Effect Of Molecular Modification Research Articles

Effects of polyphenol and gelatin types on the physicochemical properties and emulsion stabilization of polyphenol-crosslinked gelatin conjugates

Herein, six types of polyphenol-crosslinked gelatin conjugates (PGCs) with ≥ two gelatin molecules were prepared using a covalent crosslinking method with two types of polyphenols (tannic acid and caffeic acid) and three types of gelatins (bovine bone gelatin, cold water fish skin gelatin, and porcine skin gelatin) for the emulsion stabilization. The structural and functional properties of the PGCs were dependent on both polyphenol and gelatin types. The storage stability of the conjugate-stabilized emulsions was dependent on the polyphenol crosslinking, NaCl addition, and heating pretreatment. In particular, NaCl addition promoted the liquid-gel transition of the emulsions: 0.2 mol/L > 0.1 mol/L > 0.0 mol/L. Moreover, NaCl addition also increased the creaming stability of the emulsions stabilized by PGCs except tannic acid-crosslinked bovine bone gelatin conjugate. All the results provided useful knowledge on the effects of molecular modification and physical processing on the properties of gelatins.

Intermolecular interactions of tetrabenzoporphyrin- and phthalocyanine-based charge-transfer complexes.

The effect of molecular modification on the intermolecular interactions in tetrabenzoporphyrin-based charge transfer complexes is reported. TPP[FeIII(tbp)Cl2]2, TPP[CoIII(tbp)Cl2]2 and TPP[CoIII(tbp)Br2]2 (TPP = tetraphenylphosphonium and tbp = tetrabenzoporphyrin) were synthesized and their crystal structures were compared to those of the reported TPP[MIII(tbp)(CN)2]2, TPP[FeIII(tbp)Br2]2 and TPP[MIII(Pc)L2]2 complexes (Pc = phthalocyanine; and L = CN, Cl or Br). The prepared CT complexes were isostructural to reported systems. However, their intermolecular interactions were found to depend on the combination of the macrocyclic (Mc) and axial ligands (L). In Pc-based systems, the overlap integral between HOMOs of Pc decreased with the increase in the size of the axial ligand, which indicated that the intermolecular interactions in Pc-based systems were dominated by repulsive interactions. On the other hand, in tbp-based systems, attractive and repulsive interactions competed with each other. Furthermore, charge transport properties were found to depend on the central metal ion as well as the combination of Mc and L, which suggested that minor molecular modifications to porphyrin complexes will cause drastic changes in both inter- and intramolecular interactions.

Administration of two or more related drugs to investigate the effect of molecular modification and formulation on drug absorption, metabolism and excretion.

Abstract Two or more related drugs of the amphetamine class were simultaneously administered to man under acidic urine control, their urinary excretion being examined by gas-liquid chromatography. This was shown to be a suitable procedure for determining the effect of molecular modification and formulation on drug absorption, metabolism and excretion.

Nanoscale Electrical and Structural Characterization of Gold/Alkyl Monolayer/Silicon Diode Junctions

The effect of molecular modification on gold−silicon diode junctions has been investigated by electrical and structural measurements at both the macroscale and the nanoscale levels. Diode junctions...

Effect of Molecular Modification on PCL Foam Formation and Morphology of PCL

AbstractPoly(ϵ‐caprolactone) was chemically modified by using dicumyl peroxide from 0.25 to 2 % (w/w) and the effects of molecular architecture on the density and morphology of PCL foams were examined. The polymer was first blended with dicumyl peroxide at a low temperature (80°C), to prevent premature peroxide decomposition. The peroxide modification was then performed at different temperatures, from 110°C to 150°C. The reaction kinetic was followed by measuring the dynamical rheological properties of the melt in isothermal experiments by using a parallel plate rheometer. The evolution of the macromolecular structure during the chemical reaction was followed by analyzing the time evolution of the complex viscosity. Foams were prepared from the peroxide modified PCL with a batch foaming process using nitrogen as the foaming agent under different process conditions. As expected, the increase of the molecular modification led to a shift towards higher temperatures of the foaming window and, moreover, influenced the viscoelastic behavior of the expanding polymeric matrix so that the final foam properties are affected.

Effects of molecular modification on hypocholesteremic activity of 1,3-bis(substituted phenoxy)-2-propanones and related derivatives.

A series of 1,3-bis(substituted phenoxy)-2-propanones, long-chain ketones, and related derivatives has been synthesized, and it has been found that certain analogues produce significant lowering of serum cholesterol levels in Sprague-Dawley rats. These compounds possess no estrogenic properties and are nontoxic at 10 mg/kg/day. Physical studies on these compounds include an attempt to correlate hypocholesteremic activity with the lipophilic, electronic, and steric properties of the compounds. The 1-octanol-H2O partition coefficient was measured for certain derivatives and the pi constant for the substituents was calculated. Hammett's sigma constants for aromatic substituents were obtained from the literature. The only correlation found to exist is between hypocholesteremic activity and steric size and position of the aromatic substituents in the propanones.

Effect of molecular modification on the inhibition of lymphocyte blastogenesis by cardiac glycosides

Effect of molecular modification on the inhibition of lymphocyte blastogenesis by cardiac glycosides

Effect of Molecular Modification on the Inhibition of Lymphocyte Blastogenesis by Cardiac Glycosides

Cardiac glycosides are potent inhibitors of cell division. They may be useful as antitumor agents if the antimitotic effect can be dissociated from their cardiotoxic effect. We studied congeners of cardiac glycosides to determine whether the saccharide or the genin portion of the molecule contributes to its antimitotic effect. The concentration of glycoside required to inhibit PHA-stimulated 3 H-thymidine incorporation into DNA at 72 hr in human lymphocytes was studied. The inhibiting concentration varied by over tenfold if either the genin or the saccharide portion of the molecule was altered. Therefore either the genin or the saccharide influences independently the antimitotic effect of the glycosides. The relative inhibitory dose of specific genins or glycosides on lymphocyte blastogenesis was similar to the relative arrhythmogenic effects. Therefore development of congeners with antimitotic action but without arrhythmogenicity may be difficult. The arrhythmogenic effect of cardiac glycosides has been shown to be related to their ability to inhibit the plasma membrane Na-K ATPase of myocardial cells. The antimitotic effects parallel closely the arrhythmogenicity of individual glycosides. This relationship provides added evidence to support the concept that the antimitotic effect of glycosides is related to inhibition of Na-K ATPase. Moreover, these findings support the critical role of the transport ATPase in cell division.