Nano-liquid chromatography in nutraceutical analysis: Determination of polyphenols in bee pollen

Diversity of plant pollen sources, microbial communities, and phenolic compounds present in bee pollen and bee bread

The pollination of several crops, as well as wild plants, depends on honeybees. To get the nutrients required for growth and survival, honeybee colonies are dependent on pollen supply. Bee pollen (BP) is partially packed in honeycomb cells and processed into beebread (BB) by microbial metabolism. The composition of pollen is highly variable and is mainly dependent on ecological habitat, geographical origin, honey plants, climatic conditions, and seasonal variations. Although there are important differences between the BP and the BB, little comparative chemical and microbiological data on this topic exists in the literature, particularly for samples with the same origin. In this study, BP and BB pollen samples were collected from two apiaries located in the Campania and Molise regions of Southern Italy. Phenolic profiles were detected via HPLC, while antioxidant activity was determined by ABTS·+ and DPPH· assay. The next-generation sequencing (NGS) based on RNA analysis of 16S (rRNA) and internal transcribed spacer (ITS2) regions were used to investigate the microbial community (bacteria and fungi) and botanical origin of the BP and BB. Chemical analysis showed a higher content of flavonols in BP (rutin, myricetin, quercetin, and kaempferol), while in BB there was a higher content of phenolic acids. The NGS analysis revealed that the microbial communities and pollen sources are dependent on the geographical location of apiaries. In addition, diversity was highlighted between the microbial communities present in the BP and BB samples collected from each apiary.

Advances in Chromatographic Analysis of Phenolic Phytochemicals in Foods: Bridging Gaps and Exploring New Horizons

Chromatographic analysis of phenolic phytochemicals in foods has significantly advanced over the past decade (2014-2024), meeting increasing demands for precision and efficiency. This review covers both conventional and advanced chromatographic techniques used for detecting phenolic phytochemicals in foods. Conventional methods like High-Performance Liquid Chromatography, Ultra High-Performance Liquid Chromatography, Thin-Layer Chromatography, and Gas Chromatography are discussed, along with their benefits and limitations. Advanced techniques, including Hydrophilic Interaction Liquid Chromatography, Nano-LC, Multidimensional Liquid Chromatography, and Capillary Electrophoresis, are highlighted for their innovations and improved capabilities. The review addresses challenges in current chromatographic methods, emphasizing the need for standardized and validated procedures according to the Food and Drug Administration, European Cooperation for Accreditation of Laboratories, and The International Organization for Standardization guidelines to ensure reliable and reproducible results. It also considers novel strategies for reducing the environmental impact of chromatographic methods, advocating for sustainable practices in analytical chemistry.

Bee Pollen and Bread as a Super-Food: A Comparative Review of Their Metabolome Composition and Quality Assessment in the Context of Best Recovery Conditions

Recently, functional foods have been a subject of great interest in dietetics owing not only to their nutritional value but rather their myriad of health benefits. Moreover, an increase in consumers' demands for such valuable foods warrants the development in not only production but rather tools of quality and nutrient assessment. Bee products, viz., pollen (BP) and bread, are normally harvested from the flowering plants with the aid of bees. BP is further subjected to a fermentation process in bee hives to produce the more valuable and bioavailable BB. Owing to their nutritional and medicinal properties, bee products are considered as an important food supplements rich in macro-, micro-, and phytonutrients. Bee products are rich in carbohydrates, amino acids, vitamins, fatty acids, and minerals in addition to a myriad of phytonutrients such as phenolic compounds, anthocyanins, volatiles, and carotenoids. Moreover, unsaturated fatty acids (USFAs) of improved lipid profile such as linoleic, linolenic, and oleic were identified in BP and BB. This work aims to present a holistic overview of BP and BB in the context of their composition and analysis, and to highlight optimized extraction techniques to maximize their value and future applications in nutraceuticals.

Bee Products: An Emblematic Example of Underutilized Sources of Bioactive Compounds

Beside honey, honeybees (Apis mellifera L.) are able to produce many byproducts, including bee pollen, propolis, bee bread, royal jelly, and beeswax. Even if the medicinal properties of these byproducts have been recognized for thousands of years by the ancient civilizations, in the modern era, they have a limited use, essentially as nutritional supplements or health products. However, these natural products are excellent sources of bioactive compounds, macro- and micronutrients, that, in a synergistic way, confer multiple biological activities to these byproducts, such as, for example, antimicrobial, antioxidant, and anti-inflammatory properties. This work aims to update the chemical and phytochemical composition of bee pollen, propolis, bee bread, royal jelly, and beeswax and to summarize the main effects exerted by these byproducts on human health, from the anticancer and immune-modulatory activities to the antidiabetic, hypolipidemic, hypotensive, and anti-allergic properties.

