Phenolic compounds and methylglyoxal in some New Zealand manuka and kanuka honeys

Quantification of methyl glyoxal in New Zealand Mānuka honey and honey meads

Mānuka honey is New Zealand's (NZ) most globally sought-after honey variety, due to the bioactive effects conferred by methyl glyoxal (MGO). Several NZ meaderies produce Mānuka mead, being a unique NZ product with significant marketing potential; however, it has not been explored in the scientific literature, and MGO has never been quantified in mead of any type. Thus, a versatile HPLC method for the quantification of MGO in both Mānuka mead and honey has been developed, optimised and validated. Two derivatising agents, pentafluorobenzyl hydroxylamine (PFBHA) and o-phenylenediamine were compared, with o-phenylenediamine showing better sensitivity in the mead matrix. To demonstrate the developed method, a survey of the MGO content of commercially available NZ meads was conducted. MGO was detected in four Mānuka meads, with quantifiable levels of 8.20-62.45 mg L-1 present in three samples; however, its presence may be a result of back sweetening with Mānuka honey.

Antibacterial Properties, Arabinogalactan Proteins, and Bioactivities of New Zealand Honey

Honey has been used for centuries for its antibacterial and healing properties. The aim of this study was to investigate the antibacterial properties, arabinogalactan proteins (AGPs), antioxidant activities, and polyphenolic content of eight different types of New Zealand honey (clover, mānuka, beech honeydew, pōhutukawa, kānuka, rewarewa, kāmahi and thyme honey). The results showed varying antibacterial activities across the honey types, with mānuka, pōhutukawa, and kāmahi honey exhibiting significant inhibitory effects. Interestingly, all honey samples demonstrated inhibitory effects on bacterial growth at 25% concentration. Furthermore, AGPs were found in all eight honey samples, with higher amounts in kānuka, kāmahi, pōhutukawa, mānuka, and rewarewa honey. Thyme had the highest antioxidant values in terms of CUPRAC, FRAP and DPPH, while kāmahi honey had the lowest antioxidant value. Beech honeydew honey had the highest Total Flavonoid Content (TFC) values, while thyme and clover honey had the lowest TFC values. Similarly, thyme honey exhibited the highest Total Phenolic Content (TPC) value, with kāmahi and clover honey having the lowest TPC values. Furthermore, only thyme and beech honeydew New Zealand honeys contained vitamin C. The different honeys contained varying concentrations of polyphenols, with mānuka, kānuka, and pōhutukawa honeys having high amounts of quercetin, luteolin, and gallic acid, respectively. In contrast, clover honey had notable levels of chrysin, pinocembrin, caffeic acid, and pinobanksin. Overall, this study provides valuable insights into the antibacterial properties and bioactivities of native New Zealand honeys, contributing to our understanding of the potential health benefits associated with these honeys and their potential use as natural alternatives to improve human health.

Phenolic Acid and Flavonoid Content Analysis with Antioxidant Activity Assessment in Chinese C. pi. Shen Honey

The nutritional value of honey is closely related to its components, which are highly influenced by the botanic origin. C. pi. Shen (Codonopsis pilosula (Franch.) var. modesta (Nannf.) L. T. Shen), a key plant in traditional Chinese medicine, mainly produced in Gansu Province of China, has attracted much attention for its medicinal value. However, there are few reports about C. pi. Shen honey. Therefore, this study aimed to evaluate the contents of phenolic profiles and antioxidant activities in C. pi. Shen honey by colorimetric, UPLC-MS/MS, Ferric ion Reducing Antioxidant Power (FRAP), 2,2-bisazo-bis (3-ethyl-benzothiazole-6-sulfonic acid) (ABTS) free radical capacity, and 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) scavenging ability methods. In comparison with four other high-yield unifloral honeys in China (Acacia honey, linden honey, rape honey, and jujube honey), C. pi. Shen honey demonstrated remarkable advantages. Specifically, the levels of total phenolic acids, total flavonoids, and phenolic components of C. pi. Shen honey were significantly pronounced, especially protocatechuic acid and kaempferol. Furthermore, the antioxidant activity of C. pi. Shen honey was also excellent, which was attributed to its phenolic compounds, underscoring its potential biological value. This study is anticipated to serve as a reference for the identification, nutritional assessment, and functional advancement of C. pi. Shen honey.

Examining the Use of Polyphenols and Sugars for Authenticating Honey on the U.S. Market: A Comprehensive Review

The rise in honey production and imports into the United States necessitates the need for robust methods to authenticate honey origin and ensure consumer safety. This review addresses the scope of honey authentication, with a specific focus on the exploration of polyphenols and sugar markers to evaluate honeys in the U.S. In the absence of comprehensive federal standards for honey in the United States, challenges related to authenticity and adulteration persist. Examining the global landscape of honey authentication research, we observed a significant gap in the literature pertaining to U.S. honeys. While honeys from Europe, Australia, New Zealand, and Asia have been extensively studied, the decentralized nature of the U.S. honey market and the lack of comprehensive standards have limited the number of investigations conducted. This review consolidates the findings of global honey studies and emphasizes the need for further research studies on honey authenticity markers within the United States. We also explore previous studies on the U.S. that focused on identifying potential markers for honey authenticity. However, the inherent variability in polyphenol profiles and the lack of extensive studies of the sugar contents of honey on a global scale pose challenges to establishing universal markers. We conclude that by addressing these challenges, the field of research on polyphenols and sugars in honey can move toward more reliable and standardized methods. This advancement will enhance the use of polyphenols and other constituents like sugars as authenticity markers, ultimately benefiting both researchers and the honey industry in ensuring honey quality.

The Therapeutic Mechanisms of Honey in Mitigating Toxicity from Anticancer Chemotherapy Toxicity: A Review

Within the domain of conventional oncochemotherapeutics, anticancer chemotherapy (AC) has emerged as a potent strategy for the treatment of cancers. AC is the mainstay strategy for solid and non-solid cancer treatment. Its mechanistic action targets the blockage of DNA transcription and the dysregulation of cell cycle machinery in cancer cells, leading to the activation of death pathways. However, the attendant side effect of toxicity inflicted by AC on healthy tissues presents a formidable challenge. The crucial culprit in the AC side effect of toxicity is unknown, although oxidative stress, mitochondrial impairment, inflammatory cascades, autophagy dysregulation, apoptosis, and certain aberrant signaling have been implicated. Honey is a natural bee product with significant health benefits and pharmacological properties. Interestingly, the literature reports that honey may proffer a protection mechanism for delicate tissue/organs against the side effect of toxicity from AC. Thus, this review delves into the prospective role of honey as an alleviator of the AC side effect of toxicity; it provides an elucidation of the mechanisms of AC toxicity and honey's molecular mechanisms of mitigation. The review endeavors to unravel the specific molecular cascades by which honey orchestrates its mitigating effects, with the overarching objective of refining its application as an adjuvant natural product. Honey supplementation prevents AC toxicity via the inhibition of oxidative stress, NF-κB-mediated inflammation, and caspase-dependent apoptosis cascades. Although there is a need for increased mechanistic studies, honey is a natural product that could mitigate the various toxicities induced by AC.

