Antimicrobial and antioxidant activities of Russula delica Fr.

Russula delica Fr. is a well known macrofungi which is used as a food in Turkey. The ethanolic extract of R. delica exhibited antimicrobial activity against some of the tested foodborne and spoilage bacteria. The phenolic composition of R. delica ethanolic extract was analyzed by high performance liquid chromatography (HPLC). The major component in R. delica ethanolic extract was catechin (5.33 mg/L). Antioxidant activities of the ethanolic extract of R. delica was evaluated by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals scavenging and chelating ability on ferrous ions assays. Scavenging effect on DPPH radicals was 26% at 10 mg/ml and chelating effects on ferrous ions was 58% at 5 mg/ml. In addition, the amounts of total phenol content (6.23 mg/g), ascorbic acid (2.93 mg/g), β-carotene (0.11 mg/g) and lycopene (0.03 mg/g) in the macrofungi ethanolic extract were determined.     

Synthesis and characterization of a novel controlled release zinc oxide/gentamicin–chitosan composite with potential applications in wounds care

Freshly prepared ZnO nanoparticles were incorporated into a chitosan solution in weight ratios ranging from 1:1 to 12:1. Starting from the ratio of 3:1 the chitosan solution was transformed into a gel with a high consistency, which incorporates 15 mL water for only 0.1 g solid substance. The powders obtained after drying the gel were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermal analysis (TG-DSC). The electronic (UV–vis), infrared (FTIR) and photoluminescence (PL) spectra were also recorded. ZnO particles were coated with gentamicin and incorporated into the chitosan matrix, to yield a ZnO/gentamicin–chitosan gel. The release rate of gentamicin was monitored photometrically. This ZnO/gentamicin–chitosan gel proved great antimicrobial properties, inhibiting Staphylococcus aureus and Pseudomonas aeruginosa growth in both planktonic and surface-attached conditions. The results indicate that the obtained composite can be used in cutaneous healing for developing improved wound dressings, which combine the antibacterial activity of all three components with the controlled release of the antibiotic. This wound dressing maintains a moist environment at the wound interface, providing a cooling sensation and soothing effect, while slowly releasing the antibiotic. The system is fully scalable to any other soluble drug, as the entire solution remains trapped in the ZnO–chitosan gel.     

Wound Dressings Based on Chitosans and Hyaluronic Acid for the Release of Chlorhexidine Diacetate in Skin Ulcer Therapy

In the present work wound dressings, based on chitosan hydrochloride (HCS), 5-methyl-pyrrolidinone chitosan (MPC), and their mixtures with an anionic polymer, hyaluronic acid (HA), were prepared by freeze-drying. Chlorhexidine diacetate (CX) was used as an antimicrobic drug. The mechanical properties of the wound dressings were investigated. In particular, the wound dressings were subjected to dynamic hydration measurements to evaluate their capability to absorb wound exudate and to rheological analysis to investigate their resistance to mechanical stresses on hydration. The wound dressings were also characterized for drug release properties. The antioxidant and antimicrobial activities of medicated and non-medicated wound dressings were also investigated. All the wound dressings are characterized by mechanical resistance suitable for skin application. The addition of hyaluronic acid to chitosans leads to a reduction in wound dressing hydration properties and a modulation of drug release. The wound dressing based on MPC is characterized by the highest elastic properties and by the best scavenger activity. Antimicrobial activity against bacteria and C. albicans is shown by the dressing based on chitosan also in absence of chlorhexidine.     

