Antibacterial Activity Of Manuka Honey Research Articles

Antibacterial Properties of Manuka Honey and the Role of Methylglyoxal

The unique ecosystems of New Zealand have produced a diverse range of honey over the years, with Manuka honey being one of the most renowned. Produced by Western honeybees extracting nectar from Manuka flowers, this monofloral honey has become known for its distinct antibacterial and anti-inflammatory properties. Whilst antibacterial activity in other honey tend to stem from factors such as hydrogen peroxide content, high viscosity, osmotic effect, and acidic pH, the antibacterial activity of Manuka honey is mainly attributed to methylglyoxal (MGO), a dicarbonyl compound which is found in high concentrations in Manuka honey. This review paper will focus on the antibacterial properties of Manuka honey and the role that MGO plays. Understanding the specific chemical mechanisms that of attack on different strains of bacteria by Manuka honey and the role of MGO is crucial to potentially understanding how new drugs or medicines can combat antibacterial resistance to antibiotics.

Comparison of the antimicrobial and antivirulence activities of Sidr and Tualang honeys with Manuka honey against Staphylococcus aureus.

Honey is one of the oldest traditional remedies that has been widely utilized to cure a variety of human ailments. The objective of this research was to test and compare the antibacterial activity of Sidr honey (SH) and Tualang honey (TH) to that of Manuka honey (MH) against Staphylococcus aureus. The antibacterial activity of MH, SH and TH against S. aureus was investigated by agar well diffusion, Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), time-kill curve, microtiter plate and RT-qPCR analysis. Agar inhibition assay showed that MH possess highest total antibacterial activity against S. aureus with an inhibition zone 25.1 mm compared with that of SH (22.2 mm) and TH (21.3 mm). The findings showed that when compared to SH and TH (MIC: 25% and MBC: 50%), MH honey had the lowest MIC (12.5%) and MBC (25%). After S. aureus was exposed to MH, SH, and TH, there was a decrease in colony-forming unit as seen by the time-kill curve. The lowest concentration 20% of MH, SH and TH was significantly found to inhibit S. aureus biofilm. The RT-qPCR results revealed that all the selected genes in S. aureus were downregulated in gene expression following exposure to each of the tested honeys. Comparing the total antibacterial, antibiofilm, and antivirulence activities of all the tested honeys, MH demonstrated the greatest levels of these properties. According to this study, various types of each evaluated honey have the capacity to effectively suppress and modify the virulence of S. aureus via a variety of molecular targets.

An In Vitro Study of Different Types of Greek Honey as Potential Natural Antimicrobials against Dental Caries and Other Oral Pathogenic Microorganisms. Case Study Simulation of Oral Cavity Conditions

To study the antibacterial effect of different Greek honeys, samples of citrus honey, Saturja spp. Honey, and oregano and sage honey were collected directly from producers. Manuka honey and artificial honey were used as controls. The honeys were diluted in various concentrations to determine the minimum inhibitory concentration (MIC) and were also placed in agar wells to determine the inhibitory zones of growth. The bacteria tested were two reference strains and five pathogens isolated from patients with various dental ailments. A series of samples were diluted with artificial saliva instead of distilled water to simulate the conditions in the oral cavity. The results show that in most cases the Greek honeys, and particularly the citrus honey and the oregano and sage honey, outperformed the antibacterial activity of manuka honey against all tested bacteria. This performance was due to the hydrogen peroxide as well as to other components of the honeys, that is, peptides and other substances such as phenolic compounds and flavonoids. Artificial saliva enhanced the antibacterial effect of the honeys in comparison to distilled water.

Simple and Rapid Evaluation of the Unique Manuka Factor in Manuka Honey Using Fluorescence Fingerprints and Principal Component Analysis.

