A practical and fast isolation of 12 cyclolinopeptides (linusorbs) from flaxseed oil via preparative HPLC with phenyl-hexyl column

Enhancing sensory acceptance of roasted flaxseeds: The role of degumming and roasting conditions

Roasted flaxseed is a viable food for augmenting ω-3 fatty acid intake; however, their sticky mouthfeel limits broader acceptance. The relationship between flaxseed components and sensory properties remains underexplored. This study compares sensory attributes of several flaxseed cultivars and investigates the correlation between changes in composition and sensory characteristics. Flaxseed mucilage was reduced through extraction, and the effects of different roasting conditions on physical (moisture, hardness, crispness) and chemical properties (cyclolinopeptides, flax lignans, oxidative indices) were examined. Optimal roasting conditions were identified as 160 °C for 20 min, as identified through principal component analysis. Results indicated that the mucilage layer negatively affected mouthfeel, while cyclolinopeptide E and lignans impacted flavor and aroma. Degumming improved mouthfeel but reduced oxidative stability, suggesting partial degumming for optimized sensory quality and shelf life. This study provides insights into enhancing the sensory experience of roasted flaxseeds without compromising nutritional benefits and oxidative stability.

Enhanced bioaccessibility of cyclolinopeptides via zein-cyclodextrin nanoparticles: Simulated gastrointestinal digestion and cellular uptake study

Cyclolinopeptides (CLS) are hydrophobic cyclic peptides in flaxseed with multiple bioactive activities. This study developed zein (Z)-cyclodextrin (CD) binary nanoparticles (NPs) as an oral delivery system for CLS. Z-CD NP had a smaller diameter (Dh) and better encapsulation effect on CLS. Formation of CLS-loaded NPs was driven by hydrogen bonds and electrostatic interactions. Presence of CD improved the thermal, pH and storage stabilities of NPs. Besides, CD prevented premature release of CLS in the stomach and enhanced the bioaccessibility of CLS to a maximum of 86.71 % ± 2.20 %. Lipid-raft-mediated endocytosis was involved in the cell uptake of NPs, where the addition of CD significantly facilitated the uptake of NPs. Z-CD NPs also enhanced absorption and reduced secretion of CLS after digestion. Overall, this study provides a simple approach to enhance the oral delivery efficiency of CLS by modulating Z-based NPs with CD.

Optimized two-step flash chromatography method for large-scale isolation of linusorb and its antioxidant capacity evaluation

The study presents a novel purification method tailored for a range of linusorbs with comparable polarity, leveraging flash chromatography, a rapid and convenient technique, for large-scale purification of linusorbs. A two-step approach employing silica-phenylhexyl strategy was first used for linusorb (LO, also known as cyclolinopeptide) preparation, yielding fractions of cyclolinopeptide A, E, O with purity exceeding 90 % for each 850 mg linusorbs load. Additionally, other eight fractions containing various LOs exhibited average purities ranging from 60 % to 83 %. Comparative assessment of antioxidant capacity of individual LOs elucidated the role of specific amino acid residues. Met residues initially contributed to LOs' antioxidant effects but declined due to oxidation of Met to MetO. Meanwhile, Trp residues exhibited stronger antioxidant capacity, enhancing the capacity of LOs lacking Met. Furthermore, the Phe-Phe structure was identified as contributing to the antioxidant effect of linusorbs. This study not only provides an efficient and scalable method for the purification of LOs but also offers insights into their antioxidant mechanisms.

Impact of cyclolinopeptide (linusorb) on oxidative stability of hot-pressed flaxseed oil and their interaction with phospholipid

This study examines the antioxidant capacity of linusorb (LOs) and their interaction with phospholipids (PLs) in hot-pressed flaxseed oil (HO), which is valued for its enhanced oxidative stability in Northwest China. Utilizing antioxidant assays and molecular simulations, the research aims to: 1) Assess oxidation indices to identify optimal roasting conditions and monitor LOs during the oxidation of HO, triacylglycerol (TAG), and TAG + LOs; 2) Analyze the oxidation kinetics of crude LOs (cLOs) from cold-pressed oil (CO) and LOs (hLOs) from HO in the presence of PLs; and 3) Molecular dynamics simulations to explore the interactions between PLs and LOs. The findings indicate that HO exhibits superior oxidative stability due to a higher concentration of LOs and PLs, with altered the antioxidative behavior of LOs. Simulation suggests that PLs can bind to LOs, facilitating their migration to the water-oil interface and enhancing their antioxidant effects.

