Floral Sources Research Articles

Polyphenolic profile and antioxidant and antibacterial activities of monofloral honeys produced by Meliponini in the Brazilian semiarid region

This study assessed the polyphenolic profile and the antioxidant and antibacterial activities of monofloral honeys produced by Meliponini in the Brazilian semiarid region. Honeys from Ziziphus joazeiro Mart. (juazeiro) and Croton heliotropiifolius Kunth (velame branco) showed the highest total phenolic contents (TPCs) and the greatest antioxidant activity in assays with DPPH and ABTS+ radicals. Honeys from Mimosa quadrivalvis L. (malícia) presented the strongest anti-peroxyl activity in ORAC assay. Juazeiro honeys showed the highest quantities of trans-cinnamic, p-coumaric, ellagic and ferulic acids, as well as of catechin, rutin, hesperetin and chrysin when compared to the other honeys produced by the same bee species. Malícia honeys showed the greatest quantities of myricetin, quercetin and kaempferol among the studied honeys. Honeys with the highest TPCs presented the highest antimicrobial activity. The results showed the impact of the floral source on the polyphenolic profile as well as on the antioxidant and antimicrobial properties of Meliponini honeys.

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.

Apini and Meliponini foraging activities influence the phenolic content of different types of Malaysian honey

Malaysian honeys are produced by two main bee genera: Apis and Trigona. Each bee species has long been reported to exhibit unique foraging patterns and time, and it is very likely that bee foraging activities play a significant role in the phenolic composition of honeys. This work aims to justify the potential relationship between species-specific foraging activities and phenolic composition of honeys, to distinguish polyphenolic profiles and to identify possible floral markers in each type of Malaysian honey studied. Seventeen samples of Malaysian gelam, acacia, nenas, tualang, and kelulut honeys were analyzed using a high-performance liquid chromatography with diode array detector (HPLC-DAD). Total phenolic contents ranged from 1.92 to 14.84 mg/g of honey, in nenas and gelam honey, respectively. Fifteen phenolic compounds were identified, probably affected by the bee foraging preference. The highest number was seen in kelulut honey (Trigona spp.) while the lowest were in tualang honey (10 compounds, Apis dorsata). Apis cerana indica showed the highest phenolic acid and flavonoid contents (8.74 mg/g honey) compared to the other bee species, probably due to less selective floral preference, longer duration and early foraging time as well as small body size that influence their foraging activity. Similarity in two dominant polyphenols from polyhenolic profiles between acacia and tualang honeys (naringenin and ellagic acid), and between gelam and kelulut honeys (ellagic acid and benzoic acid) suggesting that the floral source of unifloral honey is an equally important food source for the analyzed multifloral honey, was confirmed by PCA analysis. This work assumes that competition between bee species for nectar and pollen might exist, affecting honey production and total polyphenolic content. From the results, some polyphenolic profiles could be regarded as possible floral markers of Malaysian unifloral honeys, with very consistent profiles observed in nenas honeys.

Near-Infrared (NIR) Spectroscopy for Rapid Measurement of Antioxidant Properties and Discrimination of Sudanese Honeys from Different Botanical Origin

The extraction methods used in wet chemical analysis of honey prior to antioxidant constituent analysis may decrease their activities due to decomposition. Therefore, near-infrared (NIR) spectroscopy technology has been used to measure these compounds. Besides, partial least squares regression (PLSR) was also applied to establish the calibration models with 105 samples and 45 unknown honeys to affirm the robustness of the established model. The outcomes of calibration models excellently affirmed the quantification of the concentrations of phenolics, flavonoids, carotenoids, ferric-reducing antioxidant power (FRAP), and 1,1-diphenyl-2-picrylhydrazy (DPPH) with high correlation coefficients (0.95–0.96), and acceptable standard error of cross validation (RMSECV) ranged from 0.92 to 13.60. The ratio performance deviation (RPD) for phenolics, flavonoids, carotenoids, FRAP, and DPPH ranged from 3.45 to 3.89, hence indicating that the NIR equations established were appropriate for unknown samples. Moreover, two discrimination modeling techniques including least squares support vector machine (LS-SVM) and linear discriminant analysis (LDA) were applied for discrimination of honey varieties. Cross validation was applied to optimize the performance of the models. The results revealed that LDA model was superior to LS-SVM model with discrimination rate of 100 % in both the training and prediction sets, whereas LS-SVM model had 99.05 and 93.33 % for the training and prediction sets, respectively. In general, the findings indicated that NIR coupled with chemometrics and linear/non-linear classification algorithms could be applied successfully to determine the antioxidant properties and discriminate honeys of different floral sources.

