1.Selective elimination of the free fatty acid fraction from esterified fatty acids in rat plasma through chemical derivatization and immobilization on amino functionalized silica nano-particles.
Chen J1, Lyu Q2, Yang M3, Chen Z2, He J4. J Chromatogr A. 2016 Jan 29;1431:197-204. doi: 10.1016/j.chroma.2015.12.078. Epub 2015 Dec 31.
A high throughput and low cost approach to separate free fatty acids (FFAs) from phospholipid and acylglycerols (esterified fatty acids, EFAs) has been demonstrated, which may be widely used as a sample preparation method in the metabolomics and lipid research. The optimal conditions for FFAs reacting with N-hydroxysuccinimide (NHS) only need 10min at room temperature to obtain a 93.5% yield of FFAs-NHS ester. The rest 6% FFA transformed into N-cyclohexyl-fatty acid-amide which is stable to methyl esterification adopted for fatty acids analysis. 10min are taken for FFAs-NHS ester to react with amino functionalized silica nanoparticles to immobilize the FFAs. The separation of FFAs from EFAs could be carried out readily by centrifugation. The whole process including derivatization, immobilization, and centrifugation takes less than 40min. Much more accurate fatty acids composition of rat plasma EFAs could be obtained by this approach than the previous reported methods.
2.Mitsunobu alkylation of cancerostatic 5-fluorouridine with (2E)-10-hydroxydec-2-enoic acid, a fatty acid from royal jelly with multiple biological activities.
Ottenhaus V1, Rosemeyer H2. Chem Biodivers. 2015 Sep;12(9):1307-12. doi: 10.1002/cbdv.201500048.
5-Fluorouridine (1) - a nucleoside antimetabolite with strong cancerostatic properties - was protected i) at the 2'- and 3'-OH groups with a heptan-4-ylidene residue and ii) at the 5'-OH group with a (4-methoxyphenyl)(diphenyl)methyl residue. This fully protected compound, 3, was submitted to a Mitsunobu reaction with the N-hydroxysuccinimide (NHS) ester, 5, of (2E)-10-hydroxydec-2-enoic acid (4) which gave nucleolipid 6. The latter was detritylated with Cl2 CHCOOH to yield the co-drug 7 as NHS ester.
3.Biocatalytic synthesis of starch esters by immobilized lipase on magnetic microparticles.
Prasertpornsakun N1, Raita M1, Laosiripojana N1, Champreda V2. Biosci Biotechnol Biochem. 2015;79(11):1750-8. doi: 10.1080/09168451.2015.1056507. Epub 2015 Jun 24.
Enzymatic esterification is an efficient approach for modifying starch to functionalized biomaterials. In this study, conversion of cassava starch to fatty acid acyl esters using immobilized Thermomyces lanuginosus lipase on Fe3O4 microparticles modified with 3-aminopropyltriethoxysilane and covalently linked by 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide and N-hydroxysuccinimide (Fe3O4-AP-ED-lipase) in a solvent-free system was studied. An optimized reaction containing 5% w/v gelatinized starch, 1% v/v Triton X-100, and 1% w/v biocatalyst with 2.5% w/v of fatty acids (palmitic, oleic, or linoleic acid) resulted in esterified products with a degree of substitution (DS) of 0.12-0.14, while a slightly lower DS was observed using crude palm fatty acid distillate as the acyl donor with 42.9-59.6% recovery yield. Increasing DS led to lower glass transition temperature and higher viscosity of the esterified products. The enzyme showed high operational stability with 85% retaining in activity after recycling in three consecutive batches with simple separation by magnetization, leading to improved process economics.
4.Controllable layer-by-layer assembly of PVA and phenylboronic acid-derivatized chitosan.
Zhang D1, Yu G2, Long Z2, Yang G3, Wang B4. Carbohydr Polym. 2016 Apr 20;140:228-32. doi: 10.1016/j.carbpol.2015.12.032. Epub 2015 Dec 17.
Phenylboronic acid-derivatized chitosan (chitosan-PBA) were prepared by grafting small molecules bearing phenylboronic acid groups onto chitosan with N-hydroxysuccinimide (NHS) and N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) as a coupling reagent pair. Self-assembly multilayer thin films of chitosan-PBA and poly(vinyl alcohol) were subsequently produced under pH control on supporting surfaces, either a silicon wafer or polystyrene latex particles. The driving force of the self-assembly was the ester formation of phenylboronic acid containing polymers with PVA, which can be "turned off" by simple pH control.
