Impact of floral sources and processing on the antimicrobial activities of different unifloral honeys

Evaluating the Antioxidant Properties of Unifloral Honey (Apis mellifera L.) from Ethiopia

The antioxidant properties of natural honey primarily rely on the floral origin from which nectar is collected by bees. Thus, the current activity evaluated the antioxidant properties of honey based on its floral type. The honey floral origin was verified by the melissopalynological technique. Antioxidant properties were determined by using standard procedures and analyzed by SAS. Six unifloral honey types with their harvesting month were identified. Accordingly, Guizotia (74% of pollen frequency), Coffea arabica (68%), Vernonia (90%), Croton macrostachyus (64%), Schefflera abyssinica (100%), and Eucalyptus (100%) were cropped in November, February, February, May, April, and June separately. Statistically, a variation (p < 0.05) in antioxidant parameters was displayed between unifloral honeys. Vernonia honey exhibited the maximum total phenol (77.2 ± 0.7), total flavonoid (65.0 ± 3.8), and total antioxidant content (65.4 ± 0.3). On the other hand, S. abyssinica honey recorded the least total phenol content (24.1 ± 0.4), total flavonoid content (18.6 ± 2.7), and total antioxidant content (5.6 ± 0.5). Statistical analysis showed a positive correlation between all the tested antioxidant parameters. Thus, the current study indicated that all the tested Ethiopian unifloral honey had good sources of antioxidants with the most Vernonia honey followed by C. macrostachyus whereas S. abyssinica honey had the least followed by Eucalyptus.

Antibacterial and wound-healing action of Ulmo honey (Eucryphia cordifolia) of differing degrees of purity

Introduction

Antibacterial properties of honey vary according to its floral origin; few studies report the percentage of pollen types in honey, making it difficult to reproduce and compare the results. This study compares the antibacterial and wound-healing properties of three kinds of monofloral Ulmo honey with different percentages of pollen from Eucryphia cordifolia.

Methods

The pollen percentage of the honey was determined by melissopalynological analysis, and they were classified into three groups: M1 (52.77% of pollen from Eucryphia cordifolia), M2 (68.41%), and M3 (82.80%). They were subjected to chemical analysis and agar diffusion test against Staphylococcus aureus. A total of 20 healthy adult guinea pigs (Cavia porcellus) of both sexes were randomly assigned to four groups for experimental burn skin wound (uninfected) production and treatment with Ulmo honey. On day 10 post-injury, biopsies were obtained, and histological analysis was performed to assess wound-healing capacity following the treatment with honey.

Results

The chemical analysis showed that M3 differed significantly from M1 in terms of pH (P = 0.020), moisture (P = 0.020), total sugars (P = 0.034), and total solids (P = 0.020). Both strains of Staphylococcus aureus were susceptible to M1 and M2 at 40% w/v but were resistant to M3 at all concentrations. All groups (I-IV) were in the initial proliferative phase, with complete or partial re-epithelialization of the epidermis.

Discussion

The antibacterial activity showed a wide range of variation in the different types of honey studied, with no significant differences between wound healing and pollen percentage in the groups studied. Higher pH and the absence of Tineo in M3 conferred a lower antibacterial capacity but not a lower wound healing capacity. Despite its variability in the percentage of Eucryphia cordifolia like primary pollen in Ulmo's monofloral honey, this has the same properties in relation to wound healing.

Ethnobotanical and antimicrobial activities of the Gossypium (Cotton) genus: A review

ETHNOPHARMACOLOGICAL RELEVANCE

The Malvaceae family, an important group of plants that have the Gossypium (cotton) genus has been used in folk medicine to treat microbial diseases and symptoms.

AIMS OF THE STUDY

This article aims to understand its ethnobotany expression in communities and scientific elucidation of antimicrobial activities of this genus through literature review.

MATERIALS AND METHODS

The bibliographic survey was carried out from 1999 to 2019 with keywords combinations such as "Gossypium + ethnobotanical", " Gossypium + medicinal ", "Gossypium + the biological activity" in scientific databases as Pubmed, Scopus, Web of Science, DOAJ, Scielo, Bireme.

