Lipids and Composition of Fatty Acids of Saccharina latissima Cultivated Year-Round in Integrated Multi-Trophic Aquaculture

This study is evaluating the seasonal lipid and fatty acid composition of the brown seaweed Saccharina latissima. Biomass was sampled throughout the year (bi-monthly) at the commercial cultivation site near a fish farm in an integrated multi-trophic aquaculture (IMTA) and at a reference site in Denmark (2013–2014). Generally, there was no difference in the biomass composition between sites; however, significant seasonal changes were found. The lipid concentration varied from 0.62%–0.88% dry weight (DW) in July to 3.33%–3.35% DW in November (p < 0.05) in both sites. The fatty acid composition in January was significantly different from all the other sampling months. The dissimilarities were mainly explained by changes in the relative abundance of 20:5n-3 (13.12%–33.35%), 14:0 (11.07%–29.37%) and 18:1n-9 (10.15%–16.94%). Polyunsaturated fatty acids (PUFA’s) made up more than half of the fatty acids with a maximum in July (52.3%–54.0% fatty acid methyl esters; FAME). This including the most appreciated health beneficial PUFA’s, eicosapentaenoic (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3), but also arachidonic (ARA) and stearidonic acid (SDA), which are not found in land vegetables such as cabbage and lettuce. Compared to fat (salmon) and lean fish (cod) this seaweed species contains higher proportions of ARA and SDA, but lower EPA (only cod) and DHA. Conclusively, the season of harvest is important for the choice of lipid quantity and quality, but the marine vegetables provide better sources of EPA, DHA and long-chain (LC)-PUFA’s in general compared to traditional vegetables.     

Polar Lipids Composition,Antioxidant and Anti-Inflammatory Activities of the Atlantic Red Seaweed Grateloupia turuturu

Grateloupia turuturu Yamada, 1941, is a red seaweed widely used for food in Japan and Korea which was recorded on the Atlantic Coast of Europe about twenty years ago. This seaweed presents eicosapentaenoic acid (EPA) and other polyunsaturated fatty acids (PUFAs) in its lipid fraction, a feature that sparked the interest on its potential applications. In seaweeds, PUFAs are mostly esterified to polar lipids, emerging as healthy phytochemicals. However, to date, these biomolecules are still unknown for G. turuturu. The present work aimed to identify the polar lipid profile of G. turuturu, using modern lipidomics approaches based on high performance liquid chromatography coupled to high resolution mass spectrometry (LC–MS) and gas chromatography coupled to mass spectrometry (GC–MS). The health benefits of polar lipids were identified by health lipid indices and the assessment of antioxidant and anti-inflammatory activities. The polar lipids profile identified from G. turuturu included 205 lipid species distributed over glycolipids, phospholipids, betaine lipids and phosphosphingolipids, which featured a high number of lipid species with EPA and PUFAs. The nutritional value of G. turuturu has been shown by its protein content, fatty acyl composition and health lipid indices, thus confirming G. turuturu as an alternative source of protein and lipids. Some of the lipid species assigned were associated to biological activity, as polar lipid extracts showed antioxidant activity evidenced by free radical scavenging potential for the 2,2′-azino-bis-3-ethyl benzothiazoline-6-sulfonic acid (ABTS^●+) radical (IC₅₀ ca. 130.4 μg mL⁻¹) and for the 2,2-diphenyl-1-picrylhydrazyl (DPPH^●) radical (IC₂₅ ca. 129.1 μg mL⁻¹) and anti-inflammatory activity by inhibition of the COX-2 enzyme (IC₅₀ ca. 33 µg mL⁻¹). Both antioxidant and anti-inflammatory activities were detected using a low concentration of extracts. This integrative approach contributes to increase the knowledge of G. turuturu as a species capable of providing nutrients and bioactive molecules with potential applications in the nutraceutical, pharmaceutical and cosmeceutical industries.     