Antioxidant and pro-oxidant properties of acylated pelargonidin derivatives extracted from red radish (Raphanus sativus var. niger,Brassicaceae)

The antioxidant and pro-oxidant potential of an extract from red radish, in which the major compounds were acylated pelargonidin derivatives, were assessed with a variety of assays in vitro. The extract appeared to form a complex with Fe³⁺ or Cu²⁺. It displayed a concentration-dependant reducing power (1.16 OD_{700 nm} at a concentration of 4 mM) and scavenging effect against 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radicals (with IC₅₀ = 1.74 ± 0.03 mM). It could promote the cleavage of plasmid DNA with Cu(II)/H₂O₂ or Cu(II) alone. This DNA damage could be inhibited by horseradish peroxidase, catalase, and EDTA, respectively. The extract also showed growth inhibition of Bel-7402 cells at lower concentration. The results suggested that the formation of reactive oxygen species might be involved in the mechanism of DNA damage. The acylated pelargonidin derivatives extracted from red radish could act as antioxidant and pro-oxidant and their antioxidant and pro-oxidant properties were relative to the reaction conditions. It might provide novel antioxidant and anticarcinogenic agents.     

Chili post-harvest residue-derived nanocellulose composite as a matrix for in vitro cell culture and Hemigraphis colorata blended nanocellulose extends antimicrobial potential

Nanocellulose is becoming a wonderful biomaterial with wider applications in food, biomedical, cosmetics, and other sectors. Nanocellulose is easily degradable, bio-derived and can be effectively used for constructing novel bioplastics which finds applications in food packaging and wound dressing. Nanocellulose was isolated from Chili post-harvest residue and its properties were evaluated using FESEM, XRD and FTIR. Cytotoxicity and viability of cells are critical characteristics defining a material for biomedical applications and these properties were investigated for Chili post-harvest residue derived nanocelluose. The cell viability of HEK293 cells was assessed and the results demonstrated that the cell viability was normal, with no cytotoxicity and DNA damaging effects. Next we examined the antimicrobial potential of NC films after blending with Hemigraphis colorata extract. The nanocellulose blended with Hemigraphis colorata extract provided effective antimicrobial activity by inhibiting the growth of Bacillus cereus, E. coli, Pseudomonas sp. and Saccharomyces cerevisiae. The antimicrobial property of NC composite suggests its potential for use in food packaging and in wound dressing material.     

Antimicrobial and antibiofilm activity of LL-37 and its truncated variants against Burkholderia pseudomallei

The Gram-negative bacterium Burkholderia pseudomallei is the aetiological agent of melioidosis, which is an endemic disease in tropical areas of Southeast Asia and Northern Australia. Burkholderia pseudomallei has intrinsic resistance to a number of commonly used antibiotics and has also been reported to develop a biofilm. Resistance to killing by antimicrobial agents is one of the hallmarks of bacteria grown in biofilm. The aim of this study was to determine the antimicrobial activity and mechanisms of action of LL-37 and its truncated variants against B. pseudomallei both in planktonic and biofilm form, as LL-37 is an antimicrobial peptide that possessed strong killing activity against several pathogens. Antimicrobial assays revealed that LL-31, a truncated variant of LL-37 lacking the six C-terminus residues, exhibited the strongest killing effect. Time-kill experiments showed that 20 μM LL-31 can reach the bactericidal endpoint within 2 h. Freeze-fracture electron microscopy of bacterial cells demonstrated that these peptides disrupt the membrane and cause leakage of intracellular molecules leading to cell death. Moreover, LL-31 also possessed stronger bactericidal activity than ceftazidime against B. pseudomallei grown in biofilm. Thus, LL-31 should be considered as a potent antimicrobial agent against B. pseudomallei both in planktonic and biofilm form.     

Biological potentials and cytotoxicity of various extracts from endemic Origanum minutiflorum O. Schwarz & P.H. Davis

The aim of the present study was to investigate antioxidative, antimicrobial and cytotoxic effects of endemic Origanum minutiflorum (O. Schwarz & P.H. Davis). Antioxidant activities of the extracts from O. minutiflorum were evaluated by using DPPH radical scavenging, β-carotene bleaching and metal chelating activity assays. In addition, the amounts of total phenol components in the plant extracts were determined. In the β-carotene bleaching test, the extracts exhibited in the range of 58.1 ± 0.2% – 98.2 ± 0.3% inhibition against linoleic acid oxidation. The antimicrobial efficiency of the plant was evaluated according to agar well diffusion and microdilution broth methods. The n-hexane extract of O. minutiflorum having an inhibition zone of 20.2 ± 0.2 mm, had the maximum antibacterial efficiency against Shigella sonnei RSKK 878. Cytotoxic effects of the extracts were determined by MTT assay. O. minutiflorum extracts (at concentration of 10–100 μg/ml) did not show any cytotoxic effect on baby hamster kidney fibroblast cell line. The results showed that O. minutiflorum could be used as a natural source in food industry.     