Investigations of Major α-Dicarbonyl Content in U.S. Honey of Different Geographical Origins

α-Dicarbonyls are significant degradation products resulting from the Maillard reaction during food processing. Their presence in foods can indicate the extent of heat exposure, processing treatments, and storage conditions. Moreover, they may be useful in providing insights into the potential antibacterial and antioxidant activity of U.S. honey. Despite their importance, the occurrence of α-dicarbonyls in honey produced in the United States has not been extensively studied. This study aims to assess the concentrations of α-dicarbonyls in honey samples from different regions across the United States. The identification and quantification of α-dicarbonyls were conducted using reverse-phase liquid chromatography after derivatization with o-phenylenediamine (OPD) and detected using ultraviolet (UV) and mass spectrometry methods. This study investigated the effects of pH, color, and derivatization reagent on the presence of α-dicarbonyls in honey. The quantification method was validated by estimating the linearity, precision, recovery, method limit of detection, and quantification using known standards for GO, MGO, and 3-DG, respectively. Three major OPD-derivatized α-dicarbonyls including methylglyoxal (MGO), glyoxal (GO), and 3-deoxyglucosone (3-DG), were quantified in all the honey samples. 3-Deoxyglucosone (3-DG) was identified as the predominant α-dicarbonyl in all the U.S. honey samples, with concentrations ranging from 10.80 to 50.24 mg/kg. The total α-dicarbonyl content ranged from 16.81 to 55.74 mg/kg, with the highest concentration measured for Southern California honey. Our results showed no significant correlation between the total α-dicarbonyl content and the measured pH solutions. Similarly, we found that lower amounts of the OPD reagent are optimal for efficient derivatization of MGO, GO, and 3-DG in honey. Our results also indicated that darker types of honey may contain higher α-dicarbonyl content compared with lighter ones. The method validation results yielded excellent recovery rates for 3-DG (82.5%), MGO (75.8%), and GO (67.0%). The method demonstrated high linearity with a limit of detection (LOD) and limit of quantitation (LOQ) ranging from 0.0015 to 0.002 mg/kg and 0.005 to 0.008 mg/kg, respectively. Our results provide insights into the occurrence and concentrations of α-dicarbonyl compounds in U.S. honey varieties, offering valuable information on their quality and susceptibility to thermal processing effects.

The Leptospermum scoparium (Mānuka)-Specific Nectar and Honey Compound 3,6,7-Trimethyllumazine (LepteridineTM) That Inhibits Matrix Metalloproteinase 9 (MMP-9) Activity

3,6,7-trimethyllumazine (Lepteridine™) is a newly discovered natural pteridine derivative unique to Mānuka (Leptospermum scoparium) nectar and honey, with no previously reported biological activity. Pteridine derivative-based medicines, such as methotrexate, are used to treat auto-immune and inflammatory diseases, and Mānuka honey reportedly possesses anti-inflammatory properties and is used topically as a wound dressing. MMP-9 is a potential candidate protein target as it is upregulated in recalcitrant wounds and intestinal inflammation. Using gelatin zymography, 40 μg/mL LepteridineTM inhibited the gelatinase activities of both pro- (22%, p < 0.0001) and activated (59%, p < 0.01) MMP-9 forms. By comparison, LepteridineTM exerted modest (~10%) inhibition against a chromogenic peptide substrate and no effect against a fluorogenic peptide substrate. These findings suggest that LepteridineTM may not interact within the catalytic domain of MMP-9 and exerts a negligible effect on the active site hydrolysis of small soluble peptide substrates. Instead, the findings implicate fibronectin II domain interactions by LepteridineTM which impair gelatinase activity, possibly through perturbed tethering of MMP-9 to the gelatin matrix. Molecular modelling analyses were equivocal over interactions at the S1' pocket versus the fibronectin II domain, while molecular dynamic calculations indicated rapid exchange kinetics. No significant degradation of synthetic or natural LepteridineTM in Mānuka honey occurred during simulated gastrointestinal digestion. MMP-9 regulates skin and gastrointestinal inflammatory responses and extracellular matrix remodelling. These results potentially implicate LepteridineTM bioactivity in Mānuka honey's reported beneficial effects on wound healing via topical application and anti-inflammatory actions in gastrointestinal disorder models via oral consumption.

Formation of Protein-Bound Maillard Reaction Products during the Storage of Manuka Honey

Honey from the nectar of the Manuka tree (Leptospermum scoparium) grown in New Zealand contains high amounts of antibacterial methylglyoxal (MGO). MGO can react with proteins to form peptide-bound Maillard reaction products (MRPs) such as Nε-carboxyethyllysine (CEL) and "methylglyoxal-derived hydroimidazolone 1" (MG-H1). To study the reactions of MGO with honey proteins during storage, three manuka honeys with varying amounts of MGO and a kanuka honey (Kunzea ericoides) spiked with various MGO concentrations up to 700 mg/kg have been stored at 37 °C for 10 weeks, and the formation of protein-bound MRPs has been analyzed via high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) following isolation of the protein fraction and enzymatic hydrolysis. During storage, contents of protein-bound CEL and MG-H1 increased continuously, directly depending on the MGO content. For honeys with large amounts of MGO, a slower formation of Nε-fructosyllysine (FL) was observed, indicating competing reactions of glucose and MGO with lysine. Furthermore, the lysine modification increased with storage independently from the MGO concentration. Up to 58-61% of the observed lysine modification was explainable with the formation of CEL and FL, indicating that other reactions, most likely the formation of Heyns products from lysine and fructose, may play an important role. Our results can contribute to the authentication of manuka honey.