Extraction of Fatty Acids and Phenolics from Mastocarpus stellatus Using Pressurized Green Solvents

Polyunsaturated fatty acids are well known for their protective properties in relation to different skin diseases. Although seaweeds possess a low lipid fraction, they could act as an alternative renewable source of polyunsaturated fatty acids whenever other valuable seaweed components are also valorized. In this study, a biorefinery process using Mastocarpus stellatus as a model seaweed was proposed. The process started with the supercritical carbon dioxide extraction of the lipid and phenolic fractions. The influence of pressure during extraction with pure supercritical CO₂ was studied while operating at a selected temperature and solvent flow rate. Kinetic data obtained during the ethanol-modified supercritical CO₂ extraction were fitted to the spline model. Sequential processing was proposed with (i) pure CO₂ to obtain a product with 30% PUFA content and ω-3:ω-6 ratio 1:1, (ii) ethanol-modified CO₂ to extract phenolics, and (iii) microwave-assisted subcritical water extraction operating under previously optimized conditions for the extraction of phenolics, carrageenan and protein fractions. The composition of the supercritical extracts showed potential for use in both dietary and topical applications in skin care products. The remaining solids are suitable for the extraction of other valuable fractions.     

Exogenous Antioxidants Improve the Accumulation of Saturated and Polyunsaturated Fatty Acids in Schizochytrium sp. PKU#Mn4

Species of Schizochytrium are well known for their remarkable ability to produce lipids intracellularly. However, during their lipid accumulation, reactive oxygen species (ROS) are generated inevitably as byproducts, which if in excess results in lipid peroxidation. To alleviate such ROS-induced damage, seven different natural antioxidants (ascorbic acid, α-tocopherol, tea extract, melatonin, mannitol, sesamol, and butylated hydroxytoluene) were evaluated for their effects on the lipid accumulation in Schizochytrium sp. PKU#Mn4 using a fractional factorial design. Among the tested antioxidants, mannitol showed the best increment (44.98%) in total fatty acids concentration. However, the interaction effects of mannitol (1 g/L) and ascorbic acid (1 g/L) resulted in 2.26 ± 0.27 g/L and 1.45 ± 0.04 g/L of saturated and polyunsaturated fatty acids (SFA and PUFA), respectively, in batch fermentation. These concentrations were further increased to 7.68 ± 0.37 g/L (SFA) and 5.86 ± 0.03 g/L (PUFA) through fed-batch fermentation. Notably, the interaction effects yielded 103.7% and 49.6% increment in SFA and PUFA concentrations in batch fermentation. The possible mechanisms underlining those increments were an increased maximum growth rate of strain PKU#Mn4, alleviated ROS level, and the differential expression of lipid biosynthetic genes andupregulated catalase gene. This study provides an applicable strategy for improving the accumulation of SFA and PUFA in thraustochytrids by exogenous antioxidants and the underlying mechanisms.     

Marine Macroalgae as Sources of Polyunsaturated Fatty Acids

Algae from cold water (Canada) and warm water (China) were analysed for the total lipid content, and for their fatty acid (FA) composition and content. The major findings are that fatty acids (FA) from Canadian algae are generally richer in polyunsaturated FA (PUFA), with a higher n–3/n–6 FA ratio, and a higher degree of total unsaturation. The C 18:4 FA (stearidonic acid, morotic acid as synonym) was detected in greater amounts in cold water samples. The high levels of total PUFA, and especially of n–3 FA in Canadian algae, suggests possible utilization for nutritional purposes.     

