蒜头果油合成1,15-十五碳二酸二甲酯的研究

研究了由蒜头果油制取1,15-十五碳二酸二甲酯的3种合成路线,比较了3种合成路线中臭氧化的吸收特征。结果表明,合成路线一为5步反应,1,15-十五碳二酸二甲酯收率为26.9%;路线二为4步反应,1,15-十五碳二酸二甲酯收率为61.7%;路线三为3步反应,1,15-十五碳二酸二甲酯收率为68.1%。通过对比确定路线3是最佳合成方案。用拟水平正交试验法对路线3的酯化反应进行优化,确定最佳的反应条件是:反应温度70℃左右;催化剂用量与原料比为1∶5(v.m-1);反应时间2 h。该优化条件可使1,15-十五碳二酸二甲酯收率达到72.4%。

麝香酮中间体——环十五酮的合成

以十五碳二酸为原料 ,经酯化、醇酮缩合反应合成了与麝香香气极相似的环十五酮 ,利用IR和1 HNMR对化合物结构进行了表征 ,讨论了反应时间和反应温度等对提取、酯化反应的影响。

Cloning and characterization of a delta-6 desaturase encoding gene from Nannochloropsis oculata

A gene （NANOC-D6D） encoding a desaturase that removes two hydrogen atoms from fatty acids at delta 6 position was isolated from a cDNA library of Nannochloropsis oculata （Droop） D. J. Hibberd （Eustigmatophyceae）. The unicellular marine microalga N. oculata synthesizes rich long chain polyunsaturated fatty acids （LCPUFAs）, including eicosapentaenoic acid （20：5n-3, EPA）. The deduced protein contains 474 amino acids that fold into 4 trans-membrane domains. The neighbor-joining phylogenetic tree indicates that NANOC-D6D is phylogenetically close to the delta-6 fatty acid desaturase of marine microalgae such as Glossomastix chrysoplasta, Thalassiosira pseudonana, and Phaeodactylum tricornutum. The gene was expressed in Saccharomyces cerevisiae INVScl to verify the substrate specificity of NAN OC-D6D. Our results suggest that the recombinant NANOC-D6D simultaneously desaturates linoleic acid （LA） and a-linolenic acid （ALA）.

A comparative analysis of fatty acid composition and fucoxanthin content in six Phaeodactylum tricornutum strains from diff erent origins

Phaeodactylum tricornutum is a potential livestock for the combined production of eicosapentaenoic acid(EPA) and fucoxanthin. In this study, six marine diatom strains identified as P. tricornutum were cultured and their total lipid, fatty acid composition and major photosynthetic pigments determined. It was found that the cell dry weight concentration and mean growth rate ranged between 0.24–0.36 g/L and 0.31–0.33/d, respectively. Among the strains, SCSIO771 presented the highest total lipid content, followed by SCSIO828, and the prominent fatty acids in all strains were C16:0, C16:1, C18:1, and C20:5(EPA). Polyunsaturated fatty acids, including C16:2, C18:2, and EPA, comprised a significant proportion of the total fatty acids. EPA was markedly high in all strains, with the highest in SCSIO828 at 25.65% of total fatty acids. Fucoxanthin was the most abundant pigment in all strains, with the highest in SCSIO828 as well, at 5.50 mg/g. The collective results suggested that strain SCSIO828 could be considered a good candidate for the concurrent production of EPA and fucoxanthin.

The effects of season on fatty acid composition and ω3/ω6 ratios of northern pike(Esox lucius L.,1758) muscle lipids

In the present study, the effects of season on fatty acid composition, total lipids, and ω3/ω6 ratios of northern pike muscle lipids in Klzlhrmak River （Klrlkkale, Turkey） were investigated. A total of 35 different fatty acids were determined in gas chromatography. Among these, palmitic, oleic, and palmitoleic acids had the highest proportion. The main polyunsaturated fatty acids （PUFAs） were found to be docosahexaenoic acid, eicosapentaenoic acid, and arachidonic acid. There were more PUFAs than monounsaturated fatty acids （MUFA） in all seasons. Similarly, the percentages of ω3 fatty acids were higher than those of total ω6 fatty acids in the fatty acid composition. ω3/ω6 ratios were calculated as 1.53, 1.32, 1.97, and 1.71 in spring, summer, autumn and winter, respectively. Overall, we found that the fatty acid composition and ω3/ω6 fatty acid ratio in the muscle of northern pike were significantly influenced by season.

