Antibacterial activity of different honeys against pathogenic bacteria

Citrus Honeys from Three Different Regions of Turkey: HPLC-DAD Profiling and in Vitro Enzyme Inhibition, Antioxidant, Anti-Inflammatory and Antimicrobial Properties with Chemometric Study

The objectives of the present study are to compare the phenolic profiles and biological activities of 15 citrus honey samples from three different locations in Turkey using a chemometric approach. The HPLC-DAD analysis was used to determine phenolic profiles. Nineteen phenolic compounds were identified. Gallic acid (107.14-717.04 μg/g) was recorded as the predominant compound. AF (Antalya-Finike) had the highest antioxidant activity in ABTS⋅+ (IC50 : 18.01±0.69 mg/mL), metal chelating (IC50 : 6.20±0.19 mg/mL) and CUPRAC (A0.50 : 12.05±0.68 mg/mL) assays, while it revealed the best anti-inflammatory activity against COX-2 (17.28±0.22 %) and COX-1 (43.28±0.91 %). AM (Antalya-Manavgat) was the most active in β-carotene-linoleic acid (IC50 : 10.05±0.19 mg/mL), anti-urease (38.90±0.69 %), anti-quorum sensing and antimicrobial activities. AKO1 (Adana-Kozan-1) in DPPH⋅ (IC50 : 34.25±0.81 mg/mL) assay, AKU1 (Antalya-Kumluca-1) in tyrosinase inhibition activity (37.73±0.38 %) assay, AKU2 (Antalya-Kumluca-2) in AChE (10.55±0.63 %) and BChE (9.18±0.45 %) inhibition activity assays showed the best activity. Chemometric tools were applied to the phenolic compositions and biological properties. PCA and HCA ensured that 15 citrus honey samples were grouped into 3 clusters. The results showed that myricetin, kaempferol, vanillin, protocatechuic acid, rosmarinic acid, rutin, vanillic acid, gallic acid, catechin and p-hydroxyphenyl acetic acid are phenolic compounds that can be used in the classification of citrus honeys.

Biological Properties, Phenolic Profile, and Botanical Aspect of Nigella sativa L. and Nigella damascena L. Seeds: A Comparative Study

The use of Nigella seeds in the food, pharmaceutical, and cosmetic fields is common, since the iniquity and the virtues of these plants are directly related to their characteristic phytochemical composition. This investigation focused on the comparative study of the botanical aspect, phenolic profile, and in vitro and in vivo biological activities of Nigella sativa L. (NS) and Nigella damascena L. (ND) seeds. The macro- and micro-morphological properties of these seeds were studied, and the key dissimilarities between them were clearly illustrated. The phytochemical contents and phenolic profiles were determined, and the in vitro antioxidant activity was assessed using four methods. The in vivo antioxidant and biochemical parameters of the blood of supplemented mice were determined. The results of the macro- and micro-structure analysis revealed differences between the two plants. Here, ND is characterized by higher phytochemical contents and the best antioxidant activities. The HPLC analysis indicated the presence of nine compounds, namely seven phenolic acids, particularly hydroxybenzoic and caffeic acids, and two flavonoids. The administration of ND extract to mice for 21 days at a concentration of 500 mg/kg allowed a substantial amelioration of plasma antioxidant properties. In addition, the extracts ameliorate blood parameters (cholesterol, triglycerides, glycemia, and urea). Furthermore, the antimicrobial activity of extracts demonstrated their effects on Staphylococcus and Aspergillus. Nigella seeds, in particular ND, expressed considerable in vitro antioxidant properties and demonstrated significant amelioration of mice blood properties. Consequently, these species can serve as a valuable source of compounds with various applications.

Biological Efficacy of Compounds from Stingless Honey and Sting Honey against Two Pathogenic Bacteria: An In Vitro and In Silico Study

Honey inhibits bacterial growth due to the high sugar concentration, hydrogen peroxide generation, and proteinaceous compounds present in it. In this study, the antibacterial activity of stingless and sting honey against foodborne pathogenic bacteria isolated from spoiled milk samples was examined. The isolated bacterial strains were confirmed as Bacillus cereus and Listeriamonocytogenes through morphological, biochemical, and 16 s RNA analysis. Physiochemical characterizations of the honey samples revealed that both of the honey samples had an acidic pH, low water content, moderate reducing sugar content, and higher proline content. Through the disc diffusion method, the antibacterial activities of the samples were assayed and better results were observed for the 50 mg/disc honey. Both stingless and sting honey showed the most positive efficacy against Bacillus cereus. Therefore, an in silico study was conducted against this bacterium with some common compounds of honey. From several retrieved constituents of stingless and sting honey, 2,4-dihydroxy-2,5-dimethyl 3(2H)-furan-3-one (furan) and 4H-pyran-4-one,2,3-dihydro of both samples and beta.-D-glucopyranose from the stingless revealed high ligand-protein binding efficiencies for the target protein (6d5z, hemolysin II). The root-mean-square deviation, solvent-accessible surface area, the radius of gyration, root-mean-square fluctuations, and hydrogen bonds were used to ensure the binding stability of the docked complexes in the atomistic simulation and confirmed their stability. The combined effort of wet and dry lab-based work support, to some extent, that the antimicrobial properties of honey have great potential for application in medicine as well as in the food industries.

The protective effects of blueberry honey from Canada against H2O2-induced cytotoxicity in human buccal mucosal cells

OBJECTIVES

Several clinical trials have been conducted worldwide to evaluate the efficacy of honey against stomatitis. However, it is unclear which types of honey are effective at preventing and/or treating stomatitis. This study aimed to evaluate the potencies of several types of honey in preventing and/or curing aphthous stomatitis in in vitro studies.

