Prevention of in vitro oxidation of low density lipoproteins (LDL) by amaranth peptides released by gastrointestinal digestion

Simultaneous extraction of crocin and geniposide from gardenia fruits (Gardenia jasminoides Ellis) by probe-type ultrasound-assisted natural deep eutectic solvents and their inhibition effects on low density lipoprotein oxidation

The simultaneous extraction of crocin and geniposide from gardenia fruits (Gardenia jasminoides Ellis) was performed by integrating natural deep eutectic solvents (NADES) and ultrasound-assisted extraction (UAE). Among the eight kinds of NADES screened, choline chloride-1,2-propylene glycol was the most suitable extractant. The probe-type ultrasound-assisted NADES extraction system (pr-UAE-NADES) demonstrated higher extraction efficiency compared with plate-type ultrasound-assisted NADES extraction system (pl-UAE-NADES). Orthogonal experimental design and a modified multi-index synthetic weighted scoring method were adopted to optimize pr-UAE-NADES extraction process. The optimal extraction conditions that had a maximum synthetic weighted score of 29.46 were determined to be 25 °C for extraction temperature, 600 W for ultrasonic power, 20 min for extraction time, and 25% (w/w) for water content in NADES, leading to the maximum yields (7.39 ± 0.20 mg/g and 57.99 ± 0.91 mg/g, respectively) of crocin and geniposide. Thirty-three compounds including iridoids, carotenoids, phenolic acids, flavonoids, and triterpenes in the NADES extract were identified by LC-Q-TOF-MS2 coupled with a feature-based molecular networking workflow. The kinetics evaluation of the conjugated dienes generation on Cu2+-induced low density lipoprotein (LDL) oxidation via the four-parameter logistic regression model showed that crocin increased the lag time of LDL oxidation in a concentration-dependent manner (15 μg/mL, 30 μg/mL, 45 μg/mL) by 12.66%, 35.44%, and 73.42%, respectively. The quantitative determination for fluorescence properties alteration of the apolipoprotein B-100 exhibited that crocin effectively inhibited the fluorescence quenching of tryptophan residues and the modification of lysine residues caused by reactive aldehydes and malondialdehydes. The pr-UAE-NADES showed significant efficiency toward the simultaneous extraction of crocin and geniposide from gardenia fruits. And this study demonstrates the potential utility of gardenia fruits in developing anti-atherogenic functional food.

Chemical and cell antioxidant activity of amaranth flour and beverage after simulated gastrointestinal digestion. Role of peptides

The potential of peptides generated by simulated gastrointestinal digestion (SGID) of two products derived from Amaranthus manteggazianus seeds, flour (F) and beverage (B), to exert peroxyl scavenging activity (ORAC) and antioxidant action on intestinal cells was studied. B was prepared by solubilisation of seed proteins, with the addition of gums and the application of a pasteurization treatment. The gastrointestinal digests FD and BD showed some differences in the peptide/polypeptide composition. The SGID produced increased ORAC activity for both samples, with some differences in the ORAC of the whole digests BD and FD and of some gel filtration fractions. Bioaccessible fractions (FDdbs and BDdbs) were obtained after treatment with cholestyramine resin to remove bile salts due to their cytotoxicity and oxidative effect. BDdbs presented a greater ORAC potency (IC50: 0.05 ± 0.01 and 0.008 ± 0.004 mg protein/ml for FDdbs and BDdbs, respectively). These fractions showed low cytotoxicity values (measured by LDH release) and produced high intracellular ROS inhibition (around 80 %), increased the SOD activity and the GSH content, with no effect on GPx activity in Caco2-TC7 cells exposed to H2O2. Several fractions with MM < 2.2 kDa presented also these cellular actions; fractions from FD induced higher increases in GSH concentration. Amaranth flour and a processed matrix like the beverage are shown as sources of bioactive peptides with potential cell antioxidant activity.

Amaranth proteins and peptides: Biological properties and food uses

Amaranthus grains have attracted great attention due to its attractive health benefits. The grains have processing properties (e.g., starch related properties) similar to those of common cereals. Amaranth grains are gluten free and protein is a significant component of these grains. Proteins of the grains have been used in various food applications such as formulations of edible films and emulsions for controlled release of bioactive compounds. The proteins have been hydrolyzed using different enzymes to produce peptides and hydrolysates, which showed a range of biological functions including anti-hypertensive and antioxidant activities among others. They have been formulated into staple foods including breads and pastas for improved nutritional quality. This review summarizes the recent advances of the last 5 years in understanding the biological functions and food applications of proteins, protein hydrolysates and peptides from the grains of different Amaranthus species. Limitations in the studies summarized are critically discussed with an aim to improve the efficiency in amaranth grain protein and peptide research.

