Effect of simulated gastrointestinal digestion on phenolic composition and antioxidant capacity of cooked cowpea (Vigna unguiculata) varieties

Consumption of diets rich in phenolic compounds has been associated with reduced risk of chronic diseases. The effect of cooking and simulated gastrointestinal digestion on phenolic compounds and antioxidant properties of two cowpea (Vigna unguiculata) types was determined. Phenolic acids, flavan‐3‐ols and flavonols were the main groups of phenolic compounds identified. Cooking and simulated enzyme digestion of the cooked cowpea samples rendered some phenolics less extractable (possibly by promoting binding with other food components) or more extractable (possibly by release of bound forms). Total phenolic contents and radical scavenging properties of the cowpeas were reduced upon cooking, but increased upon simulated enzyme digestion. Cowpea extracts inhibited human LDL oxidation at a concentration of 2 mg mL^?1 possibly due to their phenolic content. Phenolic compounds in cowpea can potentially protect against cardiovascular diseases for which LDL oxidation is a risk factor.     

Natural phenolic antioxidants electrochemistry: Towards a new food science methodology

Natural phenolic compounds are abundant in the vegetable kingdom, occurring mainly as secondary metabolites in a wide variety of chemical structures. Around 10,000 different plant phenolic derivatives have been isolated and identified. This review provides an exhaustive overview concerning the electron transfer reactions in natural polyphenols, from the point of view of their in vitro antioxidant and/or pro‐oxidant mode of action, as well as their identification in highly complex matrixes, for example, fruits, vegetables, wine, food supplements, relevant for food quality control, nutrition, and health research. The accurate assessment of polyphenols’ redox behavior is essential, and the application of the electrochemical methods in routine quality control of natural products and foods, where the polyphenols antioxidant activity needs to be quantified in vitro, is of the utmost importance. The phenol moiety oxidation pathways and the effect of substituents and experimental conditions on their electrochemical behavior will be reviewed. The fundamental principles concerning the redox behavior of natural polyphenols, specifically flavonoids and other benzopyran derivatives, phenolic acids and ester derivatives, quinones, lignins, tannins, lignans, essential oils, stilbenes, curcuminoids, and chalcones, will be described. The final sections will focus on the electroanalysis of phenolic antioxidants in natural products and the electroanalytical evaluation of in vitro total antioxidant capacity.     

Flavonoids,phenolic acids and abscisic acid in Australian and New Zealand Leptospermum honeys

Flavonoids, phenolic acids and abscisic acid of Australian and New Zealand Leptospermum honeys were analyzed by HPLC. Fifteen flavonoids were isolated in Australian jelly bush honey (Leptospermum polygalifolium), with an average content of 2.22 mg/100 g honey. Myricetin (3,5,7,3′,4′,5′-hexahydroxyflavone), luteolin (5,7,3′,4′-tetrahydroxyflavone) and tricetin (5,7,3′,4′,5′-pentahydroxyflavone) were the main flavonoids identified. The mean content of total phenolic acids in jelly bush honey was 5.14 mg/100 g honey, with gallic and coumaric acids as the potential phenolic acids. Abscisic acid was quantified as twice the amount (11.6 mg/100 g honey) of the phenolic acids in this honey. The flavonoid profile mainly consisted of quercetin (3,5,7,3′,4′-pentahydroxyflavone), isorhamnetin (3,5,7,4′-tetrahydroxyflavone 3′-methyl ethyl), chrysin (5,7-dihydroxyflavone), luteolin and an unknown flavanone in New Zealand manuka (Leptospermum scoparium) honey with an average content of total flavonoids of 3.06 mg/100 g honey. The content of total phenolic acids was up to 14.0 mg/100 g honey, with gallic acid as the main component. A substantial quantity (32.8 mg/100 g honey) of abscisic acid was present in manuka honey. These results showed that flavonoids and phenolic acids could be used for authenticating honey floral origins, and abscisic acid may aid in this authentication.     