METHODS

The following experiments were performed: H₂O₂-induced cytotoxicity and mucosal cell migration in a scratch assay using buccal mucosa squamous carcinoma (HO-1-N-1) cells and the cellular expression of heme oxygenase-1 (HO-1) mRNA encoding an enzyme involved in protection against oxidative stress by real-time RT-PCR analysis, and liquid-liquid extraction and UHPLC analysis in order to examine the active components of honey.

RESULTS

Of the 13 types of honey used, Canadian blueberry honey exhibited the protective effect on H₂O₂-induced cytotoxicity and enhanced cell migration. In addition, blueberry honey increased the expression of HO-1 mRNA with and without cotreatment with H₂O₂. With regard to active components of blueberry honey, the water-soluble components with a mass of >10 kDa showed a cytoprotective effect, but they have not been identified.

CONCLUSION

Canadian blueberry honey, but not the other types of honey, prevents H₂O₂-induced oxidation of cells, probably through activation of the antioxidant and cytoprotective enzyme HO-1. Blueberry honey also enhanced cell migration, which may be relevant to wound healing. The results of this study suggest the possibility of prophylactic and therapeutic effects of Canadian blueberry honey on human stomatitis that could complement existing treatments.

Antimicrobial Evaluation of Various Honey Types against Carbapenemase-Producing Gram-Negative Clinical Isolates

The development of antibiotic resistance is a major public health issue, as infections are increasingly unresponsive to antibiotics. Emerging antimicrobial resistance has raised researchers’ interest in the development of alternative strategies using natural compounds with antibacterial activity, like honey, which has emerged as an agent to treat several infections and wound injuries. Nevertheless, the antibacterial effect of honey was mostly evaluated against Gram-positive bacteria. Hence, the objective of our study was to evaluate the antibacterial activity, as well as the physicochemical parameters, of genuine Greek honeys against multidrug-resistant Gram-negative pathogenic bacteria. In this vein, we aimed to study the in vitro antibacterial potential of rare Greek honeys against Verona integron-encoded metallo-β-lactamase (VIM)- or Klebsiella pneumoniae carbapenemase-producing multidrug-resistant Gram-negative pathogens. Physicochemical parameters such as pH, hydrogen peroxide, free acidity, lactonic acid, total phenols total flavonoids, free radical scavenging activities, tyrosinase enzyme inhibitory activity and kojic acid were examined. Moreover, the antimicrobial activity of 10 different honey types was evaluated in five consecutive dilutions (75%, 50%, 25%, 12.5% and 6.25%) against the clinical isolates by the well diffusion method, as well as by the determination of the minimum inhibition concentration after the addition of catalase and protease. Almost all the physicochemical parameters varied significantly among the different honeys. Fir and manuka honey showed the highest values in pH and H₂O₂, while the free acidity and lactonic acid levels were higher in chestnut honey. Total phenols, total flavonoids and free radical scavenging activities were found higher in cotton, arbutus and manuka honey, and finally, manuka and oregano honeys showed higher tyrosinase inhibition activity and kojic acid levels. The antimicrobial susceptibility depended on the type of honey, on its dilution, on the treatment methodology and on the microorganism. Arbutus honey was the most potent against VIM-producing Enterobacter cloacae subsp. dissolvens in 75% concentration, while fir honey was more lethal for the same microorganism in the 25% concentration. Many honeys outperformed manuka honey in their antibacterial potency. It is of interest that, for any given concentration in the well diffusion method and for any given type of honey, significant differences were not detected among the four multidrug-resistant pathogens, which explains that the damaging effect to the bacterial cells was the same regardless of the bacterial species or strain. Although the antimicrobial potency of different honey varieties dependents on their geographical origin and on their compositional differences, the exact underlying mechanism remains yet unclear.

Bee Venom, Honey, and Royal Jelly in the Treatment of Bacterial Infections of the Oral Cavity: A Review

Oral diseases affect a very large number of people, and the applied pharmacological methods of treatment and/or prevention have serious side effects. Therefore, it is necessary to search for new, safer methods of treatment. Natural bee products, such as honey, royal jelly, and bee venom, can be a promising alternative in the treatment of oral cavity bacterial infections. Thus, we performed an extensive literature search to find and summarize all articles about the antibacterial activity of honey, royal jelly, and bee venom. Our analysis showed that these bee products have strong activity against the bacterial strains causing caries, periodontitis, gingivitis, pharyngitis, recurrent aphthous ulcers, supragingival, and subgingival plaque. An analysis of average MIC values showed that honey and royal jelly have the highest antimicrobial activity against Porphyromonas gingivalis and Fusobacterium nucleatum. In turn, bee venom has an antibacterial effect against Streptococcus mutans. Streptococcus sobrinus and Streptoccus pyogenes were the most resistant species to different types of honey, and royal jelly, respectively. Moreover, these products are safer in comparison to the chemical compounds used in the treatment of oral cavity bacterial infections. Since the antimicrobial activity of bee products depends on their chemical composition, more research is needed to standardize the composition of these compounds before they could be used in the treatment of oral cavity bacterial infections.

Bioactive compounds and antibacterial activities in crystallized honey liquefied with ultrasound

The effect of ultrasound on the crystal size, phenols, flavonoids, Maillard products and antibacterial activity of crystallized honeys was studied. Three multifloral honeys (M), one monofloral (MO) and one honeydew (HD) honey were used. Ultrasound was performed at 42 kHz for different times (0, 5, 10 and 15 min). The antibacterial activities were tested against Salmonella typhimurium, Bacillus subtilis, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus and Escherichia coli. In all honeys, the parameters analyzed had significant differences ((P < 0.05)). After 15 min of ultrasound the HD had increments of 44 mg of gallic acid/100 g of honey in phenols, and some M showed increase in flavonoids (5.64 mg of quercitin /100 g of honey) and improvement in inhibition against Salmonella typhimurium was 13.1%. In some honeys the correlation between phenols or flavonoids and antibacterial activity were significant ((P < 0.05)). No correlation was found between Maillard products and antibacterial activity. The ultrasound treatment effect on the crystal size, phenols, flavonoid, Maillard products, and antibacterial activity of crystallized honeys were different in each honey.

