LC-DAD-ESI/MS analysis of flavonoids and abscisic acid with chemometric approach for the classification of Slovenian honey

Polyphenols as the Main Compounds Influencing the Antioxidant Effect of Honey-A Review

Honey is one of the most valuable components of the human diet. It is considered to be a functional food with health-promoting properties. Honey has bactericidal and bacteriostatic effects; is used to treat wounds and ulcers; relieves stress; supports the treatment of diseases of the digestive and respiratory systems; improves kidney function; and aids in convalescence. The healing and prophylactic effects of honey are closely related to its chemical composition. According to the literature, honey contains over 300 substances belonging to various groups of chemical compounds, some with antioxidant activity, including vitamins and phenolic compounds, mainly flavonoids and phenolic acids. This article provides insight into honey's chemical composition and its pro-health activities. The antioxidant properties of honey were prioritized.

Profiling of the Polyphenol Content of Honey from Different Geographical Origins in the United States

The presence of phenolic compounds in honey can serve as potential authenticity markers for honey's botanical or geographical origins. The composition and properties of honey can vary greatly depending on the floral and geographical origins. This study focuses on identifying the specific markers that can distinguish honey based on their geographical areas in the United States. The main approach presented in this study to identify the geographic origins of honey involves chemometric methods combined with phenolic compound fingerprinting. Sample clean-up and phenolic compound extraction was carried out using solid phase extraction (SPE). Reversed phase liquid chromatography in combination with tandem mass spectrometry were utilized for the separation of the compounds. The honey physicochemical qualities were predominantly determined via spectrophotometric methods. Multivariate statistical tools such as principal component analysis (PCA), analysis of variance (ANOVA), and partial-least squares discriminant analysis (PLS-DA) were employed as both classification and feature selection tools. Overall, the present study was able to identify the presence of 12 potential markers to differentiate the honey's geographical origins. The total phenolic content ranged from 81.6 to 105.7 mg GAE/100 g corresponding to honey from Colorado and Washington, respectively (GAE: gallic acid equivalents). The regression analysis shows a tendency for the total phenolic content of honey to increase as the color of honey increases. The most important result obtained in this study is the demonstration that the geographical origin of honey plays a critical role in predicting the physical properties and phenolic composition of honey.

Evaluation of the Antioxidant Activities and Phenolic Profile of Shennongjia Apis cerana Honey through a Comparison with Apis mellifera Honey in China

This study evaluates the phenolic profile as well as the antioxidant properties of Shennongjia Apis cerana honey through a comparison with Apis mellifera honey in China. The total phenolic content (TPC) ranges from 263 ± 2 to 681 ± 36 mg gallic acid/kg. The total flavonoids content (TFC) ranges from 35.9 ± 0.4 to 102.2 ± 0.8 mg epicatechin/kg. The correlations between TPC or TFC and the antioxidant results (FRAP, DPPH, and ABTS) were found to be statistically significant (p < 0.01). Furthermore, the phenolic compounds are quantified and qualified by high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS), and a total of 83 phenolic compounds were tentatively identified in this study. A metabolomics analysis based on the 83 polyphenols was carried out and subjected to principal component analysis and orthogonal partial least squares-discriminant analysis. The results showed that it was possible to distinguish Apis cerana honey from Apis mellifera honey based on the phenolic profile.

The protective effects of baicalin and chrysin against emamectin benzoate-induced toxicity in Wistar albino rats

The aim of this study was to investigate the effects of baicalin, chrysin and their combinations against emamectin benzoate-induced toxicity in rats. For this purpose, sixty four rats were divided into evenly 8 groups with 6-8-week-old male Wistar albino rats, weighing 180-250 g, in each group. While the first group was kept as a control (corn oil), the remaining 7 groups were administered with emamectin benzoate (10 mg/kg bw), baicalin (50 mg/kg bw) and chrysin (50 mg/kg bw) alone or together for 28 days. Oxidative stress parameters, serum biochemical parameters and blood/tissue (liver, kidney, brain, testis and heart) and tissue histopathology were investigated. Compared to the control group, the emamectin benzoate-intoxicated rats had significantly higher tissue/plasma concentrations of nitric oxide (NO) and malondialdehyde (MDA), as well as lower tissue glutathione (GSH) concentrations and antioxidant enzyme activity (glutathione peroxidase/GSH-Px, glutathione reductase/GR, glutathione-S-transferase/GST, superoxide dismutase/SOD, catalase/CAT). Biochemical analysis showed that emamectin benzoate administration significantly increased serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) activities, as well as triglyceride, cholesterol, creatinine, uric acid and urea levels, and decreased serum total protein and albumin levels. The histopathological examination of the liver, kidney, brain, heart and testis tissues of the emamectin benzoate-intoxicated rats demonstrated necrotic changes. Baicalin and/or chrysin reversed the biochemical and histopathological alterations induced by emamectin benzoate on these tested organs. Therefore, baicalin and chrysin (alone or in combination) could offer protection against emamectin benzoate-induced toxicity.

