Flax phenolic compounds as inhibitors of lipid oxidation: Elucidation of their mechanisms of action

Antioxidant and Anti-Atherosclerosis Activities of Hydrolyzed Jellyfish Collagen and Its Conjugate with Black Jelly Mushroom Extract

Atherosclerosis, a noncommunicable disease caused by cholesterol plaque, can cause chronic diseases. The antiplatelet medicines used in its treatment can cause complications. Marine collagen peptides can be used as a natural atherosclerosis remedy. The present study investigated the preparation and characterization of hydrolyzed collagen (HC) from jellyfish and its conjugation with black jelly mushroom extract (BJME). Their cytotoxicity and ability to prevent cholesterol-induced endothelial cell injury were also examined. HC was prepared using Alcalase or papain hydrolysis (0.2-0.4 units/g of dry matter (DM)). Higher yield, degree of hydrolysis, and antioxidant activities (AAs) were found in the HC obtained from Alcalase, especially at 0.4 units/g DM (A-0.4), compared to other processes (p < 0.05). Thus, A-0.4 was further conjugated with BJME (1-4%, w/w of HC). The HC-2%BJME conjugate showed the highest surface hydrophobicity and AAs compared to other samples. The FTIR spectra and size distribution also confirmed the conjugation between HC and BJME. When EA.hy926 endothelial cells were treated with HC or HC-2%BJME (25-1000 µg/mL), HC-2%BJME had no cytotoxicity, whereas HC at 1000 µg/mL induced cytotoxicity (p < 0.05). Both samples also exhibited protective ability against cholesterol-induced apoptosis and VE-cadherin downregulation of cells. Therefore, HC and conjugate could be natural agents for preventing atherosclerosis.

Novel acrylonitrile derived imidazo[4,5-b]pyridines as antioxidants and potent antiproliferative agents for pancreatic adenocarcinoma

We present the design, synthesis, computational analysis, and biological assessment of several acrylonitrile derived imidazo[4,5-b]pyridines, which were evaluated for their anticancer and antioxidant properties. Our aim was to explore how the number of hydroxy groups and the nature of nitrogen substituents influence their biological activity. The prepared derivatives exhibited robust and selective antiproliferative effects against several pancreatic adenocarcinoma cells, most markedly targeting Capan-1 cells (IC50 1.2-5.3 μM), while their selectivity was probed relative to normal PBMC cells. Notably, compound 55, featuring dihydroxy and bromo substituents, emerged as a promising lead molecule. It displayed the most prominent antiproliferative activity without any adverse impact on the viability of normal cells. Furthermore, the majority of studied derivatives also exhibited significant antioxidative activity within the FRAP assay, even surpassing the reference molecule BHT. Computational analysis rationalized the results by highlighting the dominance of the electron ionization for the antioxidant features with the trend in the computed ionization energies well matching the observed activities. Still, in trihydroxy derivatives, their ability to release hydrogen atoms and form a stable O-H⋯O•⋯H-O fragment upon the H• abstraction prevails, promoting them as excellent antioxidants in DPPH• assays as well.

Effect of Different Temperatures on the Storage Stability of Flaxseed Milk

In this study, the physical and oxidative stability of flaxseed milk without food additives at different temperatures (25 °C and 37 °C) was assessed. Over in 206 days in storage, the particle size, Turbiscan stability index (TSI), centrifugal sedimentation rate, and primary and secondary oxidation products of flaxseed milk increased, viscosity decreased, and the absolute value of the potential first decreased and then increased. These phenomena indicated a gradual decrease in the physical stability of flaxseed milk, accompanied by drastic oxidative changes. The antioxidant capacity of flaxseed milk was related to the location of the physical distribution of flaxseed lignin, which was more effective in the aqueous phase compared to the non-aqueous phase. Interestingly, after 171 days in storage at 37 °C, the particle size of flaxseed milk was approximately doubled (6.98 μm → 15.27 μm) and the absolute value of the potential reached its lowest point (-13.49 mV), when the content of primary oxidation products reached its maximum (8.29 mmol/kg oil). The results showed that temperature had a significant effect on the stability of flaxseed milk and that stability decreased with increasing temperature and shortened shelf life. This work provides a theoretical basis for elucidating the stabilization-destabilization mechanism of flaxseed milk.