Effects of Temperature, Salinity, Light Intensity, and pH on the Eicosapentaenoic Acid Production of Pinguiococcus pyrenoidosus

The effects of temperature, light intensity, salinity, and initial pH on the growth and fatty acid composition of Pinguiococcus pyrenoidosus 2078 were studied for eicosapentaenoic acid (EPA) production potential. The fatty acid composition was assayed by gas chromatography-mass spectrometry, which indicated that the main fatty acids were C14:0, C16:0 and EPA. The highest EPA percentage 20.83% of total fatty acids was obtained at 20℃ with the temperature being set at 20, 24, and 28℃. Under different salinities and light intensities, the highest percentages of total polyunsaturated fatty acids (PUFAs) and EPA were 17.82% and 31.37% of total fatty acids, respectively, which were achieved at salinity 30 and 100μmol photon m-2s-1 illumination. The highest percentages of total PUFAs and EPA were 38.75% and 23.13% of total fatty acids, respectively, which were reached at an initial pH of 6 with the test range being from 5.0 to 9.0.

Construction and characterization of a normalized cDNA library of Nannochloropsis oculata(Eustigmatophyceae)

We constructed and characterized a normalized cDNA library of Nannochloropsis oculata CS-179,and obtained 905 nonredundant sequences(NRSs) ranging from 431-1 756 bp in length.Among them,496 were very similar to nonredundant ones in the GenBank(E ≤1.0e-05),and 349 ESTs had significant hits with the clusters of eukaryotic orthologous groups(KOG).Bases G and/or C at the third position of codons of 14 amino acid residues suggested a strong bias in the conserved domain of 362 NRSs(>60%).We also identified the unigenes encoding phosphorus and nitrogen transporters,suggesting that N.oculata could efficiently transport and metabolize phosphorus and nitrogen,and recognized the unigenes that involved in biosynthesis and storage of both fatty acids and polyunsaturated fatty acids(PUFAs),which will facilitate the demonstration of eicosapentaenoic acid(EPA) biosynthesis pathway of N.oculata.In comparison with the original cDNA library,the normalized library significantly increased the efficiencies of random sequencing and rarely expressed genes discovering,and decreased the frequency of abundant gene sequences.

Co-Production of Lipids, Eicosapentaenoic Acid, Fucoxanthin, and Chrysolaminarin by Phaeodactylum tricornutum Cultured in a Flat-Plate Photobioreactor Under Varying Nitrogen Conditions

The marine diatom Phaeodactylum tricornutum is a polymorphological, ecologically significant, and well-studied model of unicellular microalga. This diatom can accumulate diverse important metabolites. Herein, we cultured P. tricornutum in an internally installed tie-piece flat-plate photobioreactor under 14.5 m mol L^(-1)(high nitrogen, HN) and 2.9 m mol L^(-1)(low nitrogen, LN) of KNO_3 and assessed its time-resolved changes in biochemical compositions. The results showed that HN was inductive to accumulate high biomass(4.1 g L^(-1)). However, the LN condition could accelerate lipid accumulation in P. tricornutum. The maximum total lipid(TL) content under LN was up to 42.5% of biomass on day 12. Finally, neutral lipids(NLs) were 63.8% and 75.7% of TLs under HN and LN, respectively. The content of EPA ranged from 2.3% to 1.5% of dry weight during the growth period under the two culture conditions. Peak volumetric lipid productivity of 128.4 mg L^(-1)d^(-1) was achieved in the HN group(on day 9). The highest volumetric productivity values of EPA, chrysolaminarin, and fucoxanthin were obtained in the exponential phase(on day 6) under HN, which were 9.6, 93.6, and 4.7 mg L^(-1)d^(-1), respectively. In conclusion, extractable amounts of lipids, EPA, fucoxanthin, and chrysolaminarin could be obtained from P. tricornutum by regulating the culture conditions.

Comparison of Lipids in Organs of the Starfish Asterias amurensis Associated with Different Treatments

Lipids were extracted from organs of the starfish Asterias amurens＆ associated with different treatments （raw-control, boiling and heating）, and then analyzed for lipid content, lipid oxidation index, lipid classes and fatty acid composition. Results showed that boiling softened the hard starfish shells, thus facilitating the collection of starfish organs. As compared with raw organs, the boiled organs had lower water content and higher lipid content, possibly due to the loss of water-holding capacity caused by pro- tein denaturation. Both boiling and heating increased the peroxide value （PV）, thiobarbituric acid （TBA） value and carbon value （CV） of lipids. Despite slight increases in the content of complex lipids, associated lipid composition had no substantial variations upon boiling and heating. For simple lipids, the content of 1, 2-diglyceride decreased in boiled and heated organs, with free fatty acids observed on thin layer chromatography （TLC）. However, neither boiling nor heating significantly changed the fatty acid composi- tions of simple or complex lipids in starfish organs, suggesting that these two treatments had no significant effects on complex lipids in starfish organs. Together, our results indicated that boiling of starfish soon after capture facilitated the handling and extraction of useful complex lipids consisting of abundant glucosylceramide and eicosapentaenoic acid （EPA）-bounded phospholipids.

