10.1021/ac034876a
The study presents the development of a biosensor-based assay for the quantification of riboflavin (Rf) in milk samples using surface plasmon resonance (SPR) technology. The assay involves the indirect measurement of Rf by detecting the excess of riboflavin binding protein (RBP) that remains free after complexation with Rf molecules originally present in the sample. The sensor chip is modified with covalently immobilized Rf to bind the excess RBP. The method involves a chemical modification to introduce a reactive ester group on the Rf molecule for immobilization on the chip surface. Calibration solutions are prepared by mixing Rf standard solutions with an optimized concentration of RBP, and the Rf content in milk samples is measured by comparing the response against the calibration. The results are comparable to those obtained from an official HPLC-fluorescence procedure, with a limit of quantification determined to be 234 μg/L and a limit of detection to 70 μg/L. The study demonstrates the potential of SPR-based biosensors as a competitive alternative to traditional analytical techniques for the determination of riboflavin in food samples.
10.1039/b904863d
The study focuses on the design and synthesis of an oligothiophene molecule, 5TPY, which noncovalently functionalizes single-wall carbon nanotubes (SWNTs) to create a hybrid material for photovoltaic devices. The purpose of this hybrid material is to leverage the excellent electron transfer abilities of SWNTs, their flexibility, and optical transparency to potentially enhance the performance of flexible organic solar cells. The chemicals used in the study include pyrene as the CNT-binding group due to its ability to adsorb to carbon nanotubes through π-π stacking interactions, a quinquethiophene segment as the electronically active segment, and various reagents in the synthesis process such as 2-thiophenecarbonitrile, NBS (N-bromosuccinimide), TFA (Trifluoroacetic acid), 1-pyrenebutyric acid, DPTS (N,N'-Dicyclohexylcarbodiimide), EDCI (1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide), and tributyltin compounds. These chemicals serve to construct the 5TPY molecule and facilitate its assembly around the SWNTs, preserving the electronic properties of the nanotubes for use in photovoltaic applications.
10.1002/cber.19691020125
The research focuses on the synthesis of 3-Carbamoyl-pyridon-(6)-adenin-dinucleotid (6-Pyridon of NAD), a derivative of Nicotinamide adenine dinucleotide (NAD), which is a coenzyme essential in various biochemical reactions. The purpose of this study was to understand the role of oxidized derivatives of NAD at the pyridine ring in the mechanism of oxidative phosphorylation, particularly in phosphorylating mitochondria. The synthesis of 6-Pyridon of NAD was undertaken due to the inability to achieve it through enzymatic pathways. The process involved the synthesis of nucleotide 8 from 3-Carbamoyl-pyridons-(6) and 2,3,5-Tri-O-benzoyl-D-ribofuranosylchlorid through a series of chemical reactions, including transamination, deprotection, acetonation, and phosphorylation. The final dinucleotide product, 9, was obtained by combining nucleotide 8 with an adenylic acid component using various coupling methods. Chemicals used in the process included 3-Carbamoyl-pyridons-(6), 2,3,5-Tri-O-benzoyl-D-ribofuranosylchlorid, Cyanathylphosphat, Dicyclohexylcarbodiimid, and several other reagents and solvents. The conclusions of the research indicated that the synthesized 6-Pyridon of NAD (9) did not exhibit reducibility to NAD by mitochondria from rat liver and their ultrasonic particles, suggesting it was not involved in oxidative phosphorylation.
10.1021/jm00156a035
The research focused on the synthesis and evaluation of analogues of the competitive angiotensin antagonist [sarl,Tyr(Me)4]ANG II (sarmesin), aiming to understand the structural requirements for receptor blockade and to potentially develop more potent competitive angiotensin antagonists. The study involved modifications of the sarcosine-1, O-methyltyrosine-4, and phenylalanine-8 residues of sarmesin using the solid-phase method, resulting in the synthesis of 23 peptides. The biological activities of these peptides were assessed in the rat isolated uterus assay, revealing that modifications at positions 1, 4, and 8 significantly reduced the antagonist activity of the peptide. Key chemicals used in the synthesis process included Boc-protected amino acids, DCC (dicyclohexylcarbodiimide), HBT (1-hydroxybenzotriazole), EEDQ (N-(ethoxycarbonyl)-2-ethoxyl-1,2-dihydroquinoline), and various solvents for chromatography and peptide purification. The study concluded that the structural requirements for receptor blockade by sarmesin are remarkably stringent, and even minor modifications can markedly reduce the antagonist activity of the peptide.
