Tris(hydroxymethyl)acrylamidomethane Research Articles

Biotinylated non-ionic amphipols for GPCR ligands screening.

We present herein the synthesis of biotin-functionalized polymers (BNAPols) that have been developed for the fixation of membrane proteins (MPs) onto surfaces. BNAPols were synthesized by free-radical polymerization of a tris(hydroxymethyl)acrylamidomethane (THAM)-derived amphiphilic monomer in the presence of a thiol-based transfer agent with an azido group. Then a Huisgen-cycloaddition reaction was performed with Biotin-(PEG)8-alkyne that resulted in formation of the biotinylated polymers. The designed structure of BNAPols was confirmed by NMR spectroscopy, and a HABA/avidin assay was used for estimating the percentage of biotin grafted on the polymer end chain. The colloidal characterization of these biotin-functionalized polymers was done using both dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) techniques. BNAPols were used to stabilize a model G protein-coupled receptor (GPCR), the human Growth Hormone Secretagogue Receptor (GHSR), out of its membrane environment. Subsequent immobilization of the BNAPols:GHSR complex onto a streptavidin-coated surface allowed screening of ligands based on their ability to bind the immobilized receptor. This opens the way to the use of biotinylated NAPols to immobilize functional, unmodified, membrane proteins, providing original sensor devices for multiple applications including innovative ligand screening assays.

Inhibition of Angiogenesis by THAM‐Derived Cotelomers Endowed with Thalidomide Moieties.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Inhibition of angiogenesis by THAM-derived cotelomers endowed with thalidomide moieties

The synthesis of a tris(hydroxymethyl)acrylamidomethane (THAM)-derived cotelomer endowed with thalidomide units and a preliminary assessment of its biological activity are described. 4-Carboxy thalidomide and 4-( N-acryloyl) lysine thalidomide derivatives were prepared. The polymerization of these compounds with THAM in the presence of octanethiol as transfer reagent provided a water-soluble telomer bearing several thalidomide units. The ability of this telomer to inhibit angiogenesis in a mouse model of corneal neovascularization was compared to 4-carboxy thalidomide and thalidomide. A significant inhibition in area of neovascularization stimulated by a bFGF pellet was observed only in the mice treated with the telomer.

Neutron reflection and small-angle neutron scattering studies of a fluorocarbon telomer surfactant

Dilute aqueous phase behavior of a novel tris(hydroxymethyl)acrylamidomethane (THAM)-derived telomer bearing a perfluorohexyl hydrophobic chain, F6THAM6, has been investigated. Fluorinated polyhydroxy surfactants of this kind find use in emerging biomedical applications. Neutron reflection (NR) and drop volume surface tension (DVT) methods have been used to determine the critical micelle concentration ( cmc=4.7×10 −4 mol dm −3) and surface adsorption parameters (at the cmc NR gives a molecular area a cmc=67.4 and 62 A ̊ 2 and surface excess Γ cmc =2.46×10 −6 mol m −2) . The aggregation structures were determined by small-angle neutron scattering (SANS), indicating globular (polydisperse spheres) micelles of radius ∼30 Å are present. These findings are compared with literature on surfactants with related structures, to identify how the unusual molecular structure of F6THAM6 affects surfactant properties.

Fluorocarbon−Hydrocarbon Nonionic Surfactants Mixtures: A Study of Their Miscibility

Binary mixtures of fluorocarbon and hydrocarbon nonionic surfactants derived from the tris(hydroxymethyl)acrylamidomethane (THAM) have been examined by 19F NMR spectroscopy and UV−visible spectroscopy in the presence of pinacyanol chloride as a probe. Aqueous solutions have been studied as a function of total surfactant concentration over a range of fluorocarbon/hydrocarbon ratios. For molar fractions in fluorinated surfactant lower than 0.7, the variations of both the 19F chemical shift and of the absorbance show two inflection points as a function of surfactant concentration. This was assigned to two critical micelle concentrations (cmc's). Above the second cmc, two kinds of micelles (fluorocarbon-rich and hydrocarbon-rich) should coexist as a result of the incompatibility between the two types of surfactants. The experimental results cannot be adequately described by current models on demixing micellar systems. An explanation of this behavior is suggested, by taking into account the interactions betwee...

