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.     

Wine extracts from Sardinian grape varieties attenuate membrane oxidative damage in Caco-2 cell monolayers

One of the most important sites of polyphenol action seems to be in the gastrointestinal system before absorption. We investigated the ability of three wine phenolic extracts, obtained from grape varieties grown in Sardinia, Cannonau (red), Vermentino and Malvasia (white), to exert an antioxidant action against tert-butyl hydroperoxide (TBH)-induced oxidative damage to Caco-2 cell monolayers as a model system of the human intestine. TBH treatment caused the disruption of epithelial integrity, measured as transepithelial electrical resistance, and markers of the peroxidation process of membrane lipids, MDA, fatty acid hydroperoxides and 7-ketocholesterol. All wine extracts were able to counteract the oxidising action of TBH and, in spite of the differences in phenolic composition, exerted a comparable activity. Our findings point out a direct antioxidant action of the wine extracts on enterocytes exposed to oxidising species and further support the opinion that total phenolic content is not essential for antioxidant activity.     

The inhibitory effect of albumin extracts from white beans (Phaseolus vulgaris L.) on in vitro iron and zinc dialysability: role of phytic acid

The role of phytic acid in determining iron and zinc dialysability in albumin extracts from raw, cooked and cooked/dephytinized white beans, has been investigated. Albumin extract from raw beans was characterized by high iron (19mg/100g), zinc (6.9mg/100g) and phytic acid (11.5μmol g⁻¹) contents and a low mineral dialysablity (Fe 0.48%, Zn 2.5%). Cooking did not influence the mineral dialysability from beans but significantly increased the dialysability of iron (1%, p < 0.001) and zinc (5.3%, p < 0.001) from the albumin extract. Slight modifications in the composition of inositol phosphates after cooking, both in beans and in albumin extract, were observed. The improvement in iron and zinc dialysability from cooked/dephytinized samples was strictly dependent on the residual IP(6 + 5) (inositol hexa + pentaphosphates) content. Compared to cooked beans, in cooked/dephytinized bean a reduction of IP(6 + 5) of 49% led to an increase of the iron and zinc dialysability (29% p < 0.05 and 42%, p < 0.001, respectively). Albumin extract from this sample showed a reduction of 58% in iron and of 45% in zinc content, an almost complete reduction in IP(6 + 5) content (0.6 μmol g⁻¹) and a strong increase in the iron and zinc dialysability. The albumin digests showed peptides of similar MW profiles but of different amino acid compositions. In particular, in peptides which derived from digestion of albumin extracted from cooked/dephytinized beans, a strong increase in cysteine content was found, indicating that, after the disruption of phytate-mineral-protein complexes cysteine-rich fragments were released. The study indicates that phytic acid is responsible for the low iron and zinc dialysability from the albumin bean fraction and indicates the significance of the amino acid composition of the protein digestion products for the enhancement of mineral dialysability.     

Role of elicitation on the health-promoting properties of kidney bean sprouts

The influence of germination of kidney beans for 4, 6 and 8 days in different elicitors (ascorbic acid, folic acid, glutamic acid, glutamic acid/chitosan and lactic acid/chitosan) on the production of health-promoting ingredients was studied. Sprouts were characterized according to their protein profile, soluble phenolic compounds (SPC) and γ-aminobutyric acid (GABA) content. Additionally, the antioxidant and angiotensin-converting enzyme (ACE) inhibition activities of aqueous extracts from kidney bean elicited sprouts were determined. Elicitation by glutamic acid for 8 days led to the highest SPC and GABA accumulation in kidney bean sprouts and their extracts were selected based on their highest phytochemical content. These extracts also showed remarkable antioxidant and ACE-inhibitory activities. The IC₅₀ for ACE inhibition of glutamic acid-extracts increases 89-fold after the in-vitro gastrointestinal digestion. These results will contribute not only to improving the health-promoting potential of kidney bean sprouts but also to obtaining ingredients which might reduce oxidative stress and hypertension.     

