Production of structured triacylglycerols from microalgae

Regio- and Stereospecific Analysis of Triacylglycerols—A Brief Overview of the Challenges and the Achievements

The efforts to reveal, in detail, the molecular and intramolecular structures of one of the main lipid classes, namely, triacyl-sn-glycerols, which are now known to affect their specific and important role in all living organisms, are briefly overviewed. Some milestones of significance in the gradual but continuous development and improvement of the analytical methodology to identify the triacylglycerol regio- and stereoisomers in complex lipid samples are traced throughout the years: the use of chromatography based on different separation principles; the improvements in the chromatographic technique; the development and use of different detection techniques; the attempts to simplify and automatize the analysis without losing the accuracy of identification. The spectacular recent achievements of two- and multidimensional methods used as tools in lipidomics are presented.

Effect of salt stress on physiological parameters of microalgae Vischeria punctata strain IPPAS H-242, a superproducer of eicosapentaenoic acid

The strain IPPAS H-242 is an eustigmatophycean alga with good growth characteristics and high content of the long chain polyunsaturated eicosapentaenoic fatty acid (EPA) - a very-long-chain fatty acid with high nutraceutical value. In this study, based on 18S rRNA gene and ITS1-5.8S-ITS2 sequences the strain IPPAS H-242 was identified as an authentic strain of Vischeria punctata. The effect of salt stress (0.5 M NaCl) on growth, cell morphology, ultrastructure, and biochemical composition with the emphasis on the fatty acid (FA) profile was investigated in batch cultures. Under salt stress, biomass accumulation and cell division were severely inhibited; cells were bigger, with higher chloroplast volume and numerous mitochondria, they had more proteins (73 % from the initial concentration as compared to 23 % in control) and their lipids had higher EPA proportion (13.6 % of total FA as compared to 6.4 % of total FA in control). In salt-stressed cells, thylakoid organization and photosynthetic activity were impaired, and D1 protein content decreased to trace amounts. In spite of an increase in EPA proportion in total FA, salt stress causes a decrease in total EPA productivity (49 mg/L as compared to 130 mg/L in control).

Evaluation and Transcriptome Analysis of the Novel Oleaginous Microalga Lobosphaera bisecta (Trebouxiophyceae, Chlorophyta) for Arachidonic Acid Production

Arachidonic acid (AA) is an omega-6 long-chain polyunsaturated fatty acid and is important for human health. The coccoid green microalga Lobosphaera bisecta has been reported to be able to accumulate high AA content under certain conditions. Nutrient management and light intensity had significant effects on the biomass and accumulation of lipids and AA in L. bisecta SAG2043. Both a high nitrogen concentration (18 mM) and high light intensity (bilateral light-300 μmol m⁻² s⁻¹) were beneficial to the growth of L. bisecta, and the replacement of culture medium further enhanced the biomass, which reached 8.9 g L⁻¹. Low nitrogen concentration (3.6 mM) and high light significantly promoted the accumulation of lipids and AA. The highest lipid and AA content reached 54.0% and 10.8% of dry weight, respectively. Lipid compositions analysis showed that 88.2% of AA was distributed within the neutral lipids. We then reconstructed the lipid metabolic pathways of L. bisecta for the first time, and demonstrated that the upregulation of a key desaturase and elongase in the Δ6 pathway was conducive to the accumulation of fatty acids toward AA synthesis. L. bisecta SAG2043 exhibits high biomass, lipid and AA production. It may be a potential candidate for AA production.

Enhanced gastric therapeutic effects of Brucea javanica oil and its gastroretentive drug delivery system compared to commercial products in pharmacokinetics study

Background

Brucea javanica oil (BJO), a traditional Chinese herbal medicine, has a variety of pharmacological activities and several BJO-related patent drugs have been widely used in China.

Purpose

The objective of this study was to evaluate the gastric therapeutic effects of self-made BJO and its pharmaceutical potential to formulate novel BJO gastroretentive floating bead by comparing with commercial products.

Methods

BJO was extracted from the seeds of B. javanica, and its therapeutic effects were evaluated by comparing with commercial products in the treatment of human gastric cancer and gastric ulcer. Furthermore, the developed gastroretentive drug delivery system was evaluated by in vivo tests. A high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) method for detecting the concentration of glycerol trioleate in the pharma-cokinetic study was applied.

Results

The antitumor activity of BJO was stronger than that of the marketed preparation; the 50% inhibitory concentration (IC₅₀) values of BJO extracts on HGC27, SGC7901 and BGC823 gastric carcinoma were 0.3091, 1.736 and 2.743 μg/mL, respectively, whereas the values of marked BJO preparation were 15.26, 32.60 and 7.456 μg/mL, respectively. Histopathological studies demonstrated the ability of BJO to locally prevent and treat absolute ethanol-induced gastric ulcer. Developed BJO gastroretentive floating bead showed a satisfactory in vivo study. The highest glycerol trioleate concentration in the stomach after taking BJO gastroretentive floating bead was nearly two times higher when compared to the marketed BJO soft capsule.

Conclusion

Self-made BJO has a strong therapeutic effect on the stomach, and gastroretentive drug delivery system can be a promising approach to prolong and enhance its therapy ability when treating gastric diseases.

Production of Fatty Acids and Protein by Nannochloropsis in Flat-Plate Photobioreactors

Nannochloropsis is an industrially-promising microalga that may be cultivated for alternative sources of nutrition due to its high productivity, protein content and lipid composition. We studied the growth and biochemical profile of Nannochloropsis 211/78 (CCAP) in optimized flat-plate photobioreactors. Eighteen cultivations were performed at two nutrient concentrations. The fatty acid, protein content and calorific values were analyzed after 8, 12 and 16 days. Neutral lipids were separated and the changes in fatty acids in triglycerides (TAGs) during nutrient depletion were recorded. The maximum cell density reached 4.7 g∙L^-1 and the maximum productivity was 0.51 g∙L^-1∙d^-1. During nutrient-replete conditions, eicosapentaneoic acid (EPA) and total protein concentrations measured 4.2–4.9% and 50–55% of the dry mass, respectively. Nutrient starvation induced the accumulation of fatty acids up to 28.3% of the cell dry weight, largely due to the incorporation of C16:0 and C16:1n-7 fatty acyl chains into neutral lipids. During nutrient starvation the total EPA content did not detectibly change, but up to 37% was transferred from polar membrane lipids to the neutral lipid fraction.

Regioisomeric and enantiomeric analysis of triacylglycerols

A survey of useful methods for separation and identification of regioisomers and enantiomers of triacylglycerols. Gas chromatography, gas chromatography-mass spectrometry, ¹³C NMR determination of regioisomers by enzymatic methods, and supercritical fluid chromatography are briefly surveyed, whereas a detailed description is given of the analysis of triacylglycerols by liquid chromatography, especially with silver ion (Ag⁺; argentation), and nonaqueous reversed phase liquid chromatography. Special attention is paid to chiral chromatography. Details of mass spectrometry of triacylglycerols are also described, especially the identification of important triacylglycerol ions such as [M + H-RCOOH]⁺ in atmospheric pressure chemical ionization mass spectra.