Stabilization of polymerized vesicular systems: an application of the dynamic molecular shape concept

A series of glycolipid surfactants derived from Tris(hydroxymethyl)acrylamidomethane (THAM) and bearing hydrocarbon or perfluorocarbon tails and an acryloyl group attached to their polar head was prepared to explore the aqueous behavior of the supramolecular systems they form. The dispersion of surfactants was achieved in water under ultrasonication conditions. Hydrocarbon compounds give heterogeneous vesicular assemblies. In the case of perfluorocarbon derivatives homogeneous vesicles were obtained. However after 1-day storage, all these systems fuse. To stabilize these vesicles, polymerization by ultra violet (UV) irradiation was carried out. During this reaction, a precipitation in water was observed for the hydrocarbon surfactants, whereas fluorocarbon structures provide stable vesicles without any alteration of their size. According to these results, the polymerization process was achieved, in the case of hydrocarbon glycolipid, in the presence of different cosurfactants bearing a single hydrocarbon tail or a polyhydroxylated head and a cholesterol terminus. In such conditions, homogeneous stable vesicles were prepared. Moreover, the THAM derived telomers bearing a cholesterol terminus were able to stabilize and reduce the size of vesicles formed with synthetic glycolipid surfactants. The drug encapsulation ability of these systems was investigated by measurement of the release kinetics of a fluorescent dye, carboxyfluorescein (CF), before and after polymerization.

Nonionic amphiphilic polymers derived from Tris(hydroxymethyl)-acrylamidomethane keep membrane proteins soluble and native in the absence of detergent.

A new family of amphipols-amphiphilic polymers designed to form water-soluble complexes with membrane proteins-was synthesized by free-radical telomerization of Tris(hydroxymethyl)-acrylamidomethane (THAM) and derivatized THAM. Some of these polymers were found to prevent aggregation and denaturation of two model membrane proteins, bacteriorhodopsin and cytochrome b(6) f, in the absence of detergent micelles.

Synthesis and preliminary biological assessments of a new class of amphiphilic telomers bearing 5-fluorouracil moieties

The synthesis and biological studies of cotelomers derived from tris(hydroxymethyl)acrylamidomethane (THAM) and bearing 5-FU moieties are reported. These macromolecular carriers were obtained by radical cotelomerization of THAM and an N- 1-acyloxymethyl derivative of 5-FU. Different telomers were prepared in order to specify the influence of the prodrug on the efficiency of the therapeutic agent. An evaluation of their cytotoxic activity was performed in vitro on a melanoma cell line B16 using the colony-forming method. It appears from these biological assays that, while the monomeric substrates are less active than free 5-FU, the multiplication of active ligands obtained by telomerization involves a sharp enhancement of the antitumoral activity.

Synthesis of new cotelomers derived from tris(hydroxymethyl) aminomethane bearing arabinofuranosylcytosine moieties. Preliminary results on their in vitro and in vivo antitumoral activities

As an approach to the development of drug delivery systems, a new class of low macromolecular carriers called telomers bearing both antitumor agent such as arabinofuranosylcytosine (Ara-C) and galactose moieties were synthesized. These compounds were prepared by telomerization of tris(hydroxymethyl) acrylamidomethane (THAM) or monogalactosylated THAM and Ara-C polymerizable derivatives in the presence of transfer reagent such as alkanethiol or perfluoroalkanethiol. Their antitumor activities were assessed both in vitro and in vivo against a mouse cell line, murine B16 melanoma. The biological results show that the cytotoxic effect of Ara-C is preserved in vitro and in vivo when the drug is grafted to the telomeric structure.

A new class of sulfoxide surfactants derived from Tris. Synthesis and preliminary assessments of their properties.

A new class of non-ionic amphiphilic molecules suitable for biological purposes, especially extraction of membrane proteins, is reported. Such surfactants were prepared in two steps: addition of alkyl or fluoroalkyl mercaptan on Tris(hydroxymethyl)acrylamidomethane (THAM) derivatives, followed by the oxydation of sulfide group in sulfoxide moiety in order to provide water solubility to the molecule. The detergent efficiency of these new surfactants were assayed on rat liver cells.

Stabilization of integral membrane proteins in aqueous solution using fluorinated surfactants

Surfactants carrying either a hydrocarbon or a fluorocarbon alkyl chain have been synthesized. The polar head was either tris(hydroxymethyl)acrylamidomethane (THAM), telomerized THAM, or a glycosylated THAM moiety. The aqueous solubility of some of these molecules was increased by oxidizing to a sulfoxide the thioether function that associates their hydrophobic and hydrophilic moieties. In all cases, the critical micellar concentration was principally determined by the length and chemical nature of the alkyl chain. The usefulness of these surfactants in handling integral membrane proteins in solution has been examined using as test materials chloroplast thylakoid membranes and the photosynthetic complex cytochrome b 6 f. In keeping with earlier observations in other systems, none of the fluorinated surfactants was able to solubilize thylakoid membranes. Transfer to a solution of fluorinated surfactant of b 6 f complexes that had been solubilized and purified in the presence of a classical detergent usually resulted in aggregation and precipitation of the protein, while most homologous molecules with hydrocarbon chains did keep the b 6 f complex soluble. Two of the fluorinated surfactants, however, proved able to maintain the b 6 f complex water-soluble, intact, and enzymatically active. Because of their limited affinity for lipid alkyl chains and other hydrocarbon surfaces, fluorinated surfactants appear as potentially interesting tools for the study of membrane proteins that do not stand well exposure to classical detergents.