The Anti-Inflammatory Effect of Algae-Derived Lipid Extracts on Lipopolysaccharide (LPS)-Stimulated Human THP-1 Macrophages

Algae contain a number of anti-inflammatory bioactive compounds such as omega-3 polyunsaturated fatty acids (n-3 PUFA) and chlorophyll a, hence as dietary ingredients, their extracts may be effective in chronic inflammation-linked metabolic diseases such as cardiovascular disease. In this study, anti-inflammatory potential of lipid extracts from three red seaweeds (Porphyra dioica, Palmaria palmata and Chondrus crispus) and one microalga (Pavlova lutheri) were assessed in lipopolysaccharide (LPS)-stimulated human THP-1 macrophages. Extracts contained 34%–42% total fatty acids as n-3 PUFA and 5%–7% crude extract as pigments, including chlorophyll a, β-carotene and fucoxanthin. Pretreatment of the THP-1 cells with lipid extract from P. palmata inhibited production of the pro-inflammatory cytokines interleukin (IL)-6 (p < 0.05) and IL-8 (p < 0.05) while that of P. lutheri inhibited IL-6 (p < 0.01) production. Quantitative gene expression analysis of a panel of 92 genes linked to inflammatory signaling pathway revealed down-regulation of the expression of 14 pro-inflammatory genes (TLR1, TLR2, TLR4, TLR8, TRAF5, TRAF6, TNFSF18, IL6R, IL23, CCR1, CCR4, CCL17, STAT3, MAP3K1) by the lipid extracts. The lipid extracts effectively inhibited the LPS-induced pro-inflammatory signaling pathways mediated via toll-like receptors, chemokines and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling molecules. These results suggest that lipid extracts from P. lutheri, P. palmata, P. dioica and C. crispus can inhibit LPS-induced inflammatory pathways in human macrophages. Therefore, algal lipid extracts should be further explored as anti-inflammatory ingredients for chronic inflammation-linked metabolic diseases.     

The Effect of Low-Dose Marine n-3 Fatty Acids on Plasma Levels of sCD36 in Overweight Subjects: A Randomized,Double-Blind,Placebo-Controlled Trial

CD36 is a scavenger receptor involved in lipid uptake and inflammation. Recently, non-cell-bound CD36 (sCD36) was identified in plasma and suggested to be a marker of lipid accumulation in the vessel wall. Marine n-3 polyunsaturated fatty acids (PUFA) may have cardioprotective effects. This study evaluated the effect of marine n-3 PUFA on sCD36 levels in overweight subjects. Fifty overweight subjects were randomized to 1.1 g of n-3 PUFA or 2 g of olive oil daily for six weeks. Neutrophils were isolated at baseline and after six weeks of treatment while an adipose tissue biopsy was obtained at baseline. The content of n-3 PUFA in adipose tissue and neutrophils was analyzed by gas chromatography, while plasma levels of sCD36 were determined using an enzyme-linked immunosorbent assay (ELISA). After six weeks of supplement plasma sCD36 did not differ between supplements (P = 0.18). There was no significant correlation between plasma sCD36 levels and n-3 PUFA in neutrophils at baseline (r = −0.02, P = 0.88), after six weeks supplement (r = −0.03, P = 0.85) or in adipose tissue (r = 0.14, P = 0.34). This study therefore does not provide evidence for a cardioprotective effect of n-3 PUFA acting through a CD36-dependent mechanism.     

Polyunsaturated Fatty Acids of Marine Macroalgae: Potential for Nutritional and Pharmaceutical Applications

As mammals are unable to synthesize essential polyunsaturated fatty acids (PUFA), these compounds need to be taken in through diet. Nowadays, obtaining essential PUFA in diet is becoming increasingly difficult; therefore this work investigated the suitability of using macroalgae as novel dietary sources of PUFA. Hence, 17 macroalgal species from three different phyla (Chlorophyta, Phaeophyta and Rhodophyta) were analyzed and their fatty acid methyl esters (FAME) profile was assessed. Each phylum presented a characteristic fatty acid signature as evidenced by clustering of PUFA profiles of algae belonging to the same phylum in a Principal Components Analysis. The major PUFA detected in all phyla were C₁₈ and C₂₀, namely linoleic, arachidonic and eicosapentaenoic acids. The obtained data showed that rhodophytes and phaeophytes have higher concentrations of PUFA, particularly from the n-3 series, thereby being a better source of these compounds. Moreover, rhodophytes and phaeophytes presented “healthier” ∑n-6/∑n-3 and PUFA/saturated fatty acid ratios than chlorophytes. Ulva was an exception within the Chlorophyta, as it presented high concentrations of n-3 PUFA, α-linolenic acid in particular. In conclusion, macroalgae can be considered as a potential source for large-scale production of essential PUFA with wide applications in the nutraceutical and pharmacological industries.     