Quality of Commercially Available Manuka Honey Expressed by Pollen Composition, Diastase Activity, and Hydroxymethylfurfural Content

Manuka honey plays a significant role in modern medical applications as an antibacterial, antiviral, and antibiotic agent. However, although the importance of manuka honey is well documented in the literature, information regarding its physicochemical characteristics remains limited. Moreover, so far, only a few papers address this issue in conjunction with the examination of the pollen composition of manuka honey samples. Therefore, in this study, two parameters crucial for honey quality control-the diastase number (DN) and the hydroxymethylfurfural (HMF) content-as well as the melissopalynological analysis of manuka honey, were examined. The research found a large variation in the percentage of Leptospermum scoparium pollen in honeys labeled and sold as manuka honeys. Furthermore, a significant proportion of these honeys was characterized by a low DN. However, since low diastase activity was not associated with low HMF content, manuka honey should not be considered as a honey with naturally low enzymatic activity. Overall, the DN and HMF content results indicate that the quality of commercially available manuka honey is questionable.

Individual and social defenses in Apis mellifera: a playground to fight against synergistic stressor interactions

The honeybee is an important species for the agri-food and pharmaceutical industries through bee products and crop pollination services. However, honeybee health is a major concern, because beekeepers in many countries are experiencing significant colony losses. This phenomenon has been linked to the exposure of bees to multiple stresses in their environment. Indeed, several biotic and abiotic stressors interact with bees in a synergistic or antagonistic way. Synergistic stressors often act through a disruption of their defense systems (immune response or detoxification). Antagonistic interactions are most often caused by interactions between biotic stressors or disruptive activation of bee defenses. Honeybees have developed behavioral defense strategies and produce antimicrobial compounds to prevent exposure to various pathogens and chemicals. Expanding our knowledge about these processes could be used to develop strategies to shield bees from exposure. This review aims to describe current knowledge about the exposure of honeybees to multiple stresses and the defense mechanisms they have developed to protect themselves. The effect of multi-stress exposure is mainly due to a disruption of the immune response, detoxification, or an excessive defense response by the bee itself. In addition, bees have developed defenses against stressors, some behavioral, others involving the production of antimicrobials, or exploiting beneficial external factors.

Accelerated loss of diastase in mānuka honey: Investigation of mānuka specific compounds

Diastase is used internationally as a quality monitor for excessive heat treatment and prolonged storage of honey; honey must contain an activity of at least 8 diastase numbers (DN) for it to be considered export quality. Freshly harvested mānuka honey can have diastase activity close to the export threshold of 8 DN without excess heating, increasing susceptibility for export failure. This research investigated the effect of compounds unique to or high in concentration in mānuka honey on diastase activity. Investigation of the effect of methylglyoxal, dihydroxyacetone, 2-methoxybenzoic acid, 3-phenyllatic acid, 4-hydroxyphenyllactic acid and 2'-methoxyacetophenone on diastase activity was carried out. Mānuka honey was stored at 20 and 27 °C and clover honey spiked with compounds of interest were stored at 20, 27 and 34 °C and monitored overtime. Methylglyoxal and 3-phenyllactic acid were found to accelerate the loss of diastase above the loss normally observed with time and elevated temperature.

Proteomic Analysis of Honey: Peptide Profiling as a Novel Approach for New Zealand Mānuka (Leptospermum scoparium) Honey Authentication

New Zealand mānuka (Leptospermum scoparium) honey is a premium food product. Unfortunately, its high demand has led to "not true to label" marketed mānuka honey. Robust methods are therefore required to determine authenticity. We previously identified three unique nectar-derived proteins in mānuka honey, detected as twelve tryptic peptide markers, and hypothesized these could be used to determine authenticity. We invoked a targeted proteomic approach based on parallel reaction-monitoring (PRM) to selectively monitor relative abundance of these peptides in sixteen mānuka and twenty six non-mānuka honey samples of various floral origin. We included six tryptic peptide markers derived from three bee-derived major royal jelly proteins as potential internal standards. The twelve mānuka-specific tryptic peptide markers were present in all mānuka honeys with minor regional variation. By comparison, they had negligible presence in non-mānuka honeys. Bee-derived peptides were detected in all honeys with similar relative abundance but with sufficient variation precluding their utility as internal standards. Mānuka honeys displayed an inverse relationship between total protein content and the ratio between nectar- to bee-derived peptide abundance. This trend reveals an association between protein content on possible nectar processing time by bees. Overall, these findings demonstrate the first successful application of peptide profiling as an alternative and potentially more robust approach for mānuka honey authentication.

3-Phenyllactic Acid and Polyphenols Are Substances Enhancing the Antibacterial Effect of Methylglyoxal in Manuka Honey

Manuka honey is known for its unique antibacterial activity, which is due to methylglyoxal (MGO). After establishing a suitable assay for measuring the bacteriostatic effect in a liquid culture with a time dependent and continuous measurement of the optical density, we were able to show that honey differs in its growth retardingeffect on Bacillus subtilis despite the same content of MGO, indicating the presence of potentially synergistic compounds. In model studies using artificial honey with varying amounts of MGO and 3-phenyllactic acid (3-PLA), it was shown that 3-PLA in concentrations above 500 mg/kg enhances the bacteriostatic effect of the model honeys containing 250 mg/kg MGO or more. It has been shown that the effect correlates with the contents of 3-PLA and polyphenols in commercial manuka honey samples. Additionally, yet unknown substances further enhance the antibacterial effect of MGO in manuka honey. The results contribute to the understanding of the antibacterial effect of MGO in honey.

Physicochemical Characteristics and Bioactive Compounds of Different Types of Honey and Their Biological and Therapeutic Properties: A Comprehensive Review

Honey is considered to be a functional food with health-promoting properties. However, its potential health benefits can be affected by individual composition that varies between honey types. Although studies describing the health benefits of Tualang honey (TH), Kelulut honey (KH), and Sidr honey (SH) are scarce, these honey types showed a comparable therapeutic efficacy to Manuka honey (MH). The purpose of this review is to characterise the physicochemical, biological, and therapeutic properties of TH, KH, and SH. Findings showed that these honeys have antibacterial, antifungal, antiviral, antioxidant, antidiabetic, antiobesity, anticancer, anti-inflammatory and wound-healing properties and effects on the cardiovascular system, nervous system, and respiratory system. The physicochemical characteristics of TH, KH, and SH were compared with MH and discussed, and results showed that they have high-quality contents and excellent biological activity sources. Flavonoids and polyphenols, which act as antioxidants, are two main bioactive molecules present in honey. The activity of honey depends on the type of bee, sources of nectar, and the geographic region where the bees are established. In conclusion, TH, KH, and SH could be considered as natural therapeutic agents for various medicinal purposes compared with MH. Therefore, TH, KH, and SH have a great potential to be developed for modern medicinal use.