Anthocyanin/Honey-Incorporated Alginate Hydrogel as a Bio-Based pH-Responsive/Antibacterial/Antioxidant Wound Dressing

Infection is a major problem that increases the normal pH of the wound bed and interferes with wound healing. Natural biomaterials can serve as a suitable environment to acquire a great practical effect on the healing process. In this context, anthocyanin-rich red cabbage (Brassica oleracea var. capitata F. rubra) extract and honey-loaded alginate hydrogel was fabricated using calcium chloride as a crosslinking agent. The pH sensitivity of anthocyanins can be used as an indicator to monitor possible infection of the wound, while honey would promote the healing process by its intrinsic properties. The mechanical properties of the hydrogel film samples showed that honey acts as a plasticizer and that increasing the incorporation from 200% to 400% enhances the tensile strength from 3.22 to 6.15 MPa and elongation at break from 0.69% to 4.75%. Moreover, a water absorption and retention study showed that the hydrogel film is able to absorb about 250% water after 50 min and retain 40% of its absorbed water after 12 h. The disk diffusion test showed favorable antibacterial activity of the honey-loaded hydrogel against both Gram-positive and Gram-negative Staphylococcus aureus and Escherichia coli, respectively. In addition, the incorporation of honey significantly improved the mechanical properties of the hydrogel. 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay proved the antioxidant activity of the honey and anthocyanin-containing hydrogel samples with more than 95% DPPH scavenging efficiency after 3 h. The pH-dependent property of the samples was investigated and recorded by observing the color change at different pH values of 4, 7, and 9 using different buffers. The result revealed a promising color change from red at pH = 4 to blue at pH = 7 and purple at pH = 9. An in vitro cell culture study of the samples using L929 mouse fibroblast cells showed excellent biocompatibility with significant increase in cell proliferation. Overall, this study provides a promising start and an antibacterial/antioxidant hydrogel with great potential to meet wound-dressing requirements.

A paraguayan toad Rhinella schneideri preparation based on Mbya tradition increases mitochondrial bioenergetics with migrastatic effects dependent on AMPK in breast cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

In Paraguay, healers from the Mbya culture treat cancer with a recipe prepared with the native toad Rhinella schneideri. However, the chemical composition and biological effects of the recipe remain unknown.

AIM OF THE STUDY

The aim is to determine the composition of the traditional preparation made using the toad R. schneideri and to evaluate its effect on human breast cancer (BC) cells.

MATERIALS AND METHODS

The metabolites contained in the preparation were concentrated using XAD-7 resin, and the concentrate was analyzed by HPLC-MS/MS. The effect of the preparation was assessed in normal (MCF10F) and BC cells (MDA-MB-231 and MCF7). The mitochondrial membrane potential (Δψm), reactive oxygen species (ROS) levels, and cell cycle progression were determined by flow cytometry. The oxygen consumption rate (OCR) was measured by Clark electrode, and fibronectin-dependent migration in normoxia and hypoxia-like conditions were evaluated by transwell assay.

RESULTS

From the Amberlite-retained extract from the preparation, 24 compounds were identified, including alkaloids, amino acids, bufadienolides, and flavonoids, among others. The crude extract (CE) did not affect cell cycle progression and viability of BC cell lines. Moreover, it did not make cancer cells more sensitive to the cytotoxic effect of the chemotherapeutics doxorubicin and teniposide. On the other hand, the CE reduced the menadione-induced ROS production and increased NADH, Δψm, and the OCR. Respiratory complexes I and III as well as ATP synthase levels were increased in an AMPK-dependent manner. Moreover, the CE inhibited the migration of BC cells in normoxia and a hypoxia-like condition using CoCl₂ as a HIF1α-stabilizing agent. This latter effect involved an AMPK-dependent reduction of HIF1α levels.

CONCLUSIONS

The Paraguayan toad recipe contains metabolites from the toad ingredient, including alkaloids and bufadienolide derivatives. The CE lacks cytotoxic effects alone or in combination with chemotherapeutics. However, it increases mitochondrial bioenergetics and inhibits the cancer cell migration in an AMPK-dependent manner in BC cells. This is the first report of the in vitro anticancer effect of a traditional Rhinella sp. toad preparation based on Mbya tradition.