Advancements in the preparation and application of monolithic silica columns for efficient separation in liquid chromatography

Fast and efficient separation remains a big challenge in high performance liquid chromatography (HPLC). The need for higher efficiency and resolution in separation is constantly in demand. To achieve that, columns developed are rapidly moving towards having smaller particle sizes and internal diameters (i.d.). However, these parameters will lead to high back-pressure in the system and will burden the pumps of the HPLC instrument. To address this limitation, monolithic columns, especially silica-based monolithic columns have been introduced. These columns are being widely investigated for fast and efficient separation of a wide range of molecules. The present article describes the current methods developed to enhance the column efficiency of particle packed columns and how silica monolithic columns can act as an alternative in overcoming the low permeability of particle packed columns. The fundamental processes behind the fabrication of the monolith including the starting materials and the silica sol-gel process will be discussed. Different monolith derivatization and end-capping processes will be further elaborated and followed by highlights of the performance such monolithic columns in key applications in different fields with various types of matrices.

Chemical constituents and phytochemical properties of floral maize pollen

Currently, bee-gathered pollen (bee pollen) is commonly used worldwide as a dietary supplement and is recognized for its curative properties. Floral pollen is also important but is less recognized due to a lack of investigation. This study aims to determine the morphological characteristics and nutritional and phytochemical properties of floral maize pollen. Fresh pollen grains harvested from a farm of maize plants are yellow in colour and spheroid in shape. They change to amber and indented prismatic solid shapes when dehydrated. The main composition of floral maize pollen is carbohydrates (44.30±3.73%), followed by moisture (23.38±5.73%), crude proteins (17.16±3.13%), crude fibres (9.56±0.92%), and ash (4.98±0.11%), while the lowest content is observed for crude fats (0.62±0.06%). The predominant mineral is potassium (768.50±11.40 mg 100 g-1), followed by sodium (695.10±9.70 mg 100 g-1), calcium (147.20±12.60 mg 100 g-1), and magnesium (97.30±2.9 mg 100 g-1). The microelements (with average values) consist of iron (49.50±3.30 mg 100 g-1) and zinc (30.00±3.70 mg 100 g-1). Excellent phytochemical properties add value to floral maize pollen. Maize pollen contains a high total phenolic content (TPC) and total flavonoid content (TFC) of 783.02 mg GAE 100 g-1 and 1706.83 mg QE 100 g-1, respectively, and possesses strong antioxidant activity of 10.54 mg mL-1. Maize floral pollen and derived products can serve as future food resources for human consumption and as a source of functional and bioactive compounds in nutraceutical and pharmaceutical industries.

Increase in longevity and amelioration of pesticide toxicity by natural levels of dietary phytochemicals in the honey bee, Apis mellifera

For the past decade, migratory beekeepers who provide honey bees for pollination services have experienced substantial colony losses on a recurring basis that have been attributed in part to exposure to insecticides, fungicides, or their combinations applied to crops. The phytochemicals p-coumaric acid and quercetin, which occur naturally in a wide variety of bee foods, including beebread and many types of honey, can enhance adult bee longevity and reduce the toxicity of certain pesticides. How variation in concentrations of natural dietary constituents affects interactions with xenobiotics, including synthetic pesticides, encountered in agroecosystems remains an open question. We tested the effects of these two phytochemicals at a range of natural concentrations on impacts of consuming propiconazole and chlorantraniliprole, a triazole fungicide and an insecticide frequently applied as a tank mix to almond trees during bloom in California's Central Valley. Propiconazole, even at low field concentrations, significantly reduced survival and longevity when consumed by adult bees in a sugar-based diet. The effects of propiconazole in combination with chlorantraniliprole enhanced mortality risk. The detrimental effects of the two pesticides were for the most part reduced when either or both of the phytochemicals were present in the diet. These findings suggest that honey bees may depend on non-nutritive but physiologically active phytochemical components of their natural foods for ameliorating xenobiotic stress, although only over a certain range of concentrations; particularly at the high end of the natural range, certain combinations can incur additive toxicity. Thus, efforts to develop nectar or pollen substitutes with phytochemicals to boost insecticide tolerance or immunity or to evaluate toxicity of pesticides to pollinators should take concentration-dependent effects of phytochemicals into consideration.