Occurrence and content of hydroxycinnamic and hydroxybenzoic acid compounds in foods

Phenolic acid compounds seem to be universally distributed in plants. They have been the subject of a great number of chemical, biological, agricultural, and medical studies. Hydroxycinnamic acid compounds occur most frequently as simple esters with hydroxy carboxylic acids or glucose, while the hydroxybenzoic acid compounds are present mainly in the form of glucosides. Furthermore, phenolic acids may occur in food plants as esters or glycosides conjugated with other natural compounds such as flavonoids, alcohols, hydroxyfatty acids, sterols, and glucosides. Also, hydroxycinnamic acid amides appear to be common constituents. The occurrence of the different natural phenolic acid compounds in foods is reviewed, and data of the content in fruit, vegetables, and spices are given. The distribution of the main phenolic acid compounds in food plants as well as their changes during development and maturation of fruits are considered. Furthermore, the hydroxycinnamic acids bound to cell wall polymers, the phenolic acid compounds in coffee, cereals, oil seed, and tree nuts, and the analysis of phenolic acid derivatives are reviewed.     

Food Phenolics,Pros and Cons: A Review

Phenolic compounds like simple phenols, flavonoids, and phenolic acids are commonly in foods of plant origin. Several studies, including animal and epidemiological investigations, have demonstrated that phenolic compounds in foods possess positive attributes such as anticarcinogenesis, antioxidant potential, antiviral activity, antimicrobial activity, and antimutagenic activity. However, other studies have shown that the same phenolics have negative attributes such as carcinogenic activity and antinutritional activity, as well as imparting negative attributes to foods. This review summarizes the information about food phenolics and presents the most current knowledge with respect to its role in human health, food attributes, and toxicity among others.     

Food Phenolics, Pros and Cons: A Review

Phenolic compounds like simple phenols, flavonoids, and phenolic acids are commonly in foods of plant origin. Several studies, including animal and epidemiological investigations, have demonstrated that phenolic compounds in foods possess positive attributes such as anticarcinogenesis, antioxidant potential, antiviral activity, antimicrobial activity, and antimutagenic activity. However, other studies have shown that the same phenolics have negative attributes such as carcinogenic activity and antinutritional activity, as well as imparting negative attributes to foods. This review summarizes the information about food phenolics and presents the most current knowledge with respect to its role in human health, food attributes, and toxicity among others.     

Identification and quantification of phenolic and other polar compounds in the edible part of Annona cherimola and its by-products by HPLC-DAD-ESI-QTOF-MS

Annona cherimola fruit is native to inter-Andean valleys from Peru and Ecuador. In the Mediterranean region, the main producer of cherimoya is the coast of Granada–Malaga (Spain), also called ‘Costa Tropical’, where the two most important cultivars found are ‘Fino de Jete’ and ‘Campa’.Cherimoya, like most fruits, is an important source of bioactive compounds, such as phenolic compounds. Therefore, the aim of this study was the tentative identification and quantification of phenolic and organic acids in pulp, peel and seed of two cherimoya cultivars (‘Fino de Jete’ and ‘Campa’) using HPLC-DAD-ESI-QTOF-MS.By using the proposed method, 21 phenolic and organic acids were detected in the edible portion of cherimoya, 37 in peel and 22 in seed. Procyanidins were the main phenolic compound family identified in the pulp and peel of the two cultivars, whereas in cherimoya seeds higher quantities of organic acids and flavonoids were detected. Most of the compounds were identified for the first time in cherimoya.According to these results, cherimoya pulp and its by-products are a natural source of procyanidins and other phenolic and polar compounds. In particular, cherimoya peel, with a higher concentration of phenolic and polar compounds in comparison with pulp and seed, represents an interesting food by-product that could be used as an ingredient in the functional food and/or pharmaceutical industry.     

Metabolism of food phenolic acids by Lactobacillus plantarum CECT 748

Phenolic acids account for almost one third of the dietary phenols and are associated with organoleptic, nutritional and antioxidant properties of foods. This study was undertaken to assess the ability of Lactobacillus plantarum CECT 748^T to metabolize 19 food phenolic acids. Among the hydroxycinnamic acids studied, only p-coumaric, caffeic, ferulic and m-coumaric acids were metabolized by L. plantarum. Cultures of L. plantarum produced ethyl and vinyl derivatives from p-coumaric and caffeic acids, 4-vinyl guaiacol from ferulic acid, and 3-(3-hydroxyphenyl) propionic acid from m-coumaric acid. Among the hydroxybenzoic acids analysed, gallic acid and protocatechuic acid were decarboxylated to pyrogallol and catechol, respectively. Inducible enzymes seem to be involved, at least in m-coumaric and ferulic acid metabolism, since cell-free extracts from cultures grown in the absence of these phenolic acids were unable to metabolize them. Further work is needed for the identification of the enzymes involved, since the knowledge of the metabolism of phenolic compounds is an important issue for the food industry.     