Wound dressings based on chitosans and hyaluronic acid for the release of chlorhexidine diacetate in skin ulcer therapy

In the present work wound dressings, based on chitosan hydrochloride (HCS), 5-methyl-pyrrolidinone chitosan (MPC), and their mixtures with an anionic polymer, hyaluronic acid (HA), were prepared by freeze-drying. Chlorhexidine diacetate (CX) was used as an antimicrobic drug. The mechanical properties of the wound dressings were investigated. In particular, the wound dressings were subjected to dynamic hydration measurements to evaluate their capability to absorb wound exudate and to rheological analysis to investigate their resistance to mechanical stresses on hydration. The wound dressings were also characterized for drug release properties. The antioxidant and antimicrobial activities of medicated and non-medicated wound dressings were also investigated. All the wound dressings are characterized by mechanical resistance suitable for skin application. The addition of hyaluronic acid to chitosans leads to a reduction in wound dressing hydration properties and a modulation of drug release. The wound dressing based on MPC is characterized by the highest elastic properties and by the best scavenger activity. Antimicrobial activity against bacteria and C. albicans is shown by the dressing based on chitosan also in absence of chlorhexidine.     

Leptoglycin: A new Glycine/Leucine-rich antimicrobial peptide isolated from the skin secretion of the South American frog Leptodactylus pentadactylus (Leptodactylidae)

Antimicrobial peptides are components of innate immunity that is the first-line defense against invading pathogens for a wide range of organisms. Here, we describe the isolation, biological characterization and amino acid sequencing of a novel neutral Glycine/Leucine-rich antimicrobial peptide from skin secretion of Leptodactylus pentadactylus named leptoglycin. The amino acid sequence of the peptide purified by RP-HPLC (C₁₈ column) was deduced by mass spectrometric de novo sequencing and confirmed by Edman degradation: GLLGGLLGPLLGGGGGGGGGLL. Leptoglycin was able to inhibit the growth of Gram-negative bacteria Pseudomonas aeruginosa, Escherichia coli and Citrobacter freundii with minimal inhibitory concentrations (MICs) of 8 μM, 50 μM, and 75 μM respectively, but it did not show antimicrobial activity against Gram-positive bacteria (Staphylococcus aureus, Micrococcus luteus and Enterococcus faecalis), yeasts (Candida albicans and Candida tropicalis) and dermatophytes fungi (Microsporum canis and Trichophyton rubrum). No hemolytic activity was observed at the 2-200 μM range concentration. The amino acid sequence of leptoglycin with high level of glycine (59.1%) and leucine (36.4%) containing an unusual central proline suggests the existence of a new class of Gly/Leu-rich antimicrobial peptides. Taken together, these results suggest that this natural antimicrobial peptide could be a tool to develop new antibiotics.     

Neomycin-loaded poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA)/polyvinyl alcohol (PVA) ion exchange nanofibers for wound dressing materials

In this study, poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA) blended with polyvinyl alcohol (PVA) was electrospun and then subjected to thermal crosslinking to produce PSSA-MA/PVA ion exchange nanofiber mats. The cationic drug neomycin (0.001, 0.01, and 0.1%, w/v) was loaded onto the cationic exchange fibers. The amount of neomycin loaded and released and the cytotoxicity of the fiber mats were analyzed. In vivo wound healing tests were also performed in Wistar rats. The results indicated that the diameters of the fibers were on the nanoscale (250 ± 21 nm). The ion exchange capacity (IEC) value and the percentage of water uptake were 2.19 ± 0.1 mequiv./g-dry fibers and 268 ± 15%, respectively. The loading capacity was increased upon increasing the neomycin concentration. An initial concentration of 0.1% (w/v) neomycin (F3) showed the highest loading capacity (65.7 mg/g-dry fibers). The neomycin-loaded nanofiber mats demonstrated satisfactory antibacterial activity against both Gram-positive and Gram-negative bacteria, and an in vivo wound healing test revealed that these mats performed better than gauze and blank nanofiber mats in decreasing acute wound size during the first week after tissue damage. In conclusion, the antibacterial neomycin-loaded PSSA-MA/PVA cationic exchange nanofiber mats have the potential for use as wound dressing materials.     

