From Robinia pseudoacacia L. nectar to Acacia monofloral honey: biochemical changes and variation of biological properties

Ultrastructure and development of the floral nectary from Borago officinalis L. and phytochemical changes in its secretion

Although Boraginaceae have been classified as good sources of nectar for many insects, little is still known about their nectar and nectaries. Thus, in the present contribution, we investigated the nectar production dynamics and chemistry in Borago officinalis L. (borage or starflower), together with its potential interaction capacity with pollinators. A peak of nectar secretion (∼5.1 µL per flower) was recorded at anthesis, to decrease linearly during the following 9 days. In addition, TEM and SEM analyses were performed to understand ultrastructure and morphological changes occurring in borage nectary before and after anthesis, but also after its secretory phase. Evidence suggested that nectar was transported by the apoplastic route (mainly from parenchyma to epidermis) and then released essentially by exocytotic processes, that is a granulocrine secretion. This theory was corroborated by monitoring the signal of complex polysaccharides and calcium, respectively, via Thiéry staining and ESI/EELS technique. After the secretory phase, nectary underwent degeneration, probably through autophagic events and/or senescence induction. Furthermore, nectar (Nec) and other flower structures (i.e., sepals, gynoecia with nectaries, and petals) from borage were characterized by spectrophotometry and HPLC-DAD, in terms of plant secondary metabolites, both at early (E-) and late (L-) phase from anthesis. The content of phytochemicals was quantified and discussed for all samples, highlighting potential biological roles of these compounds in the borage flower (e.g., antimicrobial, antioxidant, staining effects). Surprisingly, a high significant accumulation of flavonoids was registered in L-Nec, with respect to E-Nec, indicating that this phenomenon might be functional and able to hide molecular (e.g., defence against pathogens) and/or ecological (e.g., last call for pollinators) purposes. Indeed, it is known that these plant metabolites influence nectar palatability, encouraging the approach of specialist pollinators, deterring nectar robbers, and altering the behaviour of insects.

Shining a light on UV-fluorescent floral nectar after 50 years

Nature is aglow with numerous captivating examples of UV-fluorescence in the animal kingdom. Despite a putative role as a visual signal, exploration of UV-fluorescence in plants and its role in plant-animal interactions is lagging in comparison. Almost 50 years ago, UV-fluorescence of floral nectar, a crucial reward for pollinators, was reported for 23 flowering plant species. Since this intriguing discovery, UV-fluorescent nectar has only seldom been addressed in the scientific literature and has not been scrutinized in a phylogenetic or ecological context. Here, we report the prevalence of vibrant UV-fluorescent floral nectar across the family Cleomaceae, including the first photographic documentation in vivo colour for flowering plants. Though Cleomaceae flowers are morphologically diverse varying in colour, nectary prominence, and nectar volume, UV-fluorescent floral nectar may be a ubiquitous characteristic of the family. Fluorescence spectra show that the identity and number of fluorescent compounds in floral nectar may differ among Cleomaceae species. As Cleomaceae pollinators range from insects to bats and birds, we suggest that the UV-fluorescent floral nectar not only functions as a visual cue for the diurnal pollinators but also for the nocturnal/crepuscular pollinators in low light settings.

Nutraceutical Content and Biological Properties of Lipophilic and Hydrophilic Fractions of the Phytocomplex from Pistacia atlantica Desf. Buds, Roots, and Fruits