Application of ultra performance liquid chromatography-photodiode detector-quadrupole/time of flight-mass spectrometry (UPLC-PDA-Q/TOF-MS) method for the characterization of phenolic compounds of Lepidium sativum L. sprouts

Some of health-protecting phytochemicals can be found in the sprouts in a much higher concentration than in the developed plants. However, the polyphenol composition of Lepidium sativum L. sprouts is still unresolved, especially with regard to flavonoids and phenolic acids. To develop a rapid and reliable UPLC-PDA-Q/TOF-MS method for the identification and quantification of main flavonoids and phenolic acids from L. sativum sprouts, the samples of L. sativum sprouts were grown with and without the exposition to light. Ten phenolic compounds were identified on the basis of their mass spectra in MS mode, MS/MS spectra, PDA spectrum, and retention times as compared with available reference substances. The major compounds were found to be sinapic acid derivatives. Acylated flavonoids in L. sativum sprouts were identified as kaempferol and quercetin with the same glycosidic substitution pattern as the major compounds, and varying degrees of acylation with sinapic and ferulic acids. Total content of phenolics in both samples was similar, but the content of flavonoids was higher and sinapine was lower in the sample of sprouts germinated in light. The determination and the evaluation of L. sativum extracts is very effective while using the UPLC-PDA-Q/TOF-MS. Even though the substances only occur in low concentrations, the combination of the retention time and the accurate molecular mass allows for their fast qualification.     

In vitro bio-accessibility and antioxidant activity of grape polyphenols

The bio-accessibility (the release of compounds from solid food matrices) of grape polyphenols using an in vitro model simulating gastro-intestinal conditions has been investigated. In vitro studies are needed to unravel factors affecting the release of antioxidants during digestion. The amount of bio-accessible polyphenols, flavonoids and anthocyanins increases during gastric digestion. The transition in the intestinal environment causes a decrease in all the analyzed classes of polyphenols followed by a renewal in the extraction of polyphenols and flavonoids but not of anthocyanins. The stability under gastro-intestinal conditions of pure phenolic acids, flavonoids and resveratrol has been analysed. Gastric digestion had no effect on any phenolic tested. Phenolic acids and resveratrol were degraded under pancreatic conditions whereas catechin and quercetin were not. Changes in antioxidant activity during digestion were correlated to the changes in polyphenols concentration as well as to the pH. Our results suggest that the gastro-intestinal tract may act as an extractor where polyphenols are progressively released from solid matrix and made available for the absorption or to exert their biological effects in the gastro-intestinal tract.     

HPLC method for screening of flavonoids and phenolic acids in berries

An HPLC method is described for the simultaneous detection of selected flavonoids (kaempferol, quercetin, myricetin) and phenolic acids (p-coumaric, caffeic, ferulic, p-hydroxybenzoic, gallic and ellagic acids) in berries. Three extraction and hydrolysis methods and three HPLC column and solvent systems were tested for strawberry and blackcurrant. The optimal extraction and hydrolysis of these phenolics was obtained by incubating freeze-dried berry samples for 16 h at 35°C in 50% methanol and 1·2 M HCl. The best separation of the hydrolysed phenolics was achieved in ODS-Hypersil column using a ternary solvent system (dihydrogen ammonium phosphate, orthophosphoric acid and acetonitrile) with increasing hydrophobicity and changing pH. The method was used for the determination of the phenolic profiles of strawberry and blackcurrant. The relative content of flavonoids was low in strawberry but over 50% in blackcurrant. Ellagic acid was the main phenolic in strawberry while its relative content was very low in blackcurrant. Although the precision of the method was not equally good for all the phenolics, a reasonable amount of information was obtained within a single analysis. This simple, semiquantitative method is suitable for routine screening of the major phenolics in berries. © 1998 SCI.     

Bioavailability of phenolic compounds

Phenolic compounds in foods originate from one of the main classes of secondary metabolites in plants. They are essential for the growth and reproduction of plants, and are produced as a response for defending injured plants against pathogens. In recent years, there is a growing interest in phenolic compounds and their presumed role in the prevention of various degenerative diseases, such as cancer and cardiovascular diseases. The importance of antioxidant activities of phenolic compounds and their possible usage in processed foods as a natural antioxidant have reached a new high in recent years. The absorption and bioavailability of phenolics in humans are also controversial. Data on these aspects of phenolics are scarce and merely highlight the need for extensive investigations of the handling of phenolics by the gastrointestinal tract and their subsequent absorption and metabolism. In this article, absorption, metabolism, and the bioavailability of pheniolic compounds are reviewed.     