Hybrids of Sterically Hindered Phenols and Diaryl Ureas: Synthesis, Switch from Antioxidant Activity to ROS Generation and Induction of Apoptosis

The utility of sterically hindered phenols (SHPs) in drug design is based on their chameleonic ability to switch from an antioxidant that can protect healthy tissues to highly cytotoxic species that can target tumor cells. This work explores the biological activity of a family of 45 new hybrid molecules that combine SHPs equipped with an activating phosphonate moiety at the benzylic position with additional urea/thiourea fragments. The target compounds were synthesized by reaction of iso(thio)cyanates with C-arylphosphorylated phenols containing pendant 2,6-diaminopyridine and 1,3-diaminobenzene moieties. The SHP/urea hybrids display cytotoxic activity against a number of tumor lines. Mechanistic studies confirm the paradoxical nature of these substances which combine pronounced antioxidant properties in radical trapping assays with increased reactive oxygen species generation in tumor cells. Moreover, the most cytotoxic compounds inhibited the process of glycolysis in SH-SY5Y cells and caused pronounced dissipation of the mitochondrial membrane of isolated rat liver mitochondria. Molecular docking of the most active compounds identified the activator allosteric center of pyruvate kinase M2 as one of the possible targets. For the most promising compounds, 11b and 17b, this combination of properties results in the ability to induce apoptosis in HuTu 80 cells along the intrinsic mitochondrial pathway. Cyclic voltammetry studies reveal complex redox behavior which can be simplified by addition of a large excess of acid that can protect some of the oxidizable groups by protonations. Interestingly, the re-reduction behavior of the oxidized species shows considerable variations, indicating different degrees of reversibility. Such reversibility (or quasi-reversibility) suggests that the shift of the phenol-quinone equilibrium toward the original phenol at the lower pH may be associated with lower cytotoxicity.

Dietary linseed supplementation improves meat quality and flavor of sheep by altering muscle fiber characteristics and antioxidant capacity

Linseed as a common oil crop that has been implicated in regulating the meat quality of animals. The aim of this investigation was to establish the effects of dietary linseed supplementation on carcass traits, meat quality, muscle fiber characteristics, volatile compounds and antioxidant capacity of sheep. Twenty-four Sunit sheep were distributed into 2 groups with different diet: control (CO) fed a standard diet and linseed (LS, 8% of extruded linseed). The results showed that linseed not only increased M. longissimus thoracis (LT) increased the loin-eye area but also decreased pH24h, L* and shear force. Meanwhile, linseed increased mRNA expression of MyHCI and MyHCIIx and decreased in cross-sectional area (CSA) and muscle fiber diameter. In addition, linseed altered the composition of meat volatile flavor compounds, such as Z-10-Pentadecen-1-ol, pentanal, 2-Octenal, (E)-, decanal, butane, and 2-heptanone. Moreover, linseed increased total antioxidative capacity (T-AOC) activity, the mRNA expression of glutathione peroxidase (GSH-Px) and catalase (CAT), decreased malondialdehyde (MDA) content. Overall, the results suggest that linseed is an effective feed additive in improving meat quality and flavor. The underlying mechanisms for its effectiveness may be partly due to a change in muscle fiber characteristics and antioxidant capacity.