Alginate-based aerogels as wound dressings for efficient bacterial capture and enhanced antibacterial photodynamic therapy

The development of novel wound dressings, such as aerogels, with rapid hemostasis and bactericidal capacities for pre-hospital care is necessary. To prevent the occurrence of bacterial resistance, antibacterial photodynamic therapy (aPDT) with broad-spectrum antibacterial ability and negligible bacterial resistance has been intensively studied. However, photosensitizers often suffer from poor water solubility, short singlet oxygen (¹O₂) half-life and restricted ¹O₂ diffusion distance. Herein, sodium alginate was covalently modified by photosensitizers and phenylboronic acid, and cross-linked by Ca(II) ions to generate SA@TPAPP@PBA aerogel after lyophilization as an antibacterial photodynamic wound dressing. Afterwards, its photodynamic and bacterial capture activities were intensively evaluated. Furthermore, its hemostasis and bactericidal efficiency against Staphylococcus aureus were assessed via in vitro and in vivo assays. First, chemical immobilization of photosensitizers led to an enhancement of its solubility. Moreover, it showed an excellent hemostasis capacity. Due to the formation of reversible covalent bonds between phenylboronic acid and diol groups on bacterial cell surface, the aerogel could capture S. aureus tightly and dramatically enhance aPDT. To sum up, the prepared aerogel illustrated excellent hemostasis capacity and antibacterial ability against S. aureus. Therefore, they have great potential to be utilized as wound dressing in clinical trials.     

Design and production of gentamicin/dextrans microparticles by supercritical assisted atomisation for the treatment of wound bacterial infections

In this work, the supercritical assisted atomisation (SAA) is proposed, for the first time, for the production of topical carrier microsystems based on alginate–pectin blend. Gentamicin sulphate (GS) was loaded as high soluble and hygroscopic antibiotic model with poor flowability. Particularly, different water solutions of GS/alginate/pectin were processed by SAA to produce spherical microparticles (GAP) of narrow size (about 2 μm). GS loading was varied between 20% and 33% (w/w) with an encapsulation efficiency reaching about 100%. The micronised powders also showed high flow properties, good stability and constant water content after 90 days in accelerated storage conditions. The release profiles of the encapsulated drug were monitored using vertical diffusion Franz cells to evaluate the application of GAP microsystems as self-consistent powder formulation or in specific fibres or gels for wound dressing. All formulations showed an initial burst effect in the first 6 h of application (40–65% of GS loaded), and in particular GAP4 produced with a GS/alginate/pectin ratio of 1:3:1, exhibited the ability to release GS continuously over 6 days. Antimicrobial tests against Staphylococcus aureus indicated that GS antibiotic activity was preserved at 6 days and higher than pure GS at 12 and 24 days for all SAA formulations, especially for GAP1.     

