Lentils (Lens culinaris Medik) as a Source of Phenolic Compounds - their Content, Changes during Processing, Antioxidant and Biological Activities.

While often recognized as a good plant protein source and a rich source of essential nutrients including folate, iron, manganese and phosphorus, lentils (Lens culinaris L.) also contain healthful bioactive compounds. They possess a number of phenolic compounds including phenolic acids, flavonoids such as flavan- 3-ols, flavonols and anthocyanins, proanthocyanidins, as well as saponins and phytic acid. This review provides a summary of the types and levels of phenolic compounds found in the cotyledon of lentils as well as their seed coats. The values define broad ranges due to varied cultivars, horticultural practices, climatic conditions during lentil development, and the different phenolic extraction approaches employed. The prepared lentil extracts were found to possess marked antioxidant activity, as assessed by in vitro assays, with the results clearly indicating that the endogenous phenolic compounds dictated this activity. Processing of raw lentils in the forms of cooking, germination and fermentation was determined to affect the phenolics' contents: phenolic content of some lentils decreased while those of others increased, most likely due to the release of bound phenolics from the plant wall matrix. Finally, a summary of some of the positive biological activities observed for lentil extracts from cell culture and animal studies is given.

Examining the Performance of Two Extraction Solvent Systems on Phenolic Constituents from U.S. Southeastern Blackberries.

Two common extraction solvent systems, namely acidified aqueous methanol and acidified aqueous acetone, were used to extract blackberry phenolics, and the antioxidant properties of the recovered extracts were compared. The crude extracts were fractionated into low- and high-molecular-weight phenolics by Sephadex LH-20 column chromatography. The hydrophilic-oxygen radical absorbance capacity (H-ORACFL), ferric reducing antioxidant power (FRAP), and the cellular antioxidant activity (CAA) assays were employed as indices to assess antioxidant capacity of the extracts and their respective fractions. The methanolic solvent system displayed a greater efficiency at extracting anthocyanin and flavonol constituents from the blackberries, while the acetonic solvent system was better at extracting flavan-3-ols and tannins. Anthocyanins were the dominant phenolic class found in the blackberries with 138.7 ± 9.8 mg C3G eq./100 g f.w. when using methanol as the extractant and 114.6 ± 3.4 mg C3G eq./100 g f.w. when using acetone. In terms of overall antioxidant capacity of blackberry phenolics, the acetonic solvent system was superior. Though present only as a small percentage of the total phenolics in each crude extract, the flavan-3-ols (42.37 ± 2.44 and 51.44 ± 3.15 mg/100 g f.w. in MLF and ALF, respectively) and ellagitannins (5.15 ± 0.78 and 9.31 ± 0.63 mg/100 g f.w. in MHF and AHF, respectively) appear to account for the differences in the observed antioxidant activity between the two solvent systems.

Effect of konjac glucomannan on metabolites in the stomach, small intestine and large intestine of constipated mice and prediction of the KEGG pathway.

The occurrence of constipation involves the whole gastrointestinal tract. Konjac glucomannan (KGM) has been clinically proven to alleviate constipation, but its mechanism has not been fully understood. The present study aimed to investigate the excretion-promoting effect of KGM on constipated mice and the underlying molecular mechanism. In this study, the UHPLC-QE orbitrap/MS method was used to determine the metabolic phenotypes of total gastrointestinal segments (i.e., the stomach {St}, small intestine {S}, and large intestine {L}) in constipated mice treated with KGM. The results showed that KGM improved the fecal water content, body weight growth rate, and serum gastrointestinal regulation related peptide levels. The metabolomics results revealed the decreased levels of amino acids, cholines, deoxycholic acid, arachidonic acid, thiamine and the increased levels of indoxyl sulfate, histamine, linoelaidic acid etc. The KEGG pathway analysis indicated that the relaxation effect of KGM supplementation was most likely driven by modulating the expression levels of various key factors involved in biosynthesis of amino acid (i.e., phenylalanine, tyrosine and tryptophan), linoleic acid metabolism, biosynthesis of secondary metabolites, and arachidonic acid metabolism signalling pathways. The results indicated that KGM alleviates constipation by regulating potential metabolite markers and metabolic pathways in different gastrointestinal segments.

