Effect of Extraction Method on the Phenolic and Cyanogenic Glucoside Profile of Flaxseed Extracts and their Antioxidant Capacity

Antioxidant activity and phytochemical analysis of fennel seeds and flaxseed

Natural herbs are now receiving more attention due to the growing demand for their antioxidant properties. This study compared flaxseed and fennel seeds for their nutritional composition, bioactive moieties, and antioxidant activity-the study comprised two different phases. According to methods, phase I analyzed flaxseed and fennel seeds for proximate composition, mineral profile, dietary fiber, and amino acid content. In phase II, seeds were extracted using three different solvents, i.e., ethanol 80%, acetone 80%, and distilled water, to probe the total phenolic and flavonoid content. Antioxidant activity was measured using DPPH and a FRAP in the final phase. Current study revealed that flaxseed had higher protein (17.33 ± 0.02%), fat content (36.76 ± 0.02%), potassium (763.66 ± 4.04 mg/100 g), iron (5.13 ± 0.03 mg/100 g), phosphorus (581.46 ± 4.07 mg/100 g), magnesium (406.60 ± 5.12 mg/100 g), and zinc (3.30 ± 0.49 mg/100 g), respectively. In fennel seed, high dietary fiber (53.2 ± 0.01 g/100 mg), calcium, manganese, and sodium (588.93 ± 7.77, 20.30 ± 0.95, and 57.34 ± 0.33 mg/100 g, respectively) were found. Acetone showed better extraction efficiency than acetone, ethanol, and distilled water. Moreover, acetone flaxseed extract showed higher total phenolic content (84.13 ± 7.73 mgGAE/g), flavonoid content (5.11 ± 1.50 mgQE/g), and FRAP (5031 ± 15.92 μMFe^2+/g) than fennel seed extract. This study showed that, among both herbs, flaxseed extract may have pharmacological potential in preventing illnesses and may be suggested for use in the food industry as a natural antioxidant.

Phenolic Compound Profile and Antioxidant Capacity of Flax (Linum usitatissimum L.) Harvested at Different Growth Stages

The profile of phenolic compounds changes during the growth of a plant and this change affects its antioxidant potential. The aim of this research has been to find the growth stage of flax with the highest antioxidant capacity, and to determine the phenolic compounds responsible for such a capacity. Flax was harvested in six growth stages: from stem extension to mature seeds. The phenolic compounds were identified using LC-TOF-MS and quantified in an extract and in the fresh matter (FM) of each growth stage. The radical scavenging activity against ABTS^•+ and DPPH^•, the ferric-reducing antioxidant power (FRAP), and the antioxidant activity in the β-carotene-linoleic acid emulsion system were determined. Mono- and di-C-glycosyl flavones were found to be the most abundant phenolics of the aerial parts of flax, which also showed the highest content of isoorientin (210-538 µg/g FM). Coniferin, its derivative, and hydroxycinnamic acid derivatives were also detected. The plant was richer in flavone C-glycosides from stem extension to seed ripening (1105-1413 µg/g FM) than at the mature seed stage (557 µg/g FM). Most of the individual flavone C-glycoside contents in the extracts decreased when increasingly older plants were considered; however, the isoorientin content did not change significantly from the steam extension to the seed ripening stages. The antiradical activity against ABTS^•+ and FRAP was higher for the aerial parts of the flax harvested at the flowering, brown capsule, and seed ripening stages, mainly due to the presence of flavone C-glycosides. The oxidation of β-carotene-linoleic acid emulsion was instead inhibited more effectively by the extracts from plants at the brown capsule and mature seed stages. Coniferin and its derivative were significantly involved in this activity. The extracts from the aerial parts of the flax harvested from flowering to seed ripening could be a valuable source of flavone C-glycosides for use as nutraceuticals and components of functional foods.