Development of dual crosslinked mumio-based hydrogel dressing for wound healing application: Physico-chemistry and antimicrobial activity

In this study, an antimicrobial mumio-based hydrogel dressing was developed for wound healing application. The mechanism of gel formation was achieved via a double crosslink network formation between gelatin (GT) and polyvinyl alcohol (PVA) using polyethylene glycol diglycidyl ether (PEGDE) and borax as crosslinking agents. To enhance the mechanical integrity of the hydrogel matrix, bacterial cellulose (BC) was integrated into the GT-PVA hydrogel to produce a composite gel dressing. The obtained hydrogel was characterized by FTIR, SEM, TGA, and XRD. Gel fraction, in vitro swelling and degradation as well as compressive modulus properties of the gel dressing were investigated as a function of change in PVA and BC ratios. By increasing the ratios of PVA and BC, the composite dressing showed lower swelling but higher mechanical strength. Comparing to other formulations, the gel with 4 %w/v PVA and 1 %w/v BC demonstrated to be most suitable in terms of stability and mechanical properties. In vitro cell cytotoxicity by MTT assay on human alveolar basal epithelial (A549) cell lines validated the gels as non-toxic. In addition, the mumio-based gel was compared to other formulations containing different bioactive agents of beeswax and cinnamon oil, which were tested for microbial growth inhibition effects against different bacteria (S. aureus and K. pneumoniae) and fungi (C. albicans and A. niger) strains. Results suggested that the gel dressing containing combinations of mumio, beeswax and cinnamon oil possess promising future in the inhibition of microbial infection supporting its application as a suitable dressing for wound healing.

Comparing the Antimicrobial Actions of Greek Honeys from the Island of Lemnos and Manuka Honey from New Zealand against Clinically Important Bacteria

Honey is a natural food with a long history as a traditional medicine because of its many biological characteristics, including antimicrobial, antioxidant, anti-tumor and anti-inflammatory properties. In this study, the antimicrobial actions of eight different honeys from Lemnos island (north-eastern Greece) plus manuka honey (from New Zealand, UMF 30+, licensed in many countries as topical medical preparation) were evaluated against 10 clinically relevant bacteria, including five Gram-positive and five Gram-negative. To achieve this, an agar well diffusion assay measured the diameter of inhibition zones (mm) of two selected concentrations for each honey (25% and 12.5% v/v). The minimum inhibitory and bactericidal concentrations (MIC and MBC) of each sample were also calculated and compared against two representative bacterial species (Salmonella Typhimurium and Staphylococcus aureus) using broth microdilution and agar spot methods, respectively. The pH, water activity (a_w), 5-hydroxymethylfurfural (HMF) and diastase levels, together with the pollen type and content of each honey, were also determined. Results revealed that all the Lemnos honeys presented antibacterial action, which for some samples was like that of manuka. These all had an acidic pH (3.61 ± 0.04), with a a_w ≤ 0.60, while it is worth noting that those found to display the strongest antibacterial actions also presented the lowest HMF content, together with the highest diastase values, both of the latter being used as quality parameters. Pollen composition of the Lemnos honeys was multifloral, underlining the rich plant biodiversity encountered on the island. To summarize, Lemnos honeys could be further exploited as natural antimicrobial systems for use in foods and medicine.

Majra Honey Abrogated the Normal and Cancer Cells Proliferation Inhibition by Juniperus procera Extract and Extract/Honey Generated AgNPs

BACKGROUND

Juniperus procera and Majra honey are well-known as a folk medicine in many countries.

OBJECTIVES

This work aimed to study the immunomodulatory effects after mixing Majra honey, J. procera water leaves extract and silver Nanoparticles (AgNPs) on immune or cancer cells.

METHODS

Juniperus procera water leaves extract and 20% Majra honey were prepared. Both the extract and honey were used separately to synthesize AgNPs. AgNPs were characterized using UV/Vis spectrophotometry and electron microscopy. Bioactive molecules in honey and the extract were explored using Fourier Transform Infrared (FT-IR) spectroscopy. Protein profile of honey was explored using Sodium Dodecyl Sulfate- Polyacrylamide Gel Electrophoresis (SDS-PAGE) and honey sugar content was determined using High- Performance Liquid Chromatography (HPLC). Biological activities of honey and the extract were tested.

RESULTS

The results demonstrated the ability of the extract/honey to produce AgNPs in a spherical shape. The extract/honey contained many functional groups. SDS-PAGE of Majra honey showed many protein bands. HPLC revealed honey is of good quality and no external additives are added to it. The extract and extract+ AgNPs inhibited the growth of normal rat splenic cells while honey stimulated it. The extract+honey turned stimulatory to the splenic cells' growth and significantly diminished the inhibitory potential of the extract containing AgNPs. Both the extract and honey have antimicrobial activities, this potential increased in the presence of AgNPs. Honey and Honey+AgNPs inhibited HepG2 cancer cell proliferation while Hela cell growth inhibited only with honey+AgNPs.

CONCLUSION

Both honey and the extract have antibacterial and immunomodulatory potentials as well as the power to produce AgNPs. Majra honey alone showed anticancer activity against HepGe2 cells, but not against Hela cells, and when contained AgNPs had anticancer activity on both cell lines. Mixing of Majra honey with J. procera extract showed characterized immunomodulatory potentials that can be described as immunostimulant.