The excellent antibacterial activity of manuka honey has been well-documented and is often evaluated according to the unique manuka factor (UMF) index. UMF is determined by an assay based on a bacterial culture, which is time-consuming and does not allow for quantitative analysis. This study developed a simple and rapid method for UMF evaluation using fluorescence fingerprints, principal component analysis (PCA), and partial least squares (PLS) regression. Manuka honey samples were diluted four times with water and fluorescence was observed at three wavelength combinations, namely 260-300 (excitation; ex) to 370 (emission; em) nm, 340 (ex) to 480 nm (em), and 440 (ex) to 520 nm (em), that are mainly attributed to lepteridine, leptosperin, 2-methoxybenzoic acid, and N-methyl phenazinium. Analyzing fluorescence fingerprints using PCA and PLS regression provided a reliable evaluation of the UMF in manuka honey and could be used to differentiate between manufacturers.

Antibacterial activity of varying UMF-graded Manuka honeys.

Honey has been used as a traditional remedy for skin and soft tissue infections due to its ability to promote wound healing. Manuka honey is recognized for its unusually abundant content of the antibacterial compound, methylglyoxal (MGO). The Unique Manuka Factor (UMF) grading system reflects the MGO concentration in Manuka honey sold commercially. Our objective was to observe if UMF values correlated with the antibacterial activity of Manuka honey against a variety of pathogens purchased over the counter. The antibacterial effect of Manuka honey with UMF values of 5+, 10+, and 15+ from the same manufacturer was assessed by the broth microdilution method. Minimum inhibitory concentration (MIC) values were determined against 128 isolates from wound cultures representing gram-positive, gram-negative, drug-susceptible, and multi-drug resistant (MDR) organisms. Lower MICs were observed with UMF 5+ honey for staphylococci (n = 73, including 25 methicillin-resistant S. aureus) and Pseudomonas aeruginosa (n = 22, including 10 MDR) compared to UMF 10+ honey (p<0.05) and with UMF 10+ compared to UMF 15+ (p = 0.01). For Enterobacteriaceae (n = 33, including 14 MDR), MIC values were significantly lower for UMF 5+ or UMF 10+ compared to UMF 15+ honey (p<0.01). MIC50 for UMF 5+, UMF 10+, and UMF 15+ honey against staphylococci was 6%, 7%, and 15%, and for Enterobacteriaceae was 21%, 21%, and 27%, respectively. For Pseudomonas aeruginosa MIC50 was 21% and MIC90 was 21–27% for all UMFs. Manuka honey exhibited antimicrobial activity against a spectrum of organisms including those with multi-drug resistance, with more potent activity overall against gram-positive than gram-negative bacteria. Manuka honey with lower UMF values, in our limited sampling, paradoxically demonstrated increased antimicrobial activity among the limited samples tested, presumably due to changes in MGO content of honey over time. The UMF value by itself may not be a reliable indicator of antibacterial effect.

Antibacterial activity of Manuka honey and its components: An overview.

The importance of honey for medicinal purposes is well documented in some of the world's oldest literature. Honey is well known and studied for its antimicrobial properties. The medicinal properties in honey originate from the floral source used by bees. Manuka honey is a dark monofloral honey rich in phenolic content, and currently it is gaining much attention for its antimicrobial activity. Researchers have found that honey is effective against a wide range of pathogens. The antibacterial potency of Manuka honey was found to be related to the Unique Manuka Factor (UMF) rating, which is correlated with the methylglyoxal and total phenols content. It is reported that different types of Manuka honey have differing effects and Gram-negative bacteria are more resistant than Gram-positive bacteria. Bacterial resistance to honey as antimicrobial agent has yet to be identified, possibly due to the presence of a complex mixture of methylglyoxal and other components. Honey is also reported to alter a bacterium's shape and size through septal ring alteration, which affects cell morphology and growth. Research has shown that Manuka honey of different UMF values has medicinal properties of interest and it can be beneficial when used as a combination treatment with other antimicrobial agents.