Amino acid composition, mineral profile, free radical scavenging ability, and carbohydrase inhibitory properties of Moringa oleifera seed globulin, hydrolysates, and membrane fractions

The nutritional-amino acid profile and mineral element of Moringa oleifera seed globulin (GLO) and its hydrolysates as well as the in vitro bioactive properties-antioxidant, alpha-amylase, and alpha-glucosidase inhibition of the GLO, hydrolysates, and membrane fractions were reported. The results showed that M. oleifera contained significant amounts of essential amino acids (EAA), which are more than the minimum required by the Food and Agricultural Organization for children, except for tryptophan, which was the limiting amino acid. However, hydrolysis mostly led to a reduction in the contents of the EAA. While the process of hydrolysis and the subsequent membrane fractionation produced peptides with improved activities in 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid radical scavenging ability and oxygen radical absorbance capacity, this process produced no activities in superoxide radical scavenging ability, α-amylase, and α-glucosidase inhibitory potentials of some of the hydrolysates and peptides fractions. In summary, M. oleifera seed peptide fraction (<3 kDa) from the alcalase-derived hydrolysate contains potent antioxidants but relatively low in vitro antidiabetic properties. PRACTICAL APPLICATIONS: Several studies have established the ability of proteins, including hydrolysate and peptide fractions to provide some bioactive properties such as antioxidant, antidiabetic, anti-inflammatory among others. However, because protein functionalities are influenced by several factors such as the source, type, processing method employed among others, research has continued to evaluate the bioactivities of proteins under different conditions. In this study, therefore, we reported the impact of processing methods (hydrolysis, enzyme type, and peptide size) on the nutritional, antioxidant, and in vitro antidiabetic properties of M. oleifera seed globulin, its hydrolysates, and membrane fractions. This information plays an important role in the further exploitation of M. oleifera seed proteins in the development of functional foods and nutraceuticals.

Composition, anti-LDL oxidation, and non-enzymatic glycosylation inhibitory activities of the flavonoids from Mesembryanthemum crystallinum

This study identified the constituents of purified flavonoid (PEF) isolated from Mesembryanthemum crystallinum and examined their inhibitory effects on low-density lipoprotein (LDL) oxidation and non-enzymatic glycosylation. More than 30 kinds of flavonoid compounds were identified in M. crystallinum, including tangeretin, nobiletin, farrerol, protocatechuic aldehyde, diosmin, and rutin. Moreover, tangeretin corresponds to approximately 51% of the total identified flavonoids. PEF had a low IC50 value for 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH·), hydroxyl radical (·OH), and superoxide anion free radical (O2-·) scavenging. They were found to effectively delay and inhibit the production of conjugated diene (CD) and thiobarbituric acid reactive substance (TBARS) during LDL oxidation. Meanwhile, scanning electron microscopy (SEM) of the LDL oxidation incubation system with PEF showed a smooth and dense surface, with no obvious cavitation phenomenon. Furthermore, PEF effectively inhibited the production of LDL glycosylation products and showed a strong inhibitory effect in the latter stage. The electrophoresis of advanced glycosylation end products (AGEs) further confirmed that PEF can effectively prevent the cross-linking between glucose and proteins, protecting LDL from glycosylation-induced damage.

Peptides derived from the gastrointestinal digestion of amaranth 11S globulin: Structure and antioxidant functionality

The relationship between structural and physicochemical properties and antioxidant activity of peptides from amaranth 11S-globulin was studied. Peptides AWEEREQGSR, TEVWDSNEQ, IYIEQGNGITGM and YLAGKPQQEH had the greatest in vitro activity (ORAC, HORAC). GDRFQDQHQ, HVIKPPSRA and KFNRPETT were the most active ones against Cu⁺²/H₂O₂-induced-LDL oxidation. In a cellular system (H₂O₂-induced-Caco2-TC7), TEVWDSNEQ, IYIEQGNGITGM, GDRFQDQHQ, LAGKPQQEHSGEHQ and KFNRPETT were the most effective in decreasing ROS, while the effects on SOD, GPx, and GSH were variable. To understand the structure-antioxidant activity relationships, the content of aromatic and acidic amino acids, the degree of hydrophobicity and the charge distribution on the accessible surface of peptides structures obtained by molecular dynamics were analysed. The low correlation between in vitro, ex vivo and cellular activities could be explained by the influence of physicochemical and structural properties on the interaction with complex systems (LDL/cells), peptide modifications and/or mechanisms other than direct ROS inhibition in the cells.