Quality, composition and health-protective properties of citrus honey: A review

Citrus honey is one of the most important monofloral honeys produced and consumed worldwide. This honey has pleasant sensorial characteristics, which include light color and typical aroma and flavor. Besides that, several constituents such as minerals, phenolic and volatile compounds, amino acids, sugars, enzymes, vitamins, methylglyoxal and organic acids are found in citrus honey. Moreover, potential biological properties have been associated with citrus honey. All these factors make it highly desired by consumers, increasing its market value, which can stimulates the practice of fraud. Also, citrus honey is susceptible to contamination and to inadequate processing. All these factors can compromise the quality, safety and authenticity of citrus honey. In this sense, this review aims to update and to discuss, for the first time, the data available in the literature about the physicochemical and the sensorial characteristics, composition, health properties, contamination, authenticity and adulteration of citrus honey. With this background, we aim to provide data that can guide future researches related to this honey.

Antibacterial Activity of Honey Samples from Ukraine

The employment of natural substances such as beehive products with a preventive and therapeutic purpose has been a widespread custom since ancient times. In this investigation, the antibacterial activity of 41 honey samples from different Ukraine regions has been evaluated. For each honey, melissopalynological and physico-chemical analysis were performed in order to determine botanical origin, pH, glucose and fructose contents and free acidity. So, antibacterial activity against Staphylococcusaureus CCM 4223, Listeria monocytogenes ATCC 7644, Salmonella enterica serovar Typhimurium CCM 3807 and Escherichia coli ATCC 25922 was assessed through the determination of MIC (Minimum Inhibitory Concentration) and MBC (Minimum Bactericidal Concentration) values by the microdilutions method. The results show that the most susceptible bacterial strain was L. monocytogenes. Its growth was inhibited at a honey concentration ranging from 0.094 to 0.188 g/mL. The most resistant bacterial strain was S. aureus. As concerns MBC values, L. monocytogenes was the most susceptible bacteria, while S. aureus was the most resistant. Helianthus spp. honeys was the most effective against all tested bacterial strains, followed by Robinia spp. and multifloral honeys. Promising results for MIC tests have been found for Brassica spp.

Complete genome sequence and comparative analysis of two potential probiotics Bacillus subtilis isolated from honey and honeybee microbiomes

BACKGROUND

We have previously isolated Bacillus subtilis HMNig-2 and MENO2 strains, from honey and the honeybee gut microbiome respectively, and demonstrated these strains to produce levansucrase with potential probiotics characteristics. Here we report their complete genome sequence and comparative analysis with other and other B. subtilis strains.

RESULTS

The complete genome sequences of Bacillus subtilis HMNig-2 and MENO2 were de novo assembled from MiSeq paired-end sequence reads and annotated using the RAST tool. Whole-genome alignments were performed to identify functional differences associated with their potential use as probiotics.

CONCLUSIONS

The comparative analysis and the availability of the genome sequence of these two strains will provide comprehensive analysis about the diversity of these valuable Bacillus strains and the possible impact of the environment on bacterial evolution.

SIGNIFICANCE AND IMPACT OF STUDY

We introduce complete genome sequence of two new B. subtilis strains HMNig-2 and MENO2 with probiotic potential and as cell factories for the production of levan and other valuable components for pharmaceutical and industrial applications.

Evaluation of Egyptian honeys and their floral origins: phenolic compounds, antioxidant activities, and antimicrobial characteristics

This study reports the physicochemical characterization of clover (Trifolium hybridum) and citrus (Citrus sinensis) honeys produced in Fayoum, Egypt, by evaluating the analysis of moisture content, pH, total soluble solids (TSS), electric conductivity (EC), total sugars, crude protein, ash content, total acidity, hydroxymethylfurfural (HMF), and total phenolic compounds (TPC). Antioxidant and antimicrobial activities of honey extracts and their flower extracts were determined. The results clearly indicated that ethanol gave the highest extraction yield of both clover and citrus flowers, while ethyl acetate showed the highest extraction recovery for the phenolic compounds, with TPC amounting to 338.5 and 536.4 mg gallic acid equivalent kg^-1 fresh weight in clover and citrus flower extracts, respectively. Honey samples have less TPC than their flowers. The results showed that the TPC of citrus honey and its flowers was higher than clover honey and its flowers, respectively. Antioxidant activity was higher in extracts obtained from citrus flower than extracts of clover flower. The same trend was noticed for honey samples. Both clover and citrus honeys showed antimicrobial effects against tested microorganisms. HPLC analysis showed that p-coumaric acid was the main phenolic component in ethanol extracts of clover and citrus honeys, contributing about 83.0% and 52.2%, respectively. In citrus and clover flower extracts, syringic acid and quercetin were the main phenolics, respectively. It would be expected that characteristics of honey samples are mainly depended on the floral origin of nectar foraged by bees.

Chronic wound biofilms: diagnosis and therapeutic strategies

OBJECTIVE

To review the diagnosis of chronic wound biofilms and discuss current treatment approaches.

DATA SOURCES

Articles included in this review were obtained from the following databases: Wanfang, China National Knowledge Infrastructure, PubMed, and the Web of Science. We focused on research published before August 2019 with keywords including chronic wound, biofilm, bacterial biofilms, and chronic wound infection.

STUDY SELECTION

Relevant articles were selected by carefully reading the titles and abstracts. Further, different diagnosis and clinical treatment methods for chronic wound biofilm were compared and summarized from the selected published articles.