Improved solubility and bioavailability of cyclolinopeptides by diacylglycerol in the β-cyclodextrin Pickering emulsions

Cyclolinopeptides (CLs) have anti-inflammatory, anti-osteoporosis, and anti-tumor effects, however, low water and oil solubility greatly limit their application. Herein, CLs-loaded β-cyclodextrin (β-CD) emulsions were prepared with different oil phases. The in vitro digestibility, cellular absorption, and anti-inflammatory effects were evaluated. Camellia oil diacylglycerol (CO DAG) showed enhanced dissolving ability for CLs due to high polarity. β-CD formed inclusion complexes with DAG through hydrogen bond and the emulsions showed smaller size and higher physical stability with 50 % (w/w) oil. The in vitro digestibility of the DAG emulsion was increased and the CLs' bioavailability was 13.6-fold higher than CLs in oil. The CLs-loaded Pickering emulsion digesta exhibited a higher nitric oxides (NO) inhibition rate (58.62 %) and Caco-2 cell penetration (3.09 × 10-6 cm/s). Therefore, emulsion formulated with β-cyclodextrin and DAG can effectively improve the solubility and bioavailability of CLs, which has significant potential for application in functional foods and pharmaceutical industry.

A two-step method of cyclolinopeptide (linusorb) preparation from flaxseed cake via dry-screening

Linusorbs (LO), cyclolinopeptides, are a group of cyclic hydrophobic peptides and considered a valuable by-product of flaxseed oil due to numerous health benefits. Currently applied acetone or methanol extraction could contaminate the feedstocks for further food-grade application. Using flaxseed cake as feedstock, this study established a practical method for preparing LO from pressed cake. Firstly, LO composition of 15 flaxseed cultivars was analyzed. Next, cold-pressed cake was milled and screened mechanically. The kernel and hull fractions were separated based on the disparity of their mechanical strength. Monitored by hyperspectral fluorescence, the LO-enriched kernel fraction separated from cold-pressed flaxseed cake was further used as feedstock for LO production. After ethanol extraction, partition, and precipitation, LOs were extracted from cold-pressed flaxseed cake with a purity of 91.4%. The proposed method could serve as feasible flaxseed cake valorization strategy and enable the preparation of other polar compounds such as flax lignan and mucilage.

Stability of tryptophan-containing LOs in flaxseed oil and their response towards γ-tocopherol

Linusorbs (LOs), significantly influence oil quality and sensory properties of flaxseed oil. Trp-containing LOs exhibit distinct oxidative behavior when γ-tocopherol (γ-T) is present. Polar fractions of crude flaxseed oil were stripped via silica absorption, and reintroduced (LO and γ-T) separately into the oil matrix to investigate their interaction during storage. Compared with crude oil, LOs account for 18.49% reduction of p-anisidine value, while LOs with γ-T contributed to most of the endogenous antioxidant effect in crude oil. γ-T was found to suppress oxidation of Trp-containing LO at early stage (Met form), while facilitate oxidation while at their mid-stage (MetO form, Methionine sulfoxide). In vitro oxidation shows that CLD more likely cleaved into peptide fragments, while few products retain intact ring structures. LC-MS/MS analysis and silicon simulation revealed proximity between MetO and Trp residues, facilitating inter- or intra-molecular reactions and ring structure rupture. Remarkably, the presence of γ-T facilitate these phenomena.

Protective Effect of Orbitides from Linseed (Linum usitatissimum L.) against Ultraviolet B-induced Photoaging in Zebrafish

Excessive ultraviolet (UV) exposure is the primary environmental factor that contributes to skin aging. Orbitides have been considered as important functional components in linseed, and they are complex and multiple. In this study, linseed orbitides (LOs) were divided into oxidized linseed orbitides (OLOs) and reduced linseed orbitides (RLOs) and used to investigate protection against ultraviolet B-induced photoaging in zebrafish. First, the results of the zebrafish embryo acute toxicity test showed that the OLOs had obvious embryo toxicity compared with RLOs. And RLOs had better effect in ultraviolet B-treated zebrafish, which may significantly reduce the reactive oxygen species levels and inhibit the degradation of collagen. Besides, we also found that RLOs could effectively inhibit the oxidation of proteins and lipids and regulate the activity of antioxidant enzymes. Furthermore, neutrophil recruitment to the dorsal and caudal fin regions was observed in UVB-treated zebrafish, and RLOs effectively alleviated this migration. In conclusion, RLOs have strong photoprotective effects and potential to be used as antiphotoaging ingredients.

Enhancing effects of 60Co irradiation on the extraction and activities of phenolic components in edible Citri Sarcodactylis Fructus

In this study, the impact of 60Co-γ ray irradiation treatment on the content of active chemicals and their functions in Citri Sarcodactylis Fructus (CSF) was assessed. Scanning electron microscopy, Fourier transform infrared spectroscopy, and γ-ray diffraction revealed physical structure changes in CSF powder. According to the findings, the content of total flavonoids in the ethanol extract of CSF increased by 9.5%-21.62%, 7-hydroxycoumarin, hesperidin, 5,7-dimethoxycoumarin, and 5-methoxypsoralen increased by 5.31%-51.8%, 10.07%-99.81%, 6.6%-62.29%, and 3.03%-300%, respectively, when the irradiation dosage was raised, and the antibacterial, anti-inflammatory, antioxidant, and anticancer properties were all raised considerably. These results imply that the principal components and activity changes are proportional to the irradiation dosage. At present, the findings of this study serve as a reference for the use of irradiation technology in assisting extraction and enhancing the effects of functional foods.