RESULTS

After data analysis, we found that the Gossypium genus, specifically Gossypium hirsutum, G. barbadense, G. herbaceum, G. arboreum are the species most cited in the treatment of microbial diseases and symptoms in communities all over the world. In light of scientific elucidation of biological activities, the Gossypium genus has been used to treat protozoal, bacterial, fungal, and viral diseases.

CONCLUSIONS

The review demonstrated that the Gossypium genus is a promising source of biological activities against microbial diseases, especially in the treatment of protozoal diseases like malaria.

Bioactive compounds and antibacterial activities in crystallized honey liquefied with ultrasound

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

Fabrication and Characterization of Chitosan/Poly(Lactic-Co-glycolic Acid) Core-Shell Nanoparticles by Coaxial Electrospray Technology for Dual Delivery of Natamycin and Clotrimazole

Natamycin (NAT) is the drug of choice for the treatment of fungal keratitis (FK). However, its inherent shortcomings, such as poor solubility, high dosing frequency, and long treatment cycle, need to be urgently addressed by designing a new delivery to widen its clinical utility. Growing research has confirmed that clotrimazole (CLZ) plays a significant role in fungal growth inhibition. Hence, coaxial electrospray (CO-ES) technology is used herein to prepare nano-systems with an average hydrodynamic particle size of 309-406 nm for the co-delivery of NAT and CLZ in chitosan (CTS) and poly(lactic-co-glycolic acid) (PLGA). The resulting NAT/CLZ@CTS/PLGA formulations were characterized by a transmission electron microscope (TEM) and in vitro release test. The results show that the formulations had obvious core-shell structures, uniform particle distribution, and also can sustain the release of drugs over 36 h. Furthermore, in vitro hemolysis, in vivo corneal irritation test, local allergenic test, and antifungal activity analyses are performed to evaluate the safety and efficiency of the formulations. Thus, good biosafety along with a significant anti-candidiasis effect are found in the NAT/CLZ@CTS/PLGA nanoparticles (NPs). Taken together, the results suggest that this design may provide a promising drug delivery system and a new option for the treatment of FK.

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

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

Physical characteristics and antimicrobial properties of Apis mellifera, Frieseomelitta nigra and Melipona favosa bee honeys from apiaries in Trinidad and Tobago

Background

Honey is a versatile and complex substance consisting of bioactive chemicals which vary according to many bee and environmental factors. The aim of this study was to assess the physical and antimicrobial properties of five honey samples obtained from three species of bees; two stingless bees, Frieseomelitta nigra and Melipona favosa and one stinging bee, Apis mellifera (fresh and aged honey). Samples were acquired from apiaries across Trinidad and Tobago. An artificial honey, made from sugar, was also used for comparison.

Methods

Physical properties such as appearance, pH, moisture content, sugar content and specific gravity were determined. Antimicrobial activity was assessed utilizing the agar diffusion assay and comparison to a phenol equivalence. The broth microdilution test was performed to determine the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of the five honey samples against four common pathogens, including Staphylococcus aureus, Escherichia coli, Streptococcus pyogenes and Haemophilus influenzae.

Results

All honey samples were acidic, with pH values ranging from 2.88 (M. favosa of Tobago) to 3.91 (fresh A. mellifera). Sugar content ranged from 66.0 to 81.6% with the highest values detected in stinging bee honeys of the A. mellifera (81.6 and 80.5°Bx). Moisture content ranged from 16.9% for aged A. mellifera honey (from Trinidad) to 32.4% for F. nigra honey (from Tobago). The MICs (2 to 16%) and MBCs (2 to 32%) of stingless bee honeys were lower than that of stinging bee and artificial honeys (16 to > 32%). Stingless bee honeys also exhibited a broad spectrum of antimicrobial activity against both Gram-positive and Gram-negative organisms with higher phenol equivalence values (4.5 to 28.6%) than the A. mellifera honeys (0 to 3.4%) against the isolates tested. M. favosa honey of Tobago displayed the greatest antimicrobial activity as indicated by the high phenol equivalence and low MIC and MBC values.

Conclusions

Stingless bee honeys from Tobago showed the greatest antimicrobial activity when compared to the other honeys used in this study. M. favosa honey of Tobago showed the most potential for use as medicinal honey.