Determination of Phenolic Compounds by Capillary Zone Electrophoresis-Mass Spectrometry

A CZE-MS method was developed for the determination of several phenolic compounds (phenolic acids, flavonoids). Since the analysis of these components necessitates the application of basic conditions for CZE separation and negative ionization mode for MS detection, the simplest choice was to use 0.5 M NH₄OH and IPA:water (1:1 v/v%) as the background electrolyte and sheath liquid, respectively. The LOD values ranged between 0.004-1.9 mg/L showing that there are relatively large differences in the ionization (and chemical) features of these compounds. The precision data were better than 0.75 RSD% for migration times and were between 5-8 RSD% for peak areas. In order to test the applicability of the developed method, a honey sample was analyzed.

Thorough Investigation of the Phenolic Profile of Reputable Greek Honey Varieties: Varietal Discrimination and Floral Markers Identification Using Liquid Chromatography–High-Resolution Mass Spectrometry

Honey is a highly consumed commodity due to its potential health benefits upon certain consumption, resulting in a high market price. This fact indicates the need to protect honey from fraudulent acts by delivering comprehensive analytical methodologies. In this study, targeted, suspect and non-targeted metabolomic workflows were applied to identify botanical origin markers of Greek honey. Blossom honey samples (n = 62) and the unifloral fir (n = 10), oak (n = 24), pine (n = 39) and thyme (n = 34) honeys were analyzed using an ultra-high-performance liquid chromatography hybrid quadrupole time-of-flight mass spectrometry (UHPLC-q-TOF-MS) system. Several potential authenticity markers were revealed from the application of different metabolomic workflows. In detail, based on quantitative targeted analysis, three blossom honey markers were found, namely, galangin, pinocembrin and chrysin, while gallic acid concentration was found to be significantly higher in oak honey. Using suspect screening workflow, 12 additional bioactive compounds were identified and semi-quantified, achieving comprehensive metabolomic honey characterization. Lastly, by combining non-targeted screening with advanced chemometrics, it was possible to discriminate thyme from blossom honey and develop binary discriminatory models with high predictive power. In conclusion, a holistic approach to assessing the botanical origin of Greek honey is presented, highlighting the complementarity of the three applied metabolomic approaches.

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.

Combined Inhibitory Effect of Fir (Abies alba Mill.) Honeydew Honey and Probiotic Bacteria Lactiplantibacillus plantarum on the Growth of Salmonella enterica Serotype Typhimurium

Honey is a natural food consisting mainly of sugars, enzymes, amino acids, organic acids, vitamins, minerals and aromatic substances. In addition to specific organoleptic properties, honey also has other components that contribute to its nutritional and health value. Proteins, vitamins, minerals, organic acids and phenolic compounds, the most variable components of honey, are predominantly responsible for its strong bioactive effect. Honeydew honey is a less known type of honey with outstanding antimicrobial and antioxidant properties that also demonstrates prebiotic effects and can promote the growth of probiotic bacteria. Foodborne illnesses can be prevented by using probiotic strains in combination with prebiotics. The aim of this study was for the first time to determine potential synergistic antimicrobial effect of fir (Abies alba Mill.) honeydew honey (HS) and probiotic bacteria Lactiplantibacillus plantarum on Salmonella enterica serotype Typhimurium, a primary cause of foodborne illnesses. The effect of three different samples of fir honeydew honey on the growth of L. plantarum in de Man, Rogosa and Sharpe (MRS) medium and the potential synergistic effect of HSs and L. plantarum on the growth of S. Typhimurium in the Brain Heart Infusion (BHI) medium were examined. The results indicate that concentrations of 1 and 5% of all three HS samples stimulate the growth and metabolic activity of L. plantarum, while a concentration of 10% inhibits the growth of L. plantarum. The concentration of 5% of all three HS and L. plantarum combined inhibits the growth of S. Typhimurium in BHI broth. Fir honeydew honey showed potential prebiotic properties and antimicrobial activity, both of which can synergistically enhance the probiotic efficacy of L. plantarum against S. Typhimurium To conclude, the combination of fir honeydew honey and L. plantarum represents a successful combination against S. Typhimurium and additional experiments are necessary regarding the mechanisms of their combined effect.

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.

Suitability of sugar, amino acid, and inorganic ion compositions to distinguish fir and spruce honey

Honeydew honey is produced by bees from excretions of plant-feeding insects, such as aphids and scale insects. Honeydew on conifers, like fir (Abies alba) or spruce (Picea abies), is produced by different species of the genera Cinara and Physokermes. This means that honeydew honey can stem from different botanical as well as zoological origins, but so far it is not possible to clearly distinguish the different types of honeys. In the attempt to identify distinguishing markers, 19 sugars, 25 amino acids and 9 inorganic ions were quantified in three groups of honeydew honey (fir/Cinara, spruce/Cinara and spruce/Physokermes) with 20 honey samples each. It could be demonstrated that the contents of isomaltose, raffinose, erlose, two undefined oligosaccharides, several amino acids, sulfate, and phosphate differed significantly between the three groups of honey. Furthermore, multivariate analyses resulted in a separation of spruce/Physokermes honey from spruce- or fir/Cinara honey due to its higher contents of phosphate, sulfate, erlose and two undefined oligosaccharides. Moreover, the amino acid composition and the isomaltose as well as the raffinose contents proved useful in the distinction between fir/Cinara and spruce/Cinara honey. In sum, the contents of sugars, amino acids, and inorganic ions in German fir and spruce honeys provide useful information about the botanical and zoological origin of honeydew honeys.