Benefits of Manuka Honey in the Management of Infectious Diseases: Recent Advances and Prospects

The benefits of honey have been recognized since ancient times for treating numerous diseases. However, in today's modern era, the use of traditional remedies has been rapidly diminishing due to the complexities of modern lifestyles. While antibiotics are commonly used and effective in treating pathogenic infections, their inappropriate use can lead to the development of resistance among microorganisms, resulting in their widespread prevalence. Therefore, new approaches are constantly required to combat drug-resistant microorganisms, and one practical and useful approach is the use of drug combination treatments. Manuka honey, derived from the manuka tree (Leptospermum scoparium) found exclusively in New Zealand, has garnered significant attention for its biological potential, particularly due to its antioxidant and antimicrobial properties. Moreover, when combined with antibiotics, it has demonstrated the ability to enhance their effectiveness. In this review, we delve into the chemical markers of manuka honey that are currently known, as well as detail the impact of manuka honey on the management of infectious diseases up to the present.

The Development and Application of a HPTLC-Derived Database for the Identification of Phenolics in Honey

This study reports on the development and validation of a HPTLC-derived database to identify phenolic compounds in honey. Two database sets are developed to contain the profiles of 107 standard compounds. Rich data in the form of Rf values, colour hues (H°) at 254 nm and 366 nm, at 366 nm after derivatising with natural product PEG reagent, and at 366 nm and white light after derivatising with vanillin–sulfuric acid reagent, λ max and λ min values in their fluorescence and λ max values in their UV-Vis spectra as well as λ max values in their fluorescence and UV-Vis spectra after derivatisation are used as filtering parameters to identify potential matches in a honey sample. A spectral overlay system is also developed to confirm these matches. The adopted filtering approach is used to validate the database application using positive and negative controls and also by comparing matches with those identified via HPLC-DAD. Manuka honey is used as the test honey and leptosperine, mandelic acid, kojic acid, lepteridine, gallic acid, epigallocatechin gallate, 2,3,4-trihydroxybenzoic acid, o-anisic acid and methyl syringate are identified in the honey using the HPTLC-derived database.

The Antimicrobial Effects of Saudi Sumra Honey against Drug Resistant Pathogens: Phytochemical Analysis, Antibiofilm, Anti-Quorum Sensing, and Antioxidant Activities

Honey exhibited potential antimicrobial activity against multidrug resistant (MDR) bacteria that continues to be a serious health problem. We reported the in-vitro activity of Saudi Sumra honey against clinical pathogenic bacteria and fungi, antibiofilm, anti-quorum-sensing (QS) and antioxidant activities in relation to its phytochemical composition assessed by gas chromatography-mass spectrometry (GC-MS). Broth dilution method and scavenging activities against 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and β-carotene bleaching assays were performed. The GC-MS analysis of Sumra honey showed that 2,4-dihydroxy-2,5-dimethyl-3(2H)-furan-3-one 1-methylcyclopropanemethanol were the major identified phytoconstituents. Sumra honey showed a minimum inhibitory concentration (MIC) to clinical isolates of Staphylococcus aureus including methicillin-resistant Staphylococcus aureus (MRSA) at 300 mg/mL, Pseudomonas aeruginosa (250 mg/mL), Escherichia coli (350 mg/mL) and Acinetobacter baumannii (250 mg/mL); clinical fungal isolates—Candida auris (600 mg/mL) and Cryptococcus neoformans (>1000 mg/mL); wild type fungal isolates—Candida krusei (>1000 mg/mL) and Candida albicans (700 mg/mL). In addition, Sumra honey demonstrated promising inhibition targeting biofilm formation by 59% for Bacillus subtilis, 48% for S. aureus, 38% for E. coli, and 33.63% for P. aeruginosa. The violacein production in Chromobacterium violaceum was reduced to 68%, whereas pyocyanin production in P. aeruginosa was reduced to 54.86% at ½ MIC. Furthermore, Sumra honey exhibited strong antioxidant activities (DPPH − IC50 = 7.7 mg/mL; ABTS − IC50 = 5.4 mg/mL; β-carotene − IC50 = >20 mg/mL). Overall, obtained data highlighted the promising potential therapeutic use of Sumra honey treating infections caused by MDR bacteria and fungi. Moreover, Sumra honey can be a good candidate as an inhibitor agent for bacterial cellular communication in strains of P. aeruginosa and C. violaceum.

Exploring the Chemical Properties and Biological Activity of Four New Zealand Monofloral Honeys to Support the Māori Vision and Aspirations

Honey production and export are significant contributors to the Aotearoa New Zealand economy, generating over 400 million dollars in revenue. Its main export is mānuka (Leptospermum scoparium) honey, which has a high commercial value due to its medicinal properties that are linked to its unique chemical composition. The compound methylglyoxal (MGO) has been identified as the main floral marker and is used as a quality indicator, often labelled as unique mānuka factor (UMF). However, the high demand for mānuka honey creates pressure on beekeepers and may have negative ecological consequences by favouring extensive mānuka monocultures to the detriment of other native species. There are other honeys native to New Zealand, such as kāmahi (Weinmannia racemosa), kānuka (Kunzea ericoides), rātā (Metrosideros robusta) and rewarewa (Knightia excelsa), that also have medicinal properties; however, they are less well known in the local and global market. Indigenous Māori communities envision the production and commercialization (locally and internationally) of these honeys as an opportunity to generate income and secure a sustainable future in alignment with their worldview (Te Ao Māori) and values (tikanga Māori). Diversifying the market could lead to a more sustainable income for beekeepers and reduce pressure on Māori and the conservation land, while supporting indigenous communities to realize their vision and aspirations. This manuscript provides an extensive review of the scientific literature, technical literature and traditional knowledge databases describing the plants of interest and their traditional medicinal uses (rongoā) and the chemical properties of each honey, potential floral markers and their biological activity. For each honey type, we also identify knowledge gaps and potential research avenues. This information will assist Māori beekeepers, researchers, consumers and other stakeholders in making informed decisions regarding future research and the production, marketing and consumption of these native monofloral honeys.