10.1248/cpb.38.312
The research focuses on the development of functional biomimetic coenzyme models, specifically the synthesis of chiral 5-deazaflavin derivatives. The purpose of this study was to prepare new types of chiral deazaflavin derivatives that could effectively discriminate the enantiotopic faces of carbonyls in asymmetric reduction reactions, potentially serving as models for enzymatic systems. The researchers synthesized 5-deazaflavin derivatives with chiral substituents at the C(6) position and a chiral tertiary asymmetric carbon center at C(5). They used various chemicals in the process, including 8-chloro derivative, chiral primary amines such as (+)-dehydroabietylamine and (S)-(-)-phenylethylamine, dicyclohexylcarbodimide (DCC), and N-(tert-butoxycarbonyl)-L-valine.
10.1021/ja00822a040
The research investigates the synthesis and properties of a dinucleoside monophosphate of 8,2'-O-cycloadenosine (AopAo). The purpose is to understand the unique conformational and enzymatic properties of this compound compared to natural nucleotides. Key chemicals used include 8,2'-O-cycloadenosine, dicyclohexylcarbodiimide (DCC) as a condensing reagent, and various protecting groups like acetyl and monomethoxytrityl. The synthesis involves multiple steps, including selective phosphorylation, protection and deprotection of functional groups, and condensation of nucleoside and nucleotide components. The study concludes that AopAo exhibits a well-stacked, thermally stable conformation with a left-handed screw axis, distinct from the right-handed stacking in natural nucleotides. This unusual conformation makes AopAo highly resistant to enzymatic hydrolysis by phosphodiesterases and affects its interaction with poly(U). The findings suggest that the stability and resistance of AopAo are due to the rigid structure imposed by the anhydro linkage and the unique torsion angle of the bases, rather than solely due to the presence of sulfur or oxygen atoms in the linkage.
10.1016/j.tetlet.2011.08.017
The study focuses on the development of an atom-efficient synthetic strategy for incorporating L-glutamine (L-Gln) into peptides during solution-phase synthesis. L-Gln is challenging to incorporate due to poor solubility and side reactions such as dehydration. The researchers propose using Na-Cbz-β-cyanomethyl-L-Ala (β-cyanomethyl-L-Ala) as a soluble and atom-efficient synthon for L-Gln. This synthon is stable under various conditions used in peptide synthesis and can be quantitatively hydrated to regenerate L-Gln within a peptide sequence. Key chemicals used include Cbz-L-Gln, dicyclohexylcarbodiimide (DCC), pyridine, hydrogen peroxide, and various protecting groups like Boc and OBut. These chemicals serve to dehydrate L-Gln to form the nitrile, protect and deprotect functional groups during synthesis, and facilitate peptide coupling reactions. The study demonstrates the utility of β-cyanomethyl-L-Ala in several peptide synthesis examples, showing its potential as a useful and efficient alternative for L-Gln incorporation in peptides.
10.1021/acs.joc.9b02042
The research focuses on the formation of enol ethers through the radical decarboxylation of α-alkoxy β-phenylthio acids, a process relevant to the synthesis of the anticancer antibiotic MPC1001, which contains a cyclic enol ether substructure. The study explores a method that involves the conversion of α-alkoxy β-phenylthio acids into enol ethers via Barton esters, utilizing phenylthio acids that are typically synthesized through the regioselective reaction of α,β-epoxy acids with PhSH in the presence of InCl3, followed by O-alkylation of the resulting alcohol. The researchers concluded that Barton esters derived from α-alkoxy-β-phenylthio acids decompose within 15 to 30 minutes upon exposure to visible light to afford enol ethers, and the parent β-phenylthio carboxylic acids can be prepared either by regioselective opening of α,β-epoxy acids with PhSH in the presence of InCl3 or by conjugate addition of PhSLi in the presence of PhSH to ethoxymethyl esters of α alkoxy α,β-unsaturated acids. Key chemicals used in this process include α,β-epoxy acids, PhSH, InCl3, N-hydroxypyridine-2(1H)-thione, and 1,3-dicyclohexylcarbodiimide, among others.
10.1021/ol702370m
The research describes the synthesis of monofunctional curcumin derivatives, a "clicked" curcumin dimer, and a PAMAM dendrimer-curcumin conjugate for therapeutic applications. The purpose of this study was to overcome the poor water and plasma solubility of curcumin, a bioactive compound found in turmeric, which possesses antioxidant, anticancer, anti-inflammatory, and anti-Alzheimer's disease properties. The researchers developed a synthetic methodology to produce curcumin conjugates with water-soluble polymers and targeting proteins, potentially enhancing curcumin's therapeutic efficacy. Key chemicals used in the process include curcumin, glutaric anhydride, amino-PEG azide, 1,3-dicyclohexylcarbodiimide (DCC), propargyl bromide, K2CO3, and copper(II) sulfate with sodium ascorbate for the "click" reaction. The study concluded that the monofunctional curcumin derivatives retained biological activity, efficiently labeled and dissolved amyloid fibrils, and the curcumin dimer selectively destroyed human neurotumor cells, making it a promising drug candidate. The conjugates were also expected to exhibit the EPR effect, enhancing their potential therapeutic applications.
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