The aim of the present investigation was to obtain 12 aqueous extracts and 1 oil from Pistacia atlantica Desf. subsp. atlantica specimens. The samples differed for processed plant organs (i.e., roots, buds, and fruits), gender and geographical station of the collected trees. Total phenols, flavonoids, and condensed tannins were determined, revealing that bud extracts exhibited the highest phenolic content (386.785 ± 16.227 mg GAE/g DM), followed by fruit and root preparations. Similar results were detected for flavonoids and tannins, whose quantitation ranged from 0.014 ± 0.005 to 74.780 ± 9.724 mg CE/g DM and from 0.037 ± 0.003 to 14.793 ± 0.821 mg CE/g DM, respectively. The biochemical profile of the extracts was further characterized by HPLC-DAD, in terms of specific phenolics. This analysis identified gallic acid as a typical metabolite for ripe fruit, while hydroxytyrosol for female roots and male buds. In parallel, P. atlantica fruit oil was profiled by GC-MS analysis, which detected 37 lipophilic components, including palmitic acid (the major component, ~55%), anacardol, tetradecanol, arachidic acid, squalene, and some terpenes. The samples revealed interesting antioxidant activity, with EC50 values ranging from 0.073 ± 0.001 to 193.594 ± 28.942 mg/mL and from 0.029 ± 0.001 to 103.086 ± 20.540 mg/mL, in that order, for DPPH and reducing power assays. Concerning the total antioxidant capacity, the results ranged from 0.053 ± 0.008 to 51.648 ± 1.659 mg AAE/g DM. Finally, the antimicrobial potential of the plant extracts was estimated against 7 bacterial species and 2 fungal strains, known to be human pathogens, demonstrating a good antibiotic effect for the bud extracts. All these findings strongly suggest that P. atlantica would represent a natural reservoir for novel additives to be used in therapeutic, food, and cosmetic products.

Shotgun Metagenomics Reveals Minor Micro"bee"omes Diversity Defining Differences between Larvae and Pupae Brood Combs

Bees represent not only a valuable asset in agriculture, but also serve as a model organism within contemporary microbiology. The metagenomic composition of the bee superorganism has been substantially characterized. Nevertheless, traditional cultural methods served as the approach to studying brood combs in the past. Indeed, the comb microbiome may contribute to determining larval caste differentiation and hive immunity. To further this understanding, we conducted a shotgun sequencing analysis of the brood comb microbiome. While we found certain similarities regarding species diversity, it exhibits significant differentiation from all previously described hive metagenomes. Many microbiome members maintain a relatively constant ratio, yet taxa with the highest abundance level tend to be ephemeral. More than 90% of classified metagenomes were Gammaproteobacteria, Bacilli and Actinobacteria genetic signatures. Jaccard dissimilarity between samples based on bacteria genus classifications hesitate from 0.63 to 0.77, which for shotgun sequencing indicates a high consistency in bacterial composition. Concurrently, we identified antagonistic relationships between certain bacterial clusters. The presence of genes related to antibiotic synthesis and antibiotic resistance suggests potential mechanisms underlying the stability of comb microbiomes. Differences between pupal and larval combs emerge in the total metagenome, while taxa with the highest abundance remained consistent. All this suggests that a key role in the functioning of the comb microbiome is played by minor biodiversity, the function of which remains to be established experimentally.

Combining AI Tools with Non-Destructive Technologies for Crop-Based Food Safety: A Comprehensive Review

On a global scale, food safety and security aspects entail consideration throughout the farm-to-fork continuum, considering food's supply chain. Generally, the agrifood system is a multiplex network of interconnected features and processes, with a hard predictive rate, where maintaining the food's safety is an indispensable element and is part of the Sustainable Development Goals (SDGs). It has led the scientific community to develop advanced applied analytical methods, such as machine learning (ML) and deep learning (DL) techniques applied for assessing foodborne diseases. The main objective of this paper is to contribute to the development of the consensus version of ongoing research about the application of Artificial Intelligence (AI) tools in the domain of food-crop safety from an analytical point of view. Writing a comprehensive review for a more specific topic can also be challenging, especially when searching within the literature. To our knowledge, this review is the first to address this issue. This work consisted of conducting a unique and exhaustive study of the literature, using our TriScope Keywords-based Synthesis methodology. All available literature related to our topic was investigated according to our criteria of inclusion and exclusion. The final count of data papers was subject to deep reading and analysis to extract the necessary information to answer our research questions. Although many studies have been conducted, limited attention has been paid to outlining the applications of AI tools combined with analytical strategies for crop-based food safety specifically.