Protection of natural antioxidants against low-density lipoprotein oxidation.

This chapter reports essential information about the protective action of antioxidants against LDL oxidation. The activity of individual compounds (tocopherols, vitamin C, phenolic compounds) as well as extracts obtained from plant material (cereals, fruits, legumes, nuts, mushrooms, by-products of food industry) is reported. The structure-antioxidant activity relationship of phenolic compounds is discussed. This article summarizes the findings to date of both in vitro and in vivo studies using foods or phenolic extracts isolated from foodstuffs at inhibiting the incidence of LDL oxidation. This chapter summarizes also the reportings to date of in vivo studies using foods or beverages at inhibiting the incidence of LDL oxidation.

Natural antioxidants of plant origin.

Interest in the content of natural antioxidants in plant-based foods can be from the human health perspective, in terms of how these compounds might help promote one's health and wellness, or from the storage point-of-view, as the endogenous antioxidant constituents aid to extend a foodstuff's shelf-life. This chapter reports essential information about the mechanism of antioxidant action and methods employed for determination of their activity, classes of phenolic compounds (phenolic acids, flavonoids, lignans, stilbenes, tannins), sources of plant antioxidants (oil seeds, cereals, legumes, plants of the Lamiaceae family, tea and coffee, tree nuts, fruits, and berries), extraction strategies of phenolic compounds from plant material, and the influence of processing and storage on the content of natural antioxidants in foods and their antioxidant activity. Thermal processing, if not releasing bound phenolics from the structural matrices of the food, tends to decrease the antioxidant potential or, in the best case scenario, has no significant negative impact. Gentler sterilization processes such as high-pressure processing tend to better retain the antioxidant potential of a foodstuff than thermal treatments such as steaming, boiling, or frying. The impact of processing can be assessed by determining the antioxidant potential of foodstuffs either at the point of formulation or after different periods of storage under specified conditions.

Cellular evaluation of the antioxidant activity of U.S. Pecans [Carya illinoinensis (Wangenh.) K. Koch].

Clinical trials show an inverse relationship between the consumption of antioxidant-rich tree nuts and the development of chronic diseases. This study examined antioxidant efficacy of U.S. pecans using a modified cellular antioxidant activity (CAA) assay with comparisons to data from in vitro antioxidant assays (hydrophilic-oxygen radical absorbance capacity {H-ORACFL} and ferric reducing antioxidant power {FRAP}). Crude phenolic extracts from both raw and roasted pecans were analyzed. In the CAA assay, pecan phenolics were taken up by human colorectal adenocarcinoma (Caco-2) cells and bestowed CAA, determined by monitoring the fluorescence of 2',7'-dichlorofluorescein. Phenolics (25-100 µg/mL) demonstrated a reduction in fluorescence by 37-69% for raw and 26-68% for roasted pecans. The primary active phenolic constituents were determined by high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) to be epi(catechin) dimers and trimers. These oligomeric procyanidins, ranging in size from 560 to 840 g/mol appear to be small enough for cellular uptake, showing pecans are an effective antioxidant in biological systems, regardless of roasting.

Characterizing the phenolic constituents and antioxidant capacity of Georgia peaches.

Acetonic crude phenolic extracts of six Georgia peach cultivars were prepared and separated into low- and high-molecular-weight (LMW and HMW) fractions by Sephadex LH-20 column chromatography. Further characterization via RP-HPLC-ESI-MS identified the main phenolics as hydroxycinnamates, (+)-catechin, and proanthocyanidins with degrees of polymerization up to seven. The LMW phenolics of the commercial cultivar, 'July Prince', were further chromatographed and examined by RP-HPLC-ESI-MS. Derivatives of phenolic acids and flavan-3-ols, along with eriodictyol and quercetin diglycosides, were identified. Antioxidant capacities of the LMW and HMW fractions were determined using in vitro assays. H-ORACFL and FRAP assays gave values of 872 to 2428 µmol Trolox eq./100 g f.w. and 309 to 432 µmol Fe2+ eq./100 g f.w., respectively. The total phenolics content (TPC) was also measured; correlations between TPCs and antioxidant assays indicated that the HMW fractions of peach extracts were major contributors to the antioxidant capacity of the cultivars analyzed.

