Biochemical and morpho-mechanical properties, and structural organization of rat tail tendon collagen in diet-induced obesity model.

We have investigated the impact of obesity on the structural organization, morpho-mechanical properties of collagen fibers from rat tail tendon fascicles (RTTFs). Polarized Raman microspectroscopy showed that the collagen bands 855, 875, 938, and 960 cm-1 as well as those 1631 and 1660 cm-1 were affected by diet. Mechanical properties exhibited an increase in the yield strength from control (CTRL) to high fat (HF) diet (9.60 ± 1.71 and 13.09 ± 1.81 MPa) (p < 0.01) and ultimate tensile strength (13.12 ± 2.37 and 18.32 ± 2.83 MPa) (p < 0.05) with no significant change in the Young's Modulus. During mechanical, the band at 875 cm-1 exhibited the most relevant frequency shift (2 cm-1). The intensity of those at 855, 875, and 938 cm-1 in HF collagen displayed a comparable response to mechanical stress as compared to CTRL collagen with no significant diet-related changes in the Full Width at Half Maximum. Second harmonic generation technique revealed i) similar fiber straightness (0.963 ± 0.004 and 0.965 ± 0.003) and ii) significant changes in fibers diameter (1.48 ± 0.07 and 1.52 ± 0.08 µm) (p < 0.05) and length (22.06 ± 2.38 and 29.00 ± 3.76 µm) (p < 0.001) between CTRL and HF diet, respectively. The quantification of advanced glycation end products (AGEs) revealed an increase in both carboxymethyl-lysine and total fluorescence AGEs from CTRL to HF RTTFs.

The Potential of the Marine Microalga Diacronema lutheri in the Prevention of Obesity and Metabolic Syndrome in High-Fat-Fed Wistar Rats.

Long-chain polyunsaturated fatty acids n-3 series (n-3 LC-PUFAs), especially eicosapentaenoic and docosahexaenoic acids, are known to exert preventive effects on obesity and metabolic syndrome. Mainly consumed in the form of fish oil, LC-PUFAs n-3 are also found in significant quantities in other sources such as certain microalgae. The aim of this study was to evaluate the effects of Diacronema lutheri (Dia), a microalga rich in n-3 LC-PUFAs, on metabolic disorders associated with obesity. Three groups of male Wistar rats (n = 6 per group) were submitted for eight weeks to a standard diet or high-fat and high-fructose diet (HF), supplemented or not with 12% of Dia (HF-Dia). Compared to HF rats, HF-Dia rats showed a 41% decrease in plasma triacylglycerol (TAG) and an increase in plasma cholesterol (+35%) as well as in high-density lipoprotein cholesterol (+51%) without change to low-density lipoprotein cholesterol levels. Although fasting glycemia did not change, glucose and insulin tolerance tests highlighted an improvement in glucose and insulin homeostasis. Dia supplementation restored body weight and fat mass, and decreased levels of liver TAG (-75%) and cholesterol (-84%). In HF-Dia rats, leptin was decreased (-30%) below the control level corresponding to a reduction of 68% compared to HF rats. Similarly, the anti-inflammatory cytokines interleukin-4 (IL-4) and IL-10 were restored up to control levels, corresponding to a 74% and 58% increase in HF rats, respectively. In contrast, the level of IL-6 remained similar in the HF and HF-Dia groups and about twice that of the control. In conclusion, these results indicated that the D. lutheri microalga may be beneficial for the prevention of weight gain and improvement in lipid and glucose homeostasis.

Contribution of n-3 Long-Chain Polyunsaturated Fatty Acids to the Prevention of Breast Cancer Risk Factors.

Nowadays, diet and breast cancer are studied at different levels, particularly in tumor prevention and progression. Thus, the molecular mechanisms leading to better knowledge are deciphered with a higher precision. Among the molecules implicated in a preventive and anti-progressive way, n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFAs) are good candidates. These molecules, like docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids, are generally found in marine material, such as fat fishes or microalgae. EPA and DHA act as anti-proliferative, anti-invasive, and anti-angiogenic molecules in breast cancer cell lines, as well as in in vivo studies. A better characterization of the cellular and molecular pathways involving the action of these fatty acids is essential to have a realistic image of the therapeutic avenues envisaged behind their use. This need is reinforced by the increase in the number of clinical trials involving more and more n-3 LC-PUFAs, and this, in various pathologies ranging from obesity to a multitude of cancers. The objective of this review is, therefore, to highlight the new elements showing the preventive and beneficial effects of n-3 LC-PUFAs against the development and progression of breast cancer.