High-Pressure Technologies for the Recovery of Bioactive Molecules from Agro-Industrial Waste

Large amounts of food waste are produced each year. These residues require appropriate management to reduce their environmental impact and, at the same time, economic loss. However, this waste is still rich in compounds (e.g., colorants, antioxidants, polyphenols, fatty acids, vitamins, and proteins) that can find potential applications in food, pharmaceutical, and cosmetic industries. Conventional extraction techniques suffer some drawbacks when applied to the exploitation of food residues, including large amounts of polluting solvents, increased time of extraction, possible degradation of the active molecules during extraction, low yields, and reduced extraction selectivity. For these reasons, advanced extraction techniques have emerged in order to obtain efficient residue exploitation using more sustainable processes. In particular, performing extraction under high-pressure conditions, such as supercritical fluids and pressurized liquid extraction, offers several advantages for the extraction of bioactive molecules. These include the reduced use of toxic solvents, reduced extraction time, high selectivity, and the possibility of being applied in combination in a cascade of progressive extractions. In this review, an overview of high-pressure extraction techniques related to the recovery of high added value compounds from waste generated in food industries is presented and a critical discussion of the advantages and disadvantages of each process is reported. Furthermore, the possibility of combined multi-stage extractions, as well as economic and environmental aspects, are discussed in order to provide a complete overview of the topic.

Scarlet Flax Linum grandiflorum (L.) In Vitro Cultures as a New Source of Antioxidant and Anti-Inflammatory Lignans

In vitro cultures of scarlet flax (Linum grandiflorum L.), an important ornamental flax, have been established as a new possible valuable resource of lignans and neolignans for antioxidant and anti-inflammatory applications. The callogenic potential at different concentrations of α-naphthalene acetic acid (NAA) and thidiazuron (TDZ), alone or in combinations, was evaluated using both L. grandiflorum hypocotyl and cotyledon explants. A higher callus induction frequency was observed on NAA than TDZ, especially for hypocotyl explants, with a maximum frequency (i.e., 95.2%) on 1.0 mg/L of NAA. The presence of NAA (1.0 mg/L) in conjunction with TDZ tended to increase the frequency of callogenesis relative to TDZ alone, but never reached the values observed with NAA alone, thereby indicating the lack of synergy between these two plant growth regulators (PGRs). Similarly, in terms of biomass, NAA was more effective than TDZ, with a maximum accumulation of biomass registered for medium supplemented with 1.0 mg/L of NAA using hypocotyls as initial explants (DW: 13.1 g). However, for biomass, a synergy between the two PGRs was observed, particularly for cotyledon-derived explants and for the lowest concentrations of TDZ. The influence of these two PGRs on callogenesis and biomass is discussed. The HPLC analysis confirmed the presence of lignans (secoisolariciresinol (SECO) and lariciresinol (LARI) and neolignan (dehydrodiconiferyl alcohol [DCA]) naturally accumulated in their glycoside forms. Furthermore, the antioxidant activities performed for both hypocotyl- and cotyledon-derived cultures were also found maximal (DPPH: 89.5%, FRAP 866: µM TEAC, ABTS: 456 µM TEAC) in hypocotyl-derived callus cultures as compared with callus obtained from cotyledon explants. Moreover, the anti-inflammatory activities revealed high inhibition (COX-1: 47.4% and COX-2: 51.1%) for extract of hypocotyl-derived callus cultures at 2.5 mg/L TDZ. The anti-inflammatory action against COX-1 and COX-2 was supported by the IC₅₀ values. This report provides a viable approach for enhanced biomass accumulation and efficient production of (neo)lignans in L. grandiflorum callus cultures.

Effect of different structural flaxseed lignans on the stability of flaxseed oil-in-water emulsion: An interfacial perspective

The influences of the different structural flaxseed lignans on flaxseed oil (FO) emulsions during storage and digestion were investigated, focusing on their interfacial behavior. From perspective of interface, more than 60% of secoisolariciresinol (SECO) and the acidic hydrolysates of flaxseed lignan macromolecule (FLEH) were located on the interface of FO emulsions. It improved the stability of FO emulsions both during storage and digestion by inhibiting of free radical penetration and improving their targeted antioxidative activity. By comparison, the secoisolariciresinol diglucoside (SDG) and the alkaline hydrolysates of flaxseed lignan macromolecule (FLE) largely located in the aqueous and exerted lower antioxidative efficiency in emulsions. Moreover, SDG, SECO, FLE and FLEH slowed down the digestive rate of FO in emulsions, which might be due to flaxseed lignans inhibited the activity of digestive enzymes. These findings suggested that the different structural flaxseed lignans had the potential as antioxidants in emulsions during storage and digestion.