Chondracanthus teedei var. lusitanicus: The Nutraceutical Potential of an Unexploited Marine Resource

Presently, there is a high demand for nutritionally enhanced foods, so it is a current challenge to look at new raw food sources that can supplement beneficially the human diet. The nutritional profile and key secondary metabolites of red seaweeds (Rhodophyta) are gaining interest because of this challenge. In this context, the possible use of the red seaweed Chondracanthus teedei var. lusitanicus (Gigartinales) as a novel nutraceutical source was investigated. As a result, we highlight the high mineral content of this seaweed, representing 29.35 g 100 g⁻¹ of its dry weight (DW). Despite the low levels of calcium and phosphorus (0.26 and 0.20 g 100 g⁻¹ DW, respectively), this seaweed is an interesting source of nitrogen and potassium (2.13 and 2.29 g⁻¹ DW, accordingly). Furthermore, the high content of carbohydrates (56.03 g 100 g⁻¹ DW), which acts as dietary fibers, confers a low caloric content of this raw food source. Thus, this study demonstrates that C. teedei var. lusitanicus is in fact an unexploited potential resource with the capability to provide key minerals to the human diet with promising nutraceutical properties.     

Screening of In-Vitro Anti-Inflammatory and Antioxidant Activity of Sargassum ilicifolium Crude Lipid Extracts from Different Coastal Areas in Indonesia

Sargassum brown seaweed is reported to exhibit several biological activities which promote human health, such as anticancer, antimicrobial, antidiabetic, anti-inflammatory, and antioxidant activity. This study aimed to investigate the anti-inflammatory and antioxidant activity of crude lipid extracts of Sargassum ilicifolium obtained from four different coastal areas in Indonesia, namely Awur Bay–Jepara (AB), Pari Island–Seribu Islands (PI), Sayang Heulang Beach–Garut (SHB), and Ujung Genteng Beach–Sukabumi (UGB). Results showed that treatment of RAW 264.7 macrophage cells with UGB and AB crude lipid extracts (12.5–50 µg/mL) significantly suppressed the nitric oxide production after lipopolysaccharide stimulation, both in pre-incubated and co-incubated cell culture model. The anti-inflammatory effect was most marked in the pre-incubated cell culture model. Both two crude lipid extracts showed 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and high ferric reducing antioxidant power, which were amounted to 36.93–37.87 µmol Trolox equivalent/g lipid extract and 681.58–969.81 µmol FeSO₄/g lipid extract, respectively. From this study, we can conclude that crude lipid extract of tropical S. ilicifolium can be further developed as a source of anti-inflammatory and antioxidant agent.     

Screening for Health-Promoting Fatty Acids in Ascidians and Seaweeds Grown under the Influence of Fish Farming Activities

The present study aimed to contrast the fatty acid (FA) profile of ascidians (Ascidiacea) and seaweeds (sea lettuce, Ulva spp. and bladderwrack, Fucus sp.) occurring in a coastal lagoon with versus without the influence of organic-rich effluents from fish farming activities. Our results revealed that ascidians and seaweeds from these contrasting environments displayed significant differences in their FA profiles. The n-3/n-6 ratio of Ascidiacea was lower under the influence of fish farming conditions, likely a consequence of the growing level of terrestrial-based ingredients rich on n-6 FA used in the formulation of aquafeeds. Unsurprisingly, these specimens also displayed significantly higher levels of 18:1(n-7+n-9) and 18:2n-6, as these combined accounted for more than 50% of the total pool of FAs present in formulated aquafeeds. The dissimilarities recorded in the FAs of seaweeds from these different environments were less marked (≈5%), with these being more pronounced in the FA classes of the brown seaweed Fucus sp. (namely PUFA). Overall, even under the influence of organic-rich effluents from fish farming activities, ascidians and seaweeds are a valuable source of health-promoting FAs, which confirms their potential for sustainable farming practices, such as integrated multi-trophic aquaculture.     

