Free Phenolic Fraction Research Articles

The profiles of free, esterified and insoluble-bound phenolics in peach juice after high pressure homogenization and evaluation of their antioxidant capacities, cytoprotective effect, and inhibitory effects on α-glucosidase and dipeptidyl peptidase-Ⅳ

The phenolic profiles, antioxidant capacities, cytoprotective effect, and α-glucosidase and DPP-IV inhibitory capacity of free (FP), esterified (EP) and insoluble-bound (IBP) phenolic fractions in ‘Lijiang snow’ peach juice after high pressure homogenization (HPH) were investigated, and the molecular docking was used to explore the enzyme inhibition mechanism. HPH increased total phenolic and total flavonoid contents in three fractions without changing compositions. The IC50 of radicals scavenged by three fractions were all reduced by HPH. The best inhibition on intracellular ROS production were found for phenolic fractions after HPH at 300 MPa, with ROS levels ranged within 95.26–119.16 %. HPH at 300 MPa reduced the apoptosis rates of FP and EP by 16.52 % and 9.33 %, respectively. All phenolic fractions showed effective inhibition on α-glucosidase and DPP-IV by formation of hydrogen bonding and van der Waals forces. This study explored the feasibility of HPH to enhance the phenolics and bioactivity of peach juice.

Guava processing waste: Biological activity profile of a natural and sustainable source of phenolic antioxidants

Guava (Psidium guajava L.) is a widely-consumed tropical fruit that can be industrially processed and generate several food products. However, about 30% of the total volume of processed guava is lost as processing waste, a homogenous fraction containing peels, seeds, and residual pulp. The valorization of the discard fraction is necessary in upcycling due to its richness of bioactive components. Therefore, the phenolic composition and biological activity of guava's processing waste and its pulp counterpart were investigated. Guava's pulp (22.32 mg gallic acid equivalents (GAE)/g) and waste (21.99 mg GAE/g) contained similar levels of total phenolic content (TPC), with the majority of phenolics occurring in the free and esterified forms. Besides, a strong positive correlation was observed between TPC and the antioxidant activity of extracts. Through HPLC-UV-MS-TOF analysis, 27 phenolic compounds were identified across the pulp (25) and waste (18) portions, with a predominance of gallic, vanillic, and ellagic acids and their derivatives. While free and esterified phenolic fractions showed higher efficiency as α-glucosidase inhibitors (84.94–98.85%), pancreatic lipase was better inhibited by the insoluble-bound phenolics in the extracts (41.55–43.31%). Guava waste's insoluble-bound phenolics strongly protected supercoiled DNA against hydroxyl radicals (80.09%). Oxidation protection by guava phenolics was also observed towards human LDL-cholesterol (10.82–22.98%), an indication of their potential cardioprotective effect. As such, guava processing waste demonstrates nutraceutical potential and should be considered as a value-added ingredient in functional foods and other related applications.

Characterization of Bioactive Phenolic Compounds in Seeds of Chilean Quinoa (Chenopodium quinoa Willd.) Germplasm

In recent years, quinoa (Chenopodium quinoa Willd.), an ancient Andean region crop, has received increased research attention because it is an excellent source of nutrients and also of bioactive phenolic compounds, which are potentially beneficial for human health. However, variation in the content and type of these metabolites in quinoa genetic resources remains, to a large extent, unexplored. We evaluated the composition of free and bound phenolic forms in the seeds of 111 Chilean quinoa accessions by using LC-DAD-MS/MS. The relative phenolic content ranged from 35.51 mg/100 g to 93.23 mg/100 g of seed dry weight. The free phenolic fraction accounted for 72% of the total phenolic content, while the bound fraction represented the remaining 28% of the total phenolic content. Our study also revealed a significant degree of variation in terms of individual phenolic compounds such as rutin, vanillic acid, quercetin, and their derivatives, which can have important implications for quinoa’s nutritional and functional properties. We conclude that our data reveal a significant phenotypic variation of bioactive phenolic content in the examined germplasm, which could be exploited in current and future genetic improvement programs in quinoa.

Comparison of Phenolic and Volatile Compounds in MD2 Pineapple Peel and Core.

