Search Results (80)

Onion (Allium cepa L.) peels represent a major agro-industrial by-product and are a rich source of polyphenols, with recognized antioxidant properties. This study compared the polyphenolic profile of two onion cultivars peels: red “Rossa di Tropea” and yellow “Recas”. Their digestive stability, intestinal bioavailability, and antioxidant activity were evaluated. Hydroalcoholic extracts were characterized by HPLC-DAD, subjected to a static gastrointestinal digestion model, and assessed for transport across differentiated Caco-2 monolayers. Antioxidant properties were determined using DPPH, FRAP, Cellular Antioxidant Activity (CAA), and intracellular glutathione (GSH) assays. Red peels contained a higher total polyphenol content (28.44 mg/g DW) than yellow peels (15.61 mg/g DW), including anthocyanins uniquely present in the red cultivar. Digestive stability varied markedly between cultivars, with yellow peels showing greater intestinal recovery (72.7%) than red peels (49.1%). Glycosylated flavonols were more stable and exhibited moderate intestinal transport (Papp = 1.1–9.9 × 10⁻⁶ cm·s⁻¹), whereas quercetin aglycone showed low permeability. Red peel extracts demonstrated stronger chemical antioxidant activity, while yellow peels were more effective in cell-based assays, displaying higher CAA values and inducing a pronounced increase in intracellular GSH. Overall, onion peel extracts exhibit promising antioxidant and biological properties. However, their limited bioavailability highlights the need for formulation strategies to enhance gastrointestinal stability and intestinal uptake, supporting their potential use as sustainable functional ingredients. Full article

This study provides the first comprehensive chemical and biological profiling of Citrus lumia Risso & Poit. var. ‘Pyriformis’, a rare Mediterranean Citrus variety with unexplored nutraceutical potential. The fresh juice (CLPJ) showed a distinctive phytochemical composition, with 38.8 ± 0.99 mg gallic acid equivalents/100 mL of total phenols and 25.96 ± 2.37 mg rutin equivalents/100 mL of flavonoids. High-performance liquid chromatography coupled with diode-array detection (HPLC-DAD) quantification revealed high levels of organic acids, including ascorbic acid (0.34 g/L) and citric acid (34.6 g/L). Liquid chromatography coupled with diode-array detection and electrospray ionization tandem mass spectrometry (LC-DAD-ESI-MS/MS) enabled the annotation of 28 polyphenolic constituents, featuring glycosylated flavanones and several uncommon flavonols and acylglycosidic derivatives whose structural patterns are typical of primitive Citrus lineages and largely absent in commercial cultivars. Functionally, CLPJ exhibited multi-target antioxidant and anti-inflammatory activities and promoted epithelial repair in Caco-2 cells without cytotoxic effects. Overall, the juice displays a distinctive chemotaxonomic fingerprint and promising multifunctional properties, supporting its potential as a functional food ingredient and contributing to the valorization of minor Mediterranean Citrus biodiversity. Full article

Motivated by the plant’s ethnopharmacological importance and the health conditions of the Sahrawi people, who have been living as refugees for over 50 years, this study comprehensively assessed the nutritional profile, secondary metabolite composition, in vitro bioaccessibility, and toxicological safety of Atriplex halimus L. leaves. The proximate analysis demonstrated richness in dietary fiber (44.41 ± 0.11 g/100 g) and essential macro/microelements, notably iron (142.0 ± 2.41 mg/100 g). The lipid profile features essential polyunsaturated fatty acids, specifically linoleic and α-linolenic acid, accounting for 40.6 ± 7.0% of total fatty acids. The UPLC-HR--MS characterization of two extracts tentatively identified 13 specialized metabolites, including uncommon flavonoids such as highly glycosylated forms of isorhamnetin and syringetin. Caffeic acid 3-sulfate and caffeic acid 4-sulfate were identified by NMR. Although in vitro antioxidant activity (DPPH/FRAP tests) was minimal, the traditional decoction showed high total polyphenol bioaccessibility (71.52 ± 0.46%) during simulated gastrointestinal digestion following the harmonized static protocol. The Ames test (using Salmonella typhimurium TA98 and TA1535) confirmed toxicological safety, as neither extract induced mutagenic or genotoxic effects. In conclusion, the robust nutritional composition, in vitro proven safety, and high polyphenol bioaccessibility suggest A. halimus leaves as a promising, nutrient-rich functional ingredient. Full article