A 5-day high-fat diet rich in cottonseed oil improves cholesterol profiles and triglycerides compared to olive oil in healthy men.

Modifying dietary fat composition is important for minimizing cardiovascular disease risk. The purpose of this study was to determine the effects of a 5-day, high-fat diet rich in cottonseed oil (CSO) or olive oil (OO) on lipid profiles. Based on previous human and animal models, we hypothesized that the CSO-rich diet would lead to lower fasting and postprandial lipid levels, whereas the OO-rich diet would not significantly change lipid levels in 5 days. Fifteen normal-weight men completed a randomized crossover design with 2 controlled feeding trials (3-day lead-in diet, prediet visit, 5-day CSO- or OO-rich diet, postdiet visit). The 5-day diets (50% fat) were rich in either CSO or OO. At pre- and postdiet visits, subjects consumed test meals rich in the oil that coincided with their 5-day diet, and blood draws were performed. Fasting total cholesterol, low-density lipoprotein cholesterol, and triglycerides (TG) were lower following CSO diet intervention (total cholesterol: 148.40 ±â€¯6.39 to 135.93 ±â€¯6.31 mg/dL; low-density lipoprotein cholesterol: 92.20 ±â€¯5.57 to 78.13 ±â€¯5.60 mg/dL; TG: 80.11 ±â€¯4.91 to 56.37 ±â€¯5.46 mg/dL for pre- to postdiet, respectively; P < .05). High-density lipoprotein cholesterol increased following CSO diet intervention (46.67 ±â€¯2.41 to 50.24 ±â€¯2.20 mg/dL for pre- to postdiet, respectively; P < .05). Postprandial TGs were lower following CSO diet (area under the curve of 954.28 ±â€¯56.90 vs 722.16 ±â€¯56.15 mg/dL/8 h for pre- vs postdiet, respectively; P < .01). No changes in blood lipids were found following OO diet. A 5-day CSO-rich diet led to improvements in cholesterol and TGs, whereas no changes were observed with an OO-rich diet.

Practical use of natural antioxidants in meat products in the U.S.: A review.

Historically, meat and poultry processors in the U.S. have relied on the use of synthetic antioxidants like butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, and propyl gallate, as well as tocopherols to prevent lipid and protein oxidation. There is a trend towards utilizing natural antioxidants as replacements for synthetic ones. Some processors are already using multi-functional ingredients, such as rosemary and oregano, approved for use as spices and natural flavors to curb oxidation. Yet, there are still other ingredients that have not been applied in this fashion. Spices and natural flavors can often be incorporated in products that have defined statements of identity or composition. Further, these ingredients allow the processor to transition to a clean label without compromising the shelf life and quality of the products. Spices and natural flavors may have higher minimum effective concentrations than their synthetic counterparts, but they will offer increased consumer acceptability, decreased potential health risks, and can often achieve the same degree of oxidation prevention.

Modification of the cellular antioxidant activity (CAA) assay to study phenolic antioxidants in a Caco-2 cell line.

In vitro assays are widely used to analyze the antioxidant potential of compounds, but they cannot accurately predict antioxidant behavior in living systems. Cell-based assays, like the cellular antioxidant activity (CAA) assay, are gaining importance as they provide a biological perspective. When the CAA assay was employed to study phenolic antioxidants using hepatocarcinoma (HepG2) cells, quercetin showed antioxidant activity in HepG2 cells; 25 and 250µM quercetin reduced fluorescence by 17.1±0.9% and 58.6±2.4%, respectively. (+)-Catechin, a phenolic antioxidant present in many foods, bestowed virtually no CAA in HepG2 cells. When Caco-2 cells were employed, more robust antioxidant activity was observed; 50µM (+)-catechin and quercetin reduced fluorescence by 54.1±1.4% and 63.6±0.9%, respectively. Based on these results, likely due to differences in active membrane transport between the cell types, the Caco-2-based CAA assay appears to be a more appropriate method for the study of certain dietary phenolics.