The peel and core discarded from the processing of MD2 pineapple have the potential to be valorized. This study evaluated the functional and volatile compounds in the extracts of MD pineapple peel and core (MD2-PPC). The total soluble solids, pH, titratable acidity, sweetness index, and astringency index were 9.34 °Brix, 4.00, 0.74%, 12.84, and 0.08, respectively, for the peel and 12.00 °Brix, 3.96, 0.32%, 37.66, and 0.03, respectively, for the core. The fat and protein contents of the peel and core were found to be significantly different (p < 0.05). The total phenolic (TPC) and flavonoid contents (TFC) were significantly higher in the peel. The peel also showed better antioxidant activity, with a half-maximal inhibitory concentration (IC50) of 0.63 mg/mL for DPPH free radical activity compared with the core. The TPC of different phenolic fractions from peel extract was highest in the glycosylated fraction, followed by the esterified, insoluble-bound, and free phenolic fractions. GC-MS analysis identified 38 compounds in the peel and 23 in the core. The primary volatile compounds were 2-furan carboxaldehyde, 5-(hydroxymethyl), and 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP). The identification of phenolics and volatile compounds provides important insights into the valorization of (MD2-PPC) waste.

Influence of Storage Conditions on Stability of Phenolic Compounds and Antioxidant Activity Values in Nutraceutical Mixtures with Edible Flowers as New Dietary Supplements.

This paper investigates the effects of storage conditions on the stability of phenolics and their antioxidant activities in unique nutraceutical supplements containing non-traditional cereal flakes, edible flowers, fruits, nuts, and seeds. Significant total phenolic content (TPC) of 1170-2430 mg GAE/kg and total anthocyanin content (TAC) with the values of 322-663 mg C3G/kg were determined with the highest TPC content established in free phenolic fractions. The most notable declines in TPC (by 53%), TAC (by 62%), phenolics (e.g., glycosylated anthocyanins by 35-67%), and antioxidant activity (by 25% using DPPH) were established in the presence of sunlight at 23 °C followed by the storage at 40 °C. Quercetin, rutin, peonidin, pelargonidin, p-coumaric, ellagic, and p-hydroxybenzoic acids were identified as the least stable phenolics when exposed to sunlight. Furthermore, glycosylated forms of anthocyanins demonstrated a greater stability when compared with anthocyanidins. The mixtures considerably eliminated ABTS and DPPH radicals. In all samples, water-soluble substances showed a higher antioxidant activity than lipid-soluble substances with the main contributors in the following order: delphinidin-3-glucoside (r = +0.9839) > p-coumaric > gallic > sinapic > p-hydroxybenzoic acids > delphinidin > peonidin and malvidin (r = +0.6538). Gluten-free nutraceutical mixtures M3 (containing red rice and black quinoa flakes, red and blue cornflowers, blueberries, and barberries) and M4 (containing red and black rice flakes, rose, blue cornflower, blueberries, raspberries, and barberries) were evaluated as the least stable under all storage conditions although they showed considerable phenolic concentrations. Phenolic contents and antioxidant activity of the nutraceutical mixtures were the highest at 23 °C without the presence of sunlight with the most stable M1 nutraceutical mixture (containing oat and red wheat flakes, hibiscus, lavender, blueberries, raspberries, and barberries).

Integrated metabolite analysis and health-relevant in vitro functionality of white, red, and orange maize (Zea mays L.) from the Peruvian Andean race Cabanita at different maturity stages.

