Synthesis and antioxidant evaluation of (S,S)- and (R,R)-secoisolariciresinol diglucosides (SDGs)

Secoisolariciresinol diglucosides (SDGs) (S,S)-SDG-1 (major isomer in flaxseed) and (R,R)-SDG-2 (minor isomer in flaxseed) were synthesized from vanillin via secoisolariciresinol (6) and glucosyl donor 7 through a concise route that involved chromatographic separation of diastereomeric diglucoside derivatives (S,S)-8 and (R,R)-9. Synthetic (S,S)-SDG-1 and (R,R)-SDG-2 exhibited potent antioxidant properties (EC₅₀ = 292.17 ± 27.71 μM and 331.94 ± 21.21 μM, respectively), which compared well with that of natural (S,S)-SDG-1 (EC₅₀ = 275.24 ± 13.15 μM). These values are significantly lower than those of ascorbic acid (EC₅₀ = 1129.32 ± 88.79 μM) and α-tocopherol (EC₅₀ = 944.62 ± 148.00 μM). Compounds (S,S)-SDG-1 and (R,R)-SDG-2 also demonstrated powerful scavenging activities against hydroxyl [natural (S,S)-SDG-1: 3.68 ± 0.27; synthetic (S,S)-SDG-1: 2.09 ± 0.16; synthetic (R,R)-SDG-2: 1.96 ± 0.27], peroxyl [natural (S,S)-SDG-1: 2.55 ± 0.11; synthetic (S,S)-SDG-1: 2.20 ± 0.10; synthetic (R,R)-SDG-2: 3.03 ± 0.04] and DPPH [natural (S,S)-SDG-1: EC₅₀ = 83.94 ± 2.80 μM; synthetic (S,S)-SDG-1: EC₅₀ = 157.54 ± 21.30 μM; synthetic (R,R)-SDG-2: EC₅₀ = 123.63 ± 8.67 μM] radicals. These results confirm previous studies with naturally occurring (S,S)-SDG-1 and establish both (S,S)-SDG-1 and (R,R)-SDG-2 as potent antioxidants and free radical scavengers for potential in vivo use.     

Flaxseed (Linum usitatissimum L.) extract as well as (+)-secoisolariciresinol diglucoside and its mammalian derivatives are potent inhibitors of α-amylase activity

Type 2 diabetes mellitus (T2DM) is one of the common global diseases. Flaxseed is by far the richest source of the dietary lignans (i.e., secoisolariciresinol diglucoside) which have been shown to delay the development of T2DM in animal models. Herein, we propose the first evidences for a mechanism of action involving the inhibition of the pancreatic α-amylase (EC 3.2.1.1) by flaxseed-derived lignans that could therefore constitute a promising nutraceutical for the prevention and the treatment of T2DM.     

HPLC method with fluorescence detection for the quantitative determination of flaxseed lignans

We report a rapid and simple HPLC method with fluorescence detection for the quantification of the major flaxseed lignan, secoisolarisiresinol diglucoside (SDG) and its major metabolites. The method is specific for SDG, secoisolarisiresinol (SECO), enterodiol (ED) and entrolactone (EL) in rat serum. The assay procedure involves chromatographic separation using a Waters Symmetry C₁₈ reversed-phase column (4.6 mm × 150 mm, 5 μm) and mobile phase gradient conditions consisting of acetonitrile (0.1% formic acid) and water (0.1% formic acid). SDG extraction from serum requires the use of Centrifuge filters while SECO, ED and EL are extracted with diethyl ether. The organic layer is evaporated and reconstituted in 100 μL of mobile phase and 50 μL of reconstituted sample or filtrate is injected onto the column. Total run time is 25 min. Calibration curves are linear (r² ≥ 0.997) from 0.05 to 10 μg/mL for SDG and EL and 0.01–10 μg/mL for SECO and ED. Precision and accuracy are within USFDA specified limits. The stability of all lignans is established in auto-injector, bench-top, freeze–thaw and long-term stability at −80 °C for 30 days. The method's reasonable sensitivity and reliance on more widely available HPLC technology should allow for its straightforward application to pharmacokinetic evaluations of lignans in animal model systems such as the rat.     

The potential protective influence of flaxseed oil against renal toxicity induced by thioacetamide in rats

The present study was aimed to evaluate the influence of flaxseed oil on renal toxicity induced by thioacetamide in male rats. The animals were distributed into four groups. Rats of the first group were served as control. Rats of the second group were exposed to thioacetamide. Rats of the third group were treated with flaxseed oil and thioacetamide. Rats of the fourth group were treated with flaxseed oil. Significant increases of blood creatinine and uric acid were observed in TAA-treated rats after three weeks. In thioacetamide group, the levels of serum creatinine, blood urea nitrogen and uric acid were significantly elevated after six weeks. Histopathologically, the renal sections from thioacetamide-treated rats showed severe alterations in the structure of renal corpuscles including a degeneration of glomeruli and Bowman’s capsules. Administration of flaxseed oil protects the observed biochemical and histopathological alterations induced by thioacetamide exposure. Hence, the results of this study suggest that flaxseed oil protects against thioacetamide-induced renal injury and the protective influence of flaxseed oil may be attributed to its antioxidant role.     