Composition and Antioxidant Ability of Extract from Different Flaxseed Cakes and Its Application in Flaxseed Oil

In this research, extracts from five flaxseed cakes (hot-pressed cake (HPC), cold-pressed cake (CPC), n-hexane extracted cake (HEC), supercritical CO₂ extracted cake (SCEC) and subcritical n-butane extracted cake (SBEC)) were analyzed for the contents of total phenolic, total flavonoid and antioxidant ability. At the same time, the antioxidant capacity of HPC extract and synthetic butylated hydroxyanisole (BHA) in the oxidative evolution of flaxseed oil was compared by accelerated storage experiment (8 days at 65°C). The results showed that compared with other flaxseed cake extract, the extract of HPC contained the highest content of total phenolic (78.01 mg GAE/g extract) and total flavonoid (2.73 mg RE/g extract), and showed the strongest antioxidant ability on DPPH, ABTS FRAP and total reducing power assay. We also found that different concentrations (800, 1000, 2000 ppm) of flaxseed cake extract could significantly slow down the oxidation of flaxseed oil during storage at 65°C, and the antioxidant effect strengthened with the increase of extract dosage. The antioxidant effect of the 2000 ppm extract was higher than that of 200 ppm BHA. The results indicated that flaxseed cake extract could effectively inhibit the oxidation of flaxseed oil and was a good substitute for synthetic antioxidants in oil industry.

Extraction Techniques and Analytical Methods for Isolation and Characterization of Lignans

Lignans are a group of natural polyphenols present in medicinal plants and in plants which are a part of the human diet for which more and more pharmacological activities, such as antimicrobial, anti-inflammatory, hypoglycemic, and cytoprotective, are being reported. However, it is their cytotoxic activities that are best understood and which have shed light on this group. Two anticancer drugs, etoposide, and teniposide, were derived from a potent cytotoxic agent—podophyllotoxin from the roots of Podophyllum peltatum. The evidence from clinical and observational studies suggests that human microbiota metabolites (enterolactone, enterodiol) of dietary lignans (secoisolariciresinol, pinoresinol, lariciresinol, matairesinol, syringaresinol, medioresinol, and sesamin) are associated with a reduced risk of some hormone-dependent cancers. The biological in vitro, pharmacological in vivo investigations, and clinical studies demand significant amounts of pure compounds, as well as the use of well-defined and standardized extracts. That is why proper extract preparation, optimization of lignan extraction, and identification are crucial steps in the development of lignan use in medicine. This review focuses on lignan extraction, purification, fractionation, separation, and isolation methods, as well as on chromatographic, spectrometric, and spectroscopic techniques for their qualitative and quantitative analysis.

A comprehensive review of flaxseed (Linum usitatissimum L.): health-affecting compounds, mechanism of toxicity, detoxification, anticancer and potential risk

Flaxseed consumption (Linum usitatissimum L.) has increased due to its potential health benefits, such as protection against inflammation, diabetes, cancer, and cardiovascular diseases. However, flaxseeds also contains various anti-nutritive and toxic compounds such as cyanogenic glycosides, and phytic acids etc. In this case, the long-term consumption of flaxseed may pose health risks due to these non-nutritional substances, which may be life threatening if consumed in high doses, although if appropriately utilized these may prevent/treat various diseases by preventing/inhibiting and or reversing the toxicity induced by other compounds. Therefore, it is necessary to remove or suppress the harmful and anti-nutritive effects of flaxseeds before these are utilized for large-scale as food for human consumption. Interestingly, the toxic compounds of flaxseed also undergoes biochemical detoxification in the body, transforming into less toxic or inactive forms like α-ketoglutarate cyanohydrin etc. However, such detoxification is also a challenge for the development, scalability, and real-time quantification of these bioactive substances. This review focuses on the health affecting composition of flaxseed, along with health benefits and potential toxicity of its components, detoxification methods and mechanisms with evidence supported by animal and human studies.

Effects of flaxseed cake fortification on bread shelf life, and its possible use as feed for Tenebrio molitor larvae in a circular economy: preliminary results

BACKGROUND

Bread represents a significant share of food waste worldwide. The extension of the bread shelf life together with innovative systems of food waste treatment might decrease waste biomass decay, the need for transportation, and the need for storage. In recent years, insects have been selected as a valuable tool for food waste treatment owing to their capability to transform low-value food waste into biomass with high nutritional value. Bakery wastes can be used profitably for this purpose. This work had two objectives: (i) to measure the impact of flaxseed cake fortification on bread shelf life depending on the leavening agent (baker's yeast vs sourdough); (ii) to evaluate the possible reuse of the stale bread fortified with flaxseed cake for Tenebrio molitor rearing.