A comprehensive review on different classes of polyphenolic compounds present in edible oils

Edible oils are used as a frying medium and in the preparation of several food products. They are mainly constituting triacylglycerols as major components, while other compounds are classified as minor constituents, which include polyphenols. This class of compounds plays an important role in the thermal stability and quality attributes of the finished industrial food products. In addition to other antioxidants, the desired thermal stability of edible is achieved by either fortification or mixing of edible oils. This comprehensive review was therefore aimed to review the different classes of polyphenolic compounds present in commonly consumed edible oils. The edible oils reviewed include soybean, olive, rapeseed, canola, sunflower, flaxseed, sesame, cottonseed, palm, almond, peanut, chestnut, coconut, and hazelnut oils. The identified classes of polyphenolic compounds such as simple phenols, hydroxybenzoic acids, phenylethanoids, hydroxycinnamic acid, esters of hydroxycinnamic acids, coumarins & chromans, stilbenes, flavonoids, anthocyanins, and lignans were discussed. It was observed that a single edible from different origins showed the varied composition of the different classes of phenolic compounds. Among the oils, soybean, sunflower, olive, and brassica oils received higher attention in terms of polyphenol composition. Some classes of phenolic compounds were either not reported or absent in one edible oil, while present in others. Among the different classes of phenolics, hydroxybenzoic acids, hydroxycinnamic acid and flavonoids were the most widely present compounds. Phenolic compounds in edible oils possess several health benefits such as antioxidant, antibacterial, anti-viral, anti-inflammatory, anti-tumour, antioxidants, cardioprotective, neuroprotective, anti-diabetic properties and anti-obesity.

Effect of sesamol on the physical and chemical stability of plant-based flaxseed oil-in-water emulsions stabilized by proteins or phospholipids

Plant-based polyphenols are increasingly being explored as functional ingredients in emulsified food systems. In this study, the effects of sesamol on the physical and chemical stability of flaxseed oil-in-water emulsions stabilized by either phospholipids (sunflower) or proteins (whey or pea) were investigated. In the absence of sesamol, the protein-based emulsions displayed better physical stability than the phospholipid-based ones, which was related to their smaller particle diameter and higher particle charge. For the phospholipid-based emulsions, sesamol addition did not improve their physical stability, but it did inhibit lipid oxidation. In particular, it decreased the formation of secondary oxidation products, with a 65% reduction in TBAR formation compared to the control after 8 days of storage. For the protein-based emulsions, sesamol addition reduced particle aggregation and inhibited lipid oxidation, reducing the secondary oxidation products by around 85% after 19 days of storage. The inhibitory efficiency of sesamol in the pea protein-based emulsions was comparable to that in the whey protein-based ones. The effects of sesamol on the physical and chemical stability of the emulsions were related to its partitioning between the oil, water, and interfacial layers. This study suggests that adding sesamol to plant-based emulsions may improve their physical and chemical stability, thereby extending their shelf life.

The Influence of Flaxseed Oil Cake Extract on Oxidative Stability of Microencapsulated Flaxseed Oil in Spray-Dried Powders

The objective of the study was to investigate the application of flaxseed oil cake extract (FOCE) for oxidative stabilization of flaxseed oil in spray-dried emulsions. Two variants of powders with 10% and 20% of flaxseed oil (FO), FOCE, and wall material (maltodextrin and starch Capsul^®) were produced by spray-drying process at 180 °C. The oxidative stability of FO was monitored during four weeks of storage at 4 °C by peroxide value (PV) and thiobarbituric acid-reactive substances (TBARS) measurements. Additionally, the fatty acids content (especially changes in α-linolenic acid content), radical scavenging activity, total polyphenolics content, color changes and free amino acids content were evaluated. Obtained results indicated that FOCE could be an adequate antioxidant dedicated for spray-dried emulsions, especially with a high content of FO (20%). These results have important implications for the flaxseed oil encapsulation with natural antioxidant agents obtained from plant-based agro-industrial by product, meeting the goals of circular economy and the idea of zero waste.