Antioxidant Phytocomplexes Extracted from Pomegranate (Punica granatum L.) Using Hydrodynamic Cavitation Show Potential Anticancer Activity In Vitro

Hydrodynamic cavitation (HC), as an effective, efficient, and scalable extraction technique for natural products, could enable the affordable production of valuable antioxidant extracts from plant resources. For the first time, whole pomegranate (Punica granatum L.) fruits, rich in bioactive phytochemicals endowed with anti-cancer properties, were extracted in water using HC. Aqueous fractions sequentially collected during the process (M1-M5) were lyophilized (L), filtered (A), or used as such, i.e., crude (C), and analyzed for their biochemical profile and in vitro antioxidant power. The fractions M3 and M4 from the L and C series showed the highest antiradical activity and phytochemical content. While the lyophilized form is preferable for application purposes, sample L-M3, which was produced faster and with lower energy consumption than M4, was used to assess the potential antiproliferative effect on human breast cancer line (AU565-PAR) and peripheral blood mononuclear (PBMC) cells from healthy donors. In a pilot study, cell growth, death, and redox state were assessed, showing that L-M3 significantly reduced tumor cell proliferation and intracellular oxygen reactive species. No effect on PBMCs was detected. Thus, the antioxidant phytocomplex extracted from pomegranate quickly (15 min), at room temperature (30 °C), and efficiently showed potential anticancer activity without harming healthy cells.

Influence of environmental conditions on the production of nutraceuticals in Italian edible plant landraces

Autochthonous plant varieties, also referred to as landraces, represent an important genetic resource, being well-adapted to the environment in which they have been selected. Landraces usually show profiles rich in nutraceuticals, making them an effective and valuable alternative to commercial agri-products, as well as potential candidates for crop improvement programs. Basilicata region is recognized as an Italian hotspot for agrobiodiversity, due to its complex orography. Thus, this work aimed to characterize and monitor, for two successive years, the content of secondary metabolites and related antioxidant properties of seven different species, four officinal (i.e., wild fennel - Feoniculum vulgare Mill.; oregano - Origanum vulgare L.; thyme - Thymus vulgaris L.; valerian - Valeriana officinalis L.) and three fruit species (i.e., fig - Ficus carica L. cv. Dottato; sweet cherry Prunus avium L. cv. Majatica; plum - Prunus domestica L. cv. Cascavella Gialla), collected in three different sites of this region. In detail, spectrophotometric tests were performed to assess the concentration of phenolic compounds, flavonoids, and - for officinal plants - also terpenoids, together with the antiradical activity (FRAP assays). In addition, to better typify the phytocomplexes of these landraces, HPLC-DAD and GC-MS analyses were carried out. In general, officinal plants showed higher values of nutraceutical compounds and related bioactivity with respect to fruit species. The data showed how different accessions of the same species had different phytochemical profiles, according to the sampling area and the year of collection, suggesting a role for both genetic and environmental factors in determining the observed results. Therefore, the final goal of this research was also to find a possible correlation between environmental factors and nutraceutics. The greatest correlation was found in valerian, where a lower water intake seemed to lead to a higher accumulation of antioxidants, and in plum, where the flavonoid content correlated positively with high temperatures. All these outcomes contribute at valorising Basilicata landraces for their aptitude to be high-quality foods and, at the same time, promoting the preservation of the agrobiodiversity for this region.

Metabarcoding of eDNA for tracking the floral and geographical origins of bee honey

Authentic honey products have a high commercial value and are often falsified via adulteration. Metabarcoding of environmental DNA (eDNA) from bacterial, floral, and entomological sources has recently been proposed as a useful tool for identifying and authenticating floral and geographical origins of bee honey. In this study, eDNA metabarcoding was applied to reveal the bacterial, plant, and honey bee DNA signatures of 48 commercial honey products from six different geographical origins. Bacterial DNA composition in commercial honey showed different relative abundance of Paenibacillus and Bacillus in geographically different samples, and high abundance of Methylobacterium in chestnut honey implying potential use of bacterial DNA composition for honey authentication. Using the chloroplast trnL (UAA) as a DNA marker, floral origins of commercial honey were investigated. Based on floral DNA signatures, 12 monofloral honey samples were identified among the 45 samples tested. Targeted amplicon sequencing of cytochrome oxidase I (COI) gene from entomological DNA identified three different Apis mellifera sequence variants, specific to geographic origin of honey, suggesting that COI can be implemented as a DNA marker to trace the origin of honey. Therefore, the current study demonstrated the potential of eDNA based metabarcoding as a robust tool for evaluating commercial bee honey by exploring their floral and geographical origins.