Isolation and Characterization of the Diatom Phaeodactylum Δ5-Elongase Gene for Transgenic LC-PUFA Production in Pichia pastoris

The diatom Phaeodactylum tricornutum can accumulate eicosapentaenoic acid (EPA) up to 30% of the total fatty acids. This species has been targeted for isolating gene encoding desaturases and elongases for long-chain polyunsaturated fatty acid (LC-PUFA) metabolic engineering. Here we first report the cloning and characterization of Δ5-elongase gene in P. tricornutum. A full-length cDNA sequence, designated PhtELO5, was shown to contain a 1110 bp open reading frame encoding a 369 amino acid polypeptide. The putative protein contains seven transmembrane regions and two elongase characteristic motifs of FLHXYHH and MYSYY, the latter being typical for microalgal Δ5-elongases. Phylogenetic analysis indicated that PhtELO5 belongs to the ELO5 group, tightly clustered with the counterpart of Thalassiosira pseudonana. Heterologous expression of PhtELO5 in Pichia pastoris confirmed that it encodes a specific Δ5-elongase capable of elongating arachidonic acid and eicosapentaenoic acid. Co-expression of PhtELO5 and IsFAD4 (a ∆4-desaturase from Isochrysis sphaerica) demonstrated that the high-efficiency biosynthetic pathway of docosahexaenoic acid was assembled in the transgenic yeast. Substrate competition revealed that PhtELO5 exhibited higher activity towards n-3 PUFA than n-6 PUFA. It is hypothesized that Phaeodactylum ELO5 may preferentially participate in biosynthesis of transgenic LC-PUFA via a n-3 pathway in the yeast host.     

Biosynthesis of Long-Chain Polyunsaturated Fatty Acids in Marine Gammarids: Molecular Cloning and Functional Characterisation of Three Fatty Acyl Elongases

Long-chain (C_20–24) polyunsaturated fatty acids (LC-PUFAs) are essential nutrients that are mostly produced in marine ecosystems. Previous studies suggested that gammarids have some capacity to endogenously produce LC-PUFAs. This study aimed to investigate the repertoire and functions of elongation of very long-chain fatty acid (Elovl) proteins in gammarids. Our results show that gammarids have, at least, three distinct elovl genes with putative roles in LC-PUFA biosynthesis. Phylogenetics allowed us to classify two elongases as Elovl4 and Elovl6, as they were bona fide orthologues of vertebrate Elovl4 and Elovl6. Moreover, a third elongase was named as “Elovl1/7-like” since it grouped closely to the Elovl1 and Elovl7 found in vertebrates. Molecular analysis of the deduced protein sequences indicated that the gammarid Elovl4 and Elovl1/7-like were indeed polyunsaturated fatty acid (PUFA) elongases, whereas Elovl6 had molecular features typically found in non-PUFA elongases. This was partly confirmed in the functional assays performed on the marine gammarid Echinogammarus marinus Elovl, which showed that both Elovl4 and Elovl1/7-like elongated PUFA substrates ranging from C₁₈ to C₂₂. E. marinus Elovl6 was only able to elongate C₁₈ PUFA substrates, suggesting that this enzyme does not play major roles in the LC-PUFA biosynthesis of gammarids.     