Differentiation of Honeydew Honeys from Blossom Honeys and According to Their Botanical Origin by Electrical Conductivity and Phenolic and Sugar Spectra

Honeydew honey, due to its higher antibacterial and antioxidant activity in comparison to blossom honeys, is in high demand and of interest to consumers. Although a differentiation of blossom honeys from honeydew honeys by way of electrical conductivity is given in many cases, criteria for a differentiation of individual honeydew honeys, such as spruce, fir, and pine, however did not exist. For this reason, 93 authentic honeydew honeys and 63 non-honeydew honeys [35 blossom and 28 nectar-honeydew (mixed)] from 13 different botanical origins were collected within the framework of the current study, and their electrical conductivity and phenolic and sugar profiles were investigated. Results showed that the higher electrical conductivity (≥0.80 mS/cm), the higher protocatechuic acid content (≥3.5 mg/kg), and the higher percentage of the oligosaccharide content (≥120 mg/g) were suitable parameters for the differentiation of authentic coniferous honeydew honeys from non-honeydew honeys; a differentiation. A differentiation of the spruce, fir, and pine honeydew honeys however could not be reached. Through the analysis of 32 carbohydrates (2 mono-, 7 di-, 10 tri-, and 13 higher oligosaccharides) in only one run by high-performance liquid chromatography equipped with an evaporative light scattering detector, marker substances can now be utilized for the classification of individual honeydew honeys. Sugar marker compounds such as α,α-trehalose, melezitose, theanderose, nystose, or maltotetraose in honeydew honeys in combination with chemometrics highlighted the good capability of sugar profiles to discriminate the honeydew honeys both from the non-honeydew honeys and from each other. All in all, a 96.75% correct classification of all studied 156 honey samples was achieved by sugar marker compounds.

LC-QqQ-MS/MS methodology for determination of purine and pyrimidine derivatives in unifloral honeys and application of chemometrics for their classification

The new liquid chromatographic-triple quadrupole tandem mass spectrometry (LC-QqQ-MS/MS) method for determination of purine and pyrimidine derivatives in honey produced by Apis mellifera was developed. 13 compounds were determined in total of 130 unifloral honey samples of 13 varieties: uracil, thymine, thymidine, xanthine, guanine, adenine, uridine, pseudouridine, xanthosine, inosine, hypoxanthine, guanosine and cytidine. The levels of some of these compounds varied between the specific honey types. The most abundant were uridine (up to 44.66 mg/kg), xanthine (up to 20.48 mg/kg) and xanthosine (up to 19.22 mg/kg). The data were evaluated by principal component analysis (PCA) and k-nearest neighbors (k-NN) classification (selected 9 and 8 honey types, respectively) to examine differences between the honey varieties allowing their discrimination based on purine and pyrimidine derivatives amounts. The data allowed to distinguish between 8 honey types (balanced accuracy 82%) and for most of the varieties obtained classification rates ranged from 96 to 100%.

HPLC-DAD-ESI-QTOF-MS/MS qualitative analysis data and HPLC-DAD quantification data of phenolic compounds of grains from five Australian sorghum genotypes

Sorghum (Sorghum bicolor) grain is a rich source of bioactive phenolic compounds and understanding the phenolic profile of different sorghum genotypes is an important step towards the selection of the most appropriate genotype for industrial applications. The free and bound phenolic compounds of sorghum bran and kernel fractions from five Australian-grown sorghum genotypes (1 white, 2 red, 1 brown and 1 black coloured grain) were identified/tentatively identified by HPLC-DAD-ESI-QTOF-MS/MS and quantified/semi-quantified by HPLC-DAD. Firstly, MS chromatograms of sorghum samples and standards and the MS/MS spectra of individual detected compounds and standards are presented. Then quantification data of these compounds is provided. This dataset is supplementary to the research paper "Comprehensive profiling of phenolic compounds by HPLC-DAD-ESI-QTOF-MS/MS to reveal their location and form of presence in different sorghum grain genotypes" [1].

