Design of polymeric nanoparticles for the encapsulation of monoacylglycerol

Dextran-covered nanoparticles were produced by two different processes: emulsion/solvent evaporation and nanoprecipitation for the encapsulation of monomyristin. The inner core was formed by poly(lactic acid) or by a hydrophobically modified dextran (carrying n-decyl chains). According to the core materials and/or to the process, the average size of nanoparticles as well as the extent of aggregate formation was modulated. It was shown that the presence of monomyristin induced significant modifications on the characteristics of the resulting suspension (size and aggregate formation). Varying the matrix polymer as well as the amount of monomyristin in the feed allowed obtaining nanoparticles with convenient size. The use of hydrophobically modified dextran as the matrix material appeared promising.     

DNA-based gels for oral delivery of probiotic bacteria

A single-stranded DNA, readily extracted from industrial discarded salmon milt, was used to prepare hydrogels and complex gels by cross-linking with gelatin and kappa-carrageenan, for the oral delivery of probiotic bacteria. The complex gels showed a higher protective capability over the hydrogels for approximately one log scale. However, the hydrogels were more stable during storage at 4 degrees C. The Lactobacillus and Lactococcus due to protection of the hydrogels could better tolerate to acid than the Bifidobacterium. Furthermore, food-graded hydrogels were prepared and optimized to a similar protective capability for future applications.     

Low-Cost Production of Green Microalga Botryococcus braunii Biomass with High Lipid Content Through Mixotrophic and Photoautotrophic Cultivation

Botryococcus braunii is a microalga that is regarded as a potential source of renewable fuel because of its ability to produce large amounts of lipid that can be converted into biodiesel. Agro-industrial by-products and wastes are of great interest as cultivation medium for microorganisms because of their low cost, renewable nature, and abundance. In this study, two strategies for low-cost production of B. braunii biomass with high lipid content were performed: (i) the mixotrophic cultivation using molasses, a cheap by-product from the sugar cane plant as a carbon source, and (ii) the photoautotrophic cultivation using nitrate-rich wastewater supplemented with CO₂ as a carbon source. The mixotrophic cultivation added with 15 g L^?1 molasses produced a high amount of biomass of 3.05 g L^?1 with a high lipid content of 36.9 %. The photoautotrophic cultivation in nitrate-rich wastewater supplemented with 2.0 % CO₂ produced a biomass of 2.26 g L^?1 and a lipid content of 30.3 %. The benefits of this photoautotrophic cultivation are that this cultivation would help to reduce accumulation of atmospheric carbon dioxide and more than 90 % of the nitrate could be removed from the wastewater. When this cultivation was scaled up in a stirred tank photobioreactor and run with semi-continuous cultivation regime, the highest microalgal biomass of 5.16 g L^?1 with a comparable lipid content of 32.2 % was achieved. These two strategies could be promising ways for producing cheap lipid-rich microalgal biomass that can be used as biofuel feedstocks and animal feeds.     

Study on glucose transport in muscle cells by extracts from Mitragyna speciosa (Korth) and mitragynine

The leaves of Mitragyna speciosa Korth (Rubiaceae) have been used in folk medicine for its unique medicinal properties. This study examined the water, methanolic and crude alkaloidal extracts from M. speciosa leaves and its major constituent mitragynine for the enhancement of glucose transport. Cellular uptake of radioactive 2-deoxyglucose was determined in rat L8 myotubes. Involving signalling pathway was determined with the specific inhibitors. Cell cytotoxicity was monitored by lactate dehydrogenase assay. Protein levels of glucose transporters (GLUTs) were measured by Western blotting. The results show that test samples significantly increased the rate of glucose uptake. The uptake was associated with increase in GLUT1 protein content. Co-incubation with insulin had no additional effect, but the cellular uptake was decreased by wortmannin and SB 203580, specific inhibitors of phosphatidylinositol 3-kinase (PI3K) and p38 mitogen-activated protein kinase (p38 MAPK), respectively. It is concluded that the increased glucose transport activity of M. speciosa is associated with increases in activities of the key enzymes dependent to the insulin-stimulated glucose transport for its acute action, and increases in the GLUT1 content for its long-term effect. This study demonstrated the effect of M. speciosa in stimulating glucose transport in muscle cells, implicating the folkloric use of M. speciosa leaves for treating diabetes.     

Enhanced Lipid Production by Co-cultivation and Co-encapsulation of Oleaginous Yeast Trichosporonoides spathulata with Microalgae in Alginate Gel Beads

This study attempted to enhance biomass and lipid productivity of an oleaginous yeast Trichosporonoides spathulata by co-culturing with microalgae Chlorella spp., optimizing culture conditions, and encapsulating them in alginate gel beads. The co-culture of the yeast with microalgae Chlorella vulgaris var. vulgaris TISTR 8261 most enhanced overall biomass and lipid productivity by 1.6-fold of the yeast pure culture at 48 h and by 1.1-fold at 72 h. After optimization and scale-up in a bioreactor, this co-culture produced the highest biomass of 12.2 g/L with a high lipid content of 47 %. The dissolved oxygen monitoring system in the bioreactor showed that the microalgae worked well as an oxygen supplier to the yeast. This study also showed that the co-encapsulated yeast and microalgae could grow and produce lipid as same as their free cells did. Therefore, it is possible to apply this encapsulation technique for lipid production and simplification of downstream harvesting process. This co-culture system also produced the lipid with high content of saturated fatty acids, indicating its potential use as biodiesel feedstock with high oxidative stability.     