Antioxidant potential of barley as affected by alkaline hydrolysis and release of insoluble-bound phenolics

Phenolic constituents of six barley varieties, namely Falcon, AC Metcalfe, Tyto, Tercel, Phoenix and Peregrine were separated into free, soluble conjugate and insoluble-bound fractions. Soluble conjugates and insoluble-bound phenolics were extracted into diethyl ether after consecutive alkaline hydrolysis for 4 h. Total phenolic content of each of the three fractions was determined by using Folin–Ciocalteau method. Total antioxidant capacity of the phenolic fractions was determined by trolox equivalent antioxidant capacity (TEAC) assay. The extracts were evaluated for their efficacy in scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. Oxygen radical scavenging capacity (ORAC_FL) of the extracts was determined using a fluorometric assay. Effectiveness of phenolic extracts in inhibiting oxidation of human LDL cholesterol and radical-induced supercoiled DNA breakage was also evaluated. The contribution of insoluble-bound phenolics toward total phenolic content was significantly (p < 0.05) higher than the soluble phenolics for all barley extracts tested. The ratio of soluble to insoluble phenolics ranged from 1:27 to 1:35. TEAC and ORAC values and DPPH radical scavenging capacity of the insoluble phenolic fraction were significantly (p < 0.05) higher than those of their insoluble counterparts. A similar trend was observed against inhibition of LDL cholesterol oxidation and radical-induced DNA breakage.     

Cytoprotective and antioxidant activity of free,conjugated and insoluble-bound phenolic acids from swallow root (Decalepis hamiltonii)

Swallow root (Decalepis hamiltonii) was extracted for free (SRFP), conjugated (SRCP) and insoluble-bound phenolic acids (SRIBP), and evaluated for cytoprotectivity, 1,1,diphenyl-2-picrylhydrazyl (DPPH) scavenging ability, reducing power and protection to DNA damage. In addition, the constituent phenolic acids in the extracts were also analysed. Results indicated a total phenol content of 20.72, 7.97 and 11.52 mg gallic acid equivalents (GAE)/g for SRFP, SRCP and SRIBP extracts, respectively. At 0.12 μg/mL concentration SRCP showed 87% cytoprotection (on NIH 3T3 cells) compared to SRFP (47%) and SRIBP (65%). DPPH radical scavenging activity indicated an IC₅₀ of 0.046, 0.06 and 0.128 μg/mL for SRCP, SRIBP and SRFP, respectively. Also, SRCP showed higher reducing power and DNA protectivity (80%). HPLC analysis of phenolic acid extracts showed the presence of hydroxybenzoate and cinnamate derivatives. Among the phenolics identified gallic, gentisic, protocatechuic and p-coumaric acids were the major contributors to antioxidant activity.     

Iron decreases the antioxidant capacity of red wine under conditions of in vitro digestion

The hypothesis that iron and phenolics interact in the lumen during digestion and, consequently, decrease the antioxidant capacity of phenolics, was investigated in vitro. Mixtures of red wine, iron, and three dietary factors that may reduce or chelate iron in the lumen, namely ascorbic acid, meat and casein, were subjected to a simulated gastrointestinal digestion. The process involved incubation of samples for 4.5 h at 37 °C, at different pHs, in the presence of peptic enzymes and fractionation of digests through a dialysis membrane. Antioxidant capacity (FRAP assay), iron concentration (ferrozine assay) and total phenolic content (Folin-Ciocalteau assay) were measured in the in vitro digests. Iron decreased the antioxidant capacity and the total phenolic concentration of red wine. Ascorbic acid increased, while meat and casein decreased, the antioxidant capacity of red wine. Based on these results, it was concluded that protein and iron interact with red wine phenolics during the in vitro digestion and decrease their antioxidant capacity, supporting the initial hypothesis.     

苹果模拟胃肠消化后的多酚释放和抗HepG2细胞增殖活性研究

分别采用80%丙酮提取以及模拟胃肠消化法提取苹果中的多酚,测定提取物的多酚释放量以及抗HepG2细胞增殖的活性。结果显示,在水晶富士、嘎啦果和青苹果的80%丙酮提取物中,绿原酸的释放量最高,分别为30.72±1.54、22.37±1.12、8.70±0.44 mg/kg FW(Fresh weight,FW)。模拟胃消化后释放量较高的为原儿茶酸、对羟基苯甲酸、没食子酸和绿原酸等酚酸;模拟肠消化后释放量较高的为槲皮苷、槲皮素-3-葡萄糖苷、扁蓄苷等黄酮醇。水晶富士、嘎啦果和青苹果的模拟胃消化及模拟肠消化后的提取物(浓度分别为297、99、255 mg/mL和198、154、106 mg/mL)作用于HepG2细胞72 h后,细胞的存活率分别为26%、42%、44%和23%、28%、28%。这表明,模拟胃消化主要促进酚酸的释放,模拟肠消化主要促进黄酮醇的释放;在一定浓度范围内,苹果模拟胃肠消化提取物对HepG2细胞有较强的抗增殖活性。     