The Marine Microalga, Tisochrysis lutea, Protects against Metabolic Disorders Associated with Metabolic Syndrome and Obesity.

Long-chain polyunsaturated fatty acids n-3 series and especially docosahexaenoic acid are known to exert preventive effects on metabolic disturbances associated with obesity and decrease cardiovascular disease risk. n-3 LC-PUFAs are mainly consumed in the form of fish oil, while other sources, such as certain microalgae, may contain a high content of these fatty acids. The aim of this study was to evaluate the effects of Tisochrysis lutea (Tiso), a microalga rich in DHA, on metabolic disorders associated with obesity. Three male Wistar rat groups were submitted for eight weeks to a standard diet or high-fat and high fructose diet (HF), supplemented or not with 12% of T. lutea (HF-Tiso). The supplementation did not affect plasma alanine aminotransferase (ALAT). Bodyweight, glycemia and insulinemia decreased in HF-Tiso rats (ANOVA, p < 0.001), while total plasma cholesterol, high-density lipoprotein-cholesterol (HDL-C) increased (ANOVA, p < 0.001) without change of low-density lipoprotein-cholesterol (LDL-C) and triacylglycerol (TAG) levels. Tiso supplementation decreased fat mass and leptinemia as well as liver TAG, cholesterol and plasma tumor necrosis factor-alpha levels (ANOVA, p < 0.001) while it did not affect interleukin 6 (IL-6), IL-4 and lipopolysaccharides levels. HF-Tiso rats showed an increase of IL-10 level in abdominal adipose tissue (ANOVA, p < 0.001). In conclusion, these results indicated that DHA-rich T. lutea might be beneficial for the prevention of obesity and improvement of lipid and glucose metabolism.

Effect of Carotenoids from Phaeodactylum tricornutum on Palmitate-Treated HepG2 Cells.

Non-alcoholic fatty liver disease represents the most common liver disease and is characterized by an excess of lipid accumulation in hepatocytes, mainly stored as triglycerides. Phaeodactylum tricornutum is a marine microalga, which is rich in bioactive molecules known to be hepatoprotective, such as n-3 long-chain polyunsaturated fatty acids and fucoxanthin. The aim of this study was to investigate the effects of a carotenoid extract from P. tricornutum in a cellular model of non-alcoholic fatty liver disease induced by palmitate treatment. The combined effects of carotenoids and lipids, especially n-3 long-chain polyunsaturated fatty acids, were also investigated by using a total lipophilic extract. HepG2 cells were exposed for 24 h to 250 µM palmitate with or without the addition of carotenoid extract (6 µg/mL) or total lipophilic extract (100 µg/mL). The addition of carotenoid extract or total lipophilic extract prevented the accumulation of triglycerides, total cholesterol and cholesterol esters. The carotenoid extract and total lipophilic extract also decreased the mRNA expression levels of genes involved in lipogenesis (ACACA, FASN, SCD and DGAT1) and cholesterol esterification (ACAT1/SOAT1). In addition, the total lipophilic extract also downregulated the LXR/NR1H3 and SREBF1 genes, which are involved in lipogenesis regulation. By contrast, the carotenoid extract increased the mRNA level of CPT1A, a ß-oxidation related gene, and reduced the lipid droplet accumulation. In conclusion, this study highlights the preventive effects against non-alcoholic fatty liver disease of the two microalga extracts.

Carbon Partitioning and Lipid Remodeling During Phosphorus and Nitrogen Starvation in the Marine Microalga Diacronema lutheri (Haptophyta).

The domesticated marine microalga Diacronema lutheri is of great interest for producing various highly valuable molecules like lipids, particularly long-chain polyunsaturated fatty acids (LC-PUFA). In this study, we investigated the impact of phosphorus (P) and nitrogen (N) starvation on growth, carbon fixation (photosynthetic activity) and partitioning, and membrane lipid remodeling in this alga during batch culture. Our results show that the photosynthetic machinery was similarly affected by P and N stress. Under N starvation, we observed a much lower photosynthetic rate and biomass productivity. The degradation and re-use of cellular N-containing compounds contributed to triacylglycerol (TAG) accumulation. On the other hand, P-starved cells maintained pigment content and a carbon partitioning pattern more similar to the control, ensuring a high biomass. Betaine lipids constitute the major compounds of non-plastidial membranes, which are rich in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. Under P and N starvations, EPA was transferred from the recycling of membrane polar lipids, most likely contributing to TAG accumulation.