Oxygenated Acyclic Diterpenes with Anticancer Activity from the Irish Brown Seaweed Bifurcaria bifurcata

Brown alga Bifurcaria bifurcata is a prolific source of bioactive acyclic (linear) diterpenes with high structural diversity. In the continuation of our investigations on Irish brown algae, we undertook an in-depth chemical study on the n-hexanes and chloroform subextracts of B. bifurcata that led to isolation of six new (1–6) and two known (7–8) acyclic diterpenes. Chemical structures of the compounds were elucidated by a combination of 1D and 2D NMR, HRMS, FT-IR, [α]_D and vibrational circular dichroism (VCD) spectroscopy. Compounds 1–8, as well as three additional linear diterpenes (9–11), which we isolated from the same seaweed before, were tested against the human breast cancer cell line (MDA-MB-231). Several compounds moderately inhibited the growth of the MDA-MB-231 cell line with IC₅₀ values ranging from 11.6 to 32.0 μg/mL. The present study carried out on the lipophilic extracts of the Irish B. bifurcata shows the enormous capacity of this seaweed to produce a large palette of acyclic diterpenes with diverse oxygenation and substitution patterns and promising bioactivities.     

Seasonal Variation of the Proximate Composition,Mineral Content,Fatty Acid Profiles and Other Phytochemical Constituents of Selected Brown Macroalgae

The main objective was to determine the chemical, phytochemical, fatty acid and mineral profiles of three commercially relevant brown macroalgae (Laminaria digitata, Laminaria hyperborea and Ascophyllum nodosum) collected each season for two years off the west coast of Ireland. All the chemical, phytochemical, fatty acid and minerals analysed varied significantly depending on the macroalgal species, season and year of collection. Overall, the protein contents of macroalgae were negatively correlated with carbohydrate content. Protein (2–11%) was at its highest during winter and/or spring, decreasing to a minimum during summer and/or autumn. The three macroalgal species analysed in this study had clearly differentiated fatty acid profiles. The concentration of fatty acids was higher in A. nodosum compared with both Laminaria species. The mineral profile of the three macroalgal species was rich in essential metals, particularly Ca, Mg and P, while the levels of I were approximately 9- to 10-fold higher in both Laminaria spp. compared with A. nodosum. The levels of toxic metals (Cd, Hg and Pb) in all the macroalgal species studied were low in the current study; while the levels of total As were high (49–64 mg/kg DW macroalgae) compared with previous reports.     

Ocean Warming and CO2-Induced Acidification Impact the Lipid Content of a Marine Predatory Gastropod

Ocean warming and acidification are current global environmental challenges impacting aquatic organisms. A shift in conditions outside the optimal environmental range for marine species is likely to generate stress that could impact metabolic activity, with consequences for the biosynthesis of marine lipids. The aim of this study was to investigate differences in the lipid content of Dicathais orbita exposed to current and predicted future climate change scenarios. The whelks were exposed to a combination of temperature and CO₂-induced acidification treatments in controlled flowthrough seawater mesocosms for 35 days. Under current conditions, D. orbita foot tissue has an average of 6 mg lipid/g tissue, but at predicted future ocean temperatures, the total lipid content dropped significantly, to almost half. The fatty acid composition is dominated by polyunsaturated fatty acids (PUFA 52%) with an n-3:6 fatty acid ratio of almost 2, which remains unchanged under future ocean conditions. However, we detected an interactive effect of temperature and pCO₂ on the % PUFAs and n-3 and n-6 fatty acids were significantly reduced by elevated water temperature, while both the saturated and monounsaturated fatty acids were significantly reduced under increased pCO₂ acidifying conditions. The present study indicates the potential for relatively small predicted changes in ocean conditions to reduce lipid reserves and alter the fatty acid composition of a predatory marine mollusc. This has potential implications for the growth and survivorship of whelks under future conditions, but only minimal implications for human consumption of D. orbita as nutritional seafood are predicted.     