Separation of Ellagitannin-Rich Phenolics from U.S. Pecans and Chinese Hickory Nuts Using Fused-Core HPLC Columns and Their Characterization.

U.S. pecans and Chinese hickory nuts possess a wide array of phenolic constituents with potential health benefits including phenolic acids and proanthocyanidins. Only limited information is available, however, on their compositions. The present study optimized the separation performance and characterized the low-molecular-weight phenolic fractions of these nuts with C18 and pentafluorophenyl (PFP) fused-core LC columns by employing a kinetic approach. Although both types of reversed-phase columns demonstrated similar performance in general, the PFP column furnished greater plate numbers and superior peak shapes for the low-molecular-weight fractions as well as overall separations of ellagic acid derivatives. The high-molecular-weight fraction of pecans, analyzed by a 3-µm HILIC column, possessed more proanthocyanidins than the Chinese hickory nuts with dimers and trimers (31.4 and 18.34 mg/g crude extract, respectively) being present at the greatest levels. Chinese hickory nuts had lower proanthocyanidin content but possessed tetramers and pentamers at 4.46 and 4.01 mg/g crude extract, respectively.

Quantification of inositol phosphates in almond meal and almond brown skins by HPLC/ESI/MS.

The extraction and measurement of all six forms of inositol phosphates (InsPs) in almond meal and brown skins were improved from existing methods by pH adjustment, supplementation of EDTA, and rapid analysis via anion-exchange high-performance liquid chromatography coupled with electrospray ionization mass spectrometry. The quantity of InsPs in six major almond cultivars ranged from 8 to 12µmol/g in the meal and 5 to 14µmol/g in the brown skins. InsP6 was the dominant form, but lower forms still accounted for ∼20% of the total InsPs molar concentration in a majority of the samples. InsPs contributed 32-55% of the organic phosphorus content and 20-38% of the total phosphorus content in the meal. In brown skins, these ranges were 44-77% and 30-52%, respectively. The successful application of this analytical method with almonds demonstrates its potential use for re-examination of the reported phytic acid contents in many other tree nuts, legumes, grains, and complex foods.

Antioxidant Activity and Phenolic Composition of a Red Bean (Phasoelus vulgaris) Extract and its Fractions.

- The activities of the crude acetonic extract of red bean and its two fractions were determined using a 0-carotene-linoleate model system as well as the total antioxidant activity (TAA), the total phenolics content (TPC), the DPPH radical-scavenging activity, and the reducing power assays. Results from the in vitro assays showed the highest values when tannins (fraction II) were tested. Specifically, the TAA of the tannins fraction was 4.37 mmol Trolox eq./g fraction; whereas, the crude extract and fraction I were 0.481 and 0.093 µmol Trolox eqi/mg extract or fraction, respectively. The content of total phenolics in fraction II was the utmost (612 mg/g); the tannins content, assayed by the vanillin method and expressed as absorbance units at 500 nm per I g, was 938. RP-HPLC- PAD-MS profiling revealed the presence of 33 compounds: quercetin arabinoglucoside, quercetin rutinoside, quercetin, p-hydroxybenzoic acid, and kaempferol rutinoside were the most abundant phenolics in the extract.

Effect of pecan phenolics on the release of nitric oxide from murine RAW 264.7 macrophage cells.

Inflammation is linked to numerous chronic disease states. Phenolic compounds have attracted attention because a number of these compounds possess anti-inflammatory properties. A phenolic crude extract was prepared from pecans and separated by Sephadex LH-20 column chromatography into low- and high-molecular-weight (LMW/HMW) fractions. Anti-inflammatory properties of these fractions were assessed in LPS-stimulated RAW 264.7 murine macrophage cells. NO and reactive oxygen species (ROS) production was monitored after 3 different experimental protocols: (1) pre-treatment with Escherichia coli O111:B4 lipopolysaccharide (LPS); (2) pre-treatment with a pecan crude extract and its fractions; and (3) co-incubation of LPS with a pecan crude extract and its fractions. The LMW fraction displayed a dose-dependent decrease in NO production and a significant decrease from the LPS control in ROS production when cells were either co-incubated with or pre-treated with LPS. The phenolics were characterized by HPLC to help identify those responsible for the observed effect.