Using flavonoids, phenolic compounds and headspace volatile profile for botanical authentication of lemon and orange honeys

This study evaluates the usefulness of flavonoids (naringenin, hesperetin, chrysin, galangin, kaempferol, luteolin, pinocembrin, and quercetin) and phenolic acids (caffeic acid and p-coumaric acid) together with 37 volatile compounds in the differentiation between lemon blossom honey (Citrus limon) and orange blossom honey (Citrus spp.). The total content of flavonoids and phenolic acids is twice as high in lemon honey (6.20 mg/100 g) as in orange honey (3.64 mg/100 g); naringenin and caffeic acid were the main compounds in all cases. Hesperetin, a floral marker of citrus honey, was not significantly different for the two types of honey. A multivariate PLS2 analysis showed that some volatile compounds such as, 4 lilac aldehydes and bencenacetaldehyde (all abundant in orange honey) were negatively correlated with 4 flavonoids: pinocembrin, chrysin, naringenin and quercetin, and caffeic phenolic acid (all abundant in lemon honey). Moreover, the last 5 compounds were positively correlated with: 6 alcohols, 2 ketones, acetaldehyde and furanmethanol. This is a first approach to employ all of these compounds together with appropriate statistical techniques to differentiate between two varieties of citrus honey, and therefore it could be an interesting tool for their authentication.     

Antibacterial phenolic components of New Zealand manuka honey

This paper describes several methods for isolation of the antibacterially active phenolic fraction of honey derived from the native New Zealand manuka tree, Leptospermum scoparium (Myrtaceae). This fraction consists of phenolic derivatives of benzoic acids, cinnamic acids and flavonoids, all of which have been identified previously in honeys which do not exhibit non-peroxide residual antibacterial activity. The flavonoids had not previously been identified in manuka honey. Furthermore, the flavonoids were different from those found in the leaves of manuka trees but were the same as those found in European honeys and propolis. While most of these phenolic products possess antibiotic activity, they do not individually or collectively account for the antibacterial activity of `active' manuka honey. Essentially all of this activity is associated with the carbohydrate fraction of the honey.     

A comparative study on phenolic profile,vitamin C content and antioxidant activity of Italian honeys of different botanical origin

The aim of our study was to identify and quantify the phenolic acids, flavonoids and vitamin C and to evaluate the antioxidant activity in ninety Italian honeys of different botanical origins (chestnut, sulla, eucalyptus, citrus and multifloral). The results showed that total phenolic and flavonoid contents varied from 11.08 to 14.26 mg GAE per 100 g honey and from 5.82 to 12.52 mg QE per 100 g honey, respectively. HPLC–UV analysis showed a similar but quantitatively different phenolic profile of the studied honeys. Vitamin C is present in all samples. Multifloral honey showed the highest amount of the detected total phenolic compounds and the highest vitamin C content. The DPPH value varied from 55.06 to 75.37%. Among the unifloral honeys, chestnut honey presented the highest levels of phenolic acids, flavonoids and vitamin C, which are closely associated with its high antioxidant activity. The results show that honey contains high amount of biologically active compounds, which play an important role in defining the nutraceutical quality of the product, and that the distribution of these compounds is influenced by the botanical origin.     

Proximate,mineral, amino acid composition,phenolic profile,antioxidant and functional properties of oilseed cakes

Proximate, minerals, amino acids (AAs), phenolic composition, antioxidant and functional properties of flaxseed (FSC), sesame (SSC), mustard (MSC), nigella (NSC) and groundnut (GSC) seedcakes were studied. SSC exhibited higher ash and fat contents while GSC and FSC had more protein and mineral contents (P, Mg, Mn and Cu), respectively. The total flavonoids, phenolics and antioxidant activity were higher in NSC (18.60 mg QE g⁻¹), MSC (5.12 mg GAE g⁻¹) and FSC (12.28 µmol TE g⁻¹), respectively. NSC exhibited the highest oil absorption capacity (2.10 g g⁻¹) and emulsifying activity index (89.52 m² g⁻¹). Twenty-one AAs including citrulline and ɣ-aminobutyric acid were detected in oilseed cakes (OSC). MSC had more essential AAs (methionine, isoleucine, tryptophan, threonine and lysine) while GSC had more total hydrophobic, acidic and basic AAs. Syringic acid and rutin were identified as major phenolic compounds in GSC and MSC, respectively. The total free phenolic acids were more in GSC while FSC had high total bound phenolic acids and flavonoids. OSC can be utilised in food products as a supplement to improve nutritional properties.     