The high maize (Zea mays L.) diversity in Peru has been recognized worldwide, but the investigation focused on its integral health-relevant and bioactive characterization is limited. Therefore, this research aimed at studying the variability of the primary and the secondary (free and dietary fiber-bound phenolic, and carotenoid compounds) metabolites of three maize types (white, red, and orange) from the Peruvian Andean race Cabanita at different maturity stages (milk-S1, dough-S2, and mature-S3) using targeted and untargeted methods. In addition, their antioxidant potential, and α-amylase and α-glucosidase inhibitory activities relevant for hyperglycemia management were investigated using in vitro models. Results revealed a high effect of the maize type and the maturity stage. All maize types had hydroxybenzoic and hydroxycinnamic acids in their free phenolic fractions, whereas major bound phenolic compounds were ferulic acid, ferulic acid derivatives, and p-coumaric acid. Flavonoids such as luteolin derivatives and anthocyanins were specific in the orange and red maize, respectively. The orange and red groups showed higher phenolic ranges (free + bound) (223.9-274.4 mg/100 g DW, 193.4- 229.8 mg/100 g DW for the orange and red maize, respectively) than the white maize (162.2-225.0 mg/100 g DW). Xanthophylls (lutein, zeaxanthin, neoxanthin, and a lutein isomer) were detected in all maize types. However, the orange maize showed the highest total carotenoid contents (3.19-5.87 μg/g DW). Most phenolic and carotenoid compounds decreased with kernel maturity in all cases. In relation to the primary metabolites, all maize types had similar fatty acid contents (linoleic acid > oleic acid > palmitic acid > α-linolenic acid > stearic acid) which increased with kernel development. Simple sugars, alcohols, amino acids, free fatty acids, organic acids, amines, and phytosterols declined along with grain maturity and were overall more abundant in white maize at S1. The in vitro functionality was similar among Cabanita maize types, but it decreased with the grain development, and showed a high correlation with the hydrophilic free phenolic fraction. Current results suggest that the nutraceutical characteristics of orange and white Cabanita maize are better at S1 and S2 stages while the red maize would be more beneficial at S3.

Ultra-High Hydrostatic Pressure Pretreatment on White Que Zui Tea: Chemical Constituents, Antioxidant, Cytoprotective, and Anti-Inflammatory Activities.

Herbal tea has numerous biological activities and exhibits broad benefits for human health. In China, the flower buds of Lyonia ovalifolia are traditionally processed as herbal tea, namely White Que Zui tea (WQT). This study was aimed to evaluate the effect of ultra-high hydrostatic pressure (UHHP) pretreatment on the chemical constituents and biological activities of free, esterified, and insoluble-bound phenolic fractions from WQT. A total of 327 chemical constituents were identified by a quasi-targeted metabolomics analysis. UHHP pretreatment extremely inhibited reactive oxygen species (ROS) production and cell apoptosis in H2O2-induced HepG2 cells, and it increased the activities of intracellular antioxidant enzymes (SOD and CAT) and GSH content in different phenolic fractions from WQT. In addition, after UHHP pretreatment, the anti-inflammatory effects of different phenolic fractions from WQT were improved by inhibiting the production of nitric oxide (NO) and pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) in LPS-induced RAW264.7 cells. Thus, the UHHP method might be a potential pretreatment strategy for improving the bioavailability of phytochemicals from natural plants.

Effect of Enriching Gingerbread Cookies with Elder (Sambucus nigra L.) Products on Their Phenolic Composition, Antioxidant and Anti-Glycation Properties, and Sensory Acceptance.

Elder products are still underutilized sources of phytochemicals, mainly polyphenols, with extensive pharmacological effects on the human body. In this study, gingerbread cookies covered in chocolate (GC) were enriched with elderflower dry extract (EF) and juice concentrate (EB). The cookies (GC, GCEF, and GCEFEB) and the additives (EF and EB) were analyzed for total phenolic content (TPC), phenolic compound profile, antioxidant capacity (AC), and advanced glycation end products' (AGEs) formation in both the free and bound phenolic fractions. Sensory analysis of the cookies was performed using an effective acceptance test (9-point hedonic scale), and purchase intent was evaluated using a 5-point scale. It was found that the flavonoid content was significantly increased (20-60%) when EF and EB were added to the cookies. Moreover, the EF addition to chocolate-covered GCs enhanced the content of phenolic acids (up to 28%) in the bound phenolic fraction. An increase in the AC values of enriched cookies was found, and the free phenolic fraction differed significantly in this regard. However, inhibition of AGEs by elder products was only observed in the bound phenolic fraction. In addition, EF and EB improved the overall acceptance of the cookies, mostly their taste and texture. Thus, elder products appear to be valuable additives to gingerbread cookies, providing good sensory quality and functional food characteristics.