In silico proteolysis and analysis of bioactive peptides from sequences of fatty acid desaturase 3 (FAD3) of flaxseed protein

Flaxseed (Linum usitatissimum), commonly known as linseed is an oilseed crop, emerging as an important and functional ingredient of food and has been paid more attention due to its nutritional value as well as beneficial effects. It is mainly rich in is α-linolenic acid (ALA, omega-3 fatty acid), fibres and lignans that have potential health benefits in reducing cardiovascular diseases, diabetes, osteoporosis, atherosclerosis, cancer, arthritis, neurological and autoimmune disorders. Due to its richness in omega-3 fatty acid, a group of enzymes known as fatty acid desaturases (FADs) mainly introduce double bonds into fatty acids’ (FAs) hydrocarbon chains that produce unsaturated fatty acids. Fatty acid desaturase 3 (FAD3), the commonest microsomal enzyme of omega-3 fatty acid, synthesizes linolenic acid (C18:3) from linoleic acid located in endoplasmic reticulum (ER) facing towards the cytosol. The emerging field of bioinformatics and large number of databases of bioactive peptides, helps in providing time-saving and efficient method for identification of potential bioactivities of any protein. In this study, 10 unique sequences of FAD3 from flaxseed protein have been used for in silico proteolysis and releasing of various bioactive peptides using three plant proteases, namely ficin, papain and stem bromelain, that are evaluated with the help of BIOPEP database. Overall, 20 biological activities were identified from these proteins. The results showed that FAD3 protein is a potential source of peptides with angiotensin-I-converting enzyme (ACE) inhibitory and dipeptidyl peptidase-IV (DPP-IV) activities, and also various parameters such as ∑A, ∑B, A_E, W, B_E, V and DHt were also calculated. Furthermore, PeptideRanker have been used for screening of novel promising bioactive peptides. Various bioinformatics tools also used to study protein’s physicochemical properties, peptide’s score, toxicity, allergenicity aggregation, water solubility, and drug likeliness. The present work suggests that flaxseed protein can be a good source of bioactive peptides for the synthesis of good quality and quantity of oil, and in silico method helps in investigating and production of functional peptides.     

Effects of flaxseed dietary supplementation on sperm quality and on lipid composition of sperm subfractions and prostatic granules in rabbit

Lipids are the main structural/functional components of the sperm, and their composition may undergo a series of modifications in relation to either physiologic events (capacitation and acrosome reaction) and/or diet. The goals of the current study were (1) to investigate whether a flaxseed (FS) dietary supplementation could affect the lipid and fatty acid profile of sperm subfractions and of prostatic granules (PGs) and (2) to evaluate the effects of dietary FS on rabbit buck semen quality. Accordingly, 20 adult New Zealand White rabbits were fed ad libitum a control diet (CO) or a diet supplemented with 5% extruded FS. Integration of diet with FS, as a consequence of the linolenic acid (C18:3n-3; LNA; 56%), increased the dietary n-3/n-6 ratio and resulted in a substantial rearrangement of sperm fatty acid composition at the subcellular level, mainly of polyunsaturated fatty acid (PUFA)n-3 (8.3% vs. 14.3%, P < 0.05). The lipid and fatty acid profiles of sperm tail membrane were the most affected, undergoing the following significant changes: (1) a reduction by half of linoleic acid (C18:2n-6; LA) and docosapentaenoic acid (22:5n-6; DPA), and a reduction of cholesterol (−70%); (2) a concomitant increase of LNA (+65%), docosahexaenoic acid (22:6n-3; DHA; +83%), and of oleic acid (C18:1n-9, +61%). As a consequence, the sperm of FS-fed rabbits had a twice higher n-3/n-6 ratio and phospholipid/cholesterol ratio compared with the control sperm. These changes might have been on the basis of the higher responsiveness to hypo-osmotic solution and, hence, the higher sperm track speed observed for the FS group. Also, the membrane integrity and viability of the LNA-enriched sperm were both improved. On the other hand, the presence of lignans in FS might have accounted for the reduction of sperm cholesterol in the semen of FS-treated rabbits. The responsiveness of sperm to acrosome reaction was not affected by the dietary treatment probably due to supranutritional level of vitamin E and to the higher number of PGs, which are known to play a key role in sperm capacitation. In conclusion, our data showed for the first time that the integration of FS into the rabbit diet may improve sperm quality by modifying the sperm lipid composition and that the sperm subfractions and the PGs respond differently to the FS-induced lipid manipulation.     