Effect of extrusion cooking and simulated in vitro gastrointestinal digestion on condensed tannins and radical scavenging activity of type II and type III whole grain sorghum

The effect of extrusion cooking and simulated in vitro gastrointestinal digestion on proanthocyanidins in type II and III tannin sorghums was studied. Extrusion cooking was performed at different feed moisture levels (2 L h^?1, 3 L h^?1, 5 L h^?1 and 8 L h^?1), with a barrel temperature of 150 °C followed by in vitro gastrointestinal digestion. Extrusion cooked samples had lower total phenols, tannin content and radical scavenging properties than unprocessed tannin sorghum flour. For extrudates, there was progressive increase in total phenols and tannin content with increase in feed moisture. Extrusion cooked samples had increased proportion of dimers and decreased oligomers in the two tannin sorghums. Gastric and duodenal digests of the extrudates contained high proportions of monomers and dimers and some oligomeric proanthocyanidin species. Undigested porridges, gastric and duodenal digests inhibited radical‐induced oxidative DNA damage. Extruded tannin sorghum may have health‐promoting potential in relation to combating chronic diseases associated with oxidative stress.     

Phytochemicals and antioxidant activity of different fruit fractions (peel,pulp, aril and seed) of Thai gac (Momordica cochinchinensis Spreng)

Three fractions (peel, pulp and aril) of gac fruit (Momordica cochinchinensis Spreng) were investigated for their phytochemicals (lycopene, beta-carotene, lutein and phenolic compounds) and their antioxidant activity. The results showed that the aril had the highest contents for both lycopene and beta-carotene, whilst peel (yellow) contained the highest amount of lutein. Two major phenolic acid groups: hydroxybenzoic acids and hydroxycinnamic were identified and quantified. Gallic acid and p-hydroxybenzoic acid were found in all fractions. Ferulic acid and p-hydroxybenzoic acid were most evident in pulp. Myricetin was the only flavonoid found in all fractions. Apigenin was the most predominant flavonoid in pulp (red), whereas rutin and luteolin gave the highest content in aril. The extracts of different fractions exhibited different levels of antioxidant activity in the systems tested. The aril extract showed the highest FRAP value. The greatest antioxidant activities of peel and pulp extracts were at immature stage, whereas those in the seed extracts increased from mature stage to ripe stage. The contents of total phenolic and total flavonoid in peel and pulp decreased during the fruit development stage (immature > ripe fruit) and subsequently displayed lower antioxidant capacity, except for the seed.     

Stability of Pycnogenol® as an ingredient in fruit juices subjected to in vitro gastrointestinal digestion

BACKGROUND: The enrichment of fruit juices with concentrated polyphenolic extracts is an expedient strategy to compensate possible phenolic loss through gastrointestinal processing. Pycnogenol®, a standardised procyanidin‐rich extract from pine bark, has been proposed as a potential candidate for polyphenol enrichment of foods. In this study the effects of in vitro digestion on the phenolic profile of fruit juices enriched with Pycnogenol® were investigated. RESULTS: After in vitro digestion the level of detectable total phenolic compounds (expressed as gallic acid equivalent) was higher in both pineapple and red fruit juices enriched with Pycnogenol® than in non‐enriched commercial juices. Five phenolic monomeric compounds were identified by high‐performance liquid chromatography, namely chlorogenic acid, caffeic acid, ferulic acid, gallic acid and taxifolin, the last two being predominant. In vitro digestion of both Pycnogenol®‐enriched pineapple and red fruit juices led to a significant (P < 0.05) increase in detectable chlorogenic and ferulic acids, indicating that hydrolysis of more complex molecules occurs. On the other hand, in vitro digestion of non‐enriched juices was associated with a decrease in gallic and caffeic acids in pineapple juice and with a decrease in ferulic acid in red fruit juice. In no case did in vitro digestion increase the amount of detectable phenolic compounds in non‐enriched juices. CONCLUSION: The stability of Pycnogenol® after in vitro gastrointestinal digestion makes it a good choice for phenolic enrichment of fruit juices. Copyright © 2010 Society of Chemical Industry     

Antioxidant properties of lotus seed and its effect on DNA damage in human lymphocytes

The antioxidant properties of lotus seeds extracts and their effect on DNA damage in human lymphocytes were investigated. The results showed that boiling water extracts of lotus seeds (WELS) exhibited stronger antioxidant activity and that boiling water gave higher yields of extracts than other organic solvents. The WELS showed significant chelating binding on ferrous ions and marked interaction with hydrogen peroxide. Phenolic acids including caffeic acid, chlorogenic acid, p-hydroxybenzoic acid, gallic acid and large amounts of phenolic compounds, as found in WELS, were conjectured to be responsible for the antioxidant activity of WELS. The WELS showed neither changes on lipid peroxidation nor DNA damage in human lymphocytes with or without inducement by hydrogen peroxide.     