Preliminary Study on the Impact of Non-Thermal Plasma Activated Water on the Quality of Triticum aestivum L. cv. Glosa Sprouts

The present study aimed to investigate the effects of non-thermal plasma-activated water (PAW) on Triticum aestivum L. cv. Glosa sprouts. Two types of PAW were generated by exposing distilled water to a high-voltage electric discharge. Wheat caryopses were treated either with PAW1 (25 mg/L NO3−, 4 mg/L NO2−, and 6 mg/L H2O2) or PAW2 (35 mg/L NO3−, 5 mg/L NO2−, and 7.5 mg/L H2O2) for 8 days, with samples being collected at days 1, 2, 3, and 8. The germination rate, growth parameters, protein, photosynthetic pigments, total phenolic contents, antioxidant activity of free and bound phenolic fractions, and activity of antioxidant enzymes were evaluated. Both PAW1 and PAW2 had positive effects on Triticum aestivum L. cv. Glosa sprouts. PAW2 had a better impact on sprouts with respect to growth parameters, free phenolic content, and antioxidant activity of the free phenolic fraction (day 3), the accumulation of proteins, and photosynthetic pigments (day 8). In conclusion, exposure to PAW increases the quality of Triticum aestivum L. cv. Glosa sprouts. Further optimization of PAW treatment is required for the most favorable impact on the accumulation of biomass and health-promoting compounds in sprouts.

Phenolic profiles of Atlantic sea cucumber (Cucumaria frondosa) tentacles and their biological properties

Sea cucumber tentacles (aquapharyngeal bulb) are a rich source of biologically active compounds, including phenolics, however they are mainly discarded as processing waste. This study evaluated free, esterified, and insoluble-bound phenolics of Atlantic sea cucumber (Cucumaria frondosa) tentacles and their antioxidant activity for the first time. Biological properties such as inhibitory activities against α-glucosidase, tyrosinase, and the formation of AGEs as well as LDL-cholesterol and DNA oxidation were investigated. The antioxidant activity of the phenolic extracts was also evaluated in a fish model system. In the UHPLC-QTOF-MS/MS analysis, 31 phenolic compounds, mainly phenolic acids and flavonoids, were identified and quantified. Among them, eight compounds were detected for the first time in any species of sea cucumber. The free phenolic fraction was the major form of phenolics, mainly protocatechuic acid, p-coumaric acid, gallic acid, ellagic acid, catechin, and quercetin, exhibiting strong antioxidant and biological activities. Fresh Atlantic salmon treated with sea cucumber phenolics delayed lipid oxidation as measured by the thiobarbituric acid reactive substances (TBARS) assay. Therefore, Atlantic sea cucumber tentacles may serve as a viable source of functional food ingredients with protective antioxidant properties.

Profiling of phenolics in cashew nut (Anacardium occidentale L.) testa and evaluation of their antioxidant and antimicrobial properties

Most of agricultural by-products are rich sources of bioactive compounds. The present study deals with profiling phenolic compounds from various phenolic fractions of cashew nut (Anacardium occidentale L.) testa. The antioxidant and antimicrobial properties of phenolic fractions (free, esterified and bound) were also evaluated. About 20, 5 and 7 phenolic compounds were identified from free, esterified, and bound phenolic fractions, respectively. UPLC-HRMS/MS analyses of phenolic fractions revealed that condensed tannins and flavanols are the primary testa polyphenols. (+)-catechin, (−)-epicatechin, epicatechin gallate and procyanidins were identified in all the fractions. Most of the phenolic compounds were concentrated in the free form (62.5%), followed by the bound (21.8%) and esterified fractions (15.62%). The free phenolic fraction (FPF) showed the highest total polyphenol and flavonoid content. The FPF showed the highest radical scavenging activity (FPF IC50 12.35 ± 1.48 μg/ml (DPPH assay), 33.77 ± 1.04 μg/ml (ABTS assay) and 62.89 ± 2.1 μmol of Fe2+ equivalent per gram of cashew nut testa (FRAP assay)). The antimicrobial activities of phenolic fractions were tested against food-borne pathogens such as Staphylococcus aureus FRI722, Escherichia coli EFR02, Micrococcus luteus ATCC 9341 and Bacillus cereus ATCC 11778. All the phenolic fractions possess antimicrobial activity; the FPF has shown a maximum zone of inhibition at a lower concentration of 3 mg/ml. The antioxidant and antimicrobial activities of the testa were strongly influenced by its total phenolic and flavonoid contents. In conclusion, cashew nut testa is a suitable source to extract phenolic compounds with strong antioxidant and antimicrobial properties.