Classification of the botanical and geographical origins of Chinese honey based on 1H NMR profile with chemometrics

In this paper, we report a newly developed non-target ¹H NMR detection associated with chemometrics method to classify the botanical and geographical origins of the monofloral Chinese honey. ¹H NMR tests of 218 monofloral honey samples of 8 classes (Acacia, Jujube, Linden, Longan, Orange, Rape, Sunflower, Vitex) collected in 2017-2019 across China were conducted under the optimal sample preparation conditions and NMR acquisition parameters. The whole profiles of NMR spectra instead of individual or partial signals from specific components were processed and extracted, then fed to SIMCA-P to classify the botanical and geographical origins through non-target statistical analysis. For the botanical origins, most of them could be classified clearly according to Principal Component Analysis (PCA) with both R² and Q² close to 1. Orthogonal Partial Least Squares Discrimination Analysis (OPLS-DA) model could classify the honey floral types successfully with R²Y and Q² greater than 0.85. It is found that the integral bin for data extraction has no obvious influence on the classification. For the geographical origins, the classification at different geographical levels (providence and town) could be successfully distinguished by OPLS-DA model. The promising preliminary results with the geographical classification at 40 km level unambiguously demonstrate the application of this NMR-based multi-species non-targeted method for the honey authenticity. Successful result is obtained on a pilot prediction of the geographical classification. Comparing with the methods based on other techniques, the advantages of this reported one are less sample amount needed, simple preparation, short test time, and non-targeted multi-species detection.

High-Performance Anion Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD) and Chemometrics for Geographical and Floral Authentication of Honeys from Southern Italy (Calabria region)

High-performance anion exchange chromatography with pulsed amperometric detection (HPAEC–PAD) combined with chemometric analysis was developed to describe, for the first time, the sugar profile of sixty-one honeys of different botanical origin produced in southern Italy (Calabria Region). The principal component and linear discriminant analysis used to describe the variability of sugar data were able to discriminate the honeys according to their botanical origin with a correlation index higher than 90%. For the purpose of the robustness of the conclusions of this study, the analytical advantages of the HPAEC–PAD method have been statistically demonstrated compared to the official Italian HPLC–RI method (Refractive Index detection). Finally, as the characterization of the floral and geographical origin of honey became an important issue due to high consumer demand, 13 acacia honeys originating from Europe and China were studied by using the same method. By chemometric method it was possible to discriminate the different geographical origin with an index of 100%. All results proved the possibility to identify the sugar profile obtained by HPAEC–PAD combined with a robust statistical analysis, as a tool of authentication.

Comparative study of toxic heavy metal residues and other properties of honey from different environmental production systems

Honeybees forage a large spatial area around the hives. In addition, honey production takes place in various environments, and polluted environment is often hard to detect. It impacts both human and beehive health, especially through honey which is used for human consumption. Pollen analysis was conducted by a novel approach through a multivariate principal component analysis where it was possible to obtain grouping patterns related to foraging plant species. Samples of honey were acquired from three different environmental production systems: (i) honey from the apiaries in the vicinity of thermal power plant, (ii) apiary of certified organic production and (iii) the conventional production with semi-controlled production. Significantly higher contents of the Pb, Cd and Zn are found in the analysed honeys taken near the thermal power plant compared with those of the other analysed honeys. The origin of Zn, Pb and Cd in the honey is the contaminated forage plants and foraging honeybees. Honey from certified organic production differentiated significantly from other two types of production by the water content, electrical conductivity and total soluble solids and notably it contained significantly less ash and lead. There is a clear advantage of certified organic honey in terms of heavy metal residues as the most prominent pollution factor in honey. Therefore, honey can be used as the broad range environmental pollution indicator, as bees will forage on polluted plants and bring the pollutant from a wide spatial range inside the hive, where it can be traced in the honey. Graphical abstract.

Comprehensive profiling of phenolic compounds by HPLC-DAD-ESI-QTOF-MS/MS to reveal their location and form of presence in different sorghum grain genotypes

In this study, comprehensive profiling of the phenolic compounds in sorghum grain was achieved by analysing the free and bound extracts of sorghum bran and kernel fractions from five Australian sorghum genotypes (1 white, 2 red, 1 brown and 1 black coloured), using HPLC-DAD-ESI-QTOF-MS/MS. A total of 110 phenolic compounds were annotated, out of which 56 were reported for the first time in sorghum grain. Compounds with matched authentic standards were quantified/semi-quantified. Multiple factor analysis (MFA) was performed and heatmaps generated, which provided direct visualisation of the distribution of individual phenolic compounds/subclasses between the sorghum samples. The results indicated that phenolic compounds were concentrated on the bran, and free and bound extracts had different phenolic composition. The phenolic compound/subclass profile varied greatly among sorghum genotypes. Brown sorghum genotype (IS131C) had the highest concentration of total phenolic contents, and the bran fraction of brown sorghum had the most abundant and diverse phenolic composition among all tested samples. This study provides the most comprehensive phenolic profile of Australian representative sorghum grains up to date.

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.