Antioxidant Activity and Phenolic Profile of Selected Organic and Conventional Honeys from Poland

Honey is a natural food product hypothesized to have significant health-beneficial value. The results of recent studies indicate that the biological activity of honey can also be ascribed to phenolic compounds and their antioxidant activity. The aims of this study were: To determine the phenolic profiles of several varieties of Polish honey and their correlation with various factors influencing the quality of honey, plus to verify the impact of production method (organic/conventional) and the pollen content on these profiles. In total, 11 organic and 11 conventional honey samples from Poland were investigated. The botanical origin of the samples was identified through melissopalynological analysis, whereas individual phenolic compounds were determined by the LC/MS analysis. The Folin-Ciocalteau assay was used for the determination of the total phenolic content (TPC). Moreover, the CIE L*a*b* color values were measured and matched with the above-mentioned parameters. The results of the study contribute to the discussion on the health benefits of organic farming. It was found that chrysin may act as a potential indicator compound. The study confirms the existence of the link between TPC and color, and it shows that there is a correlation between pinocembrin and galangin, two compounds that are reported to ameliorate insulin resistance.

In vitro antimicrobial activities of Saudi honeys originating from Ziziphus spina-christi L. and Acacia gerrardii Benth. trees

Honeys originating from Sidr (Ziziphus spina-christi L.) and Talh (Acacia gerrardii Benth.) trees in Saudi Arabia exhibited substantial antimicrobial activity against pathogenic gram-positive bacteria (Bacillus cereus, Staphylococcus aureus), gram-negative bacteria (Escherichia coli, Salmonella enteritidis), and a dermatophytic fungus (Trichophyton mentagrophytes). The diameter of zones of inhibition represents the level of antimicrobial potency of the honey samples. Precisely, Talh honey showed significantly higher antibacterial activity against all tested bacteria than Sidr honey. The antifungal activity of Talh and Sidr honey types was significantly at par against a dermatophytic fungus. The water-diluted honey types (33% w/v) significantly induced a rise in the antimicrobial activity from that of the natural nondiluted honeys. Microbial strains displayed differential sensitivity; gram-positive bacteria were more sensitive and presented larger inhibition zones than gram-negative bacteria and the fungus. The sensitivity was highest in B. cereus and S. aureus, followed by T. mentagrophytes, E. coli, and S. enteritidis. The antimicrobial activity of water-diluted honeys (Sidr and Talh) was high than that of broad-spectrum antibacterial antibiotics (tetracycline and chloramphenicol) against bacterial strains, but these honeys were relativity less potent than antifungal antibiotics (flucoral and mycosat) against a fungal strain. Our findings indicate the antimicrobial potential of Saudi honeys to be considered in honey standards, and their therapeutic use as medical-grade honeys needs further investigations.

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.

Antioxidant activities of some monofloral honey types produced across Turkey

This study was conducted with the aim of determining the chemical, biochemical properties, and antimicrobial capabilities of some of the monofloral honeys produced in Turkey. In this study, 23 different monofloral honey samples were obtained from diverse geographical regions of Turkey. Floral origin of the honey samples was determined by melissopalinological analyses. Additionally, antioxidant properties were determined. To determine the antioxidant properties of honey samples, four test methods of total phenolic content, DPPH, iron reduction power and β-carotene linoleic acid emulsion method were used. As a result of the antioxidant activity analysis among the honey samples, rhododendron and parsley honey showed most prominent results in terms of the amount of phenolic compounds and antioxidant activity. On the other hand, acacia and citrus honey samples showed least antioxidant activity. A positive correlation was determined between four methods. Differences between antioxidant activities of honey samples were significantly found (P < 0.01).