Effect of pollution on DNA damage and essential fatty acid profile in Cirrhinus mrigala from River Chenab

The objective of this study was to evaluate the effect of anthropogenic pollution on DNA damage and the fatty acid profile of the bottom dweller fish （Cirrhinus mr^gala）, collected from the River Chenab, in order to assess the effect of the toxicants on the quality of the fish meat. The levels ofCd, Hg, Cu, Mn, Zn, Pb, Cr and Sn and of phenols from this river were significantly higher than the permissible limits set by the USEPA. Comet assays showed DNA damage in Cirrhinus mr^gala collected from three different sampling sites in the polluted area of the river. Significant differences were observed for DNA damage through comet assay in fish collected from polluted compared to control sites. No significant differences were observed for DNA damage between farmed and fish collected from upstream. The micronucleus assay showed similar trends. Fish from the highly polluted sites showed less number of fatty acids and more saturated fatty acids in their meat compared to fish from less polluted areas. Several fatty acids were missing in fish with higher levels of DNA in comet tail and micronucleus induction. Long-chain polyunsaturated fatty acids, eicosapentaenoic acid （20：5n-3） was found missing in the fish from polluted environment while it was found in considerable amount in farmed fish 7.8±0.4%. Docosahexaenoic acid （22：6n-3） also showed significant differences as 0.1±0.0 and 7.0±0.1% respectively, in wild polluted and fanned fishes.

Docosahexaenoic Acid and Eicosapentaenoic Acid Modulate Calcium Signaling in Murine CD36-Positive Taste Buds Cells, via Phospholipase Pathways

DHA （docosahexaenoic acid） and EPA （eicosapentaenoic acid） induced intracellular calcium increase in taste receptor cells purified from mouse circumvallate papillae. We have demonstrated that DHA and EPA induced calcium increase respectively via cPLA2 （cytosolic phospholipase A2） type lVc and calcium independent iPLA2 （phospholipase A2） type VI. Intracellular calcium increases via PLC （phospholipase C） pathway and leads to a calcium effiux and further SOC （stored operated calcium） channels activation. An abundant increase in intracellular calcium will induce exocytosis of neurotransmitters into the extracellular medium. Our results suggest that DHA and EPA induced calcium signaling, and should be implicated in the transmission of lipid gustatory information to afferent nerve fibers, as shown previously with linoleic acid.

Effectiveness of omega-3 polyunsaturated fatty acids against microbial pathogens

Microorganisms provide both beneficial and harmful effects to human beings. Beneficial effects come from the symbiotic relationship that exists between humans and microbiota, but then several human illnesses have turned some friendly microbes into opportunistic pathogens, causing several microbial-related diseases. Various efforts have been made to create and utilize antimicrobial agents in the treatment and prevention of these infections, but such efforts have been hampered by the emergence of antimicrobial resistance. Despite extensive studies on drug dis- covery to alleviate this problem, issues with the toxicity and tolerance of certain compounds and continuous microbial evolution have forced researchers to focus on screening various phytochemical dietary compounds for antimicrobial activity. Linolenic acid and its derivatives （eicosapentaenoic acid and docosahexaenoic acid） are omega-3 fatty acids that have been studied due to their role in human health, being important for the brain, the eye, the cardiovascular system, and general human growth. However, their utilization as antimicrobial agents has not been widely appreciated, perhaps due to a lack of understanding of antimicrobial mechanisms, toxicity, and route of administration. Therefore, this review focuses on the efficacy, mechanism, and toxicity of omega-3 fatty acids as alternative therapeutic agents for treating and preventing diseases associated with pathogenic microorganisms.

Fatty acid profiles of muscle from large yellow croaker (Pseudosciaena crocea R.) of different age

We investigated the fatty acid profiles of muscle from large yellow croaker （Pseudosciaena crocea R.） of different age. One- and two-year-old fish were cultured in floating net cages and sampled randomly for analysis. Moisture, protein, lipid and ash contents were determined by methods of Association of Analytical Chemist （AOAC） International. Fatty acid profile was deter- mined by gas chromatography. Crude protein, fat, moisture and ash contents showed no significant differences between the two age groups. The contents of total polyunsaturated fatty acids and docosahexaenoic acid （DHA） were significantly higher and eicosapentaenoic acid （EPA） content was significantly lower in the two-year-old large yellow croaker than in the one-year-old （/＇〈0.05）. No significant differences were observed in the contents of total saturated fatty acids and monounsaturated fatty acids, or the ratio ofn-3/n-6 fatty acids among the large yellow croakers of the two age groups. We conclude that large yellow croakers are good food sources of EPA and DHA.