Physicochemical analysis and phenolic profile of polyfloral and honeydew honey from Montenegro

The research subject of this paper was a detail physicochemical analysis of 28 honey samples from the northern part of Montenegro. The honey from Montenegro has not been previously studied in such detail. Differentiation between samples, such as honeydew honey and polyfloral honey, was based on electrical conductivity, which was higher than 0.8 mS cm⁻¹ for honeydew honey, as was expected. Other investigated physicochemical parameters (water content, free acids, diastase activity, hydroxymethylfurfural (HMF) content and sugar content) have shown great similarity for all honey samples. The main interest of this study was the identification and quantification of phenolic compounds using ultra-high performance liquid chromatography (UHPLC) with mass spectrometry detection. The results show that honey samples are very rich in phenolic compounds, especially quercetin. Among the 31 quantified phenolic compounds, the most dominant were phenolic acids. The highlight was based on p-hydroxybenzoic acid, p-coumaric acid, caffeic acid and ferulic acid. Considering polyphenolic compounds and sugar content, a high nutritional value can be observed in all samples, with an emphasis on polyfloral honeys, as was confirmed with principal component analysis (PCA). In addition, all honey samples were tested for total phenolic content (TPC) and radical scavenging activity (RSA). The results indicate the higher antioxidant ability of honeys from Montenegro in comparison to some honey samples from other countries in the region.

The research subject of this paper was a detailed physicochemical analysis of 28 honey samples from the northern part of Montenegro.

Phenolic compounds profile and biochemical properties of honeys in relationship to the honey floral sources

INTRODUCTION

Honey has been considered to have therapeutic properties since ancient times and among the factors responsible for such activity are phenolic compounds including phenolic acids and flavonoids from different natural sources.

OBJECTIVE

This study investigated the phenolic compounds profile and bioactive properties of different honey types from Romanian flora in order to develop reliable tools for honey floral origin, thus contributing to the honey traceability in the European Union context.

MATERIAL AND METHODS

Thirty-three honey samples were examined, including unifloral (acacia and rape), polyfloral, honeydew honeys and mixture honeys. Phenolic acids and flavonoids were isolated from the water soluble honey matrix using a solid-phase extraction (SPE) method and analysed by ultra-high-performance liquid chromatography diode array detector electrospray ionisation mass spectrometry (UHPLC-DAD-ESI/MS). Honey bioactive properties were measured in honey dissolved in 80% ethanol using UV-visible spectrophotometric methods. Multivariate statistical tools (principal component analysis and hierarchical clustering analysis) were used for honey classification.

RESULTS

The results of this study confirm that honey samples had similar, but quantitatively different, phenolic acids and flavonoids profiles and bioactive properties, related with honey floral source. Coloured honeys, such as honeydew honey, show high phenolic composition and bioactive properties and implicitly a high therapeutic potential compared with the other floral honeys.

CONCLUSION

Distinctive clusters obtained by principal component analysis enabled us to consider that honeydew and polyfloral honeys could be distinguished from acacia and rape honey with the analytical methods developed. Based on this study, the methods might be promising tools for honey traceability, which needs to be explored on a larger set of samples with different regional floral origins in future studies.

Differentiation of oak honeydew and chestnut honeys from the same geographical origin using chemometric methods

Oak honeydew and chestnut honeys often share the same production area in Atlantic landscapes. Consequently these honeys have common physicochemical properties and pollen composition, making their differentiation by routine methods, a difficult task. The increase in the demands of consumers for clear honey labelling, identifying floral make-ups and the substantial health properties of both honey types, make it necessary to improve methods to differentiate the honeys. Statistical multivariate techniques were used to study the differences in the physicochemical composition and pollen spectra between chestnut honey and oak honeydew honey. Palynological analysis, moisture, pH, electrical conductivity, hydroxymethylfurfural, diastase number, colour, phenolic content, minerals and sugars were used for this purpose. The variables that had more weight in the differentiation by principal component analysis were Castanea, Cytisus type, CIELab coordinates (a^* and L), RSA, Mg and trehalose; 97.6% of the honey samples were correctly classified by linear discriminant analysis.

Physicochemical Properties and Pollen Profile of Oak Honeydew and Evergreen Oak Honeydew Honeys from Spain: A Comparative Study

This work investigates the similarities and differences of oak honeydew (Quercus pyrenaica Willd.) and evergreen honeydew (Quercus ilex L.) honey produced in Spain. For this purpose, the physicochemical characteristics of 17 samples from oak honeydew and 11 samples from evergreen honeydew collected in different geographical regions were analyzed. All the samples accomplished European Union requirements for honey consumption. Both honey types had amber dark color; however, the evergreen oak honey was clearer than oak honey, having higher mean values in a* and b* coordinates of CIELab scale. In general, both honey types exhibited high electrical conductivity, a moderate value of pH, medium to low water content, and high diastase activity. The reducing sugar content was significantly lower and maltose content was significantly higher in evergreen honeydew. In addition, total phenols and total flavonoid contents, the antioxidant activity and the melissopalynological analysis was performed. The oak honeydew honey had a higher abundance of Castanea, Rubus and Erica pollen grains, while the evergreen oak honeydew honey had a higher abundance of Lavandula, Olea europaea or Anthyllis cytisoides. A multivariate analysis using the most representative pollen types and physicochemical components facilitated the differentiation of the honey samples, thus this information can be useful for the honey characterization.