Phenolic, nutritional and molecular interaction study among different millet varieties

Millet varieties were analyzed for nutritional, antinutritional, mineral and phenolic profiles. Inhibition potential of phenolic acids for enzyme inhibition ,activity was estimated, alongside starch digestibility of millet grains was evaluated. Finger millet was found to have high contents of Ca, Mn and Cu minerals. Proso and pearl millet had high protein content, whereas kodo and foxtail millet contained high content of dietary fiber. Phytic acid was comparatively higher in kodo millet, whereas oxalic acid and total tannin content was abundant in finger millet. Total phenolic content and total flavonoid content in bound phenolic fractions were comparatively higher than the free phenolic fractions and total anthocyanin content was found highest in finger millet followed by kodo and pearl millet. The millet varieties showed optimum antioxidant potential studied through different assay methods. Ferulic acid was predominantly found among all the millets in bound fraction of phenolic extract. Furthermore, phenolic acids were used to investigate different docking techniques with α-amylase, α-glucosidase, and leptin receptor enzymes. Docking studies revealed, chlorogenic acid had a high docking score and a high binding affinity against α-amylase, α-glucosidase, and leptin receptor enzymes.

Water Caltrop (Trapa quadrispinosa Roxb.) Husk Improves Oxidative Stress and Postprandial Blood Glucose in Diabetes: Phenolic Profiles, Antioxidant Activities and α-Glycosidase Inhibition of Different Fractions with In Vitro and In Silico Analyses.

The aim of this study was to investigate the phenolic profiles, antioxidant activities and α-glycosidase inhibitory activities of three different phenolic fractions from water caltrop (Trapa quadrispinosa Roxb.) husk and to further explore the predominant compounds and their mechanisms on α-glycosidase inhibition by virtual screening and molecular dynamics. A total of 29 substances were identified and quantified in this study. Tannins were the main constituents of water caltrop husk extract. All of the free phenolic (FP), esterified phenolic (EP) and insoluble-bound phenolic (BP) fractions exhibited good antioxidant activities, and the BP had the highest radical scavenging ability with IC50 values of 0.82 ± 0.12 μg/mL (ABTS) and 1.15 ± 0.02 μg/mL (DPPH), respectively (p < 0.05). However, compared with the EP and BP, the FP showed the strongest inhibition towards the α-glycosidase and the IC50 value of FP was 1.43 ± 0.12 μg/mL. The 1,2,6-trigalloylglucose and α-glycosidase complex had better root mean square deviations (RMSD) stability via molecular dynamics simulation study. Results obtained from this study may provide a good potential natural resource for the improvement of oxidative stress injury and blood glucose control in diabetes mellitus, which could expand the use of water caltrop husk and improve its economic value.

In Vitro Oxidative Stress Threatening Maize Pollen Germination and Cytosolic Ca2+ Can Be Mitigated by Extracts of Emmer Wheatgrass Biofortified with Selenium.

In this work, we studied the effects of in vitro oxidative stress applied by H2O2 to maize pollen germination and cytosolic Ca2+, taken as an experimental model to test the biological activity of extracts of emmer (Triticum turgidum L. spp. dicoccum (Schrank ex Shubler) Thell.) wheatgrass obtained from grains sprouted with distilled water, or salinity (50 mM) or selenium (45 mg L−1 of Na2SeO3). Wheatgrass extracts were obtained in two ways: by direct extraction in methanol, which represented the free phenolic fraction of extracts (Ef), and by residual content after alkaline digestion, which made it possible to obtain extracts with the bound fraction (Eb). Comparative tests on maize pollen were carried out by differently combining H2O2 and either wheatgrass extracts or pure phenolic acids (4-HO benzoic, caffeic, p-coumaric and salicylic). The cytosolic Ca2+ of maize pollen was influenced by either H2O2 or pure phenolic acids or Ef, but not by Eb. The negative effect of H2O2 on maize pollen germination and cytosolic Ca2+ was mitigated by Ef and, slightly, by Eb. The extent of the biological response of Ef depended on the sprouting conditions (i.e., distilled water, salinity or selenium). The extracts of Se-biofortified wheatgrass were the most effective in counteracting the oxidative stress.