Potential Therapeutic Benefits of Honey in Neurological Disorders: The Role of Polyphenols

Honey is the principal premier product of beekeeping familiar to Homo for centuries. In every geological era and culture, evidence can be traced to the potential usefulness of honey in several ailments. With the advent of recent scientific approaches, honey has been proclaimed as a potent complementary and alternative medicine for the management and treatment of several maladies including various neurological disorders such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis, etc. In the literature archive, oxidative stress and the deprivation of antioxidants are believed to be the paramount cause of many of these neuropathies. Since different types of honey are abundant with certain antioxidants, primarily in the form of diverse polyphenols, honey is undoubtedly a strong pharmaceutic candidate against multiple neurological diseases. In this review, we have indexed and comprehended the involved mechanisms of various constituent polyphenols including different phenolic acids, flavonoids, and other phytochemicals that manifest multiple antioxidant effects in various neurological disorders. All these mechanistic interpretations of the nutritious components of honey explain and justify the potential recommendation of sweet nectar in ameliorating the burden of neurological disorders that have significantly increased across the world in the last few decades.

A Comprehensive Survey of Phenolic Constituents Reported in Monofloral Honeys around the Globe

The aim of this review is to provide a comprehensive overview of the large variety of phenolic compounds that have to date been identified in a wide range of monofloral honeys found globally. The collated information is structured along several themes, including the botanical family and genus of the monofloral honeys for which phenolic constituents have been reported, the chemical classes the phenolic compounds can be attributed to, and the analytical method employed in compound determination as well as countries with a particular research focus on phenolic honey constituents. This review covers 130 research papers that detail the phenolic constituents of a total of 556 monofloral honeys. Based on the findings of this review, it can be concluded that most of these honeys belong to the Myrtaceae and Fabaceae families and that Robinia (Robinia pseudoacacia, Fabaceae), Manuka (Leptospermum scoparium, Myrtaceae), and Chestnut (Castanea sp., Fagaceae) honeys are to date the most studied honeys for phenolic compound determination. China, Italy, and Turkey are the major honey phenolic research hubs. To date, 161 individual phenolic compounds belonging to five major compound groups have been reported, with caffeic acid, gallic acid, ferulic acid and quercetin being the most widely reported among them. HPLC with photodiode array detection appears to be the most popular method for chemical structure identification.

Cytoprotective Antioxidant, Anti-Inflammatory, and Antifibrotic Impact of Celery Seed Oil and Manuka Honey Against Cyclophosphamide-Induced Cystitis in Rabbits

Patients treated with cyclophosphamide (CP) usually suffer from severe hemorrhagic cystitis (HC). Our previous study exhibited that mesna + celery cotherapy partially ameliorated HC. Therefore, there is a substantial need to seek alternative regimens to get complete protection against CP-induced HC. The current study investigated the effects of mesna + celery seed oil (MCSO) or mesna + manuka honey (MMH) cotherapy against CP-induced HC in adult male rabbits. The forty rabbits were divided into four equal groups and treated for three weeks. The control group (G1) received distilled water and the second group (G2) received CP (50 mg/kg/week). The third group (G3) received CP + MCSO (CPMCSO regimen), and the fourth group (G4) received CP + MMH (CPMMH regimen). The urinary bladder (UB) specimens were processed to evaluate UB changes through histopathological, immunohistochemical, ultrastructural, and biochemical investigations. In G2, CP provoked HC features (urothelial necrosis, ulceration, and sloughing), UB fibrosis, and TNF-α immunoexpression. Besides, CP reduced the activity of antioxidant enzymes (GPx1, SOD3, and CAT) and elevated the serum levels of NF-κB, TNF-α, IL-1B, and IL-6 cytokines in G2 rabbits. In contrast, the CPMMH regimen caused significant increments of UB protection against HC in G4 rabbits compared to the partial protection by the CPMCSO regimen in G3. Therefore, our study indicated for the first time that the novel CPMMH regimen resulted in complete UB protection against CP-induced HC via combined antioxidant, anti-inflammatory, and antifibrotic properties.

An investigation of the suitability of melissopalynology to authenticate Jarrah honey

This study reports on the analysis of eleven Jarrah (Eucalyptus marginata) honeys, of which nearly half (n = 5) were re-classified as Blackbutt (E. patens) honey on the grounds of the predominant flower pollen identified by melissopalynology. Based on a comprehensive analysis of the honeys' physico- and phytochemical characteristics and antioxidant activity data, taking into account pH, electrical conductivity, refractive index and Brix values as well as moisture content, individual fructose and glucose content and derived fructose to glucose ratio alongside total phenolic content and antioxidant activity determined by the DPPH assay, no statistically significant difference was found amongst the eleven honeys classified by pollen analysis into two honey groups, ‘Jarrah’ or ‘Blackbutt’. This study therefore draws into question the value of melissopalynology as an analysis tool to authenticate Jarrah honey.

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Case study on Jarrah (Eucalyptus marginata) honey, presenting comprehensive physico-chemical, phytochemical and bioactivity data.

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The investigated honey samples can be considered as chemically equivalent although nearly half of them were reclassified as either Blackbutt (Eucalyptus patens) or multifloral honeys on the basis of melissopalynology.

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Findings challenge the value of melissopalynology for the authentication of honey harvested from botanically diverse areas.

Optical spectroscopy methods combined with multivariate statistical analysis for the classification of Cretan thyme, multi-floral and honeydew honey

BACKGROUND

The botanical origin of honey attracts both commercial and research interest. Consumers' preferences and medicinal uses of particular honey types drive the demand for the determination of their authenticity with regard to their botanical origin. This study presents the discrimination of thyme, multi-floral. and honeydew honeys by Fourier-transform infrared (FTIR) and ultraviolet (UV) absorption spectroscopy combined with multivariate statistical analysis. UV absorption spectroscopy was applied without any dilution of the sample using a custom-made cuvette. FTIR and UV absorption spectroscopic data were processed by means of the orthogonal partial least squares discriminant analysis.

RESULTS

The optimal classification of floral and honeydew honeys was accomplished with UV spectroscopy with a successful estimation of 92.65% for floral honey and 91.30% for honeydew honey. The discrimination of thyme versus the multi-floral honey was best achieved with FTIR, with a correct classification of 95.56% and 100% for multi-floral and thyme honey respectively. Furthermore, our findings revealed the region of 2400-4000 cm^-1 of the FTIR spectra as the most significant for this discrimination.

CONCLUSION

This work demonstrates that optical spectroscopic techniques in combination with multivariate statistical analysis can be a rapid, low-cost, easy-to-use approach for the determination of the botanical origin of honey without sample pretreatment. © 2021 Society of Chemical Industry.