Flavonoids and Their Biological Secrets

Flavonoids are tricyclic polyphenolic compounds naturally occurring in plants. Being nature’s antioxidants flavonoids have been shown to reduce the damages induced by oxidative stress in cells. Besides being an antioxidant, flavonols are demonstrated to have anti-infective properties, i.e., antiviral, antifungal, anti-angiogenic, anti-tumorigenic, and immunomodulatory bioproperties. Plants use them as one of their defense mechanisms against radiation-induced DNA damage and also for fungal infections. The use of flavonols for fabrication of new drugs has been underway with objectives to develop safer and effective therapeutic agents. This review covers 15 flavonols for their structure, biological properties, role in plant metabolisms, and current research focused on computational drug design using flavonols for searching drug leads.

An overview of physicochemical characteristics and health-promoting properties of honeydew honey

Honeydew honey has differentiated chemical and physicochemical characteristics besides potential functional properties such as antimicrobial, anti-inflammatory and antioxidant. In this sense, the interest and consumption of this honey as a functional product by the food industry and consumers have increased. Honeydew honeys usually present dark color, a lower content of monosaccharides and higher values of pH, acidity, electric conductivity, proteins, minerals, phenolic compounds, and oligosaccharides compared to blossom honeys, which contribute to its outstanding biological activities. Consequently, contaminations and adulterations of this honey can occur and compromise the quality, safety and authenticity of honeydew honey. Thus, detailed knowledge of the composition and properties of honeydew honeys is of great importance, especially considering that honeydew honeys are still few studied and therefore underestimated. Therefore, in this review, the physicochemical characteristics, chemical and bioactive composition, functional and health-promoting properties of honeydew honey as well as contamination, adulteration and authenticity of this honey are summarized.

Botanical influence on phenolic profile and antioxidant level of Italian honeys

Honeybees directly transfer plant compounds from nectar into honey. Each plant species possesses a specific metabolic profile, the amount and the typology of plant molecules that may be detected in honey vary according to their botanical origin. Aim of the present work was the spectrophotometrical determination of concentration ranges of simple phenols and flavonoids in 460 several Italian monofloral honeys, in order to individuate specific intervals of plant metabolites for each typology of honey. Moreover, an LC-MS analysis was performed to determine amount of various secondary metabolites in the samples, with the purpose to use them as potential molecular markers in support to honey melissopalynological classification. As plant molecules have a strong reducing power, the antioxidant activity of the honeys was evaluated by two antiradical assays, DPPH and FRAP. The free radical scavenging effect of each monofloral group was correlated to the concentration of simple phenols and flavonoids, with the aim to deduce the existence of possible relationships between these parameters. In conclusion, dark honeys (Castanea sativa, honeydew, Erica sp. and Eucalyptus sp.) appeared to be the richest in secondary metabolites and, consequently, showed higher antioxidant activity. However, all analyzed monofloral honeys showed to be good sources of antioxidants.

Honeydew Honeys: A Review on the Characterization and Authentication of Botanical and Geographical Origins

The commercial interest in honeydew honeys (from the secretions of plants or the excretions of plant-sucking insects found on plants) is increasing because of their higher therapeutic properties compared with those of most blossom honeys (from nectar). However, honeydew honeys have been less studied than blossom honeys. In this work, studies carried out to characterize and authenticate honeydew honeys by their botanical and geographical origins have been reviewed. The identification of honey origins has been approached by two ways: by the analysis of chemical markers and by the development of analytical methodologies combined with multivariate analyses. Some compounds have been suggested as specific botanical markers of several honeydew honeys, such as quercitol and trans-oak lactone for oak honey, 2-aminoacetophenone and propylanisol for holm oak honey, and 1-chloro-octane and tridecane for pine honey. The presence of 3-carene and an unidentified compound in samples was proposed as a way discriminate between Greek and Turkish pine honeys. Chemometric analyses have been applied on chemical compositions and on physicochemical, microscopic, and spectral parameters and have proved to be valuable methods for authenticating honeydew honeys. Analytical methods based on spectral information are suitable for the routine control of honeydew-honey origins because they are fast and require easy sample preparations.