Accumulation of Astaxanthin by a New Haematococcus pluvialis Strain BM1 from the White Sea Coastal Rocks (Russia)

We report on a novel arctic strain BM1 of a carotenogenic chlorophyte from a coastal habitat with harsh environmental conditions (wide variations in solar irradiance, temperature, salinity and nutrient availability) identified as Haematococcus pluvialis Flotow. Increased (25‰) salinity exerted no adverse effect on the growth of the green BM1 cells. Under stressful conditions (high light, nitrogen and phosphorus deprivation), green vegetative cells of H. pluvialis BM1 grown in BG11 medium formed non-motile palmelloid cells and, eventually, hematocysts capable of a massive accumulation of the keto-carotenoid astaxanthin with a high nutraceutical and therapeutic potential. Routinely, astaxanthin was accumulated at the level of 4% of the cell dry weight (DW), reaching, under prolonged stress, 5.5% DW. Astaxanthin was predominantly accumulated in the form of mono- and diesters of fatty acids from C16 and C18 families. The palmelloids and hematocysts were characterized by the formation of red-colored cytoplasmic lipid droplets, increasingly large in size and number. The lipid droplets tended to merge and occupied almost the entire volume of the cell at the advanced stages of stress-induced carotenogenesis. The potential application of the new strain for the production of astaxanthin is discussed in comparison with the H. pluvialis strains currently employed in microalgal biotechnology.     

Optimization of Medium Using Response Surface Methodology for Lipid Production by Scenedesmus sp.

Lipid production is an important indicator for assessing microalgal species for biodiesel production. In this work, the effects of medium composition on lipid production by Scenedesmus sp. were investigated using the response surface methodology. The results of a Plackett–Burman design experiment revealed that NaHCO₃, NaH₂PO₄·2H₂O and NaNO₃ were three factors significantly influencing lipid production, which were further optimized by a Box–Behnken design. The optimal medium was found to contain 3.07 g L⁻¹ NaHCO₃, 15.49 mg L⁻¹ NaH₂PO₄·2H₂O and 803.21 mg L⁻¹ NaNO₃. Using the optimal conditions previously determined, the lipid production (304.02 mg·L⁻¹) increased 54.64% more than that using the initial medium, which agreed well with the predicted value 309.50 mg L⁻¹. Additionally, lipid analysis found that palmitic acid (C16:0) and oleic acid (C18:1) dominantly constituted the algal fatty acids (about 60% of the total fatty acids) and a much higher content of neutral lipid accounted for 82.32% of total lipids, which strongly proved that Scenedesmus sp. is a very promising feedstock for biodiesel production.     

Interaction between Marine-Derived n-3 Long Chain Polyunsaturated Fatty Acids and Uric Acid on Glucose Metabolism and Risk of Type 2 Diabetes Mellitus: A Case-Control Study

The present case-control study explored the interaction between marine-derived n-3 long chain polyunsaturated fatty acids (n-3 LC PUFAs) and uric acid (UA) on glucose metabolism and risk of type 2 diabetes mellitus (T2DM). Two hundred and eleven healthy subjects in control group and 268 T2DM subjects in case group were included. Plasma phospholipid (PL) fatty acids and biochemical parameters were detected by standard methods. Plasma PL C22:6n-3 was significantly lower in case group than in control group, and was negatively correlated with fasting glucose (r = −0.177, p < 0.001). Higher plasma PL C22:6n-3 was associated with lower risk of T2DM, and the OR was 0.32 (95% confidence interval (CI), 0.12 to 0.80; p = 0.016) for per unit increase of C22:6n-3. UA was significantly lower in case group than in control group. UA was positively correlated with fasting glucose in healthy subjects, but this correlation became negative in T2DM subjects. A significant interaction was observed between C22:6n-3 and UA on fasting glucose (p for interaction = 0.005): the lowering effect of C22:6n-3 was only significant in subjects with a lower level of UA. In conclusion, C22:6n-3 interacts with UA to modulate glucose metabolism.