Microalgal carotenoids and phytosterols regulate biochemical mechanisms involved in human health and disease prevention.

Microalgae are photosynthetic microorganisms that produce numerous bioactive molecules that can be used as food supplement to prevent chronic disease installation. Indeed, they produce phycobiliproteins, polysaccharides, lipids, carotenoids and sterolic compounds. The use of microalgae in human nutrition provide a mixture of these molecules with synergistic effect. The aim of this review is to present the specific roles played by the xanthophylls, and specifically astaxanthin and fucoxanthin, two high added value carotenoids, and by microalgal phytosterols such as ß-sitosterol, campesterol and stigmasterol on several cell mechanisms involved in the prevention of cardiometabolic diseases and cancers. This review explains how these microalgal molecules modulate cell signaling pathways involved in carbohydrate and lipid metabolisms, inflammation, apoptosis, invasion and metastasis. Xanthophylls and phytosterols are involved in the reduction of inflammatory markers in relation with the regulation of the c-Jun N-terminal kinases and nuclear factor-kappa B signaling pathways, and suppression of production of pro-inflammatory mediators. Xanthophylls act on glucose and lipid metabolisms via both the upregulation of peroxisome proliferator-activated receptors (PPARs) and glucose transporters and its effects on the expression of enzymes involved in fatty acid synthesis and cholesterol metabolism. Their anti-cancer effects are related to the induction of intrinsic apoptosis due to down-regulation of key regulatory kinases. The anti-angiogenesis, anti-proliferative and anti-invasive effects are correlated with decreased production of endothelial growth factors and of matrix metalloproteinases. Phytosterols have a major role on cholesterol absorption via modification of the activities of Niemann-Pick C1 like 1 and ATP-binding cassette transporters and on cholesterol esterification. Their action are also related with the modulation of PPARs and sterol regulatory element-binding protein-1 activities.

Preventive Effects of the Marine Microalga Phaeodactylum tricornutum, Used as a Food Supplement, on Risk Factors Associated with Metabolic Syndrome in Wistar Rats.

Long-chain polyunsaturated fatty acids, n-3 series (n-3 LC-PUFA), are known for their preventive effects against cardiovascular disease. In an unfavourable economic and environmental context of fish oil production, marine microalgae could be an alternative source of n-3 LC-PUFA and are of interest for human nutrition. The aim of this study was to evaluate the effects of P. tricornutum, a microalga rich in eicosapentaenoic acid and used as a food supplement, on the metabolic disorders associated with metabolic syndrome and obesity development. Three male Wistar rat groups (n = 6) were submitted for eight weeks to a standard diet or high-fat diet (HF) with 10% fructose in drinking water, supplemented or not with 12% of P. tricornutum (HF-Phaeo). Supplementation led to n-3 LC-PUFA enrichment of lipids in the liver, plasma and erythrocytes. Plasma transaminases showed no difference between the HF and HF-Phaeo groups. Body weight, fat mass, inflammatory markers and insulinemia decreased in HF-Phaeo rats versus the HF group. Plasma total cholesterol, triacylglycerols and leptine diminished in HF-Phaeo rats, while HDL-cholesterol increased. In conclusion, this study highlights the beneficial effects of P. tricornutum in reducing the metabolic disorders associated with metabolic syndrome.

A comparative study on the effect of argan oil versus fish oil on risk factors for cardio-vascular disease in high-fat-fed rats.