In vitro digestibility of starch in cooked potatoes as affected by guar gum: Microstructural and rheological characteristics

Potatoes from different New Zealand cultivars (Nadine, Moonlight, Red Rascal, Agria) were analysed for starch digestibility in vitro (under simulated gastric and small intestinal conditions). The extent of starch hydrolysis (%) for all the potato cultivars ranged between 85% and 95% at the end of in vitro digestion. Nadine potatoes, which were waxy in texture, showed higher starch hydrolysis (%) whereas these levels did not differ significantly among the other three cultivars. Confocal laser scanning microscopy and scanning electron microscopy were performed on the digests in order to study the microstructural changes occurring during digestion in cooked potatoes. The micrographs clearly showed that starch was quickly hydrolysed by the enzymes present in simulated intestinal fluid (SIF) whereas the cell walls remained intact during simulated digestion process. Addition of guar gum (0.5%) to cooked potatoes reduced their starch hydrolysis (%) by ∼15% during the in vitro digestion. Online viscosity measurements were also performed on the cooked potatoes during simulated small intestinal digestion using a dynamic rheometer. Cooked potato viscosity dropped considerably upon the action of enzymes from SIF on starch as the digestion progressed. The presence of 0.5% guar gum facilitated the cooked potato matrix to maintain viscosity similar to undigested cooked potato sample throughout the in vitro digestion, which might have resulted in lower starch hydrolysis (%).     

Araçá (Psidium cattleianum Sabine) fruit extracts with antioxidant and antimicrobial activities and antiproliferative effect on human cancer cells

Araçá or strawberry guava (Psidium cattleianum Sabine) is an attractive tasty small fruit native to temperate zones of Brazil. In this study, functional chemical constituents and the nutraceutical and therapeutic potential of aqueous and acetone extracts of red and yellow accessions of araçá were characterised. While carotenes, ascorbic acid, and anthocyanins were present as minor constituents, araçá fruit presented high levels of phenolic compounds (up to 768 mg 100 g⁻¹ fresh fruit pulp, ffp), particularly (−)-epicatechin (up to 2.7 mg g⁻¹ ffp), which were in general more efficiently extracted with acetone. Abundance of phenolic compounds was positively correlated with antioxidant activity, antimicrobial and antiproliferative effects.     

The hydroxycinnamic acid content of barley and brewers’ spent grain (BSG) and the potential to incorporate phenolic extracts of BSG as antioxidants into fruit beverages

The hydroxycinnamic acid (HA) content of starting barley for brewers’ spent grains (BSG), whole BSG and phenolic extracts from BSG was measured using high performance liquid chromatography (HPLC) and correlated with antioxidant potential. The effect of BSG phenolic extracts on antioxidant activity of fruit beverages was also assessed (using the total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays). The concentration of HA present in barley extract and BSG was in the order of ferulic acid (FA), p-coumaric acid (p-CA) derivatives, FA derivatives, p-CA, caffeic acid (CA) and CA derivatives. Results suggested that brewing and roasting decreased the HA content. Antioxidant activity was significantly (P < 0.05) correlated with caffeic acid (R² = 0.8309) and total HA (R² = 0.3942) concentrations. Addition of extracts to fruit beverages resulted in a significant (P < 0.05) increase in antioxidant activity of cranberry juice, measured by the FRAP assay. In vitro digestion significantly (P < 0.05) reduced TPC, DPPH and FRAP activity of the fruit beverages.     

Variations in phenolic composition and antioxidant properties among 15 basil (Ocimum basilicum L.) cultivars

In this study, the influences of cultivar on the phenolic composition and antioxidant properties of 15 different basil varieties was determined. Cultivar had a statistically significant effect on total phenolic levels (p < 0.001) and anthocyanin concentrations (p < 0.001). Analysis of individual phenolic acid levels by high-performance liquid chromatography showed substantial variations in the phenolic acid profiles among cultivars. Rosmarinic (p < 0.001), chicoric (p = 0.002) and caffeic (p = 0.001) acid concentrations were affected by cultivar, although caftaric acid levels (p = 0.083) were not. Nine of the cultivars in this study contained chicoric acid in higher concentrations than rosmarinic acid. These are the first basil cultivars that have been identified in which rosmarinic acid is not the dominant phenolic acid. In addition, six of the cultivars in this study had caftaric and caffeic acid concentrations that were similar or higher than rosmarinic acid levels. Cultivar also had a significant impact on both FRAP (ferric reducing antioxidant power, p = 0.007) and DPPH (2,2′-diphenyl-1-picrylhydrazyl, p = 0.004) antioxidant capacities. For the basil cultivars in this study, the individual phenolic acid composition was found to be an important factor influencing the measured antioxidant capacity.     