Drying Techniques and Storage: Do They Affect the Nutritional Value of Bee-Collected Pollen?

In this study, the effect of different drying processes (freeze-drying (FD), microwave-assisted drying (MWD) and classic hot air drying (HAD)) on the polyphenols, flavonoids, and amino acids content was investigated on bee-collected chestnut, willow and ivy pollen for human consumption. Furthermore, the pollen chemical properties were monitored after three and six months of storage, and then analyzed using a multivariate approach. Chestnut pollen was the richest source of polyphenols, flavonoids, and rutin, while ivy pollen contained the highest amount of total and free amino acids, and total and free proline. Drying and storage affected pollen chemical composition with species-dependent effects. MWD allowed the best retention of flavonoids in chestnut pollen for up to six months of storage. All drying techniques led to a depletion of flavonoids in willow pollen; however, MWD ensured the highest flavonoids content after six months. FD and MWD did not lead to flavonoids depletion in ivy pollen during storage. Additionally, storage did not affect the rutin content, which was highest in FD willow samples after six months. Notably, both FD and MWD techniques are efficient in preserving amino acids-related quality of bee pollen up to six months of storage.

Characterization of phenolic compounds and antioxidative potential of pot-pollen produced by stingless bees (Tetragonula biroi Friese) from the Philippines

Eight pot-pollen samples produced by Philippine stingless bees (Tetragonula biroi Friese) were analyzed for the antioxidant composition and capacity. The methanolic extracts showed values of 7.95-24.75 mg GAE/g, 16.13-35.04 mg QE/g, and 0.19-0.74 mg CGE/g for total phenolics, flavonoids, and anthocyanins, respectively. All pot-pollens contained substantial amounts of rutin (0.471-1.547 mg/g), quercetin glucoside (1.427-3.390 mg/g), other flavonol glycosides, and hydroxycinnamic acids. Additionally, pollen samples contained 24-methylenecholesterol and Δ5-avenasterol as dominant phytosterols. Antioxidant activities based on ferric ion reducing antioxidant power (FRAP), DPPH^• , and ABTS^•+ scavenging activities, and lipid peroxidation (LPO) inhibition showed a high correlation with phenolic and flavonoid contents, except for LPO inhibition. Results suggested that there might be synergistic effects among antioxidants. Summing up, this study revealed that T. biroi Friese pot-pollen can be used as a food supplement with high nutraceutical potential. PRACTICAL APPLICATIONS: The recognition of Tetragonula biroi Friese pot-pollen as a nutraceutical product is strongly limited because its bioactive properties are not well-studied compared to other bee pollens. The results showed a rich occurrence of compounds with antioxidative effects like flavonoids and sterols. Antioxidant activities except lipid peroxidation inhibition revealed a high correlation with analyzed ingredients and shown interactions indicated that there might be synergistic effects among antioxidants.

Bee Pollen Extracts Modulate Serum Metabolism in Lipopolysaccharide-Induced Acute Lung Injury Mice with Anti-Inflammatory Effects

Bee pollen (BP) collected from different floras possesses various potential bioactivities, but the mechanism-related research on anti-inflammatory effects is limited. Here, three types of BP originating from Camellia sinensis L. (BP-Cs), Nelumbo nucifera Gaertn. (BP-Nn), and Brassica campestris L. (BP-Bc) were assessed using molecular and metabolomics methods to determine their anti-inflammatory effects. The differences in polyphenolic abundance of three types of BP extracts were determined by HPLC-DAD/Q-TOF-MS. In vitro anti-inflammatory effects of three BP extracts were evaluated in a lipopolysaccharide (LPS)-induced RAW 264.7 cells model. BP-Cs extract with the most abundant polyphenols was found to be the most effective in reducing inflammation by downregulating inflammatory-related genes expression and blocking the activation of MAPK and NF-κB signaling pathways. Polyphenol-rich BP-Cs was further evaluated for their in vivo anti-inflammatory effect in a LPS-induced acute lung injury mouse model. An UPLC-Q-TOF/MS-based metabolomics approach was applied to analyze metabolite changes in mouse serum. Weshowed that the pretreated BP-Cs extract alleviated inflammation and regulated glycerophospholipid metabolism significantly. Our findings provide a foundation for developing and justifying BP as a potential anti-inflammatory ingredient in functional foods or nutraceutical formulations.