RESULTS

Our results showed that fortification seemed to slow the hardening rate of bread, particularly if baker's yeast was used. The time necessary for mold to appear in sourdough bread doubled (from 2 to 4 days). The addition of flaxseed cake to the recipe determined an increase of its scrap consumption by T. molitor larvae. We also observed a significant increase in the body mass of the T. molitor larvae fed with bread obtained with the brewer's yeast with respect to larvae fed with the sourdough.

CONCLUSION

Taken together, these preliminary data can indicate that sourdough bread fortified with 5% of flaxseed cake can represent a promising tool to reduce food waste and to recycle bread scraps by a novel zero-waste approach. © 2021 Society of Chemical Industry.

Amygdalin: Toxicity, Anticancer Activity and Analytical Procedures for Its Determination in Plant Seeds

Amygdalin (d-Mandelonitrile 6-O-β-d-glucosido-β-d-glucoside) is a natural cyanogenic glycoside occurring in the seeds of some edible plants, such as bitter almonds and peaches. It is a medically interesting but controversial compound as it has anticancer activity on one hand and can be toxic via enzymatic degradation and production of hydrogen cyanide on the other hand. Despite numerous contributions on cancer cell lines, the clinical evidence for the anticancer activity of amygdalin is not fully confirmed. Moreover, high dose exposures to amygdalin can produce cyanide toxicity. The aim of this review is to present the current state of knowledge on the sources, toxicity and anticancer properties of amygdalin, and analytical methods for its determination in plant seeds.

A review on extraction techniques and therapeutic value of polar bioactives from Asian medicinal herbs: Case study on Orthosiphon aristatus, Eurycoma longifolia and Andrographis paniculata

Medicinal plants have gained much interest in the prevention and treatment of common human disease such as cold and fever, hypertension and postpartum. Bioactive compounds from medicinal plants were synthesised using effective extraction methods which have important roles in the pharmaceutical product development. Orthosiphon aristatus (OA), Eurycoma longifolia (EL) and Andrographis paniculata (AP) are among popular medicinal herbs in Southeast Asia. The major compounds for these medicinal plants are polar bioactive compounds (rosmarinic acid, eurycomanone and andrographolide) which have multiple benefits to human health. The bioactive compounds are used as a drug to function against a variety of diseases with the support of scientific evidence. This paper was intended to prepare a complete review about the extraction techniques (e.g. OA, EL and AP) of these medicinal plants based on existing studies and scientific works. Suitable solvents and techniques to obtain their major bioactive compounds and their therapeutic potentials were discussed.

Flaxseed and Camelina Meals as Potential Sources of Health-Beneficial Compounds

Seed meals and cakes, deriving from minor oilseed crops, represent interesting co-products for the presence of a high content of proteins and bioactive compounds that could be successfully explored as valuable plant-derived feedstocks for food and non-food purposes. In this contest, flaxseed (Linum usitatissimum L.) and camelina (Camelina sativa (L.) Crantz) are becoming increasingly important in the health food market as functional foods and cosmetic ingredients. Thus, this study aimed to evaluate the effect of genetic characteristics and cultivation sites on the chemical features of seed meals deriving from two flaxseed varieties (Sideral and Buenos Aires) and a camelina cultivar (Italia), cultivated in Central and Northern Italy (Pisa and Bologna). The content of total phenols and flavonoids, seed oil, proteins and fatty acids have been evaluated, together with the chemical profiles of flaxseed and camelina meals. In addition, radical-scavenging activity has been investigated. All the examined seed meals resulted as rich in bioactive compounds. In particular, flaxseed meal is a good source of the lignan secoisolariciresinol diglucoside (SDG) and hydroxycinnamic acid glucosides, while camelina meal contains glucosinolates and quercetin glycosides. Furthermore, all extracts exhibited a very strong radical-scavenging activity, that make these plant-derived products interesting sources for food or cosmetic ingredients with health outcomes.