Validation of botanical origins and geographical sources of some Saudi honeys using ultraviolet spectroscopy and chemometric analysis

This study aims at distinguishing honey based on botanical and geographical sources. Different floral honey samples were collected from diverse geographical locations of Saudi Arabia. UV spectroscopy in combination with chemometric analysis including Hierarchical Cluster Analysis (HCA), Principal Component Analysis (PCA), and Soft Independent Modeling of Class Analogy (SIMCA) were used to classify honey samples. HCA and PCA presented the initial clustering pattern to differentiate between botanical as well as geographical sources. The SIMCA model clearly separated the Ziziphus sp. and other monofloral honey samples based on different locations and botanical sources. The results successfully discriminated the honey samples of different botanical and geographical sources validating the segregation observed using few physicochemical parameters that are regularly used for discrimination.

Screening of Polish Fir Honeydew Honey Using GC/MS, HPLC-DAD, and Physical-Chemical Parameters: Benzene Derivatives and Terpenes as Chemical Markers

GC/MS of headspace solid phase micro extraction (HS-SPME) and solvent extractives along with targeted HPLC-DAD of Polish fir (Abies alba Mill.) honeydew honey (FHH), were used to determine the chemical profiles and potential markers of botanical origin. Additionally, typical physical-chemical parameters were also assigned. The values determined for FHH were: conductivity (1.2 mS/cm), water content (16.7 g/100 g), pH (4.5), and CIE chromaticity coordinates (L* = 48.4, a* = 20.6, b* = 69.7, C* = 72.9, and h° = 73.5). FHH contained moderate-high total phenolic content (533.2 mg GAE/kg) and antioxidant activity (1.1 mmol TEAC/kg) and (3.2 mmol Fe²⁺ /kg) in DPPH and FRAP assays. The chemical profiles were dominated by source plant-originated benzene derivatives: 3,4-dihydroxybenzoic acid (up to 8.7 mg/kg, HPLC/honey solution), methyl syringate (up to 14.5%, GC/solvent extracts) or benzaldehyde (up to 43.7%, GC/headspace). Other markers were terpenes including norisoprenoid (4-hydroxy-3,5,6-trimethyl-4-(3-oxobut-1-enyl)cyclohex-2-en-1-one, up to 20.3%, GC/solvent extracts) and monoterpenes, mainly linalool derivatives (up to 49%, GC/headspace) as well as borneol (up to 5.9%, GC/headspace). The application of various techniques allowed comprehensive characterisation of FHH. 4-Hydroxy-3,5,6-trimethyl-4-(3-oxobut-1-enyl)cyclohex-2-en-1-one, coniferyl alcohol, borneol, and benzaldehyde were first time proposed for FHH screening. Protocatechuic acid may be a potential marker of FFH regardless of the geographical origin.

Implementation of chemometrics in quality evaluation of food and beverages

Conventional methods for food quality evaluation based on chemical or microbiological analysis followed by traditional univariate statistics such as ANOVA are considered insufficient for some purposes. More sophisticated instrumental methods including spectroscopy and chromatography, in combination with multivariate analysis-chemometrics, can be used to determine food authenticity, identify adulterations or mislabeling and determine food safety. The purpose of this review is to present the current state of knowledge on the use of chemometric tools for evaluating quality of food products of animal and plant origin and beverages. The article describes applications of several multivariate techniques in food and beverages research, showing their role in adulteration detection, authentication, quality control, differentiation of samples and comparing their classification and prediction ability.

Strategy for comparative untargeted metabolomics reveals honey markers of different floral and geographic origins using ultrahigh-performance liquid chromatography-hybrid quadrupole-orbitrap mass spectrometry

Honey discrimination based on floral and geographic origins is limited by the ability to determine reliable markers because developing hypothetical substances in advance considerably limits the throughput of metabolomics studies. Here, we present a novel approach to screen and elucidate honey markers based on comparative untargeted metabolomics using ultrahigh-performance liquid chromatography-hybrid quadrupole-orbitrap mass spectrometry (UHPLC-Q-Orbitrap). To reduce metabolite information losses during sample preparation, the honey samples were dissolved in water and centrifuged to remove insoluble particles prior to UHPLC-Q-Orbitrap analysis in positive and negative electrospray ionization modes. The data were pretreated using background subtraction, chromatographic peak extraction, normalization, transformation and scaling to remove interferences from unwanted biases and variance in the experimental data. The pretreated data were further processed using principal component analysis (PCA) and a three-stage approach (t-test, volcano plot and variable importance in projection (VIP) plot) to ensure marker authenticity. A correlation between the molecular and fragment ions with a mass accuracy of less than 1.0ppm was used to annotate and elucidate the marker structures, and the marker responses in real samples were used to confirm the effectiveness of the honey discrimination. Moreover, we evaluated the data quality using blank and quality control (QC) samples based on PCA clustering, retention times, normalized levels and peak areas. This strategy will help guide standardized, comparative untargeted metabolomics studies of honey and other agro-products from different floral and geographic origins.