Antioxidant Activity as Biomarker of Honey Variety

Honey variety is commonly defined by beekeepers based on nectar flow availability and the only laboratory method to provide verification is the melissopalynological analysis. Therefore, a quick and simple method for accurate assessment of honey variety is still being researched. The aim of the study was to evaluate the antioxidant activity of honey as an indicator of variety through the use of multivariate statistical analysis. Materials for the study consisted of 90 samples of varietal Polish honeys (rape-12, tilia-10, goldenrod-11, dandelion-5, buckwheat-6, multifloral-17, nectar-honeydew-8 and coniferous honeydew-16 and leafy honeydew-5) obtained directly from apiaries. Honeys were investigated in aspect of antioxidant capacity by photochemiluminescence (PCL) methods using standard ACW and ACL kits. As the reference FRAP and DPPH methods were used. The total phenolics content (TPC) was determined through the Folin-Ciocalteu method. The strongest antioxidant activity was found for buckwheat, while the weakest was found for rape honeys regardless of the used method. Results of the used methods were positively correlated (r = 0.42 to 0.94). Analysis conducted by PCL method confirmed that the minor fraction of honey antioxidants exhibits hydrophobic properties. Clear separation of honey varieties using PCA and Clustering method indicate that antioxidant activity can be a useful parameter for determining the botanical origin of honey.

Hydrogen peroxide-dependent antibacterial action of Melilotus albus honey

Honey originating from different floral sources exhibits the broad spectrum of antibacterial activity as a result of the presence of hydrogen peroxide as well as nonperoxide bioactive compounds. The mechanisms of antibacterial activity of Polish melilot honey were investigated for the first time. Polish melilot honey samples (Melilotus albus biennial = 3 and annual = 5, Melilotus officinalis = 1) were collected directly from beekeepers and analysed for pollen profile, basic physicochemical parameters, antioxidant capacity, radical scavenging activity, total phenolic contents as well as antibacterial properties against pathogenic bacteria Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Salmonella spp. The physicochemical properties of melilot honey were specific for light-coloured unifloral honey samples and were not dependent on its botanical and geographical origin (P > 0·05). All tested honey samples exhibited inhibitory activity (above 90%) against Gram-positive bacteria at the concentration of 12·5-25%. Above 30-50% of antibacterial activity of melilot honey was connected with glucose oxidase enzyme action and was destroyed in the presence of catalase. Hydrogen peroxide-dependent antibacterial activity of honey was inversely correlated with its radical scavenging activity (r = -0·67) and phenolic compounds (r = -0·61). Antibacterial action of melilot honey depends not only on hydrogen peroxide produced by glucose oxidase, but also on other nonperoxide bioactive components of honey.

SIGNIFICANCE AND IMPACT OF THE STUDY

Melilot honey is used in traditional medicine as an anticoagulant agent due to the possibility of the presence of the coumarin compounds which are specific for Melilotus plant. Melilotus albus is rarely used to produce honey, and antibacterial properties of this variety of honey had not been studied yet. Nine samples of melilot honey produced in different regions of Poland were analysed according to their antibacterial activity which was correlated with physiochemical parameters and antioxidant activity. It was shown that antibacterial activity of melilot honey is created by hydrogen peroxide and other bioactive compounds.

Effects of Selected Egyptian Honeys on the Cellular Ultrastructure and the Gene Expression Profile of Escherichia coli

The purpose of this study was to: (i) evaluate the antibacterial activities of three Egyptian honeys collected from different floral sources (namely, citrus, clover, and marjoram) against Escherichia coli; (ii) investigate the effects of these honeys on bacterial ultrastructure; and (iii) assess the anti-virulence potential of these honeys, by examining their impacts on the expression of eight selected genes (involved in biofilm formation, quorum sensing, and stress survival) in the test organism. The minimum inhibitory concentration (MIC) of the honey samples against E. coli ATCC 8739 were assessed by the broth microdilution assay in the presence and absence of catalase enzyme. Impacts of the honeys on the cellular ultrastructure and the expression profiles of the selected genes of E. coli were examined using transmission electron microscopy (TEM) and quantitative real-time polymerase chain reaction (qPCR) analysis, respectively. The susceptibility tests showed promising antibacterial activities of all the tested honeys against E. coli. This was supported by the TEM observations, which revealed “ghost” cells lacking DNA, in addition to cells with increased vacuoles, and/or with irregular shrunken cytoplasm. Among the tested honeys, marjoram exhibited the highest total antibacterial activity and the highest levels of peroxide-dependent activity. The qPCR analysis showed that all honey-treated cells share a similar overall pattern of gene expression, with a trend toward reduced expression of the virulence genes of interest. Our results indicate that some varieties of the Egyptian honey have the potential to be effective inhibitor and virulence modulator of E. coli via multiple molecular targets.