The Anti-Inflammatory Mechanism of Flaxseed Linusorbs on Lipopolysaccharide-Induced RAW 264.7 Macrophages by Modulating TLR4/NF-κB/MAPK Pathway

Flaxseed linusorbs (FLs), cyclic peptides derived from flaxseed oils, have shown multiple activities such as anticancer, antibacterial, and anti-inflammatory effects. However, the anti-inflammatory monomers of FLs and their mechanisms are still unclear. In this study, we have elucidated that FLs suppress the modulation of NF-κB/MAPK signaling pathways by targeting the inhibition of activating TLR4 in LPS-induced RAW 264.7 cells. Therefore, the transcription and expression of inflammatory cytokines (i.e., TNF-α, IL-1β, and IL-6) and inflammatory mediator proteins (i.e., iNos and Cox-2) were significantly suppressed by FLs. In addition, an in silico study discovered that eight monomers of FLs showed high-affinity bindings with TLR4. In silico data combined with HPLC results indicated that FLA and FLE, accounting for 44%, were likely the major anti-inflammatory monomers in FLs. In summary, FLA and FLE were proposed as the main anti-inflammatory active cyclopeptides via hindering TLR4/NF-κB/MAPK signaling pathways, suggesting the potential use of food-derived FLs as natural anti-inflammatory supplements in a daily diet.

Identification and Characterization of the Stability of Hydrophobic Cyclolinopeptides From Flaxseed Oil

Flaxseed (linseed) is a cultivar of the spring flowering annual plant flax (Linum usitatissimum) from the Linaceae family. Derivatives of this plant are widely used as food and as health products. In recent years, cyclic peptides isolated from flaxseed and flaxseed oil, better known as cyclolinopeptides (CLPs), have attracted the attention of the scientific community due to their roles in the inhibition of osteoclast differentiation or their antimalarial, immunosuppressive, and antitumor activities, as well as their prospects in nanotechnology and in the biomedical sector. This study describes the detection, identification, and measurement of CLPs in samples obtained from nine different flaxseed oil manufacturers. For the first time, Q Exactive Hybrid Quadrupole-Orbitrap Mass Spectrometer was used for CLP identification together with RP-HPLC. The routine analyses were performed using RP chromatography, measuring the absorption spectra and fluorescence detection for identifying tryptophan-containing peptides using the native fluorescence of tryptophan. In addition, existing protocols used for CLP extraction were optimized and improved in a fast and cost-efficient way. For the first time, 12 CLPs were separated using methanol/water as the eluent with RP-HPLC. Finally, the stability and degradation of individual CLPs in the respective flaxseed oil were examined over a period of 60 days at different temperatures. The higher temperature was chosen since this might reflect the cooking practices, as flaxseed oil is not used for high-temperature cooking. Using HPLC–MS, 15 CLPs were identified in total in the different flaxseed oils. The characterization of the peptides via HPLC–MS highlighted two types of CLP profiles with a substantial variation in the concentration and composition of CLPs per manufacturer, probably related to the plant cultivar. Among the observed CLPs, CLP-O, CLP-N, and CLP-B were the least stable, while CLP-C and CLP-A were the most stable peptides. However, it is important to highlight the gradual degradation of most of the examined CLPs over time, even at room temperature.

Enantioseparation in high performance liquid chromatography: preparation and evaluation of a vancomycin-based chiral stationary phase via surface-initiated atom transfer radical polymerization

A chromatographic technique based on a chiral stationary phase (CSP) has been explored for enantioseparation. Herein, poly(glycidyl methacrylate) (poly(GMA)) brushes were grafted on the surface of silica gel via surface-initiated atom transfer radical polymerization (SI-ATRP), followed by the introduction of vancomycin as a chiral selector. The as-synthesized material was characterized by elemental analysis, scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) and thermogravimetric analysis (TGA), proving the formation of vancomycin-immobilized brushes. Then the resulting CSP was explored to separate 7 racemic drugs (bicalutamide, 1-benzyl-5-phenylbarbituric acid, chlorpheniramine maleate, fluoxetine hydrochloride, verapamil hydrochloride, benzoxazocine hydrochloride and isoprenaline hydrochloride) in high performance liquid chromatography (HPLC). Several factors affecting the enantioseparation performance of the vancomycin-immobilized CSP, including the triethylamine (TEA) content in the buffer, pH value, content of organic solvent in the mobile phase, flow rate and injection volume, were mainly optimized. Under the optimal conditions, baseline separation of fluoxetine hydrochloride (R_S = 2.52) was achieved, which was better than that on a commercial Chirobiotic V column, while enantioseparation of bicalutamide (R_S = 1.01), chlorpheniramine maleate (R_S = 0.77), 1-benzyl-5-phenylbarbituric acid (R_S = 0.67), isoprenaline hydrochloride (R_S = 0.73), verapamil hydrochloride (R_S = 0.91) and benzoxazocine hydrochloride (R_S = 1.03) was partly achieved. It was concluded that SI-ATRP is a robust way to fabricate vancomycin-based CSPs for enantioseparation.