Effect of High-Pressure Processing (HPP) on Phenolics of North Atlantic Sea Cucumber (Cucumaria frondosa).

Sea cucumber contains a wide range of bioactive compounds, including phenolics. This study investigated the free, esterified, and insoluble-bound phenolics of sea cucumber body wall as affected by high-pressure processing (HPP) pretreatment. Sea cucumber body wall was subjected to HPP (200, 400, and 600 MPa for 5, 10, and 15 min), followed by the extraction of phenolics. The contents of total phenolics and antioxidant activity were monitored. Compared to untreated samples, those treated with HPP exhibited significantly higher total phenolics, flavonoids, and antioxidant activities. Treatment of 600 MPa for 10 min offered the optimal results. The highest amount of phenolics was observed in the free phenolic fraction, followed by esterified and insoluble-bound phenolic fractions. Moreover, phenolic extracts showed inhibitory effects against cupric ion-induced low-density lipoprotein (LDL)-cholesterol oxidation, peroxyl and hydroxyl radical-induced DNA scission, α-glucosidase activity, and formation of advanced glycation end products (AGEs). Ultra-high-performance liquid chromatography equipped with a quadrupole time of fight and mass spectrometer (UHPLC-QTOF-MS/MS) identified 20 phenolic compounds, mainly phenolic acids and flavonoids, from the body wall of this species for the first time. Thus, sea cucumber may lead to the production of a multitude of value-added products.

Biotransformation of quinoa phenolic compounds with Monascus anka to enhance the antioxidant capacity and digestive enzyme inhibitory activity

This research aims to change the phenolic fractions and the bioactivities of quinoa by solid-state fermentation (SSF) with the edible fungus Monascus anka (M. anka). The contents of protein and fat increased in the fermented product, while the carbohydrate decreased. After 6-day fermentation with M. anka, the amount of phenolic compound reached the highest level. The majority of phenolic forms in fermented quinoa were phenolic acids, mainly ferulic acid, protocatechuic acid and p-hydroxybenzoic acid. Ultrahigh-performance liquid chromatography-mass spectrometry (UHPLC-MS) results showed that SSF was an effective method to transform quinoa phenolic compounds. Free fractions could be rapidly absorbed in the small intestine, suggesting that SSF with M. anka was a useful method to enhance bioavailable antioxidants. Antioxidant ability in vitro results showed that phenolic fractions from fermented quinoa were greater than the unfermented quinoa, and a significant cellular antioxidant activity (CAA) increment of 135% was obtained in the free phenolic fraction of fermented quinoa. Moreover, α-amylase and α-glucosidase inhibition activities were enhanced with fermentation. Correlation matrix analysis revealed that most of the free phenolic compounds showed strong positive correlations with antioxidant activities and digestive enzyme activities. Consequently, fermentation with M. anka was a particularly promising method to enhance the bioactivity of quinoa.

Identification of polyphenols from Rosa roxburghii Tratt pomace and evaluation of in vitro and in vivo antioxidant activity

Rosa roxburghii Tratt pomace (RRTP) has increasingly attracted attention due to its various nutritional ingredients and health benefits. In this study, the free phenolic fraction (RRTP-FPF) and bound phenolic fraction (RRTP-BPF) were extracted from RRTP by solvent extraction method and alkaline hydrolysis method, respectively. The composition of polyphenols in RRTP-FPF and RRTP-BPF were identified by ultra-high performance liquid chromatography equipped with an electrospray ionization and quadrupole time-of-flight mass spectrometry (UHPLC-ESI-QTOF-MS/MS). In vitro antioxidant assays indicated that RRTP-FPF and RRTP-BPF could scavenge radicals in a dose-dependent manner, and RRTP-BPF exhibited better scavenging activity than RRTP-FPF. In addition, RRTP-FPF and RRTP-BPF (20 ∼ 100 μg/mL) treatment for 24 h could significantly increase the survival rate and decrease reactive oxygen species (ROS) level of paraquat-exposed nematodes through improving the activities of superoxide dismutase (SOD) and catalase (CAT). These results suggest that RRTP could be as a good and cheap source of natural antioxidants.