RESULTS

Recent guidelines on medical biofilms stated that approaches such as the use of scanning electron microscopy and confocal laser scanning microscopy are the most reliable types of diagnostic techniques. Further, therapeutic strategies include debridement, negative pressure wound therapy, ultrasound, antibiotic, silver-containing dressing, hyperbaric oxygen therapy, and others.

CONCLUSION

This review provides the identification and management of biofilms, and it can be used as a tool by clinicians for a better understanding of biofilms and translating research to develop best clinical practices.

Antibiotics, Acid and Heat Tolerance of Honey adapted Escherichia coli, Salmonella Typhi and Klebsiella pneumoniae

The medicinal importance of honey has been known for many decades due to its antimicrobial properties against life-threatening bacteria. However, previous studies revealed that microorganisms are able to develop adaptations after continuous exposure to antimicrobial compounds. The present study was conducted to explore the impact of subinhibitory concentrations of branded honey (Marhaba) and unbranded honey (extracted from Ziziphus mauritiana plant) locally available in Pakistan on Escherichia coli ATCC 10536, Salmonella Typhi and Klebsiella pneumoniae by investigating the development of self- or cross-resistance to antibiotics (gentamicin, kanamycin and imipenem). Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of autoclaved honeys were determined. The bacterial cells of E. coli ATCC 10536, S. Typhi and K. pneumoniae were subjected to honey adaptation by exposing to ¼ × MIC (4 passages) and ½ × MIC (4 passages) of both honeys. Moreover, tolerance to low pH and high temperature was also studied in adapted and unadapted cells. The decreasing trend in growth pattern (OD_600nm) of E. coli ATCC 10536, S. Typhi and K. pneumoniae was observed with increases in the concentration of honeys (6.25–50% v/v) respectively. Our results showed that continuous exposure of both honeys did not lead to the development of any self- or cross-resistance in tested bacteria. However, percent survival to low pH was found to be significantly higher in adapted cells as compared to unadapted cells. The results indicate that both branded honey (Marhaba) and unbranded honey (extracted from Ziziphus mauritiana plant) were effective in controlling the growth of tested pathogenic bacteria. However, the emergence of tolerance to adverse conditions (pH 2.5, temperature 60 °C) deserves further investigation before proposing honey as a better antibacterial agent in food fabrication/processing, where low pH and high temperatures are usually implemented.

Study of anticancer, antimicrobial, immunomodulatory, and silver nanoparticles production by Sidr honey from three different sources

Sidr honey is used as food and medicine in many countries. Study of immunomodulatory and anticancer activity of Sidr honey did not tested before. The aim of this work was to study the anticancer activity and immunomodulatory as well as antimicrobial potential of Sidr honey and its synthesized silver nanoparticles (AgNPs). Sidr honey from three sources (two from Kingdom of Saudi Arabia (KSA) and one from Pakistan) was diluted to 20% and tested for its biological activities and to synthesize AgNPs. The results demonstrated that honeys could produce AgNPs (spherical shape), modulated the growth of normal splenic cells, and have antimicrobial activities. Sidr honey has anticancer activity against HepG2 but not Hela cells. Sidr honey can be used as antimicrobial agent, but can be used as anticancer agent with care as it stimulated cell growth of some lines (e.g., Hala) and inhibited another (e.g., HepG2).

Exosome-like vesicles in Apis mellifera bee pollen, honey and royal jelly contribute to their antibacterial and pro-regenerative activity

Microvesicles are key players in cellular communication. As glandular secretions present a rich source of active exosomes, we hypothesized that exosome-like vesicles are present in Apis mellifera hypopharyngeal gland secretomal products (honey, royal jelly and bee pollen), and participate in their known antibacterial and pro-regenerative effects. We developed an isolation protocol based on serial centrifugation and ultracentrifugation steps and demonstrated the presence of protein-containing exosome-like vesicles in all three bee-derived products. Assessing their antibacterial properties, we found that exosome-like vesicles had bacteriostatic, bactericidal and biofilm-inhibiting effects on Staphylococcus aureus Furthermore, we demonstrated that mesenchymal stem cells (MSCs) internalize bee-derived exosome-like vesicles and that these vesicles influence the migration potential of the MSCs. In an in vitro wound-healing assay, honey and royal jelly exosome-like vesicles increased migration of human MSCs, demonstrating their inter-kingdom activity. In summary, we have discovered exosome-like vesicles as a new, active compound in bee pollen, honey and royal jelly.

Different incubation patterns affect selective antimicrobial properties of the egg interior: experimental evidence from eggs of precocial and altricial birds

Avian eggs contend with omnipresent microorganisms entering the egg interior, where they affect embryo viability and hatchling phenotype. The incubation behaviour and deposition of egg white antimicrobial proteins (AMPs) vary highly across the avian altricial-precocial spectrum. Experimental evidence of how these alterations in avian reproductive strategies affect the antimicrobial properties of the precocial and altricial egg interior is lacking, however. Here, we tested the egg white antimicrobial activity in eggs of two representative model species, from each end of the avian altricial-precocial spectrum, against potentially pathogenic and beneficial probiotic microorganisms. Eggs were experimentally treated to mimic un-incubated eggs in the nest, partial incubation during the egg-laying period, the onset of full incubation and the increased deposition of two main egg white AMPs, lysozyme and ovotransferrin. We moreover assessed to what extent egg antimicrobial components, egg white pH and AMP concentrations varied as a result of different incubation patterns. Fully incubated precocial and altricial eggs decreased their antimicrobial activity against a potentially pathogenic microorganism, whereas partial incubation significantly enhanced the persistence of a beneficial probiotic microorganism in precocial eggs. These effects were most probably conditioned by temperature-dependent alterations in egg white pH and AMP concentrations. While lysozyme concentration and pH decreased in fully incubated precocial but not altricial eggs, egg white ovotransferrin increased along with the intensity of incubation in both precocial and altricial eggs. This study is the first to experimentally demonstrate that different incubation patterns may have selective antimicrobial potential mediated by species-specific effects on antimicrobial components in the egg white.