Role of support nature （γ-Al2O3 and SiO2-Al2O3） on the performances of rhenium oxide catalysts in the metathesis of ethylene and 2-pentene

The metathesis of ethylene and 2-pentene was studied as an alternative route for propylene production over Re2O7/γ-Al2O3 and Re2O7/SiO2-Al2O3 catalysts. Both NH3 temperature-programmed desorption (NH3-TPD) and H2 temperature-programmed reduction (H2-TPR) results showed that Re2O7/SiO2-Al2O3 exhibited stronger acidity and weaker metal-support interaction than Re2O7/γ-Al2O3. At 35 60℃, isomerization free metathesis was observed only over Re2O7/γ-Al2O3, suggesting that the formation of metal-carbene metathesis active sites required only weak acidity. Our results suggest that on the Re2O7/SiO2-Al2O3, hydrido-rhenium species ([Re]-H) were formed in addition to the metathesis active sites, resulting in the isomerization of the initial 1-butene product into 2-butenes. A subsequent secondary metathesis reaction between these 2-butenes and the excess ethylene could explain the enhanced yields of propylene observed. The results demonstrate the potential for high yield of propylene from alternative feedstocks.     

Industrial Waste Utilization for Low-Cost Production of Raw Material Oil Through Microbial Fermentation

In view of ever-growing demand of biodiesel, there is an urgent need to look for inexpensive and promising renewable raw material oils for its production. In this context, the aim of this study was to evaluate the potential use of industrial wastes for low-cost production of oils through microbial fermentation. Among the strains tested, Yarrowia lipolytica grew best and produced highest lipid when grown on decanter effluent from palm oil mill. When crude glycerol by-product from a biodiesel plant was added into the effluent as a co-substrate, Y. lipolytica produced a higher biomass of 3.21 g/L and a higher amount of lipid of 2.21 g/L which was 68 % of the dry weight. The scale up and process improvement in a 5-L bioreactor increased the biomass and lipid up to 5.53 and 2.81 g/L, respectively. A semi-continuous mode of operation was an effective mode for biomass enhancement while a fed-batch mode was effective for lipid enhancement. These yeast lipids have potential to be used as biodiesel feedstocks because of their similar fatty acid composition to that of plant oil.     

A high-performance liquid chromatographic method for determination of mitragynine in serum and its application to a pharmacokinetic study in rats

A simple HPLC technique for determining mitragynine levels in serum was developed. The separation system consisted of a C18 column heated to 35 degrees C, a methanol-water (80:20, v/v) mobile phase, a flow rate of 0.8 mL/min and detection in the ultraviolet at 225 nm. Mitragynine, with a retention time of 10.09 min, was well resolved from any interferences in human serum and the internal standard peak. The calibration curve was linear from 0.1 to 10 microg/mL (r = 0.9995). Extraction of mitragy-nine from alkalinized serum using diethyl ether gave a high recovery (>or=85%). The intra- and inter-day precisions of the method were 4.29-5.88%RSD and 7.06-8.45%RSD, respectively. The accuracy ranged from -9.54 to +0.67%DEV. The limit of detection was 0.03 microg/mL and the lower limit of quantification was 0.1 microg/mL. Mitragynine in the stock solution was stable during 30 days of storage at 4 degrees C. This method was successfully applied to determine the pharmacokinetic characteristics of mitragynine levels in the serum of rats after it was administered orally.     

Solid phase extraction for GC-FID determination of 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA) and methamphetamine (MA) in human urine

A simple solid phase extraction method was developed for estimating the amounts of 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA) and methamphetamine (MA) in urine by using the GC-FID technique. The urine sample was alkalinized prior to undergoing solid phase extraction using Oasis HLB®. A 5% methanol-water mixture containing 2% ammonium hydroxide was used for washing, whereas a 70% methanol-water mixture containing 2% acetic acid was used for elution. The compounds were analyzed using the standard GC-FID conditions previously established for ecstasy samples, i.e., column: CP-SIL 24 CB WCOT (30 m × 0.32 mm i.d., 0.25 μm film thickness); carrier gas: N₂ (2.6 mL/min); injector temperature: 290°C; detector temperature: 300°C; oven temperature: initial 80°C, final 270°C (1 min), ramp rate 20°C/min. Validation demonstrated the linearity of the calibration curves between 1 and 20 μg/mL (r > 0.99) for all analytes. The precisions (% RSD) were approximately 3–17%, 6–16% and 7–17% for MDMA, MDA and MA, respectively. The accuracies (% DEV) were (?)17-(+)5%, (?)18-(+)15% and (?)18-(+)0.6% for MDMA, MDA and MA, respectively. The recovery ranged from 80 to 107% and the lower limit of quantification (LLOQ) was 1 μg/mL. The method was successfully applied to determine the levels of these compounds in the urine of drug abuse suspects.     

Production of propylene from an unconventional metathesis of ethylene and 2-pentene over Re2O7/SiO2-Al2O3 catalysts

An unconventional metathesis of ethylene and 2-pentene over Re2O7/SiO2-Al2O3 catalysts has been studied as an alternative route for the production of propylene. Complete conversion of 2-pentene and propylene yield as high as 88 wt% were obtained under mild reaction conditions at 35°C and atmospheric pressure. Unlike the conventional metathesis of ethylene and 2-butenes in which isomerization is a competing side reaction, the isomerization of 1-butene product from the unconventional metathesis of ethylene and 2-pentene to 2-butenes can further react with excess ethylene in the feed, resulting in additional increase in propylene yield. The secondary metathesis reaction was found to be favored under ethylene/2-pentene (E/2P) molar ratio 3 and gas hourly space velocity (GHSV) 1000 h-1 at the reaction temperature of 35°C. No catalyst deactivation was observed during the 455 min time-on-stream under the selected reaction conditions.