Enhanced Lignanamide Absorption and Antioxidative Effect of Extruded Hempseed (Cannabis sativa L.) Hull in Caco-2 Intestinal Cell Culture.

Despite the latest pursuit to discover novel phenolic compounds in hempseed and its biological properties, it remains a mystery whether they can be absorbed in the human body. Extrusion treatment and extraction of the free phenolic fraction significantly (p < 0.05) improved human Caco-2 intestinal cell absorption for hempseed hull lignanamides including cannabisin B (Papp value of 1.35 × 10-5 ± 1.0 × 10-6) as compared to the bound fraction of raw hull (Papp value of 2.82 × 10-6 ± 5.2 × 10-7). Co-supplementation of the flavonoid naringenin (20 μM) further improved these absorption rates. Higher cellular antioxidant activity was observed in the free extraction fractions. Treatment with the free phenolic fraction of extruded hempseed hull (100 mg/mL) alleviated tert-butyl hydroperoxide's (25 μM) negative effects on cell viability, intracellular malondialdehyde levels, apoptosis induction, glutathione S-transferase, and glutathione levels. RNA-sequencing with the limma method unveiled a total of 2795 differentially expressed genes in 21 day-old Caco-2 intestinal cells, suggesting the changes in cell metabolism after exposure to extruded hempseed hull extract. This study could promote the utilization of extrusion technology to improve the absorption and antioxidant capacities of bioactive phenolics in plant food processing byproducts.

The effect of ultra-high pretreatment on free, esterified and insoluble-bound phenolics from mango leaves and their antioxidant and cytoprotective activities

Ultra-high pressure (UHP) is a novel non-thermal pretreatment method in food processing for improving the extraction yield of polyphenols and functional properties. The present work investigated the phenolic profiles, antioxidant activities, and cytoprotective effects of the free, esterified, and insoluble-bound phenolic fractions from mango leaves before and after ultra-high pressure (UHP) treatment. UHPLC-Q-Orbitrap-MS/MS analysis resulted in the identification of 42 phenolic compounds in the different phenolic forms. UHP pretreatment could significantly influence the contents of total phenols, total flavonoids and individual compounds in the different phenolic fractions (p < 0.05). After UHP pretreatment, these phenolic fractions exhibited greater antioxidant activity, and inhibited reactive oxygen species production and cell apoptosis (p < 0.05). Meanwhile, IBP were the most potential antioxidative and cytoprotective ingredients. Therefore, UHP pretreated mango leaves with enhanced bioactivity could be used as biological agents in the health food industry to improve its application and economic values.

Phytochemical bioaccessibility and in vitro antidiabetic effects of Chinese sumac (Rhus chinensis Mill.) fruits after a simulated digestion: insights into the mechanisms with molecular docking analysis

AbstractThis work studied the effects of gastrointestinal digestion on the phytochemical bioaccessibility and in vitro anti‐diabetic effects of different fractions from Chinese sumac fruits and delineated the underlying mechanisms by molecular docking. Results showed that gastric digestion significantly increased the phytochemical bioaccessibility and inhibitions for α‐glucosidase, dipeptidyl peptidase‐4 (DPP‐IV) and advanced glycation end product (AGE) formation of the ethanol‐extracted fraction, whereas intestinal digestion remarkably decreased these parameters (P &lt; 0.05). For the free phenolic fraction, the parameters were remarkably reduced after gastric digestion but significantly increased after intestinal digestion (P &lt; 0.05). Quercitrin and gvajaverin contributed the most to the α‐glucosidase and DPP‐IV inhibitions, and trigalloyl glucose and its isomer could be the primary bioactive substance responsible for AGE suppression. Quercitrin, the predominant phenolic compound, could effectively interact with crucial amino acid residues in α‐glucosidase, DPP‐IV and bovine serum albumin with hydrogen bonds and hydrophobic interactions to exert its inhibitions.