OBJECTIVES: The aim of this study was to investigate the effects of two different sources of polyunsaturated fatty acid-fish oil (FO) and argan oil (AO)-on some risk factors for cardiovascular disease, such as platelet aggregation, dyslipidemia, and oxidative stress. METHODS: To explore this, four groups of six male rats were fed with different diets: The first group received a standard diet (control); the second group received a high-fat diet; the third was fed with a high-fat diet supplemented with 5% FO, and the last group received a high-fat diet supplemented with 5% AO. RESULTS: After 8 wk of the diet, AO showed a decrease in plasma lipids similar to that of FO. However, unlike FO, AO had no significant effect on hepatic lipid levels. On the other hand, supplementation with AO and FO similarly reduced platelet hyperactivity induced by high-fat diet. Concerning the results of oxidative stress, AO showed an antioxidant effect in the tissues and platelets greater than that observed in the high-fat FO group. CONCLUSIONS: For rats, the consumption of FO prevented the development of adiposity, restored insulin sensitivity, decreased plasma and liver lipid levels, and also prevented the prothrombotic effect. Intake of AO as a food supplement did not affect adiposity or liver lipid levels but decreased plasma lipid levels and improved oxidative status and platelet activity. FO and, to a lesser degree, AO thus represent promising nutritional tools in the prevention of cardiovascular disease.

Modulation of lipid biosynthesis by stress in diatoms.

Diatoms are responsible for up to 40% of the carbon fixation in our oceans. The fixed carbon is moved through carbon metabolism towards the synthesis of organic molecules that are consumed through interlocking foodwebs, and this process is strongly impacted by the abiotic environment. However, it has become evident that diatoms can be used as 'platform' organisms for the production of high valuable bio-products such as lipids, pigments and carbohydrates where stress conditions can be used to direct carbon metabolism towards the commercial production of these compounds. In the first section of this review, some aspects of carbon metabolism in diatoms and how it is impacted by environmental factors are briefly described. The second section is focused on the biosynthesis of lipids and in particular omega-3 long-chain polyunsaturated fatty acids and how low temperature stress impacts on the production of these compounds. In a third section, we review the recent advances in bioengineering for lipid production. Finally, we discuss new perspectives for designing strains for the sustainable production of high-value lipids.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'.

Microalgal Fatty Acids and Their Implication in Health and Disease.

BACKGROUND: The fatty acids of seed plants and microalgae stored in triglyceride are all produced in the plastid and incorporated into triglycerides by a complex biochemical exchange between the plastid envelope and the endoplasmic reticulum. The oils of seed plants provide the basis for vegetal fat production and the microalgal fats represent an important part of the basal food web of the marine environment. The health-promoting properties of these various sources of fats and in particular the long-chain polyunsaturated fatty acids of marine microalgae are widely recognized. The omega-3 fatty acids are known to have benefits on health and disease. Indeed, alpha-linolenic, eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) are linked to the regulation of mechanisms involved in numerous biological functions associated with cardiovascular disease and cancer prevention. Most EPA and DHA sources for human nutrition are provided by decreasing global stocks of fish. This is one of the reasons why industrial research has been directed towards more sustainable sources of these "marine" lipids. The synthesis of fatty acids and triglycerides are in many respects similar in higher plants and marine algae, but there are also important differences. CONCLUSION: This mini-review covers the biochemistry of fatty acid and lipid synthesis in marine microalgae, and the potential health impact of the different fats is also discussed.

Fish Oil and Microalga Omega-3 as Dietary Supplements: A Comparative Study on Cardiovascular Risk Factors in High-Fat Fed Rats.

Dietary supplementation with marine omega-3 polyunsaturated fatty acids (n-3 PUFA) can have beneficial effects on a number of risk factors for cardiovascular disease (CVD). We compared the effects of two n-3 PUFA rich food supplements (freeze-dried Odontella aurita and fish oil) on risk factors for CVD. Male rats were randomly divided into four groups of six animals each and fed with the following diets: control group (C) received a standard diet containing 7 % lipids; second group (HF high fat) was fed with a high-fat diet containing 40 % lipids; third group (HFFO high fat+fish oil) was fed with the high-fat diet supplemented with 0.5 % fish oil; and fourth group (HFOA high fat+O. aurita) received the high-fat diet supplemented with 12 % of freeze-dried O. aurita. After 8 weeks rats fed with the high-fat diet supplemented with O. aurita displayed a significantly lower bodyweight than those in the other groups. Both the microalga and the fish oil significantly reduced insulinemia and serum lipid levels. O. aurita was more effective than the fish oil in reducing hepatic triacyglycerol levels and in preventing high-fat diet-induced steatosis. O. aurita and fish oil also reduced platelet aggregation and oxidative status induced by high fat intake. After an OA supplementation, the adipocytes in the HFOA group were smaller than those in the HF group. Freeze-dried O. aurita showed similar or even greater biological effects than the fish oil. This could be explained by a potential effect of the n-3 PUFA but also other bioactive compounds of the microalgae.