Manuka Honey: A Potent Cariostatic Agent–Anin vitroStudy

AimThe aim of the study was to test the antibacterial activity of manuka honey and compare its efficacy with another commercially available honey (Dabur honey) on the cariogenic bacteria on Streptococcus mutans and Lactobacillus.Materials and methodsAn in vitro study was carried out on 40 agar specimens; the samples were divided into two groups of 20 samples consisting of S. mutans and Lactobacil-lus respectively. The 20 samples in each group were further subdivided into four groups of five each, which were tested with 25% manuka honey, 100% manuka honey, 25% Dabur honey, and 100% Dabur honey for both Lactobacillus and S. mutans groups. The antibacterial activity was tested using the agar well diffusion method against S. mutans and Lacto-bacillus. Antibacterial activity was assessed by measuring the diameter of inhibition of zones surrounding the wells. The results obtained were statistically analyzed (one-way analysis of variance test, p-value).ResultsThe results showed that 25% of manuka honey has statistically significant (p ≤ 0.001) antibacterial effect than 25% of Dabur honey on both Streptococcus and Lactobacillus species, and manuka honey with 100% concentration showed a statistically significant (p ≤ 0.001) antibacterial effect than 100% Dabur honey on the same species of bacteria. 100% of both the honeys showed statistically significant (p ≤ 0.001) antibacterial effect than 25% concentrations of the same on S. mutans and Lactobacillus.ConclusionManuka honey had more antibacterial activity than Dabur honey on S. mutans and Lactobacillus bacteria in the in vitro study. This effect was dependent on the concentration of honey used.How to cite this article: Beena JP, Sahoo P, Konde S, Raj SN, Kumar NC, Agarwal M. Manuka Honey: A Potent Cariostatic Agent—An in vitro Study. Int J Clin Pediatr Dent 2018;11(2):105-109.

Periodontal Application of Manuka Honey: Antimicrobial and Demineralising Effects In Vitro.

Background. Topical application of manuka honey is effective in the treatment of burns and soft-tissue infections. The aim of this study was to assess the antibacterial activity of manuka honey against plaque-associated bacteria in vitro in order to evaluate the potential application as an adjunct to periodontal treatment. Materials and Methods. The minimum bacteriostatic and bactericidal concentrations (MIC and MBC) of manuka honey were compared to those of white clover honey against a variety of plaque-associated bacteria, at the natural and neutral pH. Dissolved calcium was measured following incubation of honeys with hydroxyapatite (HA) beads to assess their potential to demineralise oral hard tissues. Results. Both honeys inhibited most tested oral bacteria at similar MIC/MBC, but Streptococcus mutans was comparatively resistant. The honeys at pH neutral had little effect on antimicrobial activity. Incubation of HA beads in honey solutions resulted in pH-dependent calcium dissolution, and inoculation with S. mutans promoted further demineralisation by both types of honey. Conclusion. Manuka honey is antimicrobial towards representative oral bacteria. However, the relative resistance of S. mutans in association with the high concentrations of fermentable carbohydrates in honey and the direct demineralising effect at natural pH mitigate against the application of honey as an adjunct in the treatment of periodontal disease.

Antibacterial activity of manuka honey on the growth of pure and mixed bacterial biofilms formed by sulphate reducing bacteria and Escherichia coli

Antibacterial activity of manuka honey on the growth of pure and mixed bacterial biofilms formed by sulphate reducing bacteria and Escherichia coli

Antibacterial effect of Manuka honey on Clostridium difficile

BackgroundManuka honey originates from the manuka tree (Leptospermum scoparium) and its antimicrobial effect has been attributed to a property referred to as Unique Manuka Factor that is absent in other types of honey. Antibacterial activity of Manuka honey has been documented for several bacterial pathogens, however there is no information on Clostridium difficile, an important nosocomial pathogen. In this study we investigated susceptibility of C. difficile to Manuka honey and whether the activity is bactericidal or bacteriostatic.MethodsThree C. difficile strains were subjected to the broth dilution method to determine minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) for Manuka honey. The agar well diffusion method was also used to investigate sensitivity of the C. difficile strains to Manuka honey.ResultsThe MIC values of the three C. difficile strains were the same (6.25% v/v). Similarly, MBC values of the three C. difficile strains were the same (6.25% v/v). The activity of Manuka honey against all three C. difficile strains was bactericidal. A dose–response relationship was observed between the concentrations of Manuka honey and zones of inhibition formed by the C. difficile strains, in which increasing concentrations of Manuka honey resulted in increasing size of zone of inhibition formed. Maximum zone of inhibition was observed at 50% (v/v) Manuka honey and the growth inhibition persisted over 7 days.ConclusionC. difficile is appreciably susceptible to Manuka honey and this may offer an effective way of treating infections caused by the organism.