The terpenes of leaves, pollen, and nectar of thyme (Thymus vulgaris) inhibit growth of bee disease-associated microbes

Honey bees are highly prone to infectious diseases, causing colony losses in the worst case. However, they combat diseases through a combination of their innate immune system and social defence behaviours like foraging for health-enhancing plant products (e.g. nectar, pollen and resin). Plant secondary metabolites are not only highly active against bacteria and fungi, they might even enhance selective foraging and feeding decisions in the colony. Here, we tested six major plant terpenes and their corresponding acetates, characterizing six natural Thymus vulgaris chemotypes, for their antimicrobial activity on bacteria associated with European foulbrood. Comparison of the inhibitory activity revealed the highest activity for carvacrol and thymol whereas the acetates mostly did not inhibit bacterial growth. All terpenes and acetates are present in the nectar and pollen of thyme, with pollen containing concentrations higher by several orders of magnitude. The physiological response was tested on forager and freshly emerged bees by means of antennal electroantennography. Both responded much stronger to geraniol and trans-sabinene hydrate compared to carvacrol and thymol. In conclusion, bee-forageable thyme product terpenes (mainly from pollen) yield effective antibiotic activity by reducing the growth of bee disease-associated bacteria and can be detected with different response levels by the honey bees' antennae. This is a further step forward in understanding the complex pathogen-pollinator-plant network.

Comparison of the Antimicrobial Activities of Four Honeys From Three Countries (New Zealand, Cuba, and Kenya)

Skin and chronic wound infections are an increasing and urgent health problem worldwide. Their management is difficult and the development of antibiotic resistance by both planktonic and biofilm-associated bacteria necessitates the use of alternative treatments. The purpose of this study was to compare the antimicrobial activity of four honeys from different floral and geographical origins: Melipona beecheii honey (Cuba) and three Apis mellifera honeys [Manuka honey (New Zealand), A. mellifera honey (Cuba), and African honey (Kenya)]. The physicochemical parameters were within the ranges reported for these honeys and M. beecheii honey stood out due to its acidic character. An agar incorporation technique was used to determine the minimum active dilution of each honey against 52 clinical isolates (34 Gram-positive, 17 Gram-negative, and 1 Candida albicans). The antibiofilm activity of honeys was tested by assessing their ability to inhibit biofilm formation and to disrupt preformed biofilms. Overall, M. beecheii honey had the highest antimicrobial and antibiofilm activity, although a marked disruption in preformed biofilms was shared by all tested honeys. Structural changes induced by M. beecheii honey on Staphylococcus aureus and Pseudomonas aeruginosa cells were observed by transmission electron microscopy suggesting that this honey has a potent antimicrobial action and may be an excellent candidate for the development of topical preparations for the treatment of infected wounds.

Isolation and identification of bacteria causing mastitis in small ruminants and their susceptibility to antibiotics, honey, essential oils, and plant extracts

Aim:

The present work aims to isolate and identify bacteria that cause mastitis in small ruminants and evaluates the antibacterial activity of some antibiotics, honey, essential oils, and plant extracts.

Materials and Methods:

A total of 289 milk samples were collected from udder secretions of sheep (n=189) and goat (n=100) from El-Fayoum, Beni-Suef, and Giza governorates. Screening subclinical mastitis (SCM) was done using California Mastitis Test (CMT); identification of the isolates was achieved using Gram’s staining, hemolytic pattern, colony morphology, and biochemical tests using Analytical Profile Index.

Results:

On clinical examination, the incidence of clinical mastitis (CM) was found to be 5.88% and 7% in sheep and goat, respectively. On CMT, SCM was found to be 25 (13.23%) and 11 (10%) in sheep and goat, respectively. Bacteriological examination of all milk samples found the presence of Staphylococcus aureus (SA) (31.1%), coagulase-negative staphylococci (CNS) (19.5%), Escherichia coli (EC) (8.3%), Streptococcus spp. (5.6%), Klebsiella spp. (3.77%), and Pseudomonas spp. (1.89%), while no bacteria were cultured from 81.66% of the samples. Identification of 9 isolates of CNS was achieved by using API staph test to Staphylococcus epidermidis, Staphylococcus hominis, Staphylococcus cohnii, and Staphylococcus saprophyticus. The highest bacterial resistance was found in EC (67.14%) followed by Kp (45.28%) and SA (26.57%).

Conclusion:

Onion and black cumin essential oils followed by Egyptian honey showed strong antibacterial effects against multidrug-resistant bacteria. Finally, our study proved that Egyptian honey, onion, and black cumin essential oils have a marked strong antibacterial effect against bacteria isolated from small ruminant mastitis, but still further extensive studies are needed to discover the therapeutic properties of these plant extracts and honey.

Bioactive properties of honey with propolis

Nowadays, propolis is used as an innovative preservative and as a bioactive food supplement. Due to its bitter and astringent flavour, propolis is hardly accepted by consumers. The aim of this study was to obtain a likeable food product made with honey and propolis, whose antimicrobial, antioxidant and anti-inflammatory properties were enhanced in comparison with those of the base honeys used. 0.1%, 0.3% and 0.5% soft propolis extracts were added to honeys and the products that most appealed to the users were subjected to further research. Total phenolics, flavonoids, ABTS free radical and hydroxyl radicals scavenging and anti-inflammatory activities increased in all mixtures. Antimicrobial activity of the combined products showed synergic effects, resulting in higher results than those of the base honeys and propolis extracts. Therefore, honeys enriched with small amounts of propolis extracts are promising functional foods.