Leaf-buds of Pistacia atlantica: a novel source of bioactive molecules with high anti-inflammatory, antioxidant, anti-tyrosinase and antimicrobial properties

In this study, for the first time, the anti-inflammatory, antioxidant, anti-tyrosinase and antimicrobial property of P. atlantica Desf. subsp. atlantica leaf-bud extract have been investigated. The anti-inflammatory activity was determined in vivo by reducing carrageenan-induced hind paw edema in mice, while the antiradical function was evaluated using DPPH, total antioxidant capacity (TAC) and reduction power assays. The extract induced a significant reduction of the edema, from 1 to 6 h in a dose-dependent manner (150, 200 and 300 mg/kg). Histological observations of the inflamed tissues also confirmed this. An effective antioxidant activity of the plant samples was demonstrated, showing an EC50 = 0.183 ± 0.005 mg/mL for the DPPH test, a value of 28.776 ± 2.541 mg AAE/g for the TAC and an EC50 = 0.136 ± 0.003 mg/mL for reducing power. The leaf-bud extract also revealed a good antimicrobial activity against S. aureus and L. monocytogenes (mean diameter of inhibition zones of 13.2 and 17.0 mm, respectively), while a slight antifungal effect was observed. The plant preparation was then documented to inhibit tyrosinase activity, with an EC50 value of 0.098 ± 0.00 mg/mL in a dose-dependent manner. HPLC-DAD analysis revealed that dimethyl-allyl caffeic acid and rutin were the most abundant molecules. The current data documented that P. atlantica leaf-bud extract has strong biological properties and constitutes a potential source of pharmacological molecules.

Evaluation of the antioxidant potency of Greek honey from the Taygetos and Pindos mountains using a combination of cellular and molecular methods

Honey is a complex mixture, containing ~180 compounds, produced by the Apis melifera bees, with promising antimicrobial and antioxidant properties. Nevertheless, the mechanisms through which honey exerts its effects remain under investigation. Plant antioxidants are found in honey and other bee products exhibiting a high bioactivity and molecular diversity. The aim of the present study was to estimate the antioxidant capacity of honey collected from areas in Greece by small‑scale producers by i) using in vitro cell free assays; and ii) by investigating the effects of honey varieties on the redox status of a liver cancer cell line (HepG2) using non‑cytotoxic concentrations. The findings of the present study will allow for the identification of Greek honeys with promising antioxidant capacity. For this purpose, six types of honey with various floral origins were examined in cell‑free assays followed by cell‑based techniques using flow cytometric analysis and redox biomarker level determination in order to evaluate the potential alterations in the intracellular redox system. The results indicated various mechanisms of action that are dependent on the honey type, concentration dependency and high antioxidant capacity. The extended findings from the literature confirm the ability of raw honey to influence the redox status of HepG2 cells. Nevertheless additional investigations are required to elucidate their mechanisms of action in cell line models.

Physicochemical quality indicators of honey: An evaluation in a Ukrainian socioecological gradient