Study of the phenolic compound profile and antioxidant activity of human milk from Spanish women at different stages of lactation: A comparison with infant formulas

Human milk (HM) has been proven to have important and essential antioxidant properties to counteract infant susceptibility to oxidative stress. Phenolic compounds are secondary metabolites which come from plants and are potent natural antioxidants. The ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method used in the present study allowed the quantification of 26 phenolic compounds (ten hydroxybenzoic acids, seven hydroxycinnamic acids, four flavonoids, three hydroxybenzaldehydes and two other polyphenols) in HM samples at different stages of lactation (colostrum, transitional milk and mature milk) and infant formulas (IF). Many of the phenolic compounds identified have been reported to be present in HM for the first time. The total phenolic compound content (TPC) was quantified using the Folin assay and the antioxidant activity (AC) was evaluated with the DPPH, ABTS and FRAP assays. Significant differences were evidenced between HM and IF. HM from mothers with an adherence to a Mediterranean diet contained twice as many individual phenolic compounds as infant formulas, with a higher proportion of hydroxybenzoic acids. Conversely, IF showed a higher proportion of hydroxycinnamic acids. Overall, the antioxidant activity of HM showed small variations during lactation.

Impact of a novel partial defatting technology on oxidative stability and sensory properties of peanut kernels

A novel process, 'mechanical expression preserving shape integrity', was conceived to prepare low-fat peanuts in response to health-conscious consumer demands. The main purpose of this study was to preserve the taste, aroma, and oxidative stability of the defatted product. Results generated from a central composite rotatable design showed that highest consumer sensory scores were reached at low pressures (4-6 MPa). Free fatty acid, peroxide, p-anisidine, and total oxidation values were mostly affected by water content [W] and pressure [P] with high correlation coefficients (82% < R² < 87%). Overall, lipid oxidation and flavor fade were associated with higher defatting ratios and greater physical damage. The latter plays a major role in increasing the surface area and facilitating the access of oxygen to the remaining oil, thus rendering the defatted product more prone to oxidation. However, oxidation was reduced significantly using a Response Surface Methodology to optimize conditions ([W] 12.2 ± 0.6%d.b., [P] 6 ± 0.3 MPa and time [t] 18.2 ± 0.6 min).

An untargeted liquid chromatography-mass spectrometry-based workflow for the structural characterization of plant polyesters

Cell wall localized heterogeneous polyesters are widespread in land plants. The composition of these polyesters, such as cutin, suberin, or more plant-specific forms such as the flax seed coat lignan macromolecule, can be determined after total hydrolysis of the ester linkages. The main bottleneck in the structural characterization of these macromolecules, however, resides in the determination of the higher order monomer sequences. Partial hydrolysates of the polyesters release a complex mixture of fragments of different lengths, each present in low abundance and therefore are challenging to structurally characterize. Here, a method is presented by which liquid chromatography-mass spectrometry (LC-MS) profiles of such partial hydrolysates are searched for pairs of related fragments. LC-MS peaks that show a mass difference corresponding to the addition of one or more macromolecule monomers were connected in a network. Starting from the lowest molecular weight peaks in the network, the annotation of the connections as the addition of one or more polyester monomers allows the prediction of consecutive and increasingly complex adjacent peaks. Multi-stage MS (MSn) experiments further helped to reject, corroborate, and sometimes refine the structures predicted by the network. As a proof of concept, this procedure was applied to partial hydrolysates of the flax seed coat lignan macromolecule, and allowed to characterize 120 distinct oligo-esters, consisting of up to six monomers, and containing monomers and linkages for which incorporation in the lignan macromolecule had not been described before. These results showed the capacity of the approach to advance the structural elucidation of complex plant polyesters.

