Unexpected Value of Honey Color for Prediction of a Non-Enzymatic HO Production and Honey Antibacterial Activity: A Perspective.

Hydrogen peroxide is the principal antibacterial compound of honey and its concentration determines honey bacteriostatic (MIC) and bactericidal (MBC) potencies. Levels of HO produced are highly relevant to honey therapeutic potential, but they vary extensively among honey with reasons not immediately apparent. According to a traditional view, HO is produced as a by-product of glucose oxidation by the honey bee enzyme, glucose oxidase; however, significant levels of HO could be produced in a non-enzymatic way via polyphenol autooxidation.

Honey as an Ecological Reservoir of Antibacterial Compounds Produced by Antagonistic Microbial Interactions in Plant Nectars, Honey and Honey Bee.

The fundamental feature of "active honeys" is the presence and concentration of antibacterial compounds. Currently identified compounds and factors have been described in several review papers without broader interpretation or links to the processes for their formation. In this review, we indicate that the dynamic, antagonistic/competitive microbe-microbe and microbe-host interactions are the main source of antibacterial compounds in honey.

Colloidal structure of honey and its influence on antibacterial activity.

Honey colloidal structure emerges as a new trend in research on honey functions since it became recognized as a major factor altering bioactivity of honey compounds. In honey complex matrix, macromolecules self-associate to colloidal particles at the critical concentration, driven by honey viscosity. Sequestration of macromolecules into colloids changes their activities and affects honey antibacterial function.

A current perspective on hydrogen peroxide production in honey. A review.

Hydrogen peroxide plays a key role in honey antibacterial activity. The production of HO in honey requires glucose oxidase (GOx) that oxidizes glucose to gluconolactone and reduces molecular oxygen to hydrogen peroxide. The content of GOx of honeybee origin was believed to be the main predictor of HO concentration in honey.

Accumulation of soluble menaquinones MK-7 in honey coincides with death of spp. present in honey.

Long-chain menaquinones (MK) are of bacterial origin. We investigated the possibility that MKs observed in honey are also the products of bacteria present in honey. The bacterial composition of honey was analyzed using culture-dependent methods.

Identification of Ubiquinones in Honey: A New View on Their Potential Contribution to Honey's Antioxidant State.

Honey is composed of macromolecules arranged into multicomponent colloidal particles dispersed in a supersaturated sugar solution. The core part of colloidal particles in honey is made up of high-molecular weight protein-polyphenol complexes. We designed a multi-step extraction process to gain better insight into the phenolic compounds strongly bound to proteins in honey.

Identification of menaquinones (vitamin K2 homologues) as novel constituents of honey.

Our recent research indicated that honey active macromolecules form colloidal particles that scatter the light and produce elaborate UV spectral profile dominated by double absorption peaks at 240-250 nm. The absorption at 240-250 nm signified the stable honey conformation that supported antibacterial activity and hydrogen peroxide production. Our aim was to identify the bioactive constituent relevant to this absorption.

Active macromolecules of honey form colloidal particles essential for honey antibacterial activity and hydrogen peroxide production.

Little is known about the global structure of honey and the arrangement of its main macromolecules. We hypothesized that the conditions in ripened honeys resemble macromolecular crowding in the cell and affect the concentration, reactivity, and conformation of honey macromolecules. Combined results from UV spectroscopy, DLS and SEM showed that the concentration of macromolecules was a determining factor in honey structure.

MRJP1-containing glycoproteins isolated from honey, a novel antibacterial drug candidate with broad spectrum activity against multi-drug resistant clinical isolates.

The emergence of extended- spectrum β-lactamase (ESBL) is the underlying cause of growing antibiotic resistance among Gram-negative bacteria to β-lactam antibiotics. We recently reported the discovery of honey glycoproteins (glps) that exhibited a rapid, concentration-dependent antibacterial activity against both Gram-positive Bacillus subtilis and Gram-negative Escherichia coli that resembled action of cell wall-active β-lactam drugs. Glps showed sequence identity with the Major Royal Jelly Protein 1 (MRJP1) precursor that harbors three antimicrobial peptides: Jelleins 1, 2, and 4.

Honey glycoproteins containing antimicrobial peptides, Jelleins of the Major Royal Jelly Protein 1, are responsible for the cell wall lytic and bactericidal activities of honey.

We have recently identified the bacterial cell wall as the cellular target for honey antibacterial compounds; however, the chemical nature of these compounds remained to be elucidated. Using Concavalin A-affinity chromatography, we found that isolated glycoprotein fractions (glps), but not flow-through fractions, exhibited strong growth inhibitory and bactericidal properties. The glps possessed two distinct functionalities: (a) specific binding and agglutination of bacterial cells, but not rat erythrocytes and (b) non-specific membrane permeabilization of both bacterial cells and erythrocytes.

Antibacterial compounds of Canadian honeys target bacterial cell wall inducing phenotype changes, growth inhibition and cell lysis that resemble action of β-lactam antibiotics.