Physical and chemical quality indicators of 65 polyfloral honey samples from three administrative districts of Chernivtsi region in South Western Ukraine were studied. The chosen administrative districts were Putyla (representing the ‘Traditional villages’ stratum), Storozhynets (the ‘Intermediate’ stratum) and Khotyn (the ‘Intensive agriculture’ stratum), which reflect a steep gradient of social and ecological conditions such as land cover and land use, level of economic development, culture and demography. The quality of honey was determined in accordance with the requirements of the Ukrainian national standard and the EU Directive relating to honey (or Codex Alimentarius Honey Standard) by using the following indicators: reducing sugars and moisture content, diastase activity, free acidity, pH, electrical conductivity, hydroxymethylfurfural (HMF) and proline content. The profile of carbohydrates was analyzed, in particular glucose, fructose, sucrose, maltose, trehalose, melezitose, raffinose. The ratio of fructose to glucose (F/G) was determined. All tested samples complied with the international standards for the mass fraction of reducing sugars, diastase activity and hydroxymethylfurfural content. For physical and chemical parameters, the studied honey samples were of high quality. The content of the reducing sugars in the honey samples varied within the range of 66.0–97.6%. The fructose content ranged from 342 to 549 mg/g, and the glucose content variation ranged within 283–517 mg/g. The average fructose/glucose ratio was 1.2 for honey samples from the three studied districts. Besides fructose and glucose, some oligosaccharides, such as maltose, trehalose and melezitose, were found in the examined honey. Melezitose was detected in the honey samples from ‘Traditional village’ (21 samples) and ‘Intermediate’ (5 samples) districts. The total variability of HMF content in the studied 65 honey samples from apiaries in the three districts of Chernivtsi region ranged from 0.19 to 30.8 mg/kg. The minimum moisture content was found to be 16.2% (in the ‘Traditional village’ and ‘Intermediate’ strata), and 22.2% was the maximum (in the ‘Intermediate’ stratum). Our studies have shown that free acidity of the samples varied within the range 13.5 to 58.0 meq/kg. Proline content variability for the three studied geographical areas ranged from 82.3 to 1201.2 mg/kg. The studied samples of honey had a low pH level (~ 3.7), high content of proline (~ 513 mg/kg) and reducing sugars (~ 80%), which indicates its nutritional value and naturalness. Deviations from the honey standards in moisture content, acidity and electrical conductivity was revealed in 8% to 10% of all samples.

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.

Investigation of the Maturity Evaluation Indicator of Honey in Natural Ripening Process: The Case of Rape Honey

Honey maturity, a critical factor for quality evaluation, is difficult to detect in the current industry research. The objective of this study was to explore the changes in the composition and find potential maturity indicators of rape honey at different maturity stages through evaluating physicochemical parameters (moisture, sugars, pH, electrical conductivity, total protein, total phenols, total flavonoids, proline, and enzyme activity), the antioxidant capacity, and volatile components. The relevant results are as follows: 1. As the maturity increased, the moisture, sucrose, and maltose content of rape honey gradually decreased, while the glucose, fructose, and total protein content gradually increased. The activities of diastase, invertase, and β-glucosidase showed a significant increase with the elevation of ripening days, and the activity of glucose oxidase reached the highest before completely capping. 2. The antioxidant capacity of honey increased with the increase in honey maturity. There is a significant and strong correlation between the bioactive components of rape honey and antioxidant capacity (p < 0.01, |r| > 0.857). 3. Thirty-five volatile components have been identified. Nonanal, benzaldehyde monomer, and benzaldehyde dimer can be used as potential indicators for the identification of honey maturity stages. Principal component analysis (PCA) based on antioxidant parameters and volatile components can identify the maturity of honey.

Bioactive Molecules for Discriminating Robinia and Helianthus Honey: High-Performance Liquid Chromatography-Electron Spray Ionization-Mass Spectrometry Polyphenolic Profile and Physicochemical Determinations

Bioactive molecules from the class of polyphenols are secondary metabolites from plants. They are present in honey from nectar and pollen of flowers from where honeybees collect the “raw material” to produce honey. Robinia pseudoacacia and Helianthus annuus are important sources of nectar for production of two monofloral honeys with specific characteristics and important biological activity. A high-performance liquid chromatography–electro spray ionization–mass spectrometry (HPLC–ESI–MS) separation method was used to determine polyphenolic profile from the two types of Romanian unifloral honeys. Robinia and Helianthus honey showed a common flavonoid profile, where pinobanksin (1.61 and 1.94 mg/kg), pinocembrin (0.97 and 1.78 mg/kg) and chrysin (0.96 and 1.08 mg/kg) were identified in both honey types; a characteristic flavonoid profile in which acacetin (1.20 mg/kg), specific only for Robinia honey, was shown; and quercetin (1.85 mg/kg), luteolin (21.03 mg/kg), kaempferol (0.96 mg/kg) and galangin (1.89 mg/kg), specific for Helianthus honey, were shown. In addition, different phenolic acids were found in Robinia and Helianthus honey, while abscisic acid was found only in Robinia honey. Abscisic acid was correlated with geographical location; the samples collected from the south part of Romania had higher amounts, due to climatic conditions. Acacetin was proposed as a biochemical marker for Romanian Robinia honey and quercetin for Helianthus honey.