基于网络药理学预测我国蜂胶改善代谢性疾病的生物学机制

为系统分析我国蜂胶改善2型糖尿病、肥胖等代谢性疾病的生物学机制,开发防控慢性代谢性疾病的标准化功能性食品提供科学参考,以我国蜂胶中的主要黄酮类、酚酸及酯类化合物成分为研究对象,利用结构相似比对法预测其作用靶点,并利用网络药理学方法建立"成分-靶标-疾病"的关联,阐述蜂胶成分改善代谢性疾病的"多成分、多靶点"特征,分析核心作用通路。通过与现有文献报道的对比分析,计算得到靶标预测成功率为86.2%。PPARγ、ESR1、ESR2、SIRT1、PTPN1是蜂胶化合物总体作用概率最高的靶标,其中PPARγ是黄酮类化合物与酚酸类化合物的共同重要靶标。蜂胶中的黄酮类化合物是与改善糖脂代谢活性关联最为密切的一类物质,此外部分酚酸及酯类化合物也发挥了协同作用。网络分析结果表明,蜂胶成分可能分别或者共同作用于糖脂代谢相关的多条通路,通过促进糖摄取、促进胰岛素分泌、改善胰岛素抵抗、促进脂代谢、抑制脂肪细胞分化等途径改善糖脂代谢。研究结果为我国蜂胶在改善代谢性疾病领域的应用及相关功能性食品活性成分标准的制定提供了参考。同时,本研究证明,结构相似比对结合网络药理学研究手段对于现代化功能性食品研发有重要的指引作用,可以在早期为复杂体系的物质基础及生物学机制研究提供科学证据。     

Sacha inchi (Plukenetia volubilis L.) shell: an alternative source of phenolic compounds and antioxidants

Sacha inchi seed (SI) is known as a rich source of oil with high content of polyunsaturared fatty acids of the ω‐3 and ω‐6 type (~85% of total fatty acids). However, few studies have focused on the use of by‐products from the seed. The aim of this study was to characterise the main phenolic families present in SI shell and to evaluate the best extraction solvent for the extraction of phenolic compounds (PC) and antioxidant capacity (AOXC). The PC content corresponded to 74.5 ± 5.1 mg g^?1 of which 93.1% were condensed tannins and the remaining compounds corresponded to free and bound phenolic acids, hydrolyzable tannins, flavonoids and flavanoids. Protocatechic and p‐coumaric acids but also hydroxycinammic acid derivatives of ferulic and o‐coumaric type and lignan derivatives were identified. Acetone containing solvents favoured the extraction of higher amounts of total PC and AOXC. This study highlights the potential use of SI shell as a novel and alternative source of PC antioxidants for the nutraceutical and/or functional food industries.     

Free and bound phenolic compounds in leaves of pak choi (Brassica campestris L. ssp. chinensis var. communis) and Chinese leaf mustard (Brassica juncea Coss)

Eleven pak choi cultivars and two leaf mustard cultivars grown under field conditions in China were investigated for the free polyphenol content in their outer and inner leaves, as well as in their leaf blades and leaf stalks. In most cases, there were no significant differences between the hydroxycinnamic acid derivative and flavonoid derivative contents in the outer and inner leaves for the 13 cultivars. However, the contents of blades and stalks differed: hydroxycinnamic acids and flavonoids were present in greater amounts in the leaf blade than in the leaf stalk. Trace or small amounts of flavonoids were detected in the pak choi and leaf mustard stalks. Additionally, the bound phenolic contents of two pak choi cultivars and two leaf mustard cultivars were investigated. The concentrations of cell wall-bound phenolic compounds were higher in the leaf blade than in the leaf stalk under field conditions in China. These compounds represent only a minor portion of the total phenolic contents (flavonoids and hydroxycinnamic acids) in leaf stalks (0.81–1.18%) and leaf blades (0.05–0.08%) from fresh plant material. The storage of plant samples from four Chinese cabbage cultivars resulted, in most cases, in an increase of phenolic content, within six days, at 4 °C and 20 °C. The increase might have been triggered by post-harvest plant stresses, which stimulate the biosynthesis of polyphenols.