Antioxidant effect of amaranth flour or protein isolate incorporated in high-fat diets fed to Wistar rats. Influence of dose and administration duration

This study evaluated the effect on Wistar rat's oxidative status of incorporating amaranth flour (AF) and protein isolate (AI) in increased-fat diets. Five of the groups were fed for 4 weeks with either BD (basal diet), Chol+F (2% cholesterol, 10% porcine fat), Chol+F+E (0.005% α-tocopherol), Chol+F+AF₁ or Chol+F+AI₁ (25% of protein replacement) diets. The other two groups were fed for 4 weeks with Chol+F and then 1 week with Chol+F+AF₂ or Chol+F+AI₂ diet (50% of protein replacement). Various effects on the oxidative stress biomarkers in tissues (intestine and liver) were observed. These effects were dependent on the ingredients, dose, and administration time. In the intestinal cells, Chol+F+AF₁ and Chol+F+AI₂ produced an increment in the reduced glutathione (GSH) content (56% and 39%, respectively), while Chol+F+AF₂ induced an increment in the superoxide dismutase (SOD) (25%) and glutathione peroxidase (GPx) (46%) activities. The presence of certain components in flour (e.g., fiber, polyphenols, squalene) could explain the higher activity recorded for AF. In the liver, Chol+F+AF₂ produced a decrease in SOD (19%) and GSH (36%), as well as an increase in GPx (255%); Chol+F+AI₁ and Chol+F+AI₂ also produced a decrease in GSH (36% and 24%, respectively) and important increments in GPx activity (273% for Chol+F+AI₁ and 2,900% for Chol+F+AI₂ ). These effects were dependent on the AI dose and were probably produced by absorbed peptides. PRACTICAL APPLICATIONS: It is known that redox imbalances are involved in the genesis of many chronic diseases. Therefore, it is possible to prevent them or limit their severity by improving the body's antioxidant defense mechanisms through dietary incorporation of antioxidant substances. The results suggest that amaranth protein isolate and amaranth flour have the potential for regulating intestinal and liver cells redox balance; effects were more evident when they contributed 50% of the diet's protein content and were administered for 1 week. Both amaranth ingredients could be used as ingredients in the development of functional foods with beneficial antioxidant properties.

Amaranth as a Source of Antihypertensive Peptides

Amaranth is an ancestral crop used by pre-Columbian cultures for 6000 to 8000 years. Its grains have a relevant chemical composition not only from a nutritional point of view but also due to the contribution of components with good techno-functional properties and important potential as bioactive compounds. Numerous studies have shown that amaranth storage proteins possess encrypted sequences that, once released, exhibit different physiological activities. One of the most studied is antihypertensive activity. This review summarizes the progress made over the last years (2008-2020) related to this topic. Studies related to inhibition of different enzymes of the Renin-Angiotensin-Aldosterone system, in particular Angiotensin Converting Enzyme (ACE) and Renin, as well as those referring to potential modulation mechanisms of tissue or local Renin-Angiotensin-Aldosterone system, are analyzed, including in silico, in vitro, in vivo, and ex vivo assays. Furthermore, the potential use of these bioactive peptides or products containing them, in the elaboration of functional food matrices is discussed. Finally, the most relevant conclusions and future requirements in research and development of food products are presented.

Characteristics of New Peptides GQLGEHGGAGMG, GEHGGAGMGGGQFQPV, EQGFLPGPEESGR, RLARAGLAQ, YGNPVGGVGH, and GNPVGGVGHGTTGT as Inhibitors of Enzymes Involved in Metabolic Syndrome and Antimicrobial Potential

The aim of this study was to determine the cytotoxic properties, influence on enzyme activity involved in metabolic syndrome, and antimicrobial activity of synthetic peptides with GQLGEHGGAGMG, GEHGGAGMGGGQFQPV, EQGFLPGPEESGR, RLARAGLAQ, YGNPVGGVGH, and GNPVGGVGHGTTGT sequences. Peptides have no cytotoxic effect on cells. The highest inhibitory effect on angiotensin converting enzyme I was noted for peptide GT-14 (IC50 = 525.63 µg/mL). None of the tested peptides had an influence on α-glucosidase. The highest α-amylase and lipase inhibitory activity was noted for GG-12 (IC50 = 56.72 and 60.62 µg/mL, respectively). The highest lipoxidase inhibitory activity was determined for peptide ER-13 (IC50 = 84.35 µg/mL). Peptide RQ-9 was characterized by the highest COX inhibitory activity (0.31 and 4.77 µg/mL for COX-1 and COX-2, respectively). Only peptide RQ-9 inhibited S. enteritidis ATCC 4931 growth (42%-48%) in all tested concentrations (15.62-250 mg/mL).

Pseudocereal grains: Nutritional value, health benefits and current applications for the development of gluten-free foods

Nowadays, consumers are more conscious of the environmental and nutritional benefits of foods. Pseudocereals grains, edible seeds belonging to dicotyledonous plant species, are becoming a current trend in human diets as gluten-free (GF) grains with excellent nutritional and nutraceutical value. Pseudocereals are a good source of starch, fiber, proteins, minerals, vitamins, and phytochemicals such as saponins, polyphenols, phytosterols, phytosteroids, and betalains with potential health benefits. The present review aims to summarize the nutritional quality and phytochemical profile of the three main pseudocereal grains: quinoa, amaranth and buckwheat. In addition, current evidence about their health benefits in animal models and human studies is also provided in detail. Based on the accumulating research supporting the inclusion of pseudocereals grains in the diet of celiac persons, this review discusses the recent advances in their application for the development of new GF products. Future directions for a wider cultivation and commercial exploitation of these crops are also highlighted.