Development of an HPTLC-based dynamic reference standard for the analysis of complex natural products using Jarrah honey as test sample

In this paper, we describe a novel approach to the development of a reference standard for the quality control of complex natural products, which will assist in the assessment of their authenticity and purity. The proposed method provides a template for the selection of samples, which can be pooled to obtain a reference standard. A shortfall of such an approach is, however, that the pooled sample is static in nature and therefore unable to capture difference in processing conditions or natural variations triggered by geographical or climatic impacts over time. To address this, the paper also outlines the development of a dynamic reference standard, which allows for ongoing adjustments to future variations. The method employs High-Performance Thin Layer Chromatography (HPTLC) derived extract profiles processed by multivariate analysis. The development of the dynamic reference standard is illustrated using honey, a complex natural matrix, as an example.

Chemical Elements and the Quality of Mānuka (Leptospermum scoparium) Honey

Soil properties in the foraging range of honeybees influence honey composition. We aimed to determine relationships between the antimicrobial properties of New Zealand mānuka (Leptospermum scoparium) honey and elemental concentrations in the honey, plants, and soils. We analyzed soils, plants, and fresh mānuka honey samples from the Wairarapa region of New Zealand for the chemical elements and the antimicrobial activity of the honey as indicated by methylglyoxal (MGO) and dihydroxyacetone (DHA). There were significant negative correlations between honey MGO and the concentrations of Mn, Cu, Mg, S, Na, Ba, K, Zn, and Al. These elements may provide a low-cost means of assessing mānuka honey quality. For individual elements, except for K, there were no correlations between the honeys, plants, and soils. Soil nitrate concentrations were negatively correlated with concentrations of MGO and DHA in the honey, which implies that soil fertility may be a determiner of mānuka honey quality.

Monofloral Honeys as a Potential Source of Natural Antioxidants, Minerals and Medicine

Background: vegetative diversity is based on different climate and geographical origins. In terms of beekeeping, herbal diversity is strongly correlated to the production of a wide variety of honey. Therefore, based on the existing plant diversity in each country, multiple honey varieties are produced with different health characteristics. While beekeeping potential and consumption preferences are reflected in products’ variety, this leads to an increase in the region’s economy and extensive export. In the last years, monofloral honey has gained interest from consumers and especially in the medicinal field due to the presence of phytochemicals which are directly linked to health benefits, wound healing, antioxidant, anticancer and anti-inflammatory activities. Scope and approach: this review aims to highlight the physicochemical properties, mineral profiles and antioxidant activities of selected monofloral honeys based on their botanical and geographical origin. Moreover, this review focuses on the intercorrelation between monofloral honey’s antioxidant compounds and in vitro and in vivo activities, focusing on the apoptosis and cell proliferation inhibition in various cell lines, with a final usage of honey as a potential therapeutic product in the fight towards reducing tumor growth. Key findings and conclusions: multiple studies have demonstrated that monofloral honeys have different physicochemical structures and bioactive compounds. Useful chemical markers to distinguish between monofloral honeys were evidenced, such as: 2-methoxybenzoic acid and trimethoxybenzoic acid are distinctive to Manuka honey while 4-methoxyphenylacetic acid is characteristic to Kanuka honey. Furthermore, resveratrol, epigallocatechin and pinostrobin are markers distinct to Sage honey, whereas carvacrol and thymol are found in Ziziphus honey. Due to their polyphenolic profile, monofloral honeys have significant antioxidant activity, as well as antidiabetic, antimicrobial and anticancer activities. It was demonstrated that Pine honey decreased the MDA and TBARS levels in liver, kidney, heart and brain tissues, whereas Malicia honey reduced the low-density lipoprotein level. Consumption of Clover, Acacia and Gelam honeys reduced the weight and adiposity, as well as trygliceride levels. Furthermore, the antiproliferative effect of chrysin, a natural flavone in Acacia honey, was demonstrated in human (A375) and murine (B16-F1) melanoma cell lines, whereas caffeic acid, a phenolic compound found in Kelulut honey, proves to be significant candidate in the chemoprevention of colon cancer. Based on these features, the use of hiney in the medicinal field (apitherapy), and the widespread usage of natural product consumption, is gaining interest by each year.

Honey Phenolic Compound Profiling and Authenticity Assessment Using HRMS Targeted and Untargeted Metabolomics

Honey consumption is attributed to potentially advantageous effects on human health due to its antioxidant capacity as well as anti-inflammatory and antimicrobial activity, which are mainly related to phenolic compound content. Phenolic compounds are secondary metabolites of plants, and their content in honey is primarily affected by the botanical and geographical origin. In this study, a high-resolution mass spectrometry (HRMS) method was applied to determine the phenolic profile of various honey matrices and investigate authenticity markers. A fruitful sample set was collected, including honey from 10 different botanical sources (n = 51) originating from Greece and Poland. Generic liquid-liquid extraction using ethyl acetate as the extractant was used to apply targeted and non-targeted workflows simultaneously. The method was fully validated according to the Eurachem guidelines, and it demonstrated high accuracy, precision, and sensitivity resulting in the detection of 11 target analytes in the samples. Suspect screening identified 16 bioactive compounds in at least one sample, with abscisic acid isomers being the most abundant in arbutus honey. Importantly, 10 markers related to honey geographical origin were revealed through non-targeted screening and the application of advanced chemometric tools. In conclusion, authenticity markers and discrimination patterns were emerged using targeted and non-targeted workflows, indicating the impact of this study on food authenticity and metabolomic fields.

Quantification of Hydrogen Peroxide in Cretan Honey and Correlation with Physicochemical Parameters

The aim of the present study is to quantify hydrogen peroxide, generated from various types of honey produced in Crete, as a potent antimicrobial agent, and establish any correlation with their physicochemical parameters. The basic physicochemical parameters (diastase activity, HMF content, moisture, electrical conductivity, color, and sugars) of 30 authentic honey samples were determined. The concentration of hydrogen peroxide in all samples was found to be within the range 0.010-0.092 mM. The known correlation between the electrical conductivity and the color of honey was confirmed in this study. Univariate and multivariate statistics applied to the results indicate that the results can be used to discriminate honey sample groups of different botanical origins.