Background and Objectives: Anthocyanin-rich barley varieties have recently gained attention due to their high (poly)phenolic content and potential health benefits, yet human data on their bioavailability remain scarce. This study aimed to characterize the absorption, metabolism, and excretion of (poly)phenolic compounds from a novel hull-less purple whole-grain barley (WGB) genotype. Methods: Eleven healthy volunteers consumed 140 g of purple WGB biscuits, and plasma and urine samples were collected over 6 h and 48 h, respectively. Results: UPLC-MS/MS analysis revealed a broad range of metabolites, with 11 (poly)phenolic compounds identified in plasma and 80 in urine. The biscuits were particularly rich in flavones (217 mg/140 g, mainly chrysoeriol derivatives), followed by hydroxycinnamic acids (~54 mg, mainly 4′-hydroxy-3′-methoxycinnamic acid), anthocyanins (44.8 mg), and flavan-3-ols (16.8 mg). In plasma, glycosylated anthocyanins and flavone conjugates (e.g., peonidin-3-O-glucuronide, chrysoeriol-O-glucuronide) were detectable within 1–2 h, consistent with early absorption. In contrast, microbial-derived catabolites—including valerolactones, phenylacetic and benzoic acids—were mainly excreted in urine between 8 and 24 h, reaching concentrations above 1000 nM. Conclusions: These findings provide novel insights into the bioavailability and metabolic fate of barley (poly)phenols, supporting their potential contribution to host and gut health. As a proof-of-concept study, it complements the limited data available from pigmented cereals and underscores the need for validation in larger cohorts. Full article

Abeliophyllum distichum is rich in polyphenols and flavonoids with various bioactivities; however, studies on enzymatic modifications to enhance its functional properties remain limited. This study investigated the effect of Viscozyme^® L treatment on the secondary metabolite profile of A. distichum leaves. Phytochemical profiling using liquid chromatography–electrospray ionization tandem mass spectrometry revealed a decrease in the total number of detectable compounds, from 26 in the untreated extract to 16 in the enzyme-treated extract. Following Viscozyme^® L treatment, a notable shift in metabolite composition was observed, with significant enrichment of flavonoid glycosides, pyranone derivatives, and amino acid-related metabolites. Quantitative high-performance liquid chromatography analysis showed significant reductions in glycosylated compounds such as rutin (1), acteoside (2), and isoacteoside (3), while the aglycone quercetin (4) content increased more than four-fold compared to the control. These results indicate that Viscozyme^® L facilitates the deglycosylation of flavonoid glycosides into their aglycone forms. This enzymatic transformation suggests a potential strategy to enhance the bioavailability and functional value of A. distichum leaf extracts for nutraceutical and pharmaceutical applications. Full article

Natural polyphenols, especially the ones in their glycosylated form like hesperidin, rutin, and anthocyanins, are the most abundant phenolic compounds in citric fruits, apples, and red fruits, respectively. They stand out for their high nutraceutical potential, with various reported properties, like antioxidant, anti-inflammatory, anticarcinogenic, and cardioprotective. Nevertheless, these compounds have low bioavailability and are rapidly excreted and released by the organism. Therefore, the main goal of this work was to obtain polyphenols with increased bioactivity by functionalizing biocompounds in fruit juices, namely, orange, apple, and red fruits. This modification was achieved via hesperidinase, an enzyme that catalyzes the hydrolysis of several natural bioactive compounds. Hesperidinase was produced with Penicillium sp. The activity and stability of the produced enzyme, in its free and immobilized form, using the sol–gel method, were assessed, as well as the bioactivity of the bioprocessed juices. Moreover, after immobilizing hesperidinase in sol–gel lens-shaped particles, the activity and operational stability of the bioencapsulates were evaluated by measuring the residual activity over several runs. Using the specific substrate p-NPG, β-D-glucosidase retained 31% of its activity in the second run, 22.6% in the third, and 35% in the fourth. For α-L-rhamnosidase, using the substrate p-NPR, residual activity was 31.1% in both the fourth and fifth runs. In fruit juices, the bioencapsulates exhibited residual activities around 100% in the second run, approximately 81% in the third, and around 90% in the fourth. The antioxidant and anti-inflammatory activities of the bioprocessed juices were evaluated, and an increase in the anti-inflammatory activity was observed when compared with the non-processed juices. Full article