Investigating the Drought and Salinity Effect on the Redox Components of Sulla Coronaria (L.) Medik

For the Mediterranean region, climate models predict an acceleration of desertification processes, thus threatening agriculture. The present work aimed to investigate the effect of drought and salinity on Sulla coronaria (L.) Medik., a Mediterranean forage legume, for understanding plant defence systems activated by these stressors. In detail, we focused our attention on the variations on the plant redox status. Plants were subjected to suboptimal watering and irrigation with sodium chloride (NaCl) solutions. The same salt treatment was applied for in vitro tests on seedlings. Water content did not change after treatments. Salt negatively influenced seed germination and seedling development, but it did not affect photosynthesis parameters, contrary to what was observed in adult plants. Proline concentration increased in all samples, while abscisic acid level increased exclusively in seedlings. NaCl caused accumulation of superoxide anion in plants and seedlings and hydrogen peroxide only in seedlings; nevertheless, lipid peroxidation was not detected. Total phenolics, glutathione, expression level, and activity of antioxidant enzymes were assayed, revealing a complex antiradical molecular response, depending on the type of stress and development stage. Our results confirm Sulla as a drought- and salt-tolerant species and highlight its ability to counteract oxidative stress. This evidence suggests a key role for the redox components, as signal transduction messengers, in Sulla acclimation to desertification. Finally, plants and seedlings showed different acclimation capacity to salinity, revealing a greater genomic plasticity for seedlings.

Bioactive compounds in Apis mellifera monofloral honeys

Honey is a natural product with a sweet flavor. Honey is made by the honeybee (Apis mellifera L.) from the nectar of flowers or other plant secretions that are collected near the hive. These products are mixed with bee saliva and stored. Several studies have demonstrated that honey exhibits antioxidant, antimicrobial, nematicidal, antifungal, anticancer, and anti-inflammatory activities. These properties are influenced by the plants from which the secretions are harvested, from the naturally occurring compounds present in the nectar. Studies of the properties and applications of honey have distinguished honey from other natural products due to the presence of certain compounds and due its bioactive properties. The focus of this review is to discuss the identified and isolated compounds from monofloral honey produced by A. mellifera, with specific emphasis on antioxidant and antimicrobial properties of honey and its therapeutic health benefits.

Antibacterial potential of Swiss honeys and characterisation of their bee-derived bioactive compounds

BACKGROUND

Antibacterial activity of honey is not only crucial characteristic in selection of honey for medical usage but also an important honey quality marker. The aim of the study was to characterise the antibacterial potential of 29 honey samples representing the main types of multi-floral blossom and honeydew honeys produced in Switzerland. Antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa was expressed as a minimum inhibitory and bactericidal concentrations (MIC and MBC). Furthermore, the content of bee-derived glucose oxidase (GOX) and its enzymatic product, H₂ O₂ , were also evaluated.

RESULTS

All honey samples successfully met basic defined criteria (moisture and hydroxymethylfurfural (HMF)) tested in this study. Honeydew honeys were the most effective honey samples and generated the highest levels of H₂ O₂ . A strong significant correlation was found between the overall antibacterial activity and the level of H₂ O₂ among all honey samples. Interestingly, the content of GOX in honey samples did not correlate with their antibacterial activity as well as H₂ O₂ production capacity. A weak antibacterial activity was determined in five floral honeys, most likely due to increased enzymatic activity of pollen-derived catalase.

CONCLUSION

This study showed that antibacterial effect of Swiss honey samples is associated mainly with H₂ O₂ . © 2019 Society of Chemical Industry.