The antioxidant requirement for plasma membrane repair in skeletal muscle.

Vitamin E (VE) deficiency results in pronounced muscle weakness and atrophy but the cell biological mechanism of the pathology is unknown. We previously showed that VE supplementation promotes membrane repair in cultured cells and that oxidants potently inhibit repair. Here we provide three independent lines of evidence that VE is required for skeletal muscle myocyte plasma membrane repair in vivo. We also show that when another lipid-directed antioxidant, glutathione peroxidase 4 (Gpx4), is genetically deleted in mouse embryonic fibroblasts, repair fails catastrophically, unless cells are supplemented with VE. We conclude that lipid-directed antioxidant activity provided by VE, and possibly also Gpx4, is an essential component of the membrane repair mechanism in skeletal muscle. This work explains why VE is essential to muscle health and identifies VE as a requisite component of the plasma membrane repair mechanism in vivo.

Separation and characterization of soluble esterified and glycoside-bound phenolic compounds in dry-blanched peanut skins by liquid chromatography-electrospray ionization mass spectrometry.

A large variety of soluble phenolic compounds, including phenolic acids (hydroxybenzoic acids, ethyl protocatechuate, and hydroxycinnamic acids, as well as phenylacetic acid and phenyllactic acid), stilbenes (trans-piceatannol and trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene), flavan-3-ols (e.g., (-)-epicatechin, (+)-catechin, (-)-epiafzelechin, and their polymers (the proanthocyanidins, PACs)), other flavonoids (e.g., isoflavones, flavanols, and flavones), and biflavonoids, were released from esters and glycosides by base/acid hydrolysis and identified in acetonic extracts of dry-blanched peanut skins (PS). Reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with electrospray ionization mass spectrometry (ESI-MS(n)) was applied to separate and identify the phenolic constituents. Tentative identification of the separated phenolics was based on molecular ions and MS(n) fragmentation patterns acquired by ESI-MS in the negative-ion mode. Identification of free phenolic acids, stilbenes, and flavonoids was also achieved by commercial standards and by published literature data. Quantification was performed on the basis of peak areas of the UV signals from the HPLC chromatograms and calibration curves of the commercial standards. The flavonoids of PS exist mostly in glycoside-bound forms, but the aglycones can be liberated upon acid hydrolysis. PS contain significantly more PACs compared to free phenolic compounds: PAC monomers to tetramers constituted 92.0% of esterified phenolic compounds. The PAC monomer ((+)-catechin) and dimers are the main phenolics released from glycosides and account for 31.7 and 59.1%, respectively, of the total glycoside-bound phenolic compounds.

Separation and characterization of phenolic compounds from dry-blanched peanut skins by liquid chromatography-electrospray ionization mass spectrometry.

A large variety of phenolic compounds, including phenolic acids (hydroxybenzoic acids, hydroxycinnamic acids, and their esters), stilbenes (trans-resveratrol and trans-piceatannol), flavan-3-ols (e.g., (-)-epicatechin, (+)-catechin, and their polymers {the proanthocyanidins, PACs}), other flavonoids (e.g., isoflavones, flavanols, and flavones, etc.) and biflavonoids (e.g., morelloflavone), were identified in dry-blanched peanut skins (PS) by this study. High-performance liquid chromatography (HPLC) coupled with electrospray ionization mass spectrometry (ESI-MS(n)) was applied to separate and identify the phenolic constituents. Reversed-phase HPLC was employed to separate free phenolic compounds as well as PAC monomers, dimers, and trimers. PACs with a degree of polymerization (DP) of >4 were chromatographed via hydrophilic interaction liquid chromatography (HILIC). Tentative identification of the separated phenolics was based solely on molecular ions and MS(n) fragmentation patterns acquired by ESI-MS in the negative-ion mode. The connection sequence of PAC oligomers (DP <5) could be deduced mainly through characteristic quinone methide (QM) cleavage ions. When the DP reached 6, only a proportion of the flavan-3-ols could be ascertained in the PACs because of the extremely complicated fragmentation patterns involved. The identification of free phenolic acids, stilbenes, and flavonoids was achieved by authentic commercial standards and also by published literature data. Quantification was performed based on peak areas of the UV (free phenolic compounds) or fluorescence (PACs) signals from the HPLC chromatograms and calibration curves of commercial standards. Overall, PS contain significantly more PACs compared to free phenolic compounds.