Light Intensity Regulates LC-PUFA Incorporation into Lipids of Pavlova lutheri and the Final Desaturase and Elongase Activities Involved in Their Biosynthesis.

The microalga Pavlova lutheri is a candidate for the production of omega-3 long-chain polyunsaturated fatty acid (LC-PUFA), due to its ability to accumulate both eicosapentaenoic (EPA) and docosahexaenoic acids. Outstanding questions need to be solved to understand the complexity of n-3 LC-PUFA synthesis and partitioning into lipids, especially its metabolic regulation, and which enzymes and/or abiotic factors control their biosynthesis. In this study, the radioactivity of 14C-labeled arachidonic acid incorporated into the total lipids of P. lutheri grown under different light intensities and its conversion into labeled LC-PUFA were monitored. The results highlighted for the first time the light-dependent incorporation of LC-PUFA into lipids and the light-dependent activity of the final desaturation and elongation steps required to synthesize and accumulate n-3 C20/C22 LC-PUFA. The incorporation of arachidonic acid into lipids under low light and the related Δ17-desaturation activity measured explain the variations in fatty acid profile of P. lutheri, especially the accumulation of n-3 LC-PUFA such as EPA under low light conditions.

Maternal supplementation with n-3 long chain polyunsaturated fatty acids during perinatal period alleviates the metabolic syndrome disturbances in adult hamster pups fed a high-fat diet after weaning.

Perinatal nutrition is thought to affect the long-term risk of the adult to develop metabolic syndrome. We hypothesized that maternal supplementation with eicosapentaenoic acid and docosahexaenoic acid during pregnancy and lactation would protect offspring fed a high-fat diet from developing metabolic disturbances. Thus, two groups of female hamsters were fed a low-fat control diet, either alone (LC) or enriched with n-3 long chain polyunsaturated fatty acids (LC-PUFA) (LO), through the gestational and lactation periods. After weaning, male pups were randomized to separate groups that received either a control low-fat diet (LC) or a high-fat diet (HC) for 16 weeks. Four groups of pups were defined (LC-LC, LC-HC, LO-LC and LO-HC), based on the combinations of maternal and weaned diets. Maternal n-3 LC-PUFA supplementation was associated with reduced levels of basal plasma glucose, hepatic triglycerides secretion and postprandial lipemia in the LO-HC group compared to the LC-HC group. Respiratory parameters were not affected by maternal supplementation. In contrast, n-3 LC-PUFA supplementation significantly enhanced the activities of citrate synthase, isocitrate dehydrogenase and α-ketoglutarate dehydrogenase compared to the offspring of unsupplemented mothers. Sterol regulatory element binding protein-1c, diacylglycerol O-acyltransferase 2, fatty acid synthase, stearoyl CoA desaturase 1 and tumor necrosis factor α expression levels were not affected by n-3 LC-PUFA supplementation. These results provide evidence for a beneficial effect of n-3 LC-PUFA maternal supplementation in hamsters on the subsequent risk of metabolic syndrome. Underlying mechanisms may include improved lipid metabolism and activation of the mitochondrial oxidative pathway.

Plastids of marine phytoplankton produce bioactive pigments and lipids.

Phytoplankton is acknowledged to be a very diverse source of bioactive molecules. These compounds play physiological roles that allow cells to deal with changes of the environmental constrains. For example, the diversity of light harvesting pigments allows efficient photosynthesis at different depths in the seawater column. Identically, lipid composition of cell membranes can vary according to environmental factors. This, together with the heterogenous evolutionary origin of taxa, makes the chemical diversity of phytoplankton compounds much larger than in terrestrial plants. This contribution is dedicated to pigments and lipids synthesized within or from plastids/photosynthetic membranes. It starts with a short review of cyanobacteria and microalgae phylogeny. Then the bioactivity of pigments and lipids (anti-oxidant, anti-inflammatory, anti-mutagenic, anti-cancer, anti-obesity, anti-allergic activities, and cardio- neuro-, hepato- and photoprotective effects), alone or in combination, is detailed. To increase the cellular production of bioactive compounds, specific culture conditions may be applied (e.g., high light intensity, nitrogen starvation). Regardless of the progress made in blue biotechnologies, the production of bioactive compounds is still limited. However, some examples of large scale production are given, and perspectives are suggested in the final section.