A review of nanoscale LC-ESI for metabolomics and its potential to enhance the metabolome coverage

Liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS) platforms are widely used to perform high throughput untargeted profiling of biological samples for metabolomics-based approaches. However, these LC-ESI platforms usually favour the detection of metabolites present at relatively high concentrations because of analytical limitations such as ion suppression, thus reducing overall sensitivity. To counter this issue of sensitivity, the latest in terms of analytical platforms can be adopted to enable a greater portion of the metabolome to be analysed in a single analytical run. Here, nanoflow liquid chromatography-nanoelectrospray ionisation (nLC-nESI), which has previously been utilised successfully in proteomics, is explored for use in metabolomic and exposomic research. As a discovery based field, the markedly increased sensitivity of these nLC-nESI platforms offer the potential to uncover the roles played by low abundant signalling metabolites (e.g. steroids, eicosanoids) in health and disease studies, and would also enable an improvement in the detection of xenobiotics present at trace levels in biological matrices to better characterise the chemical exposome. This review aims to give an insight into the advantages associated with nLC-nESI for metabolomics-based approaches. Initially we detail the source of improved sensitivity prior to reviewing the available approaches to achieving nanoflow rates and nanospray ionisation for metabolomics. The robustness of nLC-nESI platforms was then assessed using the literature available from a metabolomic viewpoint. We also discuss the challenging point of sample preparation which needs to be addressed to fully enjoy the benefits of these nLC-nESI platforms. Finally, we assess metabolomic analysis utilising nano scale platforms and look ahead to the future of metabolomics using these new highly sensitive platforms.

An overview to nano-scale analytical techniques: Nano-liquid chromatography and capillary electrochromatography

Nano-liquid chromatography (nano-LC) and CEC are microfluidic techniques mainly used for analytical purposes. They have been applied to the separation and analysis of a large number of compounds, e.g., peptides, proteins, drugs, enantiomers, antibiotics, pesticides, nutraceutical, etc. Analytes separation is carried out into capillaries containing selected stationary phase. The mobile phase is moved either by a pump (nano-LC) or by an EOF, respectively. The two tools can offer some advantages over conventional techniques, e.g., high selectivity, separation efficiency, resolution, short analysis time and consumption of low volumes of mobile phase. Flow rates in the range 50-800 nL/min are usually applied. The low flow rate reduces the chromatographic dilution increasing the mass sensitivity. Special attention must be paid in avoiding peak dispersion selecting the appropriate detector, injector and tube connection. Finally due to the low flow rate these microfluidic techniques can be easily coupled with mass spectrometry.

Antioxidant and Anti-tyrosinase Activities of Phenolic Extracts from Rape Bee Pollen and Inhibitory Melanogenesis by cAMP/MITF/TYR Pathway in B16 Mouse Melanoma Cells

Rape bee pollen possesses many nutritional and therapeutic properties because of its abundant nutrimental and bioactive components. In this study, free (FPE) and bound (BPE) phenolic extracts of rape bee pollen were obtained, phenolic and flavonoid contents were determined, and composition of phenolic acids was analyzed. In vitro antioxidant and anti-tyrosinase (TYR) activities of FPE and BPE were compared, and inhibitory melanogenesis of FPE was further evaluated. Results showed FPE and BPE contain total phenolic contents of 11.76 and 0.81 mg gallic acid equivalents/g dry weight (DW) and total flavonoid contents of 19.24 and 3.65 mg rutin equivalents/g DW, respectively. Phenolic profiling showed FPE and BPE fractions contained 12 and 9 phenolic acids, respectively. FPE contained the highest rutin content of 774.87 μg/g. FPE and BPE showed the high antioxidant properties in vitro and high inhibitory activities for mushroom TYR. Higher activities of FPE than those of BPE can be attributed to difference in their phenolic compositions. Inhibitory melanogenesis activities of FPE against B16 were further evaluated. Results showed suppressed intracellular TYR activity, reduced melanin content, and promoted glutathione synthesis (p < 0.05) in FPE-treated cells. FPE reduced mRNA expression of TYR, TYR-related protein (TRP)-1 and TRP-2, and significantly suppressed cyclic adenosine monophosphate (cAMP) levels through down-regulation of melanocortin 1 receptor gene expression (p < 0.05). FPE reduced mRNA expression of microphthalmia-associated transcription factor (MITF), significantly inhibiting intracellular melanin synthesis (p < 0.05). Hence, FPE regulates melanogenesis of B16 cells involved in cAMP/MITF/TYR pathway. These results revealed that FPE can be used as pharmaceutical agents and cosmetics to protect cells from abnormal melanogenesis.