The Effect of Roasting on the Protein Profile and Antiradical Capacity of Flaxseed Meal

Roasting is more and more often used as a pre-treatment of flaxseeds. However, the process can influence flaxseed proteins that may be crucial for their properties. The aim of this research was to study changes in the electrophoretic protein profile (SDS-PAGE) and the antiradical capacity of flaxseed meals after roasting. The roasting temperature (160, 180, and 200 °C) and flaxseed cultivars (golden and brown seed) were factors including in the study. The free (F-MRP) and bound-to-protein (B-MRP) Maillard reaction products were also analyzed. The most significant changes in the SDS-PAGE protein profiles of roasted seeds of each of the tested flax cultivars were observed for the 13 kDa protein fraction (decrease) and for the 19 kDa and 17 kDa fractions (increase). The research revealed a significant correlation between the roasting temperature and B-MRP content, and changes in the percentage share of those three protein fractions. The antiradical capacity of roasted flaxseeds decreased, as compared with untreated seeds. After roasting at 200 °C the antiradical capacity of flaxseeds improved slightly, probably due to the MRP formation, but it was still significantly lower than that of the raw seeds. The research provides novel information about key protein fractions that seem to be important changing during heat treatment.

Advances and Prospects of Phenolic Acids Production, Biorefinery and Analysis

Biotechnological production of phenolic acids is attracting increased interest due to their superior antioxidant activity, as well as other antimicrobial, dietary, and health benefits. As secondary metabolites, primarily found in plants and fungi, they are effective free radical scavengers due to the phenolic group available in their structure. Therefore, phenolic acids are widely utilised by pharmaceutical, food, cosmetic, and chemical industries. A demand for phenolic acids is mostly satisfied by utilising chemically synthesised compounds, with only a low quantity obtained from natural sources. As an alternative to chemical synthesis, environmentally friendly bio-based technologies are necessary for development in large-scale production. One of the most promising sustainable technologies is the utilisation of microbial cell factories for biosynthesis of phenolic acids. In this paper, we perform a systematic comparison of the best known natural sources of phenolic acids. The advances and prospects in the development of microbial cell factories for biosynthesis of these bioactive compounds are discussed in more detail. A special consideration is given to the modern production methods and analytics of phenolic acids.

Linseed Components Are More Effective Than Whole Linseed in Reversing Diet-Induced Metabolic Syndrome in Rats

Linseed is a dietary source of plant-based ω–3 fatty acids along with fiber as well as lignans including secoisolariciresinol diglucoside (SDG). We investigated the reversal of signs of metabolic syndrome following addition of whole linseed (5%), defatted linseed (3%), or SDG (0.03%) to either a high-carbohydrate, high-fat or corn starch diet for rats for the final eight weeks of a 16–week protocol. All interventions reduced plasma insulin, systolic blood pressure, inflammatory cell infiltration in heart, ventricular collagen deposition, and diastolic stiffness but had no effect on plasma total cholesterol, nonesterified fatty acids, or triglycerides. Whole linseed did not change the body weight or abdominal fat in obese rats while SDG and defatted linseed decreased abdominal fat and defatted linseed increased lean mass. Defatted linseed and SDG, but not whole linseed, improved heart and liver structure, decreased fat vacuoles in liver, and decreased plasma leptin concentrations. These results show that the individual components of linseed produce greater potential therapeutic responses in rats with metabolic syndrome than whole linseed. We suggest that the reduced responses indicate reduced oral bioavailability of the whole seeds compared to the components.

Covalent modification of flaxseed protein isolate by phenolic compounds and the structure and functional properties of the adducts

Covalent modification of flaxseed protein isolate by phenolic compounds including flaxseed polyphenols, ferulic acid, and hydroxytyrosol was studied under alkaline condition and in the presence of oxygen. The structure and function of the adducts was evaluated. The extent of covalent reaction and the physicochemical characteristics of flaxseed protein isolate-phenolic adducts were found to depend on the structure of the phenolic compounds. The decrease in free amino, thiol and tryptophan groups and increase in molecular weight were different. Crosslinks were found in flaxseed protein isolate-hydroxytyrosol adducts while ferulic acid and flaxseed polyphenols were unable to crosslink flaxseed proteins. The thermal stability and antioxidative capacity of the adducts were higher than those of flaxseed protein isolate. The structural conformation and hydrophobicity of the adducts were also found to depend on the nature of phenolic compounds. These adducts can be used in food formulations as natural antioxidants, emulsifiers and encapsulating shell materials.