A voltammetric tool for the evaluation of propolis antioxidant activity

Propolis (bee glue) is a sticky dark-colored material that honeybees collected from parts of plants, buds and exudates, and used as construction and defense material in the hive. This resinous substance is a rich source of phenolic compounds, and its chemical composition is strongly influenced by its phytogeographic origin. This research outlines the evaluation of the redox profile and the quantification of the total antioxidant capacity in Portuguese propolis from different origins and potential floral sources Populus x canadensis Moench and Cistus ladanifer L through cyclic voltammetry and differential pulse voltammetry. Although several oxidation processes were showed by propolis samples, which were dependent of the resin origin, common oxidation potentials within the majority of samples of a region were detected, suggesting an analogous chemical composition in respect of electroactive species. Based on the quantification of the total electroactive antioxidant power, it was found that propolis with higher antioxidant activity was from coast center, followed by north ~ Azores Archipelago > central interior > Madeira Island > south.

Extraction of Honey Polyphenols: Method Development and Evidence of Cis Isomerization.

Honey polyphenols have been studied with the objective of relating honeys to their floral sources. Initially synthesized by plant, these polyphenols can be found in the plant’s nectar, which are collected by bees, which convert the nectar into honey. Consequently, polyphenols constitute minor components of honey. The development of a solid-phase extraction method for honey polyphenols is presented in this study. The technique employs Amberlite XAD-2 adsorbent and was tested on monofloral honeys from six different plants: acacia, chestnut, eucalyptus, thyme, sunflower, and wild carrot. Analyses were performed using high-performance liquid chromatography coupled with UV detection and mass spectrometry. Several phenolic acids and flavonoids were identified: caffeic and p-coumaric acids, quercetin, kaempferol, naringenin, chrysin, and pinocembrin. Generally, the quantity of a given polyphenol in the honey was around 0.2 mg/100 g of honey, except for chestnut honey, which contained around 3.0 mg of p-coumaric acid/100 g of honey. Analyses highlighted significant formation of cis isomers for phenolic acids during the extraction despite protection from light.

Modulation of cytochrome P450 3A4 mediated quinine metabolism in healthy volunteers by two honey samples from different floral and geographical sources

Background: Honey is widely used both for its nutritional and medicinal benefits and reports exist to suggest it may alter the disposition of conventional drugs whose metabolism is mediated by CYP3A4. The study aimed at investigating the effect of multiple dose administration of honey sourced from two different geographical zones in Nigeria, on an antimalarial, quinine and its CYP3A4 mediated metabolism. Methods: In a randomized cross-over study, twenty healthy volunteers divided into two groups A and B [A used honey (HA) from Northern and B used honey (HB) from Eastern Nigeria; n=10 respectively] received single oral doses of 600 mg quinine sulphate tablet alone and after 7 days administration of 10 ml of honey (HA or HB) twice daily. Blood samples collected at the 16 th hour following quinine administration were subjected to HPLC analysis. Results: Compared to baseline, 10 ml of honey HA significantly increased (0.86±0.22 versus 1.36±0.43) (p 0.05) (0.84±0.19 versus. 0.69±0.34) of the metabolic ratio of quinine in group B volunteers. Also, the geometric mean [95% CI: 0.63(0.45, 0.91)] of quinine metabolic ratio in the presence of honey HA alone was significantly increased (p=0.02, t-test). Conclusions: Honey sample from Northern Nigeria significantly stimulated CYP3A4-mediated quinine metabolism as reflected by an increased metabolic ratio of quinine. In conclusion some honey samples may have the potential to significantly modulate CYP3A4 activity, thus honey effects cannot be generalized.

