Interactions of polyphenols with carbohydrates, lipids and proteins

Nutrient values and bioactivities of the extracts from three fern species in China: a comparative assessment

Pteridium aquilinum, Osmunda cinnamomea Linn, and Athyrium multidentatum (Doll.) Ching are three fern species widely consumed as potherbs and traditional medicinal herbs in China. Nevertheless, no detailed comparative assessments of their nutrient values and bioactivities have been reported. In this paper, we examined the nutrient content of these ferns and the bioactivities of their extracts with a comparative method. The results indicated that they were nutrient dense for proteins, carbohydrates, fat and minerals. Compared with Pteridium aquilinum and Osmunda cinnamomea Linn, the extract from Athyrium multidentatum (Doll.) Ching was found to possess the strongest antioxidant activity, protective effects on biomolecules, cellular antioxidant activity, and antiproliferative effects owing to its highest total phenolic (476.52 ± 11.26 mg GAE per g extract) and total flavonoid (924.81 ± 4.25 mg RNE per g extract) contents. Further, Athyrium multidentatum (Doll.) Ching can lead to caspase-3 activation, poly ADP-ribose polymerase cleavage, mitochondrial membrane potential (MMP) reduction and inhibition of wound-healing in a dose-dependent manner in HepG2 cells. These results demonstrate the remarkable potential of Pteridium aquilinum, Osmunda cinnamomea Linn, and Athyrium multidentatum (Doll.) Ching as valuable sources of nutrients and natural antioxidants, and among which Athyrium multidentatum (Doll.) Ching has potential anticancer properties.

Impact of chemical structure of flavanol monomers and condensed tannins on in vitro anthelmintic activity against bovine nematodes

Plants containing condensed tannins (CT) may have potential to control gastrointestinal nematodes (GIN) of cattle. The aim was to investigate the anthelmintic activities of four flavan-3-ols, two galloyl derivatives and 14 purified CT fractions, and to define which structural features of CT determine the anti-parasitic effects against the main cattle nematodes. We used in vitro tests targeting L1 larvae (feeding inhibition assay) and adults (motility assay) of Ostertagia ostertagi and Cooperia oncophora. In the larval feeding inhibition assay, O. ostertagi L1 were significantly more susceptible to all CT fractions than C. oncophora L1. The mean degree of polymerization of CT (i.e. average size) was the most important structural parameter: large CT reduced larval feeding more than small CT. The flavan-3-ols of prodelphinidin (PD)-type tannins had a stronger negative influence on parasite activity than the stereochemistry, i.e. cis- vs trans-configurations, or the presence of a gallate group. In contrast, for C. oncophora high reductions in the motility of larvae and adult worms were strongly related with a higher percentage of PDs within the CT fractions while there was no effect of size. Overall, the size and the percentage of PDs within CT seemed to be the most important parameters that influence anti-parasitic activity.

Biophysical evaluation of protein structural flexibility for ligand biorecognition in solid solution

The structural flexibility of biomolecules may have a large influence on ligand–receptor recognition.

Factors Influencing Oral Bioavailability of Thai Mango Seed Kernel Extract and Its Key Phenolic Principles

Mango seed kernel extract (MSKE) and its key components (gallic acid, GA; methyl gallate, MG; and pentagalloyl glucopyranose, PGG) have generated interest because of their pharmacological activities. To develop the potential use of the key components in MSKE as natural therapeutic agents, their pharmacokinetic data are necessary. Therefore, this study was performed to evaluate the factors affecting their oral bioavailability as pure compounds and as components in MSKE. The in vitro chemical stability, biological stability, and absorption were evaluated in Hanks' Balanced Salt Solution, Caco-2 cell and rat fecal lysates, and the Caco-2 cell model, respectively. The in vivo oral pharmacokinetic behavior was elucidated in Sprague-Dawley rats. The key components were unstable under alkaline conditions and in Caco-2 cell lysates or rat fecal lysates. The absorptive permeability coefficient followed the order MG > GA > PGG. The in vivo results exhibited similar pharmacokinetic trends to the in vitro studies. Additionally, the co-components in MSKE may affect the pharmacokinetic behaviors of the key components in MSKE. In conclusion, chemical degradation under alkaline conditions, biological degradation by intestinal cell and colonic microflora enzymes, and low absorptive permeability could be important factors underlying the oral bioavailability of these polyphenols.

Metabolic Characteristics in Meal of Black Rapeseed and Yellow-Seeded Progeny of Brassica napus-Sinapis alba Hybrids

Breeding of yellow-seeded rapeseed (Brassica napus) is preferred over black-seeded rapeseed for the desirable properties of the former. This study evaluated the metabolites and nutritive values of black-seeded rapeseed meal and yellow-seeded meal from the progeny of a B. napus–Sinapis alba hybrid. Yellow-seed meal presented higher protein (35.46% vs. 30.29%), higher sucrose (7.85% vs. 7.29%), less dietary fiber (26.19% vs. 34.63%) and crude fiber (4.56% vs. 8.86%), and less glucosinolates (22.18 vs. 28.19 μmol/g) than black-seeded one. Amounts of ash (3.65% vs. 4.55%), phytic acid (4.98% vs. 5.60%), and total polyphenols (2.67% vs. 2.82%) were decreased slightly in yellow-seeded meal compared with black-seeded meal. Yellow-seeded meal contained more essential amino acids than black-seeded meal. Levels of the mineral elements Fe, Mn, and Zn in yellow-seeded meal were higher than black-seeded meal. By contrast, levels of P, Ca, and Mg were lower in yellow-seeded meal. Moreover, yellow-seeded meal showed lower flavonol (kaempferol, quercetin, isorhamnetin, and their derivatives) content than black-seeded meal. Comparison of metabolites between yellow and black rapeseed confirmed the improved nutritional value of meal from yellow-seeded B. napus, and this would be helpful to the breeding and improvement of rapeseed for animal feeding.

