxide nanomaterials shows an be higher as compared to plant species extract against different bacteria. Scavenging activity of plant extracts along with nanomaterials have been accessed using previously reported protocols employing ascorbic acid as standard. Scavenging activity of copper oxide nanomaterials shows an increase with increase in concentration. The biological activity (bactericidal and scavenging efficiency) of plant derived copper oxide nanomaterials revealed that these materials can be used as potent antimicrobial agent and DPPH scavengers in industrial as well as pharmacological fields.