Rapid and sensitive determination of polyphenols composition of unifloral honey samples with their antioxidant capacities

A micellar electrokinetic chromatography method was developed to quantify the levels of four main polyphenols in various floral sources honeys. The effect of several parameters—such as pH, sodium dodecyl sulfate (SDS) of the buffer, separation voltage and injection time—were systematically investigated. The main polyphenols were successfully separated within 13 min of UV detection at 214 nm. In the tested concentration range, regression equations revealed good linear relationships between the peak areas and corresponding concentration (correlation coefficients ranged from 0.9984 to 0.9997). Moreover, the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical-scavenging activities were also quantified. These compounds are not present in large amounts, but can reach up to 2758 μg in 100 g−1 of honey, which are the main flavonoid aglycones found in honey. The flavonoid glycosides are hydrolyzed by bee enzymes to render the aglycones. Therefore, the flavonoid aglycones should be served as a potential marker and capillary electrophoresis could be used as an effective way to look for in various floral sources.

Honey – Food or Medicine? The How, Where, and Why of Bioactivity Testing

Honey has been used for its medicinal and health-promoting properties for thousands of years, but only in the last 50–60 years has science caught up and been able to explain many of these beneficial properties. Most honeys exhibit at least some bioactive properties (e.g., antibacterial activity and nutritional benefits); however, others from specific floral sources demonstrate properties that may be of more value. This article discusses some of the more common tests that can used to assess the bioactive potential of honey samples.

Taking the Long View: Peter Molan’s Articles in Bee World

Honey has been used as a medicine by man since the earliest times. Peter Molan was instrumental in researching and bringing to our attention why honey is important in healing. He identified that Manuka honey is somehow special with its seemingly unique “Manuka factor.” International recognition followed, and he was made an MBE (Member of the British Empire) in 1995 for services to the honey industry. Peter Molan wrote a number of articles for Bee World, which to this day are still highly cited. They cover how honey is effective as a medicine, the antibacterial properties of honey and the limitations of identifying the floral source of honey.

Effect of Thermal Processing on Antibacterial Activity of Multifloral Honeys

In this study, the effects of thermal processing in the antibacterial activity of four multifloral honeys were determined. The thermal treatments were carried out at 30, 40, 50, 60, 70 and 80C, and the following characteristics were determined: total phenols and antibacterial activity of three gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus and Listeria monocytogenes) and three gram-negative bacteria (Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa). The results showed that the behavior of total phenols in relation to temperature depended on the floral sources of honey. The honeys presented curves of either linear or quadratic responses of the antibacterial activity in relation to the thermal process, depending on the honey's floral sources and the kind of bacterium to inhibit. The results suggest that the honey's antibacterial activities and behavior with the temperature are different depending on the honey's floral sources and the kind of bacteria that they inhibit. Practical Applications The consumer trend to search for minimally processed foods has increased in recent years due to the perception that food processing decreases its health benefits and antibacterial activities. Honey can inhibit pathogenic bacteria, but this inhibition is determined by the floral source from which the honey is collected. In this study, it was shown that thermal processing has a different effect on the antibacterial activities of each honey. These effects were linear or quadratic according to the bacteria (Bacillus subtilis, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa) and the floral source of the honey. This effect did not depend on the Gram (the inhibition against Salmonella typhimurium was linear with respect to the thermal process in all honey), in contrast to E. coli (where the effect was quadratic with a peak at 60C in all of the honey). The results led to the conclusion that the thermal processing of each honey must be different to maximize their beneficial health effects as well as their antibacterial activities.

Biomedical Activity and Related Volatile Compounds of Thai Honeys from 3 Different Honeybee Species.