Polyphenolics in plants exist in free, soluble-bound, and insoluble-bound structural forms. The concentration of these structural forms depends on the plant’s developmental stage, tissue type, soil water availability, and food preparation methods. In this study, for the first time, the effects of growth temperature (RT—room temperature—23 °C day/18 °C night, HT—high temperature—38 °C day/33 °C night, LT—low temperature—12 °C day/7 °C night) on variations of polyphenolic structural forms—free, soluble-bound (esterified and glycosylated), and insoluble-bound—in broccoli (Brassica oleracea L. convar. botrytis (L.) Alef. var. cymosa Duch.) microgreens were investigated. Using spectrophotometric, RP-HPLC, and statistical analyses, it was found that the highest amount of total phenolics (TP) in broccoli microgreens was present in the esterified form, regardless of the temperature at which they were grown (63.21 ± 3.49 mg GAE/g dw in RT, 65.55 ± 8.33 mg GAE/g dw in HT, 77.44 ± 7.82 mg GAE/g dw in LT). LT significantly increased the amount of free (from 13.30 ± 2.22 mg GAE/g dw in RT to 18.33 ± 3.85 mg GAE/g dw) and esterified soluble TP (from 63.21 ± 3.49 mg GAE/g dw in RT to 77.44 ± 7.82 mg GAE/g dw), while HT significantly increased the amount of TP glycosylated forms (from 14.85 ± 1.45 mg GAE/g dw in RT to 17.84 ± 1.20 mg GAE/g dw). LT also enhanced free and esterified forms of total flavonoids, tannins, hydroxycinnamic acids, and flavonols. HT, on the other hand, increased glycosylated forms of TP, flavonoids, tannins, hydroxycinnamic acids, flavonols, and phenolic acids, and decreased insoluble-bound tannins. According to the ABTS method, HT induced antioxidant potential of free and glycosylated forms, while LT increased antioxidant capacity of free forms only. According to the FRAP method, LT increased antioxidant potential of free and esterified polyphenolic forms. Also, based on ABTS and FRAP assays, esterified polyphenolics showed significantly higher antioxidant capacity than any other form. Principal component analysis showed that structural form had a greater impact than temperature. Hierarchical clustering showed that RT-, HT- and LT-broccoli microgreens were most similar in their glycosylated polyphenolics, but differed the most in esterified forms, which were also the most distinct overall. In conclusion, HT and LT induced specific shifts in the structural forms of broccoli polyphenolics and their antioxidant capacity. Based on the results, we recommend applying LT to increase the amount of free and esterified polyphenolics in broccoli microgreens, while HT may be used to enhance glycosylated forms. Full article

Geoffroea decorticans (Gill. ex Hook. & Arn) Burk. is a native tree of the dry areas of Northwestern and Central Argentina. Its seeds are considered waste material. The flour of seeds was analyzed as a source of nutritional and bioactive compounds. It has a low carbohydrate content, containing about 9% protein and between 10 and 14% fat. Approximately 82–84% of the fatty acids were unsaturated (oleic and linoleic acids). A high polyphenol and dietary fiber content was detected. Flavonoids and condensed tannins were the dominant phenolics. Polyphenol-enriched extracts were obtained from seed flour. The HPLC–ESI-MS/MS analysis of these concentrated extracts allowed for the identification of six compounds including C-glycosyl flavones (vitexin and isovitexin), type A procyanidins (dimer and trimer), and epicatequin gallate. Polyphenolic extracts showed antioxidant capacity and were able to inhibit enzymes (α-glucosidase and α-amylase) related to carbohydrate metabolism and (lipoxygenase) pro-inflammatory enzymes and were not toxic. Flour and polyphenolic extract from chañar seeds could be considered as new alternative ingredients for the formulation of functional foods, nutraceuticals, or food supplements. The use of the seed flour in addition to the pulp of the fruit along with the rest of the plant would encourage the propagation of this species resistant to extreme arid environments for commercial and conservation purposes to boost the regional economies of vulnerable areas of South America. Full article