Metabolic Transit of Dietary Methylglyoxal

Methylglyoxal (MGO) is responsible for the pronounced antibacterial activity of manuka honey, in which it may reach concentrations up to 800 mg/kg. As MGO formed in vivo is discussed to play a role in diabetic complications, the metabolic transit of dietary MGO was studied within a 3 day dietary recall with four healthy volunteers. Determination of MGO in 24 h urine was performed with GC-MS after derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine, and D-lactate was quantified enzymatically. Following a diet virtually free from MGO and other glycation compounds, a defined amount of MGO (500 μmol in manuka honey) was administered in the morning of day 2. Renal excretion was between 0.1 and 0.4 μmol/day for MGO and between 50 and 220 μmol/day for D-lactate. No influence on excretion of both compounds was observed following administration of MGO. To investigate the stability of MGO under physiological conditions, a simulated in vitro gastrointestinal digestion was performed with MGO-containing honey. After 8 h of in vitro digestion, only 5-20% of the initial methylglyoxal was recovered. This indicates that dietary MGO is rapidly degraded during the digestion process in the intestine and, therefore, exerts no influence on the MGO level in vivo.

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.

A Survey of the Antibacterial Activity of Some New Zealand Honeys

To assess the variation in antibacterial activity of honey a survey was carried out on 345 samples of unpasteurized honey obtained from commercial apiarists throughout New Zealand. Most of the honeys were considered to be monofloral, from 26 different floral sources. The honeys were tested against Staphylococcus aureus in an agar well diffusion assay, with reference to phenol as a standard. Antibacterial activity was found to range from the equivalent of less than 2% (w/v) phenol to 58% (w/v) phenol, with a median of 13.6 and a standard deviation of 12.5. Neither the age of the honey samples nor whether they had been processed by the apiarist was associated with lower activity. However, the difference between floral sources in the antibacterial activity was very highly significant. Kanuka (Kunzea ericoides (A. Rich.) J. Thompson. Family: Myrtaceae), manuka (Leptospermum scoparium J. R. et G. Forst. Family: Myrtaceae), ling heather (Calluna vulgaris (L.) Hull. Family: Ericaceae) and kamahi (Weinmannia racemosa Linn. f. Family: Cunoniaceae) were shown to be sources likely to give honey with high antibacterial activity. When antibacterial activity was assayed with catalase added to remove hydrogen peroxide, most of the honeys showed no detectable antibacterial activity. Only manuka and vipers bugloss (Echium vulgare L. Family: Boraginaceae) honeys showed this type of activity in a significant proportion of the samples. The high antibacterial activity of manuka honey was in many cases due entirely to this non-peroxide component.

Methylglyoxal—A Potential Risk Factor of Manuka Honey in Healing of Diabetic Ulcers

Honey has been considered as a remedy in wound healing since ancient times. However, as yet, there are inadequate supportive robust randomized trials and experimental data to fully accept honey as an effective medical product in wound care. Manuka honey has been claimed to have therapeutic advantages over other honeys. Recently, it has been documented that the pronounced antibacterial activity of manuka honey is due, at least in part, to reactive methylglyoxal (MG). The concentration of MG in manuka honeys is up to 100-fold higher than in conventional honeys. MG is a potent protein-glycating agent and an important precursor of advanced glycation end products (AGEs). MG and AGEs play a role in the pathogenesis of impaired diabetic wound healing and can modify the structure and function of target molecules. This commentary describes the concern that MG in manuka honey may delay wound healing in diabetic patients. Further detailed research is needed to fully elucidate the participation of honey/derived MG in healing diabetic ulcers. We advocate randomized controlled trials to determine efficacy and safety of manuka honey in this population.