Argan oil prevents prothrombotic complications by lowering lipid levels and platelet aggregation, enhancing oxidative status in dyslipidemic patients from the area of Rabat (Morocco).

BACKGROUND: It is now established that patients with hyperlipidemia have a high risk of atherosclerosis and thrombotic complications, which are two important events responsible for the onset and progression of cardiovascular disease. In the context of managing dyslipidemia by means of dietary advice based on the consumption of argan oil, we wanted to investigate the effect of virgin argan oil on plasma lipids, and for the first time, on the platelet hyperactivation and oxidative status associated with dyslipidemia. This study concerns patients recruited in the area of Rabat in Morocco. METHODS: 39 dyslipidemic (79% women) patients were recruited for our study in the area of Rabat in Morocco. They were randomly assigned to the two following groups: the argan group, in which the subjects consumed 25 mL/day of argan oil at breakfast for 3 weeks, and the control group in which argan oil was replaced by butter. RESULTS: After a 3-week consumption period, blood total cholesterol was significantly lower in the argan oil group, as was LDL cholesterol (23.8% and 25.6% lower, respectively). However, the HDL cholesterol level had increased by 26% at the end of the intervention period compared to baseline. Interestingly, in the argan oil group thrombin-induced platelet aggregation was lower, and oxidative status was enhanced as a result of lower platelet MDA and higher GPx activity, respectively. CONCLUSIONS: In conclusion, our results, even if it is not representative of the Moroccan population, show that argan oil can prevent the prothrombotic complications associated with dyslipidemia, which are a major risk factor for cardiovascular disease.

Use of radiolabeled substrates to determine the desaturase and elongase activities involved in eicosapentaenoic acid and docosahexaenoic acid biosynthesis in the marine microalga Pavlova lutheri.

The marine flagellate Pavlova lutheri is a microalga known to be rich in long-chain polyunsaturated fatty acids (LC-PUFAs) and able to produce large amounts of n-3 fatty acids, such as eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). As no previous study had attempted to measure the metabolic step of fatty acid synthesis in this alga, we used radiolabeled precursors to explore the various desaturation and elongation steps involved in LC-PUFA biosynthesis pathways. The incorporation of (14)C-labeled palmitic ([1-(14)C] 16:0) and dihomo-γ-linolenic ([1-(14)C] 20:3n-6) acids as ammonium salts within the cells was monitored during incubation periods lasting 3, 10 or 24h. Total lipids and each of the fatty acids were also monitored during these incubation periods. A decrease in the availability and/or accessibility of the radiolabeled substrates was observed over the incubation time. This decrease with incubation time observed using [1-(14)C] 16:0 and [1-(14)C] 20:3n-6 as substrates was used to monitor the conversion of (14)C-labeled arachidonic acid ([1-(14)C] 20:4n-6) into longer and more unsaturated fatty acids, such as 20:5n-3 and 22:6n-3, over shorter incubation times (1 and 3h). A metabolic relationship between the n-6 and n-3 fatty acid series was demonstrated in P. lutheri by measuring the Δ17-desaturation activity involved in the conversion of eicosatetraenoic acid to 20:5n-3. Our findings suggest that the biosynthesis pathway leading to n-3 LC-PUFA involves fatty acids of the n-6 family, which act as precursors in the biosynthesis of 20:5n-3 and 22:6n-3. This preliminary work provides a method for studying microalgal LC-PUFA biosynthesis pathways and desaturase and elongase activities in vivo using externally-radiolabeled fatty acid precursors as substrates. The use of the [1-(14)C] 20:4n-6 substrate also highlighted the relationships between the n-6 and the n-3 fatty acid series (e.g. Δ17-desaturation), and the final elongation and desaturation steps required for n-3 LC-PUFA formation in P. lutheri.

The role of Odontella aurita, a marine diatom rich in EPA, as a dietary supplement in dyslipidemia, platelet function and oxidative stress in high-fat fed rats.