Raisins are an important source of polyphenolic compounds in plant foods, and polyphenols are associated with antioxidant and anti-aging activity. In this work, 628 polyphenols in raisin extracts were characterized using UPLC-MS/MS, mainly including tricetin 3′-glucuronide, diisobutyl phthalate, butyl isobutyl phthalate, isoquercitrin and 6-hydroxykaempferol-7-O-glucoside. The oxidative stress in H₂O₂-induced HepG2 cells and D-gal-induced aging mice was alleviated by raisin polyphenols (RPs) via increases in the cellular levels of superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH), along with decreases in malonaldehyde (MDA), reactive oxygen species (ROS) and advanced glycosylation end-products (AGEs) levels. In addition, it was observed that RPs enhanced Sirt1 and Sirt3 expression, initiating the Keap1-Nrf2 signaling pathway, by upregulating the levels of nuclear Nrf2, facilitating the expressions of the antioxidant proteins NQO1 and HO-1, and downregulating Keap1 and cytoplasmic Nrf2 protein levels in H₂O₂-induced HepG2 cells and D-gal-induced aging mice. In summary, RP exerted antioxidant and anti-aging effects via regulating the Sirt1–Nrf2 signaling pathway in vitro and in vivo. Full article

Butterfly pea flower (BPF), roselle calyx (RC), and grape skin (GS) are rich in bioactive phenolics with health benefits. Due to its simplicity, safety, and environmental friendliness, this study used water as a solvent to explore different extraction conditions in these plant materials and compared the heat stability of anthocyanins in the aqueous extracts. To maximize the total anthocyanins and polyphenols in the aqueous extracts, the powders of BPF, GS, and RC should be extracted for 30 min at 90 °C; 30 min and 120 min at 90 °C; and 30 min and 60 min at 60 °C, respectively. Among the tested plant materials, the content of total anthocyanins was RC > GS > BPF, while the total phenolic content was GS > BPF > RC. Anthocyanins of the aqueous extracts underwent rapid thermal degradation at high temperatures and high pH values. The thermal stability of anthocyanins in the materials was in the order: BPF > GS > RC. This is likely related to the types and structures of the anthocyanins such as the degree of acylation and glycosylation. The study demonstrates that hot water extraction is efficient and practical for these materials, yielding extracts suitable for food and nutraceutical applications. Full article

Hyperuricemia (HUA), or elevated uric acid in the blood, has become more prevalent in recent years. Polyphenols, which are known to have good inhibitory activity on xanthine oxidoreductase (XOR), are effective in uric acid reduction. In this review, we address the structure–activity relationship of flavonoids that inhibit XOR activity from two perspectives: the key residues of XOR and the structural properties of flavonoids. Flavonoids’ inhibitory effect is enhanced by their hydroxyl, methoxy, and planar structures, whereas glycosylation dramatically reduces their activity. The flavonoid structure–activity relationship informed subsequent discussions of the changes that occur in polyphenols’ XOR inhibitory activity during their extraction, processing, gastrointestinal digestion, absorption, and interactions. Furthermore, gastrointestinal digestion and heat treatment during processing can boost the inhibition of XOR. Polyphenols with comparable structures may have a synergistic effect, and their synergy with allopurinol thus provides a promising future research direction. Full article

About one-third of the global food supply is wasted. Brewers’ spent grain (BSG), being produced in enormous amounts by the brewery industry, possesses an eminence nutritional profile, yet its recycling is often neglected for multiple reasons. We employed integrated metagenomics and metabolomics techniques to assess the effects of enzyme treatments and Lactobacillus fermentation on the antioxidant capacity of BSG. The biotreated BSG revealed improved antioxidant capability, as evidenced by significantly increased (p < 0.05) radical scavenging activity and flavonoid and polyphenol content. Untargeted metabolomics revealed that Lactobacillus fermentation led to the prominent synthesis (p < 0.05) of 15 novel antioxidant peptides, as well as significantly higher (p < 0.05) enrichment of isoflavonoid and phenylpropanoid biosynthesis pathways. The correlation analysis demonstrated that Lactiplantibacillus plantarum exhibited strong correlation (p < 0.05) with aucubin and carbohydrate-active enzymes, namely, glycoside hydrolases 25, glycosyl transferases 5, and carbohydrate esterases 9. The fermented BSG has potential applications in the food industry as a culture medium, a functional food component for human consumption, and a bioactive feed ingredient for animals. Full article