Honeys show a desirable broad spectrum activity against Gram-positive and negative bacteria making antibacterial activity an intrinsic property of honey and a desirable source for new drug development. The cellular targets and underlying mechanism of action of honey antibacterial compounds remain largely unknown. To facilitate the target discovery, we employed a method of phenotypic profiling by directly comparing morphological changes in Escherichia coli induced by honeys to that of ampicillin, the cell wall-active β-lactam of known mechanism of action.

A new look on protein-polyphenol complexation during honey storage: is this a random or organized event with the help of dirigent-like proteins?

Honey storage initiates melanoidin formation that involves a cascade of seemingly unguided redox reactions between amino acids/proteins, reducing sugars and polyphenols. In the process, high molecular weight protein-polyphenol complexes are formed, but the mechanism involved remains unknown. The objective of this study was twofold: to determine quantitative and qualitative changes in proteins in honeys stored for prolonged times and in different temperatures and to relate these changes to the formation of protein-polyphenol complexes.

Unraveling a mechanism of honey antibacterial action: polyphenol/H₂O₂-induced oxidative effect on bacterial cell growth and on DNA degradation.

Several compounds with antibacterial activities were identified in honey however, a mechanism by which they lead to bacterial growth inhibition and bacterial death remains still unknown. We recently found that honeys possess DNA degrading activity mediated by honey hydrogen peroxide and an unknown honey component(s). Here we provide evidence that active honeys (MIC90 of 6.

Powerful bacterial killing by buckwheat honeys is concentration-dependent, involves complete DNA degradation and requires hydrogen peroxide.

Exposure of bacterial cells to honey inhibits their growth and may cause cell death. Our previous studies showed a cause-effect relationship between hydroxyl radical generated from honey hydrogen peroxide and growth arrest. Here we explored the role of hydroxyl radicals as inducers of bacterial cells death.

Mechanism of Honey Bacteriostatic Action Against MRSA and VRE Involves Hydroxyl Radicals Generated from Honey's Hydrogen Peroxide.

It has been recently reported that honey hydrogen peroxide in conjunction with unknown honey components produced cytotoxic effects resulting in bacterial growth inhibition and DNA degradation. The objective of this study was twofold: (a) to investigate whether the coupling chemistry involving hydrogen peroxide is responsible for a generation of hydroxyl radicals and (b) whether (•)OH generation affects growth of multi-drug resistant clinical isolates. The susceptibility of five different strains of methicillin-resistant Staphylococcus aureus (MRSA) and four strains of vancomycin-resistant Enterococcus faecium (VRE) isolates from infected wounds to several honeys was evaluated using broth microdilution assay.

Re-examining the role of hydrogen peroxide in bacteriostatic and bactericidal activities of honey.

The aim of this study was to critically analyze the effects of hydrogen peroxide on growth and survival of bacterial cells in order to prove or disprove its purported role as a main component responsible for the antibacterial activity of honey. Using the sensitive peroxide/peroxidase assay, broth microdilution assay and DNA degradation assays, the quantitative relationships between the content of H(2)O(2) and honey's antibacterial activity was established(.) The results showed that: (A) the average H(2)O(2) content in honey was over 900-fold lower than that observed in disinfectants that kills bacteria on contact.

Honey melanoidins: Analysis of the compositions of the high molecular weight melanoidins exhibiting radical-scavenging activity.

Size-exclusion chromatography (SEC) and activity-guided fractionation of honeys allowed the isolation of high molecular weight brown compounds, ranging in size from 66 to 235kDa that exhibited peroxyl radical-scavenging activity. Their concentrations, antioxidant activity and degree of browning increased after heat-treatment of honeys, suggesting that they represent melanoidins. Chemical analysis of melanoidins demonstrated the presence of proteins, polyphenols and oligosaccharides.

Effect of hydrogen peroxide on antibacterial activities of Canadian honeys.

Honey is recognized as an efficacious topical antimicrobial agent in the treatment of burns and wounds. The antimicrobial activity in some honeys depends on the endogenous hydrogen peroxide content. This study was aimed to determine whether honey's hydrogen peroxide level could serve as a honey-specific, activity-associated biomarker that would allow predicting and assessing the therapeutic effects of honey.

Stage-dependent modulation of limb regeneration by caffeic acid phenethyl ester (CAPE)--immunocytochemical evidence of a CAPE-evoked delay in mesenchyme formation and limb regeneration.

Caffeic acid phenethyl ester (CAPE), a natural compound of bee propolis, selectively inhibits proliferation of transformed cells in several cancer models in vitro. To examine in vivo CAPE function, we used the newt regeneration blastema as a model system wherein the processes of de-differentiation and subsequent proliferation of undifferentiated cells mimic changes associated with oncogenic transformation and tumorigenesis. We have shown that a single dose of CAPE significantly increased cell proliferation at the stages of blastema growth and re-differentiation.