Essential oil composition and antioxidant and antimicrobial properties of the aerial parts of Salvia eremophila Boiss. from Iran

The essential oil composition and in vitro antioxidant and antimicrobial activity of the essential oil and methanol extract of Salvia eremophila were evaluated in this research. GC and GC/MS analysis of the plant essential oil resulted in the identification of 28 compounds representing 99.24% of the oil. Borneol (21.83%), α-pinene (18.80%), bornyl acetate (18.68%) and camphene (6.54%) were detected as the major components consisting 65.85% of the oil. The plant essential oil and methanol extract were also subjected to screenings for the evaluation of their antioxidant activities using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene–linoleic acid tests. While the plant essential oil showed only weak antioxidant activities, its methanol extract was considerably active in both DPPH (IC₅₀ = 35.19 μg/ml) and β-carotene–linoleic acid (inhibition percentage: 72.42%) tests. Appreciable total phenolic content (101.25 μg/mg) was also detected for the plant methanol extract as gallic acid equivalent in the Folin–Ciocalteu test. The plant was also screened for its antimicrobial activity and good to moderate inhibitions were recorded for its essential oil and methanol extract against most of the tested microorganisms.     

Biosynthesis of Silver Nanoparticles from Marine Seaweed Sargassum cinereum and their Antibacterial Activity

Seaweed extracts of Sargassum cinereum was used as a reducing agent in the eco-friendly extracellular synthesis of silver nanoparticles from an aqueous solution of silver nitrate (AgNO₃). High conversion of silver ions to silver nanoparticles was achieved with a reaction temperature of 100^° and a seaweed extract concentration of 10% with a residential time of 3 h. Formation of silver nanoparticles was characterised by spectrophotometry and the scanning electron microscope. The average particles size was ranging from 45 to 76 nm. Antimicrobial activities indicate the minimum inhibitory concentration of biologically synthesised nanoparticles tested against the pathogen Staphylococcus aureus with 2.5 μl (25 μg/disc). High inhibitions over the growth of Enterobacter aerogenes, Salmonella typhi and Proteus vulgaris were witnessed against the concentrations of 100 μg/disc. Promising potential and the future prospects of S. cinereum nanoparticles in pharmaceutical research are the highlights in this paper.     

Evaluation of Antimicrobial and Wound Healing Potentials of Ethanol Extract of Wedelia biflora Linn D.C. Leaves

To rationalize scientifically the traditional claim on use of Wedelia biflora (Linn.) D. C. for the treatment of wounds and infections, the present study was designed to evaluate the antimicrobial and wound healing activity of ethanol extract of leaves of W. biflora. In in vitro assays the test extract was subjected to antimicrobial activity by agar well-diffusion method and minimum inhibitory concentration method in different microbial strains. Wound healing activity of the test extract was studied by excision wound model and incision wound model in Wistar albino rats. In excision wound model, 97.90% wound healing was recorded in 10% w/w extract treated group on 16^th days of postsurgery, whereas only 58.50% was observed in control group. In incision model, higher breaking strength, high hydroxyl proline content and histopathological study in extract treated groups revealed higher collagen redeposition than the control group. The agar well-diffusion evaluation and minimum inhibitory concentration established antimicrobial efficacy of ethanol extracts of W. biflora. These observations established the traditional claim and therapeutic activity of W. biflora and it could be a potent wound healing candidate for use in future.     

Volatile compounds in the stem bark of Sclerocarya birrea (Anacardiaceae) possess antimicrobial activity against drug-resistant strains of Helicobacter pylori

The aim of this study was to isolate and identify phytochemicals with anti-Helicobacter pylori activity from the stem bark of Sclerocarya birrea. The plant crude extract was fractionated by silica gel column and thin layer chromatography techniques, initially with ethyl acetate (EA) and subsequently with a combination of ethyl acetate/methanol/water (EMW). Further fractionation and identification of the phytoconstituents was achieved by gas chromatography and mass spectrometry (GC/MS) analysis. The antimicrobial activity of the fractions and compounds was evaluated against five metronidazole- and clarithromycin-resistant strains of H. pylori as well as a reference strain ATCC 43526 using the microbroth dilution technique. Amoxicillin was included in the experiments as a positive control antibiotic. Of the 18 fractions collected, 16 demonstrated anti-H. pylori activity with 50% minimum inhibitory concentration (MIC₅₀) values ranging from 310 μg/mL to 2500 μg/mL. Two of the fractions (EMW fraction 6 and EA fraction 1) revealed the presence of 5 and 24 compounds, respectively, representing 40.5% and 86.57% of the total composition. Most of the compounds were essential oils, with terpinen-4-ol being the most abundant agent (35.83%), followed by pyrrolidine (32.15%), aromadendrene (13.63%) and α-gurjunene (8.77%). MIC₅₀ ranges for amoxicillin, terpinen-4-ol and pyrrolidine were 0.0003-0.06 μg/mL, 0.004-0.06 μg/mL and 0.005-6.3 μg/mL, respectively. The inhibitory activities of terpinen-4-ol and pyrrolidine were similar to amoxicillin (P > 0.05). Most of these compounds are being reported in this plant for the first time and may represent new sources of therapeutically useful compounds against H. pylori.     