The Immunomodulatory Effects of Honey and Associated Flavonoids in Cancer

Honey has exerted a high impact in the field of alternative medicine over many centuries. In addition to its wound healing, anti-microbial and antioxidant properties, several lines of evidence have highlighted the efficiency of honey and associated bioactive constituents as anti-tumor agents against a range of cancer types. Mechanistically, honey was shown to inhibit cancer cell growth through its pro-apoptotic, anti-proliferative and anti-metastatic effects. However, the potential of honey to regulate anti-tumor immune responses is relatively unexplored. A small number of in vitro and in vivo studies have demonstrated the ability of honey to modulate the immune system by inducing immunostimulatory as well as anti-inflammatory effects. In the present review, we summarize the findings from different studies that aimed to investigate the immunomodulatory properties of honey and its flavonoid components in relation to cancer. While these studies provide promising data, additional research is needed to further elucidate the immunomodulatory properties of honey, and to enable its utilization as an adjuvant therapy in cancer.

The antibacterial activities of honey

Honey is a powerful antimicrobial agent with a wide range of effects. Various components contribute to the antibacterial efficacy of honey: the sugar content; polyphenol compounds; hydrogen peroxide; 1,2-dicarbonyl compounds; and bee defensin-1. All of these elements are present at different concentrations depending on the source of nectar, bee type, and storage. These components work synergistically, allowing honey to be potent against a variety of microorganisms including multidrug resistant bacteria and modulate their resistance to antimicrobial agents. The effectiveness and potency of honey against microorganisms depends on the type of honey produced, which is contingent on its botanical origin, the health of the bee, its origin, and processing method. The application of antibiotics with honey yielded better antimicrobial potential and synergistic effects were noted against biofilms. In medicine, honey has been used in the treatment of surface wounds, burns, and inflammation, and has a synergistic effect when applied with antibiotics. Tissue repair is enhanced by the low pH of honey (3.5-4): causing a reduction in protease activity on the wound site, elevating oxygen release from hemoglobin and stimulating fibroblast and macrophage activity. Furthermore, H2O2 has antiseptic effects, and it disinfects the wound site and stimulates production of vascular endothelial growth factor. The use of honey will clean wounds or burn areas from free radicals and reduces scarring and contractures. The anti-inflammatory and antibacterial potential of honey will keep the injured area moist and as such prevents it from deterioration and fibrosis. Honey can promote fast healing and reduce scarring and is very convenient for plastic surgery. Skin maceration is protected by honey due to its high osmolarity and because it keeps the injury moist. In non-infected areas, honey still reduced pain and inflammation. In general, the use of honey in medical settings has reduced economic loss and provided proven economic benefits by lowering direct costs in comparison to conventional treatments and by using less antibiotics, faster healing and less hospitalization stay. This review is intended to provide an overview of the antibacterial activities of honey and its applications.

The Isorhamnetin-Containing Fraction of Philippine Honey Produced by the Stingless Bee Tetragonula biroi Is an Antibiotic against Multidrug-Resistant Staphylococcus aureus

Honey exhibits antibacterial and antioxidant activities that are ascribed to its diverse secondary metabolites. In the Philippines, the antibacterial and antioxidant activities, as well as the bioactive metabolite contents of the honey, have not been thoroughly described. In this report, we investigated the in vitro antibacterial and antioxidant activities of honey from Apis mellifera and Tetragonula biroi, identified the compound responsible for the antibacterial activity, and compared the observed bioactivities and metabolite profiles to that of Manuka honey, which is recognized for its antibacterial and antioxidant properties. The secondary metabolite contents of honey were extracted using a nonionic polymeric resin followed by antibacterial and antioxidant assays, and then spectroscopic analyses of the phenolic and flavonoid contents. Results showed that honey extracts produced by T. biroi exhibits antibiotic activity against Staphylococcal pathogens as well as high antioxidant activity, which are correlated to its high flavonoid and phenolic content as compared to honey produced by A. mellifera. The bioassay-guided fractionation paired with Liquid Chromatography Mass Spectrometry (LCMS) and tandem MS analyses found the presence of the flavonoid isorhamnetin (3-methylquercetin) in T. biroi honey extract, which was demonstrated as one of the compounds with inhibitory activity against multidrug-resistant Staphylococcus aureus ATCC BAA-44. Our findings suggest that Philippine honey produced by T. biroi is a potential nutraceutical that possesses antibiotic and antioxidant activities.

The effects of honey on pro- and anti-inflammatory cytokines: A narrative review

Honey contains flavonoids and phenolic acids, and because of their antioxidant and anti-inflammatory properties, they may play an important role in human health. The purpose of this review was to synthesize the effects of natural honey on pro- and anti-inflammatory cytokines. The effects of honey on wound healing and immunity appear to be inconsistent. The available databases )PubMed and Scopus) were searched and 42 studies were assessed. In patients with cancer, honey has been reported to inhibit the effects of pro-inflammatory factors such as TNF-α and IL-6. In patients with neuro-inflammatory disorders honey has been shown to inhibit the expression of pro-inflammatory markers. It has also been reported that honey can reduce TNF-α expression in conditions associated with liver injury, by suppressing TNF-α converting enzyme activity. Honey inhibits APAP-induced hepatocellular necrosis by modulating the expression of IL-10 and IL-1ß. Animal studies have shown that honey can reduce serum IL-1ß, IL-6 and TNF-α concentration and increase IL-10 concentrations in a model of gastric ulcer. Some studies in diabetics have shown that honey can reduce serum TNF-α, IL-6, IL-1ß and TGF-ß by inhibiting NF-Kß. The source and type of honey and its component have not been indicated in various clinical and practical studies, which are a limitation of these studies, in relation to reproducing them. Sigma, Manuka, Gelam and Tulang honey have been used in most of the in vitro and animal studies. The animal studies have demonstrated similar effects on pro-inflammatory factors, which include reducing serum TNF-α, IL-6 and IL-1β as well as increasing IL-10. There are few human RCTs investigating the effects of honey on inflammatory cytokines. Only one RCT has reported the type of honey that they have used. Tulang honey has been reported to increase serum TNF-α and decrease hs-CRP, which is therefore controversial. Further high-quality studies are needed to firmly establish the clinical efficacy of honey. Because most studies had used different duration, type of honey and dosage, which make them difficult to contextualize, as the phytochemical content of a honey may depend on its source. Furthermore, it is unclear whether honey's anti-inflammatory effects are related to its phenolic or tocopherol compounds, and whether its effects are greater than these individual components.