Automatic, rapid screening of seed resistance in cowpea, Vigna unguiculata (L.) Walpers, to the seed beetle Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) using acoustic monitoring

The biomonitor technique was investigated as a rapid and automatic method for measuring the resistance of cowpea varieties to the seed beetle Callosobruchus maculatus. This technique measures the activity of internally feeding insect larvae by counting ultrasonic emissions produced as they feed. Activity throughout the development of C. maculatus larvae in known susceptible and resistant cowpea varieties was recorded. This showed details of the development of each larval instar, and showed clear differences between the resistant and susceptible cowpeas. A rapid method for comparing cowpeas was proposed in which the activity of larvae was recorded for 24 h starting 14 days after oviposition. Using this method, significant differences in activity were apparent between one susceptible and two resistant cowpea varieties. Further comparisons using a randomised block experimental design also showed a clear difference in activity between one susceptible and one known resistant cowpea variety. This experimental protocol took 21 days. It is suggested that the biomonitor offers a promising method for screening seeds for resistance to insect pests with a reduction in the time and effort required over conventional bioassay methods.     

Relationship between the solubility,dosage and antioxidant capacity of carnosic acid in raw and cooked ground buffalo meat patties and chicken patties

Antioxidant capacity of oil soluble and water dispersible carnosic acid (CA) extracted from dried rosemary leaves using HPLC was evaluated at two different dosages (22.5 ppm vs 130 ppm) in raw and cooked ground buffalo meat patties and chicken patties. Irrespective of total phenolic content, CA extracts reduced (p < 0.05) the thiobarbituric acid reactive substances (TBARS) by 39%–47% and 37%–40% in cooked buffalo meat and chicken patties at lower dosage (22.5 ppm) relative to control samples. However, at higher dosage (130 ppm) the TBARS values were reduced (p < 0.05) by 86%–96% and 78%–87% in cooked buffalo meat and chicken patties compared to controls. The CA extracts were also effective in inhibiting (p < 0.05) peroxide value and free fatty acids in cooked buffalo meat and chicken patties. The CA extracts when used at higher dosage, were also effective in stabilizing raw buffalo meat color.     

Phenolic profile of Sercial and Tinta Negra Vitis vinifera L. grape skins by HPLC–DAD–ESI-MS: Novel phenolic compounds in Vitis vinifera L. grape

This study represents the first phytochemical research of phenolic components of Sercial and Tinta Negra Vitis vinifera L. The phenolic profiles of Sercial and Tinta Negra V. vinifera L. grape skins (white and red varieties, respectively) were established using high performance liquid chromatography–diode array detection–electrospray ionisation tandem mass spectrometry (HPLC–DAD–ESI-MSⁿ), at different ripening stages (véraison and maturity). A total of 40 phenolic compounds were identified, which included 3 hydroxybenzoic acids, 8 hydroxycinnamic acids, 4 flavanols, 5 flavanones, 8 flavonols, 4 stilbenes, and 8 anthocyanins. For the white variety, in both ripening stages, hydroxycinnamic acids and flavonols were the main phenolic classes, representing about 80% of the phenolic composition. For red variety, at véraison, hydroxycinnamic acids and flavonols were also the predominant classes (71%), but at maturity, anthocyanins represented 84% of the phenolic composition. As far as we know, 10 compounds were reported for the first time in V. vinifera L. grapes, namely protocatechuic acid-glucoside, p-hydroxybenzoyl glucoside, caftaric acid vanilloyl pentoside, p-coumaric acid-erythroside, naringenin hexose derivate, eriodictyol-glucoside, taxifolin-pentoside, quercetin-glucuronide-glucoside, malylated kaempferol-glucoside, and resveratrol dimer. These novel V. vinifera L. grape components were identified based on their MSⁿ fragmentation profile. This data represents valuable information that may be useful to oenological management and to valorise these varieties as sources of bioactive compounds.