Effects of flaxseed supplementation on milk production,milk fatty acid composition and nutrient utilization by lactating dairy cows

Twelve multiparous Holstein cows at 72 ± 20 days in milk were used in a switch-back design with 14-d periods to determine the effect of replacing barley grain into a dairy total mixed ration with micronized or raw flaxseed on nutrient digestibility, milk yield, milk composition. Total mixed diets were (DM basis) 50% barley silage, 50% concentrate mix mainly rolled barley grain and canola meal. Diets were supplemented with 1 kg raw (RF) or micronized (MF) flaxseed to substitute 1 kg of rolled barley grain (C). Neutral detergent fibre, ADF and CP digestibility of the diets were not significantly affected by supplementation; however, calcium digestibility was reduced by 62% and 46% when raw and micronized flax were fed, respectively. Milk yield (38.3, 39.6, and 38.4 kg/d for diets C, RF and MF, respectively) was similar for all diets. Milk fat (3.50, 3.48, and 3.52%) and protein (3.31, 3.34, and 3.31%) for diets C, RF and MF, respectively, were not affected by treatment diets. Concentrations of c9, t11 conjugated linoleic acid (CLA; 0.51, 0.72 and 0.76 g/100 g fatty acids) in milk fat increased (P < 0.05) similarly among the two flaxseed supplemented diets. The RF and MF diets significantly increased the C18:1, C18:1 trans-11, C18:2 cis-9, cis-12 and C18:3 in milk fat however, C12:0, C14:0 and C16:0 were significantly reduced compared with control. Replacing barley grain with flaxseed in the diet of lactating cows increased the beneficial fatty acids in milk without depressing nutrient digestibility. Micronization of flaxseed did not reveal any advantage over raw flaxseed.     

Effects of extrusion of flaxseed on ruminal and postruminal nutrient digestibilities

A study was conducted to determine the effects of extrusion on ruminal, post-ruminal and whole tract digestibility of flaxseed. Extrusion was performed at 155°C with a residence time of 43?s. Two non-lactating Holstein cows fitted with ruminal and duodenal cannulas were used in a randomized complete block design. Results showed that extruded flaxseed had higher (P?in situ soluble and lower (P?P?P?P?P?P?相似文献   

Ultrasound-assisted extraction of flaxseed oil using immobilized enzymes

An aqueous enzymatic process assisted by ultrasound extraction (AEP-UE) was applied to the extraction of oil from flaxseed (Linum usitatissimum L.). The highest oil recovery of 68.1% was obtained when ground flaxseed was incubated with 130 U/g of cellulase, pectinase, and hemicellulase for 12 h, at 45 °C and pH 5.0. The IC₅₀ values of oil obtained by AEP-UE and organic solvent extraction (OSE), as measured by DPPH scavenging activity essay, were 2.27 mg/mL and 3.31 mg/mL. The AEP-UE-derived oil had a 1.5% higher content of unsaturated fatty acids than the OSE-derived oil. AEP-UE is therefore a promising environmentally friendly method for large-scale preparation of flaxseed oil.     

Uncovering molecular events associated with the chemosuppressive effects of flaxseed: a microarray analysis of the laying hen model of ovarian cancer

Background

The laying hen model of spontaneous epithelial ovarian cancer (EOC) is unique in that it is the only model that enables observations of early events in disease progression and is therefore also uniquely suited for chemoprevention trials. Previous studies on the effect of dietary flaxseed in laying hens have revealed the potential for both amelioration and prevention of ovarian cancer. The objective of this study was to assess the effect of flaxseed on genes and pathways that are dysregulated in tumors. We have used a bioinformatics approach to identify these genes, followed by qPCR validation, immunohistochemical localization, and in situ hybridization to visualize expression in normal ovaries and tumors from animals fed a control diet or a diet containing 10% flaxseed.

Results

Bioinformatic analysis of ovarian tumors in hens led to the identification of a group of highly up-regulated genes that are involved in the embryonic process of branching morphogenesis. Expression of these genes coincides with expression of E-cadherin in the tumor epithelium. Levels of expression of these genes in tumors from flax-fed animals are reduced 40-60%. E-cadherin and miR200 are both up-regulated in tumors from control-fed hens, whereas their expression is decreased 60-75% in tumors from flax-fed hens. This does not appear to be due to an increase in ZEB1 as mRNA levels are increased five-fold in tumors, with no significant difference between control-fed and flax-fed hens.

Conclusions

We suggest that nutritional intervention with flaxseed targets the pathways regulating branching morphogenesis and thereby alters the progression of ovarian cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-709) contains supplementary material, which is available to authorized users.