NMR carbohydrate profile in tracing acacia honey authenticity

The sugar profile in honey can be used as a fingerprint to confirm the authenticity or reveal the adulteration of the product by sweetener addition. In this work, we have accurately determined the profile of 20 minor saccharides in a set of 46 European acacia honeys using a recently proposed NMR approach based on the CSSF-TOCSY experiment. Comparison of this reference profile with the sugar composition of several Chinese honey samples of the same declared botanical origin has revealed important differences. A detailed analysis of the saccharide profile of these Chinese honeys suggests product adulteration by overfeeding bee colonies with industrial sugars syrups during the main nectar flow period.

Induction of Antioxidant Metabolites in Moringa oleifera Callus by Abiotic Stresses

Moringa oleifeira has recently been subjected to numerous scientific studies pursuing its biological properties. However, biotechnological approaches promoting the synthesis of pharmacological compounds in this species are still scarce, despite the fact that moringa metabolites have shown significant nutraceutical effects. For this reason, in vitro cultures of moringa callus, obtained from leaf explantation, were subjected to various abiotic stresses such as temperature, salicylic acid, and NaCl, to identify the best growth conditions for the production of high levels of antioxidant molecules. Temperature stresses (exposure to 4 and 45 °C) led to no significant variation in moringa callus, in terms of antiradical metabolites, whereas salicylic acid (200 μM) and NaCl (50-100 μM) affected an increase of total phenolic compounds, after 15 and 30 days of treatment. Overall, the treatment with 100 μM NaCl for 30 days showed the highest free radical scavenging activity, comparable to that measured in moringa leaf. In addition, high doses of NaCl (200 μM) inhibited callus growth and reduced the amount and bioactivity of the secondary metabolites of callus. This study provides useful information to standardize growth conditions for the production of secondary metabolites in moringa in vitro cultures, a biotechnological system that could be employed for a rapid, controlled, and guaranteed production of antioxidant molecules for pharmaceutical purposes.

Antibacterial Activity of Different Blossom Honeys: New Findings

Antibacterial activity is the most investigated biological property of honey. The goal of this study was to evaluate the antibacterial activity of 57 Slovak blossom honeys against Staphylococcus aureus and Pseudomonas aeruginosa and investigate the role of several bioactive substances in antibacterial action of honeys. Inhibitory and bactericidal activities of honeys were studied to determine the minimum inhibitory and bactericidal concentrations. The contents of glucose oxidase (GOX) enzyme, hydrogen peroxide (H2O2), and total polyphenols (TP) were determined in honeys. We found that honey samples showed different antibacterial efficacy against the tested bacteria as follows: wildflower honeys > acacia honeys > rapeseed honeys. Overall antibacterial activity of the honeys was statistically-significantly correlated with the contents of H2O2 and TP in honeys. A strong correlation was found between the H2O2 and TP content. On the other hand, no correlation was found between the content of GOX and level of H2O2. Antibacterial activity of 12 selected honeys was markedly reduced by treatment with catalase, but it remained relatively stable after inactivation of GOX with proteinase-K digestion. Obtained results suggest that the antibacterial activity of blossom honeys is mainly mediated by H2O2 levels present in honeys which are affected mainly by polyphenolic substances and not directly by GOX content.

Ascophyllan Induces Activation of Natural Killer Cells in Mice In Vivo and In Vitro

Natural marine polysaccharides have demonstrated immune stimulatory effects in both mice and humans. Our previous study compared the ability of ascophyllan and fucoidan to activate human and mouse dendritic cells (DCs). In this study, we further examined the effect of ascophyllan on the activation of mouse natural killer (NK) cells in vivo and in vitro and compared it to that of fucoidan, a well-studied natural marine polysaccharide. Specifically, administration of ascophyllan to C57BL/6 mice increased the number of NK cells in the spleen when compared to the number in PBS-treated mice. Moreover, the number of IFN-γ-producing NK cells and expression of CD69 were markedly upregulated by ascophyllan treatment. Ascophyllan treatment also induced IFN-γ production and CD69 upregulation in isolated NK cells, but did not promote cell proliferation. Finally, ascophyllan treatment increased the cytotoxicity of NK cells against Yac-1 cells. The effects of ascophyllan on NK cell activation were considerably stronger than those of fucoidan. These data demonstrated that ascophyllan promotes NK cell activation both in mice and in vitro, and its stimulatory effect on NK cells is stronger than that of fucoidan.