This study investigated the effect of 3 factors (floral source, honeybee species, and postcollection processing) that influence the antibacterial activity, free radical reduction, and other biochemical compositions of different honey types typical of Thailand. Honey samples from 3 honeybee species (Apis mellifera, Apis cerana, and Apis dorsata) were obtained from 9 floral sources (longan, wild flower, lychee, coffee, sunflower, sesame, bitter bush, para-rubber, and manuka as a control) in different regions of Thailand. These samples were evaluated for both their total and nonperoxide antibacterial activity against 10 human pathogens by agar incorporation technique. Honey samples were further analyzed to evaluate the capacity for free radical-scavenging activity, total phenolic content, and the total flavonoid contents by the 2,2-diphenyl-1-picrylhydrazyl assay, Folin-Ciocalteu method, and aluminum chloride colorimetric assay, respectively. Furthermore, the volatile organic compounds (VOCs) of Thai honey samples were investigated by headspace solid-phase microextraction and gas chromatography-mass spectrometry analysis. Findings of this study suggest a strong correlation between floral origin and honeybee species on one hand, and differences in %Brix, total acidity, protein content, antimicrobial activities, free radical reduction, phenolic, and flavonoid contents on the other hand. Moreover, VOCs of wild and coffee honey types were remarkably different, depending on the floral source. Both honeys contained characteristics of VOCs, some of which are involved in antibacterial and antioxidant activities. Different origins and processing (floral source, honeybee species, and postcollection processing) of Thai honeys result in different antibacterial activities, physico-chemical properties, and aroma. Based on these findings, consumers of honey could select the type of honey based on their needs and preferred aroma.

Sugar profile, physicochemical and sensory aspects of monofloral honeys produced by different stingless bee species in Brazilian semi-arid region

Monofloral honeys produced by the stingless bee M. Subnida Duke and Melipona scutellaris Latrelle in a Brazilian semi-arid region were analyzed regarding their physicochemical (moisture, protein, proline, hydroxymethyl-furfural, color, electrical conductivity, pH, free acidity, and sugar profile) and sensory aspects (color, viscosity and flavor). The floral source influenced the color, acidity, sugar profile, ash and proline content in the honeys. The intensity of the acidic flavor, sweet taste and color in the honeys varied according to the floral source. No differences were perceived for honeys from the same floral source produced by different bee species. Principal component analysis revealed that most of the variability was defined by the water content, total acidity, glucose, sucrose and color, as well as by acid taste, acid flavor, honey flavor and sweet taste. These findings reveal that Brazilian monofloral honeys produced by stingless bees possess well-defined characteristics that are influenced by the floral source.

Evolutionary Trends and Specialization in the Euglossine Bee–pollinated Orchid GenusGongora1,2

The family Orchidaceae exhibits some of the most diverse and intricate modes of animal pollination across angiosperms. Highly specialized pollination by male euglossine bees (Apidae, Euglossini) occurs in more than 600 species of Neotropical orchids. Male euglossine bees acquire volatile compounds from both floral and nonfloral sources, which they store in their specialized hind tibiae and later expose during courtship display. Euglossine-pollinated Orchidaceae produce large quantities of floral scent, which serves as both the attractant and reward for male euglossine bees. Upon collecting floral volatiles and aided by the intricate orchid floral morphology, male bees remove and subsequently deposit orchid pollinaria, resulting in pollination. Among euglossine-pollinated Orchidaceae is the species-rich genus Gongora Ruiz & Pav., which provides exceptional opportunities to investigate the evolution of scent-mediated pollinator specialization. Here we review the taxonomy, systematics, and pollination biology of Gongora. We also describe a new physical mechanism of pollination observed for Gongora and discuss the significance of different modes of pollinaria attachment in an evolutionary framework. This work provides the foundation for future research on the evolution of specialized plant–pollinator mutualisms, including elucidating the evolutionary relationships of cryptic species, understanding the evolution of floral adaptations, and investigating the mechanisms of speciation.

Chemical profiles of honeys originating from different floral sources and geographic locations examined by a combination of three extraction and analysis techniques

The chemical profiles of Tasmanian Leatherwood and Manuka honeys from Tasmania and New Zealand have been compared by a combination of GC-MS analysis of volatiles and semi-volatiles, RP-HPLC-DAD analysis of phenolics and flavonoids and HPLC-DAD analysis of derivatised dihydroxyacetone, hydroxymethylfurfural and methylglyoxal. This study found that Tasmanian and New Zealand Manuka honeys have high concentrations of methylglyoxal. However, syringic acid was only detected in Manuka honeys grown in New Zealand. The Tasmanian honeys can be distinguished by the higher concentration of 3-phenyllactic acid in Manuka compared to Leatherwood floral sources.