Changes in oxidative stability and protein profile of flaxseeds resulting from thermal pre-treatment

BACKGROUND

The oxidative stability of oilseeds is crucial for their technological/nutritional quality and shelf life. This research aimed to evaluate the effect of thermal pre-treatment (steaming and roasting under various time/temperature conditions) on flaxseed oil and protein stability. The monitoring of changes in oil oxidation in situ and protein profiles (SDS-PAGE) and analysis of the antiradical activity of ethanolic and aqueous fractions were included in the study.

RESULTS

Flaxseed stability during storage was considerably affected by thermal pre-treatment conditions. Dynamics of oil oxidation was accelerated at 160 °C and 180 °C but slowed at 200 °C. Influence of pre-treatment conditions on the antiradical activity of the aqueous fraction was clearly observed and no effect concerning the ethanolic fraction was found. The most significant changes in protein profile of 200 °C-roasted flaxseed were found with the observed disappearance of 19 kDa protein. A treatment-dependent decrease in the 13 kDa protein was also detected. Based on the aqueous extract protein profiles, roasting conditions were found to be crucial for protein extractability.

CONCLUSIONS

The study has broadened knowledge of the consequences of flaxseed thermal treatment. The deterioration of flaxseed oil oxidative stability is shown. The changes of 19 and 13 kDa proteins suggest their sensitivity to thermally induced aggregation and/or cross-link. © 2018 Society of Chemical Industry.

Effect of liver pâté enrichment with flaxseed oil and flaxseed extract on lipid composition and stability

BACKGROUND

There is an increase interest from food technologists in the improvement of the nutritional value of meat products, especially their lipid profile and shelf life. The aim of this study was to determine the effect of animal fat replacement with flaxseed oil (20%) and flaxseed extract addition (0.05%-0.25%) on changes in composition and stability of liver pâté lipid fractions.

RESULTS

Replacement of animal fat with flaxseed oil was observed to lower the saturated and monoenoic fatty acid in the product's fatty acid profile by around 12% and to raise the polyene fatty acid contribution by more than 70% when compared to the control. The replacement also resulted in enriching the pâté with phytosterols (β-sitosterol, campesterol, and cycloartenol). The addition of 0.05% and 0.10% ethanol flaxseed extract significantly slowed down lipid oxidation changes during storage of the pâté.

CONCLUSIONS

The study showed that a storage-stable meat product - liver pâté - characterized by a high nutritional value can be designed through the addition of flax oil rich in unsaturated fatty acids and flaxseed extract. The addition of 0.05% of the extract was found to be sufficient to improve the liver pâté's oxidative stability; it can thus be recommended for this type of product. © 2018 Society of Chemical Industry.

Characterization of Chemical Compounds with Antioxidant and Cytotoxic Activities in Bougainvillea x buttiana Holttum and Standl, (var. Rose) Extracts

Bougainvillea is widely used in traditional Mexican medicine to treat several diseases. This study was designed to characterize the chemical constituents of B. x buttiana extracts with antioxidant and cytotoxic activities using different solvents. The extraction solvents used were as follows: distilled water (dH₂O), methanol (MeOH), acetone (DMK), ethanol (EtOH), ethyl acetate (EtOAc), dichloromethane (DCM), and hexane (Hex) (100%) at an extraction temperature of 26 °C. Analysis of bioactive compounds present in the B. x buttiana extracts included the application of common phytochemical screening assays, GC-MS analysis, and cytotoxicity and antioxidant assays. The results show that the highest extraction yield was observed with water and methanol. The maximum total phenolic content amount and highest antioxidant potential were obtained when extraction with methanol was used. With the exceptions of water and ethanol extractions, all other extracts showed cytotoxicity ranging between 31% and 50%. The prevailing compounds in water, methanol, ethanol, and acetone solvents were as follows: 4H-pyran-4-one, 2,3-dihydro-3, 5-dihydroxy-6-methyl (2), 2-propenoic acid, 3-(2-hydrophenyl)-(E)- (3), and 3-O-methyl-d-glucose (6). By contrast, the major components in the experiments using solvents such as EtOH, DMK, EtOAc, DCM, and Hex were n-hexadecanoic acid (8), 9,12-octadecadienoic acid (Z,Z) (12); 9-octadecenoic acid (E)- (13), and stigmasta-5,22-dien-3-ol (28).