Cell targeting by glycosidic telomers. Specific recognition of the Kb CWL1 lectin by galactosylated telomers.

This work deals with the synthesis and lectinic recognition ability of galactosylated telomers. To investigate if telomeric carriers could exhibit cellular recognition properties, we have synthesized mono- and polygalactosylated tris(hydroxymethyl)acrylamidomethane (THAM) telomers. The affinity of such macromolecular drug carriers toward a receptor, the yeast Kb CWL1 lectin, was defined, and the influence of mono- or polygalactosylation of THAM units on the recognition phenomenon was assessed. The lectinic affinity of the compounds was estimated by measuring the inhibition of yeast aggregation. The average degree of polymerization as well as the hydrophilic-lipophilic balance of such galactosylated telomers affects their recognition ability for the lectin.

Synthesis of cotelomers derived from tris(hydroxymethyl)acrylamidomethane (THAM) bearing cytosine arabinoside moieties. Preliminary investigation of their biological activity

The telomerization of tris(hydroxymethyl)acrylamidomethane (THAM) and cytosine arabinoside (Ara-C) polymerizable derivatives in the presence of transfer reagent such as alkane or perfluoroalkane thiol is described. The cytotoxic activities of these different compounds are determined on B16, a mouse melanoma cell line. Noteworthy is that all telomers exhibit a biological activity. These preliminary results show that macromolecular carriers such as cotelomers penetrate into the cell and release the drug after an enzymatic hydrolysis.

Perfluoroalkylated telomers derived from tris(hydroxymethyl)acrylamidomethane as surfactants and co-surfactants in fluorocarbon emulsions

The ability of perfluoroalkylated telomers derived from tris(hydroxymethyl)acrylamidomethane (TAC) to stabilize fluorocarbon emulsions has been investigated. For this purpose, 50% w/v emulsions of perfluorodecalin (FDC) and perfluoro-octyl bromide (PFOB) were prepared with a total 3% w/v of surfactant and were compared with emulsions prepared with Pluronic F-68 ® or egg yolk phospholipids (EYP). When used as the sole surfactant, telomers 1 (TAC with a C 6F 13 chain and a number average degree of polymerization n ∼ 6) and 2 (C 8F 17TAC, n ∼ 6) produced FDC emulsions that were more stable than with Pluronic F-68 alone; when compared to EYP no improvement was found. When associated to other, less hydrophilic perfluoroalkylated surfactants, such as the monoadduct 3 (C 6F 13TAC, n = 1) or [1- O-(perfluoro-octyl)-2′-propenyl]xylitol ( 4), for certain formulations these telomers resulted in somewhat enhanced stabilization of both FDC and PFOB emulsions. In some cases, the emulsions were as stable as those prepared with EYP alone. When telomer 1 was used as a co-emulsifier with EYP, no noticeable stabilization was observed; with Pluronic F-68 emulsion stability was reduced.

Double‐tailed perfluoroalkyl telomeric surfactants derived from tris(hydroxymethyl)acrylamidomethane for medical applications

AbstractA new family of perfluoroalkyl double‐tailed amphiphiles was synthesized in order to develop a new drug carrying and delivery system. They were obtained by telomerization of tris(hydroxymethyl)acrylamidomethane (THAM) in the presence of various double‐tailed primary and secondary thiols as chain‐transfer agents, and with AIBN as the initiator. With secondary thiols, telomerization occurred in low yields (25–35% with respect to the thiol), because of the competitive formation of a disulfide by‐product, but proceeded in higher yields (45–90%, depending on the stoichiometry of the reagents) with primary thiols, thus allowing the preparation of a new family of perfluoroalkyl telomeric THAM double‐tailed amphiphiles. Preliminary biological tests showed no detectable hemolytic activity on human red blood cells at concentrations up to 20 mmol/L (50–65 g/L), whereas the hydrocarbon analogs proved to be hemolytic at 0,002 mmol/L. The LD50 was found to be higher than 2500 mg/kg of animal.