BACKGROUND: Dietary changes are a major factor in determining cardiovascular risk. n-3 polyunsaturated fatty acids modulate the risk factors for metabolic syndrome via multiple mechanisms, including the regulation of the lipid metabolism. We therefore investigated the effect of Odontella aurita, a microalga rich in EPA, which is already used as a food supplement, on the risk factors for high-fat diet induced metabolic syndrome in rats. METHODS: Male Wistar rats were divided into 4 groups and were fed with a standard diet (control); with the standard diet supplemented with 3% freeze-dried O. aurita (COA); with a high-fat diet (HF); or with the high-fat diet supplemented with 3% of freeze-dried O. aurita (HFOA) for 7 weeks. In this study we evaluated the impact of these different diets on the risk factors for metabolic syndrome, such as hyperlipidemia, platelet aggregation, thromboxane B2 production, and oxidative stress. RESULTS: After 7 weeks of treatment, high fat feeding had increased final body weight, glycemia, triacylglycerol, and total cholesterol levels in plasma and liver compared to the control diet. Collagen-induced platelet aggregation and basal platelet thromboxane B2 were also higher in the high-fat fed rats than in those in the control group. In the liver, oxidative stress was greater in the HF group than in the control group. O. aurita intake in HFOA-fed rats resulted in lower glycemia and lipid levels in the plasma and liver relative than in the HF group. Thus, in the HFOA group, n-3 polyunsaturated fatty acid levels in the tissues studied (plasma, liver, and platelets) were higher than in the HF group. Platelet hyper-aggregability tended to decrease in HFOA-fed rats as basal platelet thromboxane B2 production decreased. Finally, O. aurita reduced oxidative stress in the liver, with lower malondialdehyde levels and increased glutathione peroxidase activity. CONCLUSIONS: O. aurita is a marine diatom rich in EPA as well as in other bioactive molecules, such as pigments. The synergistic effect of these microalgal compounds, displayed a beneficial effect in reducing the risk factors for high-fat induced metabolic syndrome: hyperlipidemia, platelet aggregation, and oxidative stress.

The potential of microalgae for the production of bioactive molecules of pharmaceutical interest.

Through the photosynthetic activity, microalgae process more than 25% of annual inorganic carbon dissolved in oceans into carbohydrates that ultimately, serve to feed the other levels of the trophic networks. Besides, microalgae synthesize bioactive molecules such as pigments and lipids that exhibit health properties. In addition, abiotic stresses, such as high irradiance, nutrient starvation, UV irradiation, trigger metabolic reorientations ending with the production of other bioactive compounds such as ω-3 fatty acids or carotenoids. Traditionally, these compounds are acquired through the dietary alimentation. The increasing, and often unsatisfied, demand for compounds from natural sources, combined with the decrease of the halieutic resources, forces the search for alternative resources for these bioactive components. Microalgae possess this strong potential. For instance, the diatom Odontella aurita is already commercialized as dietary complement and compete with fish oil for human nutrition. In this contribution, the microalga world is briefly presented. Then, the different types of biologically active molecules identified in microalgae are presented together with their potential use. Due to space limitation, only the biological activities of lipids and pigments are described in details. The contribution ends with a description of the possibilities to play with the environmental constrains to increase the productivity of biologically active molecules by microalgae and by a description of the progresses made in the field of alga culturing.

No altered blood pressure and serum markers of oxidative stress after a long time dietary fish oil in the genetically 9 month-old type-2 diabetes Zucker rat.

In this study, we investigated the effect of a high n-3 fatty acid diet (eicosapentaenoic and docosahexaenoic acids) in Zucker obese and lean rats on blood pressure in association with physiological parameters, serum biochemistry and oxidative stress analysis. After 150 days of treatment, dietary fish oil supplementation in Zucker obese rats (9 months of age) reduces bodyweight gain and serum triglyceridemia and nitrite levels, increases serum glucose and angiotensin converting enzyme activity, but does not alter blood pressure, cholesterol levels and serum markers of oxidative stress (malondialdehyde, glutathione), compared to the Zucker rats fed control diet. According to these results, we can consider that after 150 days of treatment, fish oil is not enough to regulate parameters involved in the metabolic syndrome, such as cholesterolemia and blood pressure, in a 9 month-old genetically type-2 diabetes rat.