Effect of theanine and polyphenols enriched fractions from decaffeinated tea dust on the formation of Maillard reaction products and sensory attributes of breads

The antiglycoxidative properties of theanine (TEF) and polyphenols enriched fractions (PEF) prepared from tea dust were tested in a model system composed of bovine serum albumin (BSA) and methylglyoxal (MGO). PEF caused a decrease in available free amino groups of BSA in presence and absence of MGO, suggesting the simultaneous occurrence of glycoxidation reaction and phenols-protein interaction. The presence of PEF and TEF inhibited formation of fluorescent advanced glycation end-products (AGEs). Moreover, theanine (TB) and polyphenol-enriched bread (PB) were formulated. A significant increase in free amino groups was observed in TBs with a dose-response effect, while addition of PEF in bread produced a significant decrease (p<0.05). PEF efficiently reduced fluorescent AGE formation in breads compared with TEF. The results are in line with the simplified model systems. PEF used as food ingredient allows obtaining a tasty food possessing health promoting properties and lower content of potential harmful compounds (AGEs).

Enhanced stability of anthocyanin-based color in model beverage systems through whey protein isolate complexation

Anthocyanins are often used in functional foods and beverages as colorants and nutraceuticals. However, these natural compounds may undergo chemical degradation during storage leading to color fading and loss of bioactivity. In particular, vitamin C (l-ascorbic acid) is known to accelerate anthocyanin degradation. In this study, the influence of various food-grade biopolymers on the physical and chemical stability of model beverages containing anthocyanin (0.025%), ascorbic acid (0 or 0.05%), and calcium salt (0 or 0.01%) was examined under accelerated conditions (40°C for 7days). Four biopolymers (1%) were examined for their potential to inhibit anthocyanin degradation: native whey protein; denatured whey protein; citrus pectin; and beet pectin. The physical stability was determined by measuring changes in absorbance, color, and visual appearance. Solutions containing anthocyanin and calcium salt (0 or 0.01%) were stable throughout storage, while those with added ascorbic acid were the least stable. The addition of biopolymers, particularly heat denatured whey protein, significantly enhanced the stability of the anthocyanin during storage. Fluorescence quenching studies showed that the anthocyanin may have formed complexes with the whey protein through hydrogen bonding that resulted in their enhanced stability in the presence of ascorbic acid. This study provides information that may improve the stability of anthocyanins in food and beverage systems.

A validated liquid chromatography-tandem mass spectrometry method for the determination of methyl gallate and pentagalloyl glucopyranose: application to pharmacokinetic studies

Methyl gallate (MG) and pentagalloyl glucopyranose (PGG) are bioactive phenolic compounds that are widely distributed in herbs and plant foods. Their potential activities include anti-oxidant, anti-inflammatory, anti-cancer, anti-bacterial and anti-viral activities. However, knowledge concerning the pharmacokinetic characteristics of MG and PGG is limited. The purpose of this study was to develop a sensitive and reproducible ultra-performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) method to simultaneously quantify MG and PGG in rat blood samples. The linear response ranges for MG and PGG were 0.0195-20 and 0.0390-20 μM, respectively. The lower limit of quantification was 0.0195 μM for MG and 0.0390 μM for PGG. The intra- and inter-day variances were less than 15%, and accuracy was within 80-120%. This assay was successfully applied to pharmacokinetic studies in Sprague-Dawley rats after intraperitoneal administration of MG and PGG (20 mg/kg). The values of areas under the blood concentration time curves (AUC₀₋₂₄ h) for MG and PGG were 109.9 ± 73.40 and 38.78 ± 24.53 h*μM, respectively. The maximum blood concentrations (Cmax) of MG and PGG were 34.72 ± 17.32 and 6.39 ± 4.25 μM, respectively. The time required to reach the maximum concentration (Tmax) was 0.85 ± 0.70 h for both MG and PGG. The values of the elimination rate constant (Ke), elimination half-life (t1/2), volume of distribution (Vd), clearance (Cl) and mean resident time (MRTlast) were 0.056 ± 0.032 h(-1), 17.50 ± 12.25 h, 530.95 ± 247.54 L/kg, 159.91±76.05L/h/kg, 8.71 ± 2.53 h for MG and 0.023 ± 0.012 h(-1), 38.66 ± 22.89 h, 7838.89 ± 3474.72 L/kg, 30.98 ± 21.73 L/h/kg, 12.47 ± 2.77 h for PGG, respectively. In conclusion, a UPLC-MS/MS method was fully validated over a wide linear range and used to quantify the levels of MG and PGG in pharmacokinetic studies of MG and PGG in rats. The main advantages of this method are the use of small blood volumes (10 μL), rapid analysis (5 min) and excellent recoveries.

Effects of various fibre-rich extracts on cholesterol binding capacity during in vitro digestion of pork patties

Intake of foods containing high levels of cholesterol harms human health, and an increase in the intake of dietary fibre (DF) may mitigate these negative effects.

Glycosylation improves the functional characteristics of chlorogenic acid–lactoferrin conjugate

Chlorogenic acid (CA)–lactoferrin (LF) conjugate prepared via alkali treatment was glycoslated with glucose (Glc) or polydextrose (PD) by the Maillard reaction, and the modification improved the functional properties of the conjugate.