Effectiveness of Honey on S.aureus and P.aeruginosa Biofilms

Problem Biofilms formed by Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) have been shown to be an important factor in the pathophysiology of chronic rhinosinusitis (CRS). Growth in biofilms increases bacterial resistance to antibiotics, which may explain why CRS responds poorly to antibiotic therapy. Honey has been used as an effective topical antimicrobial agent in the treatment of antibiotic-resistant bacterial wound infections. To our knowledge, no research has studied the effect of honey on biofilms. Methods We used a previously established biofilm model to assess antibacterial activity of Manuka honey from New Zealand and Sidr honey from Yemen. These were tested at a 1 in 2 dilution against 11 isolates of methicillin-susceptible SA (MSSA), 11 methicillin-resistant SA (MRSA), and 11 PA isolates. Honeys were tested against both planktonic (broth) and biofilm-grown bacteria. Results Both honeys were effective in killing 100% of the isolates in the planktonic form. Biofilm-grown bacteria were less susceptible to the honeys, but honey still had significant bactericidal activity. The bactericidal rate for the Sidr and Manuka honeys against MSSA MRSA and PA were 63%, 73%, 91% and 82%, 63% and 91%, respectively. These rates were significantly higher (p&lt;0.001) than those seen with single antibiotics commonly used against MSSA and MRSA (e.g. cloxacillin and vancomycin) in a previous study done on the same bacterial isolates. Conclusion Honey, which is a natural, non-toxic and inexpensive product, is effective in killing SA and PA bacterial biofilms. Significance This intriguing observation may have important clinical implications and could lead to a new approach for treating refractory CRS.

Identification of some antibacterial constituents of New Zealand manuka honey

Some components responsible for the exceptionally high antibacterial activity of manuka honey were isolated by testing fractions of the honey for activity against Staphylococcus aureus. An ethanol-ether extract of the honey was separated by preparative-layer chromatography and the fractions thus obtained were assessed for antibacterial activity. One fairly homogeneous fraction was identified as methyl 3,5-dimethoxy-4-hydroxybenzoate (methyl syringate, 1b). Combined gas chromatography-mass spectroscopy indicated the presence of this compound in some of the other antibacterial fractions together with methyl 3,4,5-trimethoxybenzoate (1c) and 3,4,5-trimethoxybenzoic acid (1a). Authentic specimens of 3,5-dimethoxy-4-hydroxybenzoic acid (syringic acid, 1d) and 3,4,5-trimethoxybenzoic acid (1a) and their methyl esters were tested against S. aureus. The acids and, to a lesser extent, methyl syringate were found to possess significant antibacterial activity.

Antibacterial Activity of Indonesian Local Honey Against Strains of P. Aeruginosa, S. Aureus and MRSA

Background: Honey has been used in wound care since ancient times. Many publications attest antibacterial activity of manuka honey against Pseudomonas aeruginosa, S. aureus, and Methicillin-resistant S. aureus (MRSA). However, antibacterial effect of local honey from Indonesia has never been studied and compared to medical grade honey before. This study aim to compare antibacterial activity of local honey and manuka honey against P. aeruginosa, S. aureus and MRSA.Methods: The honeys were tested for their antimicrobial activities with broth dilution method. Different concentrations of honey were prepared in reaction tubes. Strains of P.aeruginosa, S. aureus, and MRSA were grown in nutrient broth. These strains of bacteria then added to the different concentrations of honey. Minimum Inhibitory Concentrations (MIC) is the lowest concentration of the honey that yielded no growth of bacteria.Results: MIC of local honey for P. aeruginosa is 50%, for S. aureus is 100% and for MRSA is 100%. MIC of manuka honey for P. aeruginosa is 12,5%, for S. aureus is 25%, and for MRSA is 12,5%.Conclusion: Nusantara Manuka have the similar antibacterial activity spectrum against P. aeruginosa, MRSA and S. aureus, but it must be given in greater concentration to exert the same level of antibacterial activity with Manuka honey.