Antimicrobial properties of honey

Honey has been widely accepted as food and medicine by all generations, traditions, and civilizations, both ancient and modern. For at least 2700 years, honey has been used by humans to treat a variety of ailments through topical application, but only recently have the antiseptic and antimicrobial properties of honey been discovered. Honey has been reported to be effective in a number of human pathologies. Clinical studies have demonstrated that application of honey to severely infected cutaneous wounds rapidly clears infection from the wound and improves tissue healing. A large number of in vitro and limited clinical studies have confirmed the broad-spectrum antimicrobial (antibacterial, antifungal, antiviral, and antimycobacterial) properties of honey, which may be attributed to the acidity (low pH), osmotic effect, high sugar concentration, presence of bacteriostatic and bactericidal factors (hydrogen peroxide, antioxidants, lysozyme, polyphenols, phenolic acids, flavonoids, methylglyoxal, and bee peptides), and increase in cytokine release, and to immune modulating and anti-inflammatory properties of honey; the antimicrobial action involves several mechanisms. Despite a large amount of data confirming the antimicrobial activity of honey, there are no studies that support the systemic use of honey as an antibacterial agent.

Evaluation of bactericidal activity of Hannon honey on slowly growing bacteria in the chemostat

There is renewed interest in the therapeutic use of honey, including use in the treatment of infected wounds and burn patients. In this study, we have assessed the antibacterial activity of Libyan floral Hannon honey on Escherichia coli and Staphylococcus aureus, both known to infect wounds. The effects of four concentrations (5%-30%) of honey were compared with that of four antibiotics (ampicillin, tetracycline, polymyxin, and ciprofloxacin) on the growth of these bacteria at early log, mid log, and late log phases. It has been shown that E. coli and S. aureus are to some degree susceptible during mid log phase compared with late log phase, demonstrated by their complete resistance to antibiotics. Chemostat culture was used to investigate the effect of honey on E. coli grown at a steady state with specific growth rates between 0.1 to 0.5 hour(-1). The rate of killing was distinctively clear during the two stages of growth monitored: there was a relatively moderate reduction at the slow growth phase (0.1 to 0.3 hour(-1)), while a dramatic reduction was obtained at the fast growth phase (0.3 to 0.5 hour(-1)), reaching a complete reduction at 0.5 hour(-1). These results complement data using the cup-cut technique. The antibacterial effect of honey was concentration and time dependent, the bactericidal effect was indeed observed at low concentrations, it demonstrates that the honey has more impact on slow growing bacteria than antibiotics have. We suggest that more reduction could be achieved at higher concentrations of honey. These results may have important clinical implications, such as for the management of wound and burn patients.

Antibacterial activity of different natural honeys from Transylvania, Romania

Honey is used in food industry and medicine due to its nutritive, therapeutic and dietetic qualities. The microbiological characteristics of 10 unpasteurized honey samples of known origin, collected from Transylvania beekeepers (Romania) were determined. The antibacterial activity of these types of honey against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Salmonella enteritidis, Salmonella anatum, Salmonella choleraesuis, Bacillus cereus, Bacillus subtilis subsp. spizizenii and Listeria monocytogenes strains was studied. The most sensitive to the antibacterial activity were the two staphylococus strains (the largest diameter of inhibition zone was 18 mm) and B. subtilis strains (13.5 mm). The strains of B. cereus, E. coli, L. monocytogenes and Salmonella spp. were found to present resistance to some of the honey samples. Manna, sunflower and polyfloral honeys presented high antibacterial activity while acacia and linden honeys had a lower activity in terms of the number of sensible strains. Statistical analysis shows that the type of strains and the type of honey have influence on the diameter of inhibition.

Cultivable microorganisms associated with honeys of different geographical and botanical origin

In this study, the composition of the cultivable microbial populations of 38 nectar honey and honeydew honey samples of different botanical and geographical origin were assessed. After growth in specific media, various colonies with different appearance were isolated and purified before phenotypic (morphological, physiological and biochemical traits) and genotypic [randomly amplified polymorphic DNA (RAPD), repetitive DNA elements-PCR (rep-PCR) and restriction fragment length polymorphism (RFLP)] differentiation. The identification was carried out by 16S rRNA gene sequencing for bacteria and, in addition to RFLP, by sequencing the D1/D2 region of the 26S rRNA gene for yeasts and the 5.8S-ITS rRNA region for filamentous fungi. The results showed the presence of 13 species of bacteria, 5 of yeasts and 17 of filamentous fungi; the species most frequently isolated were Bacillus amyloliquefaciens, Zygosaccharomyces mellis and Aspergillus niger for the three microbial groups, respectively. The highest microbial diversity was found in multifloral honeys. No correlation among the microbial species and the botanical/geographical origin was found, but some strains were highly adapted to these matrices since they were found in several samples of different origin.

24-Branched Δ5 sterols from Laurencia papillosa red seaweed with antibacterial activity against human pathogenic bacteria

Methanol extract of thirty-eight seaweeds samples were first screened against Gram-positive (Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 6051) and -negative (Escherichia coli ATCC 8739 and Pseudomonas aerugenosa ATCC 9027) bacteria. Laurencia papillosa (Ceramiales, Rhodomelaceae, Rhodophyta) gave maximum antimicrobial activity against these bacteria. It was finally tested against four clinical Gram-negative isolates (E. coli, P. aerugenosa, Klebsiella pneumoniae and Shigella flexineri) and exhibited antibacterial activity. The extract was fractionated by column chromatography and the active fraction was identified as a cholesterol derivative, 24-propylidene cholest-5-en-3β-ol using gas chromatography mass spectrometry (GC-MS). The electrospray ionization mass spectrometry (ESI-MS) and FT-IR spectroscopic analysis also supported the structure of the compound. The minimum inhibitory concentration ranged from 1.2 to 1.7 μg/mL (IC50) against clinical isolates. This is the first report of antibacterial activity of this cholesterol derivative. This compound could be exploited as potential lead molecule against broad spectrum drug development. The results also affirm the potential of seaweeds as an important natural source of antimicrobial compounds for pharmaceutical industries.