Separation and characterization of phenolic compounds from U.S. pecans by liquid chromatography-tandem mass spectrometry.

The phenolic acids and proanthocyanidins (PACs) of pecans possess bioactive properties, which might be useful in retarding the onset of and ameliorating the status of certain chronic disease states. There is a general lack of information in the literature regarding such compounds, especially the PACs. Crude phenolic extracts pooled from eight commercially significant cultivars were selected based on their relatively high antioxidant capacities. The pooled extracts were separated via Sephadex LH-20 column chromatography into five ethanolic low-molecular-weight (LMW) fractions and one acetonic high-molecular-weight (HMW) fraction. The preparations were then characterized using RP-HPLC-ESI-MS/MS and diol-phase HPLC-ESI-MS/MS in order to determine the key constituents present in the LMW and HMW fractions, respectively. As previously observed in pecan nutmeat, ellagic acid and (+)-catechin were found to be the major phenolics in the LMW fractions. The last eluting LMW fraction did not contain phenolic acids; rather it possessed PAC monomers and dimers. The HMW fraction comprised a majority of its PACs as dimers; yet, monomers, trimers, tetramers, pentamers, and hexamers were also separated and characterized.

Peanut skins-fortified peanut butters: effect of processing on the phenolics content, fibre content and antioxidant activity.

Incorporation of ground peanut skins (PS) into peanut butter at 1.25%, 2.5%, 3.75%, and 5.0% (w/w) resulted in a marked concentration-dependent increase in both the total phenolics content (TPC) and antioxidant activity. Using dry-blanched PS to illustrate, the TPC increased by 86%, 357%, 533%, and 714%, respectively, compared to the peanut butter control devoid of PS; the total proanthocyanidins content (TPACs) rose by 633%, 1933%, 3500%, and 5033%, respectively. NP-HPLC detection confirmed that the increase in the phenolics content was attributed to the endogenous proanthocyanidins of the PS, which were characterised as dimers to nonamers by NP-HPLC/ESI-MS. FRAP values increased correspondingly by 62%, 387%, 747%, and 829%, while H-ORAC(FL) values grew by 53%, 247%, 382%, and 415%, respectively. The dietary fibre content of dry-blanched PS was ~55%, with 89-93% being insoluble fibre. Data revealed that PS addition enhances the antioxidant capacity of the peanut butter, permits a "good source of fibre" claim, and offers diversification in the market's product line.

Antioxidant and enzyme inhibitory activities of blueberry anthocyanins prepared using different solvents.

We compared the biological activities of anthocyanins prepared from whole blueberries or pomace and extracted with acetone, ethanol, and methanol. Crude Amberlite extracts (CAE) and rehydrated powders of freeze-dried anthocyanins were used. Ethanolic CAE yielded the highest total monomeric anthocyanin content [TMAC] (160 ppm), ferric reducing antioxidant power [FRAP] (3.4 mM Fe(2+)), total phenolics content [TPC] (382 ppm gallic acid equivalents [GAE]), and α-amylase inhibitory activity (36.8%). The rehydrated powder from acetonic extract gave the greatest FRAP (5.19) and TPC (422.7). α-Amylase (26.1%) and α-glucosidase (91.5%) inhibitory activities were also sustained. Methanolic CAE yielded values intermediate between ethanolic and acetonic extracts. Comparison of mass spectra between Amberlite extracts and rehydrated preparations revealed putative degradation and dimerization products in the rehydrated powders, which could account for loss in biological activities for rehydrated methanolic and ethanolic powders. Results of this study provide useful information in optimizing anthocyanin preparation methods for improved biological activity.