Recent advances and comparisons of conventional and alternative extraction techniques of phenolic compounds

Phenolic compounds are a group of secondary metabolites produced by plants under stressful conditions. Phenolic compounds play an important role in the prevention and treatment of certain illnesses and are exploited by the food and pharmaceutical industries. Conventional methods are commonly used as models to compare the efficiencies of alternative extraction methods. Among alternative extraction processes, microwave-assisted extraction (MAE), pressurized liquid extraction (PLE), supercritical fluid extraction (SFE) and ultrasonic-assisted extraction (UAE) are the most studied. These methods produce extracts rich in phenolic compounds using moderate temperatures, short extraction times, and solvents generally recognized as safe. The combination of extraction time and temperature plays a critical role in the stability of the compounds. Solvents of higher polarity enhance the extraction of phenolic compounds. The use of the ethanol-water mixture for MAE, PLE, and UAE is recommended. MAE and UAE involve shorter extraction times than do PLE and SFE. SFE requires a low average temperature (40 °C). MAE produces the highest total phenolic content [227.63 mg GAE/g dry basis (d.b.)], followed by PLE (173.65 mg GAE/g d.b.), UAE (92.99 mg GAE/g d.b.) and SFE (37 mg GAE/g d.b.). Extraction yields and recovery rates of the phenolic compounds can be enhanced by combining and integrating extraction methods.

UPLC-HRMS Analysis Revealed the Differential Accumulation of Antioxidant and Anti-Aging Lignans and Neolignans in In Vitro Cultures of Linum usitatissimum L

Over the last few decades, methods relating to plant tissue culture have become prevalent within the cosmetic industry. Forecasts predict the cosmetic industry to grow to an annual turnover of around a few hundred billion US dollars. Here we focused on Linum usitatissimum L., a plant that is well-known for its potent cosmetic properties. Following the a) establishment of cell cultures from three distinct initial explant origins (root, hypocotyl, and cotyledon) and b) selection of optimal hormonal concentrations, two in vitro systems (callus vs cell suspensions) were subjected to different light conditions. Phytochemical analysis by UPLC-HRMS not only confirmed high (neo)lignan accumulation capacity of this species with high concentrations of seven newly described (neo)lignans. Evaluation over 30 days revealed strong variations between the two different in vitro systems cultivated under light or dark, in terms of their growth kinetics and phytochemical composition. Additionally, antioxidant (i.e. four different in vitro assays based on hydrogen-atom transfer or electron transfer mechanism) and anti-aging (i.e. four in vitro inhibition potential of the skin remodeling enzymes: elastase, hyaluronidase, collagenase and tyrosinase) properties were evaluated for the two different in vitro systems cultivated under light or dark. A prominent hydrogen-atom transfer antioxidant mechanism was illustrated by the DPPH and ABTS assays. Potent tyrosinase and elastase inhibitory activities were also observed, which was strongly influenced by the in vitro system and light conditions. Statistical treatments of the data showed relationship of some (neo)lignans with these biological activities. These results confirmed the accumulation of flax (neo)lignans in different in vitro systems that were subjected to distinct light conditions. Furthermore, we showed the importance of optimizing these parameters for specific applications within the cosmetic industry.

Effect of flaxseed polyphenols on physical stability and oxidative stability of flaxseed oil-in-water nanoemulsions

Recent studies have shown that the high susceptibility of flaxseed oil nanoemulsions to lipid oxidation limits their incorporation into functional foods and beverages. For this reason, the impact of various flaxseed phenolic extracts on the physical and oxidative stability of flaxseed oil nanoemulsions was investigated. Flaxseed lignan extract (FLE) and secoisolariciresinol (SECO) exhibited antioxidant activity whereas secoisolariciresinol diglucoside (SDG) and p-coumaric acid (CouA) exhibited prooxidant activity in the flaxseed oil nanoemulsions. The antioxidant potential of flaxseed phenolics in the nanoemulsions was as follows: SECO < CouA < SDG ≈ FLE. Moreover, the antioxidant/prooxidant activity of the phenolics was also related to their free radical scavenging activity and partitioning in the nanoemulsions. Our results suggested that both SECO and FLE were good plant-based antioxidants for improving the stability of flaxseed oil nanoemulsions.