Glycosylation is one of the most common and important modifications in natural products (NPs), which can alter the biological activities and properties of NPs, effectively increase structural diversity, and improve pharmacological activities. The biosynthesis of glycosylation in natural products involves multiple complex biological processes, which are coordinated by many enzymes. UDP-glycosyltransferases (UGTs) play a crucial role in glycosylation modification, and have attracted long-term and widespread research attention. UGTs can catalyze the O-, C-, S-, and N-glycosylation of different substrates, producing a variety of glycosides with broad biological activity, while improving the solubility, stability, bioavailability, pharmacological activity, and other functions of NPs. In recent years, the rapid development of synthetic biology and advanced manufacturing technologies, especially the widespread application of artificial intelligence in the field of synthetic biology, has led to a series of new discoveries in the biosynthesis of NP glycosides by UGT. This work summarizes the latest progress and challenges in the field of NP glycosylation, covering the research results and potential applications of glycosylated derivatives of terpenes, flavonoids, polyphenols, aromatic compounds, and other compounds in terms of biogenesis. Looking to the future, research may leverage artificial intelligence-driven synthetic biology techniques to decipher genes related to the synthetic pathway, which is expected to further promote the large-scale synthesis and application of glycosylated NPs, and increase the diversity of NPs in the pharmaceutical, functional food, and cosmetic industries. Full article

Enzymatic fructosylation has emerged as a strategy to enhance the hydrophilicity of polyphenols by introducing sugar moieties, leading to the development of phenolic glycosides, which exhibit improved solubility, stability, and biological activities compared to their non-glycosylated forms. This study provides a detailed analysis of the interactions between five phenolic fructosides (4MFPh, MFF, DFPh, MFPh, and MFPu) and twelve proteins (11β-HS1, CRP, DPPIV, IRS, PPAR-γ, GK, AMPK, IR, GFAT, IL-1ß, IL-6, and TNF-α) associated with the pathogenesis of T2DM. The strongest interactions were observed for phlorizin fructosides (DFPh) with IR (−16.8 kcal/mol) and GFAT (−16.9 kcal/mol). MFPh with 11β-HS1 (−13.99 kcal/mol) and GFAT (−12.55 kcal/mol). 4MFPh with GFAT (−11.79 kcal/mol) and IR (−12.11 kcal/mol). MFF with AMPK (−9.10 kcal/mol) and PPAR- γ (−9.71 kcal/mol), followed by puerarin and ferulic acid monofructosides. The fructoside group showed lower free energy binding values than the controls, metformin and sitagliptin. Hydrogen bonding (HB) was identified as the primary interaction mechanism, with specific polar amino acids such as serin, glutamine, glutamic acid, threonine, aspartic acid, and lysine identified as key contributors. ADMET results indicated favorable absorption and distribution characteristics of the fructosides. These findings provide valuable information for further exploration of phenolic fructosides as potential therapeutic agents for T2DM. Full article

The study aimed to develop encapsulation systems to maintain the preservation of everlasting (Helichrysum plicatum) flower extract polyphenols. Spray-dried encapsulates were formulated using β-cyclodextrin (BCD) and 2-hydroxypropyl-β-cyclodextrin (HPBCD) as supramolecular hosts, and their macromolecule mixtures with the conventional carriers, maltodextrin (MD) and whey protein (WP). The obtained microparticles were comparatively assessed regarding technological, physicochemical, and phytochemical properties. The highest yields were achieved by combining cyclodextrins with whey protein (73.96% for WP+BCD and 75.50% for WP+HPBCD compared to 62.48% of pure extract). The extract–carrier interactions and thermal stability were evaluated by FTIR and DSC analysis, suggesting successful entrapment within the carriers. Carriers reduced the particle diameter (3.99 to 4.86 μm compared to 6.49 μm of pure extract), classifying all encapsulates as microsystems. Carrier blends made the particle size distribution uniform, while SEM analysis revealed the production of more spherical and less aggregated particles. The HPBCD provided the highest encapsulation efficiency, with the highest content of detected aglycones and slightly lower values of their glycosylated forms. An analysis of the dual macromolecule encapsulation systems revealed the highest bioactive preservation potential for SHE+MD+BCD and SHE+WP+HPBCD. Overall, macromolecule combinations of cyclodextrins and conventional biopolymers in the spray-drying process can enhance the functional properties of H. plicatum extract. Full article