Cytotoxicity in L929 fibroblasts and inhibition of herpes simplex virus type 1 Kupka by estuarine cyanobacteria extracts

The cyanobacteria are known to be a rich source of metabolites with a variety of biological activities in different biological systems. In the present work, the bioactivity of aqueous and organic (methanolic and hexane) crude extracts of cyanobacteria isolated from estuarine ecosystems was studied using different bioassays. The assessment of DNA damage on the SOS gene repair region of mutant PQ37 strain of Escherichia coli was performed. Antiviral activity was evaluated against influenza virus, HRV-2, CVB3 and HSV-1 viruses using crystal violet dye uptake on HeLa, MDCK and GMK cell lines. Cytotoxicity evaluation was performed with L929 fibroblasts by MTT assay. Of a total of 18 cyanobacterial isolates studied, only the crude methanolic extract of LEGE 06078 proved to be genotoxic (IF > 1.5) in a dose-dependent manner and other four were putative candidates to induce DNA damage. Furthermore, the crude aqueous extract of LEGE 07085 showed anti- herpes type 1 activity (IC50 = 174.10 μg dry extract mL⁻¹) while not presenting any cytotoxic activity against GMK cell lines. Of the 54 cyanobacterial extracts tested, only the crude methanolic and hexane ones showed impair on metabolic activity of L929 fibroblasts after long exposure (48-72 h). The inhibition of HSV-1 and the strong cytotoxicity against L929 cells observed emphasizes the importance of evaluating the impact of those estuarine cyanobacteria on aquatic ecosystem and on human health. The data also point out their potential application in HSV-1 treatment and pharmacological interest.     

Controlled Release of Chitosan and Sericin from the Microspheres-Embedded Wound Dressing for the Prolonged Anti-microbial and Wound Healing Efficacy

One approach in wound dressing development is to incorporate active molecules or drugs in the dressing. In order to reduce the frequency of dressing changes as well as to prolong wound healing efficacy, wound dressings that can sustain the release of the active molecules should be developed. In our previous work, we developed chitosan/sericin (CH/SS) microspheres that released sericin in a controlled rate. However, the difficulty of applying the microspheres that easily diffuse and quickly degrade onto the wound was its limitations. In this study, we aimed to develop wound dressing materials which are easier to apply and to provide extended release of sericin. Different amounts of CH/SS microspheres were embedded into various compositions of polyvinyl alcohol/gelatin (PVA/G) scaffolds and fabricated using freeze-drying and glutaraldehyde crosslinking techniques. The obtained CH/SS microspheres-embedded scaffolds with appropriate design and formulation were introduced as a wound dressing material. Sericin was released from the microspheres and the scaffolds in a sustained manner. Furthermore, an optimized formation of the microspheres-embedded scaffolds (2PVA2G+2CHSS) was shown to possess an effective antimicrobial activity against both gram-positive and gram-negative bacteria. These microspheres-embedded scaffolds were not toxic to L929 mouse fibroblast cells, and they did not irritate the tissue when applied to the wound. Finally, probably by the sustained release of sericin, these microspheres-embedded scaffolds could promote wound healing as well as or slightly better than a clinically used wound dressing (Allevyn®) in a mouse model. The antimicrobial CH/SS microspheres-embedded PVA/G scaffolds with sustained release of sericin would appear to be a promising candidate for wound dressing application.