Physicochemical characteristics and antiproliferative and antioxidant activities of Moroccan Zantaz honey rich in methyl syringate

Zantaz honey is a monofloral variety produced from the melliferous plant Bupleurum spinosum (Apiaceae), a shrub that grows mainly in the Atlas Moroccan Mountains. Determination of the polyphenol composition revealed that methyl syringate accounts for more than 50% of total polyphenols, which represents a very useful parameter for the characterization of this monofloral honey. Epicatechin, syringic acid and catechin are also abundant. Caco-2 and THP-1 cells were used for determination of antioxidant and antiproliferative activities in Zantaz honey, respectively. All six commercial samples that were used for these studies exhibited antioxidant activity and inhibited cell proliferation. Interestingly, these activities had a positive correlation mainly with the content in methyl syringate and gallic acid. The recognition of health promoting activities in Zantaz honey should increase its commercial value, which would have a positive economic impact on the poor rural communities of Morocco where it is produced.

Methylglyoxal binds to amines in honey matrix and 2'-methoxyacetophenone is released in gaseous form into the headspace on the heating of manuka honey

Reports on the thermal stability of manuka honey in terms of food processing have been few. This study investigated changes in nine characteristic chemicals of manuka honey during heating. Among these, methylglyoxal (MGO) and 2'-methoxyacetophenone (MAP) were significantly decreased by heating at 90 °C. To elucidate the mechanism for this decrease, artificial honey was prepared from sugars and water with MAP or MGO and then heated. The decrease of MGO was enhanced with l-proline, lysine, or arginine derivatives, accompanied by formation of 2-acetyl-1-pyrroline, MGO-derived lysine dimer, or argpyrimidine, respectively, suggesting that an amino-carbonyl reaction is one pathway for the loss of MGO. The decrease of MAP in the artificial honey depended on the volume of headspace in a vessel. MAP from heated manuka honey was also detected in the gas phase, indicating that MAP was vaporized. Heating could thus reduce the beneficial and/or signature molecules in honey.

Utility of the Leptospermum scoparium Compound Lepteridine as a Chemical Marker for Manuka Honey Authenticity

Manuka honey is a premium food product with unique antimicrobial bioactivity. Concerns with mislabeled manuka honey require robust assays to determine authenticity. Lepteridine is a Leptospermum-specific fluorescent molecule with potential as an authenticity marker. We describe a mass spectrometry-based assay to measure lepteridine based on an isotopically labeled lepteridine standard. Using this assay, lepteridine concentrations in manuka honey samples strongly correlated with concentrations quantitated by either high-performance liquid chromatography-ultraviolet (HPLC-UV) or fluorescence. A derived minimum lepteridine threshold concentration was compared with the New Zealand regulatory definition for manuka honey to determine "manuka honey" authenticity on a set of commercial samples. Both methods effectively distinguished manuka honey from non-manuka honeys. The regulatory definition excludes lepteridine but otherwise includes the quantification of multiple floral markers together with pollen analysis. Our findings suggest that the quantification of lepteridine alone or in combination with leptosperin could be implemented as an effective screening method to identify manuka honey, likely to achieve an outcome similar to the regulatory definition.

Honey can inhibit and eliminate biofilms produced by Pseudomonas aeruginosa

Chronic wound treatment is becoming increasingly difficult and costly, further exacerbated when wounds become infected. Bacterial biofilms cause most chronic wound infections and are notoriously resistant to antibiotic treatments. The need for new approaches to combat polymicrobial biofilms in chronic wounds combined with the growing antimicrobial resistance crisis means that honey is being revisited as a treatment option due to its broad-spectrum antimicrobial activity and low propensity for bacterial resistance. We assessed four well-characterised New Zealand honeys, quantified for their key antibacterial components, methylglyoxal, hydrogen peroxide and sugar, for their capacity to prevent and eradicate biofilms produced by the common wound pathogen Pseudomonas aeruginosa. We demonstrate that: (1) honey used at substantially lower concentrations compared to those found in honey-based wound dressings inhibited P. aeruginosa biofilm formation and significantly reduced established biofilms; (2) the anti-biofilm effect of honey was largely driven by its sugar component; (3) cells recovered from biofilms treated with sub-inhibitory honey concentrations had slightly increased tolerance to honey; and (4) honey used at clinically obtainable concentrations completely eradicated established P. aeruginosa biofilms. These results, together with their broad antimicrobial spectrum, demonstrate that manuka honey-based wound dressings are a promising treatment for infected chronic wounds, including those with P. aeruginosa biofilms.

Dynamics of the Cellular Metabolism of Leptosperin Found in Manuka Honey

Leptosperin (methyl syringate β-d-gentiobioside) is abundantly found in manuka honey, which is widely used because of its antibacterial and possible anti-inflammatory activities. The aim of this study was to examine the molecular mechanism underlying the metabolism of leptosperin. Five phytochemicals (leptosperin, methyl syringate (MSYR), glucuronate conjugate of MSYR (MSYR-GA), sulfonate conjugate of MSYR (MSYR-S), and syringic acid (SYR)) were separately incubated with HepG2 and Caco-2 cells. After incubation, we found that the concentration of MSYR decreased, whereas the concentrations of SYR, MSYR-GA, and MSYR-S increased. By profiling with inhibitors and carboxylesterases (CES1, 2), we found that the conversion from MSYR to SYR was mediated by CES1. Lipopolysaccharide-stimulated RAW264.7 cells restored MSYR-GA to MSYR possibly by the secreted β-glucuronidase. All of the mice administered with leptosperin, MSYR, or manuka honey showed higher MSYR (13.84 ± 11.51, 14.29 ± 9.19, or 6.66 ± 2.30 nM) and SYR (1.85 ± 0.66, 6.01 ± 1.20, or 8.16 ± 3.10 nM) levels in the plasma compared with that of the vehicle controls (3.33 ± 1.45 (MSYR) and 1.85 ± 0.66 (SYR) nM). The findings of our study indicate that the unique metabolic pathways of these compounds may account for possible functionalities of manuka honey.

Advanced strategies for combating bacterial biofilms

Biofilms are communities of microorganisms that are formed on and attached to living or nonliving surfaces and are surrounded by an extracellular polymeric material. Biofilm formation enjoys several advantages over the pathogens in the colonization process of medical devices and patients' organs. Unlike planktonic cells, biofilms have high intrinsic resistance to antibiotics and sanitizers, and overcoming them is a significant problematic challenge in the medical and food industries. There are no approved treatments to specifically target biofilms. Thus, it is required to study and present innovative and effective methods to combat a bacterial biofilm. In this review, several strategies have been discussed for combating bacterial biofilms to improve healthcare, food safety, and industrial process.