Total phenolic contents and antioxidant activities of Korean domestic honey from different floral sources

Total phenolic contents and antioxidant activities of 7 Korean domestic honey varieties and fractions from different floral sources were determined. Extracts of 7 varieties of honey were fractionated in the sequence of n-hexane, chloroform, ethyl acetate, n-butanol, and water. The ethyl acetate fraction (EAF) of all 7 honey varieties retained the majority of the antioxidant activity and the total phenolic content. The antioxidant activities of the EAF from Korean raisin honey were 52.74 and 24.44 mg of vitamin C equivalents/g of dry fraction based on ABTS and DPPH radicals, respectively. Total EAF phenolic contents of 7 honey varieties ranged from 5.27 to 29.17 mg of gallic acid equivalents/g of dry fraction. High correlation coefficients between total phenolic contents and antioxidant activities indicated that phenolic compounds were the major components responsible for the antioxidant activities of honey.

Ultra high performance liquid chromatography with mass spectrometry method for the simultaneous determination of phenolic constituents in honey from various floral sources using multiwalled carbon nanotubes as extraction sorbents.

An ultra high performance liquid chromatography with mass spectrometry method has been developed for the simultaneous separation, identification and determination of 22 phenolic constituents in honey from various floral sources from Yemen. Solid-phase extraction was used for extraction of the target phenolic constituents from honey samples, while multiwalled carbon nanotubes were used as solid-phase adsorbent. The chromatographic separation of all phenolic constituents was performed on a BEH C18 column using a linear gradient elution with a binary mobile phase mixture of aqueous 0.1% formic acid and methanol. The quantitation was carried out in selected ion reaction monitoring acquisition mode. The total amount of phenolic acids, flavonoids and other phenols in each analyzed honey was found in the range of 338-3312, 122-5482 and 2.4-1342 μg/100 g of honey, respectively. 4-Hydroxybenzoic acid was found to be the major phenolic acid. The main detected flavonoid was chrysin, while cinnamic acid was found to be the major other phenol compound. The regeneration of solid phase adsorbent to be reused and recovery results confirm that the proposed method could be potentially used for the routine analysis of phenolic constituents in honey extract.

Health Benefits and Medicianl Value of Honey

Honey has been used for medicinal purposes for thousands of years. It is rich in sugars such as glucose and fructose, but it also contains small amounts of vitamins, minerals, amino acids, and antioxidants such as phenolic acids and flavonoids. These nutrients help to make honey a unique, natural health product. Its market niche as a health product is growing, and current research supports the potential of honey as a medicinal product. This 3-page fact sheet describes health aspects of honey deriving from the floral source and color, beneficial compounds, anti-microbial properties, and anti-inflammatory properties. Written by Sara Marshall, Liwei Gu, and Keith R. Schneider, and published by the UF Department of Food Science and Human Nutrition, April 2015.

Comparison of Anti-oxidant Activity of Ethyl Acetate Extracts of Different Floral Honeys from Korea

This study was done to compare anti-oxidant capacity of honeys from different floral sources (acacia, chestnut, linden, citrus and styrax). The ethyl acetate extracts of individual honey samples were taken to measure the anti-oxidant activity and total phenolic content (TPC) by 2,2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging assay, and Folin-Ciocalteu

Potential Role of Honey in Learning and Memory.

The composition and physicochemical properties of honey are variable depending on its floral source and often named according to the geographical location. The potential medicinal benefits of Tualang honey, a multifloral jungle honey found in Malaysia, have recently been attracting attention because of its reported beneficial effects in various diseases. This paper reviews the effects of honey, particularly Tualang honey, on learning and memory. Information regarding the effects of Tualang honey on learning and memory in human as well as animal models is gleaned to hypothesize its underlying mechanisms. These studies show that Tualang honey improves morphology of memory-related brain areas, reduces brain oxidative stress, increases brain-derived neurotrophic factor (BDNF) and acetylcholine (ACh) concentrations, and reduces acetylcholinesterase (AChE) in the brain homogenates. Its anti-inflammatory roles in reducing inflammatory trigger and microglial activation have yet to be investigated. It is hypothesized that the improvement in learning and memory following Tualang honey supplementation is due to the significant improvement in brain morphology and enhancement of brain cholinergic system secondary to reduction in brain oxidative damage and/or upregulation of BDNF concentration. Further studies are imperative to elucidate the molecular mechanism of actions.