Influence of in vitro simulated gastroduodenal digestion on methylglyoxal concentration of Manuka ( Lectospermum scoparium ) honey

Manuka honey (MH) is a functional food that shows in vitro antimicrobial activity and to which wound healing properties, positive effects on oral health, and beneficial properties during the treatment of gastrointestinal infection diseases and upper gastrointestinal dyspepsia are assigned. The antibacterial activity of MH is mainly due to its high concentration of methylglyoxal (MGO), a highly bifunctional alkylating agent that can induce rapid nonenzymatic modifications of proteins. The aim of the present study was to investigate the influence of in vitro simulated gastric and gastroduodenal digestion on MGO content of MH. To this aim commercial MH samples, with different MGO concentrations, were submitted to digestion, and MGO was determined before and after digestion by a validated RP-HPLC-DAD method. Moreover, the role of MGO in causing carbonylation of the digestive proteins and influencing their enzymatic activities was investigated. The results showed that after digestion MGO concentration decreases because it reacts with digestive enzymes by carbonylating their free amino groups. Nevertheless, carbonylation of pepsin and pancreatin does not influence their physiological activity and therefore does not seem to interfere with the digestion process.

Phenolic content, antioxidant and antibacterial activity of selected natural sweeteners available on the Polish market

Seventeen natural sweeteners available on the Polish market were screened for total phenolic content, by the Folin-Ciocalteu method, and for antioxidant activity, using the ferric reducing antioxidant power (FRAP) assay and the 2,2'-Azinobis (3-ethylbenzthiazoline-6-sulphonic acid) radical cation decolorization assay (ABTS(·+)). In addition, we analyzed antibacterial activities against Staphylococcus aureus strains: both those susceptible and those resistant to methicillin (MRSA). The results of the study showed that total phenolic content, antioxidant activity and antibacterial activity differ widely among different samples of sweeteners. Phenolic content, expressed as a gallic acid equivalent, ranged from 0 mg kg(-1) in white, refined sugar, xylitol and wheat malt syrup to 11.4 g kg(-1) in sugarcane molasses. Antioxidant activity was lowest in refined white sugar, xylitol, brown beet sugar, liquid fructose, and rape honey; it was average in spelt syrup and corn syrup, and highest in sugar cane, beet molasses, date and barley syrups. Despite the great variety of sweeteners, a strong correlation was noted between the concentration of phenolics and antioxidant properties, as determined by the ABTS(·+) method (r = 0.97) and the FRAP assay (r = 0.77). The strongest antibacterial activity was observed in sugarcane molasses, which was lethal to S. aureus strains at 2 and 4% concentrations in medium for susceptible and MRSA strains respectively. Other sweeteners kill bacteria in 6-15% solutions, whereas some did not show any antibacterial activities against S. aureus strains, even at 20% concentrations. Due to their high antioxidant and antibacterial activities, some of the tested sweeteners have potential therapeutic value as supporting agents in antibiotic therapy.

Antimicrobial activity of different Finnish monofloral honeys against human pathogenic bacteria

The antimicrobial activity and phenolic compounds of five Finnish honey products against important human pathogens Streptococcus pneumoniae, S. pyogenes, Staphylococcus aureus, and methicillin-resistant S. aureus were analyzed. Microbroth dilution method and HPLC-DAD were used in antimicrobial testing and phenolic compound determination, respectively. Significant antimicrobial activity (p < 0.01) against all the tested pathogens was found from willow herb (Epilobium angustifolium), heather (Calluna vulgaris), and buckwheat (Fagopyrum esculentum) honeys. This is the first report on antimicrobial activity of Finnish monofloral honeys against streptococcal and staphylococcal bacteria. To our knowledge this is also the first report on the antimicrobial effect of honey against S. pneumoniae.

Manuka honey inhibits the development of Streptococcus pyogenes biofilms and causes reduced expression of two fibronectin binding proteins

Streptococcus pyogenes (group A Streptococcus; GAS) is always of clinical significance in wounds where it can initiate infection, destroy skin grafts and persist as a biofilm. Manuka honey has broad spectrum antimicrobial activity and its use in the clinical setting is beginning to gain acceptance with the continuing emergence of antibiotic resistance and the inadequacy of established systemic therapies; novel inhibitors may affect clinical practice. In this study, the effect of manuka honey on S. pyogenes (M28) was investigated in vitro with planktonic and biofilm cultures using MIC, MBC, microscopy and aggregation efficiency. Bactericidal effects were found in both planktonic cultures and biofilms, although higher concentrations of manuka honey were needed to inhibit biofilms. Abrogation of adherence and intercellular aggregation was observed. Manuka honey permeated 24 h established biofilms of S. pyogenes, resulting in significant cell death and dissociation of cells from the biofilm. Sublethal concentrations of manuka honey effectively prevented the binding of S. pyogenes to the human tissue protein fibronectin, but did not inhibit binding to fibrinogen. The observed inhibition of fibronectin binding was confirmed by a reduction in the expression of genes encoding two major fibronectin-binding streptococcal surface proteins, Sof and SfbI. These findings indicate that manuka honey has potential in the topical treatment of wounds containing S. pyogenes.