Search

Micrometer sized copolymeric particles of glycidyl methacrylate and octadecyl methacrylate (poly(GMA-co-OMA) were prepared by reversible addition fragmentation chain transfer (RAFT) mediated dispersion copolymerization technique using polyvinyl pyrrolidone (PVP) as steric stabilizer and 2-cyano-2-propyl benzodithioate (CPB) as RAFT agent in ethanol. Different reaction parameters on the characteristics of poly(GMA-co-OMA) particles and their effects were investigated thoroughly in the presence of RAFT agent. Formation of poly(GMA-co-OMA) particle sizes, its stability and morphology depends on the concentration of RAFT agent, stabilizer as well as the monomer ratio. Spherical poly(GMA-co-OMA) particles of size ranges1-13 μm were obtained after optimization of the ratio between GMA and OMA. In the presence of RAFT, with the increased amount of hydrophobic monomer OMA, instabilities of the particles are observed while particle sizes found to be decreased with the increased amount of GMA in the reaction mixture. Prepared poly(GMA-co-OMA) particles were characterized by different analytical techniques such as NMR, IR, GPC, TGA etc. while Field Emission Scanning Electron Microscope (FE-SEM) was applied to study the poly(GMA-co-OMA) particle sizes and its morphology. [ABSTRACT FROM AUTHOR]

A green method of silver nanoparticle (AgNP) preparation using curcumin caffeate (CCaf) as stabilizing/capping and reducing group is reported here. CCaf is prepared through esterification of curcumin and caffeic acid in presence of p‐toluene sulphonic acid as catalyst. CCaf facilitates production of AgNPs in aqueous medium and room temperature without any external reducing agents. The antioxidant, antibacterial and BSA binding interactions of these CCafAgNPs are evaluated. The antioxidant activity and the corresponding IC50 value for the CCafAgNPs is found to be comparable with ascorbic acid taken as standard antioxidant for the study. The results of bactericidal screening of CCafAgNPs are better compared to CCaf capping group and found to exhibit broad spectrum antibacterial property against Gram‐positive and Gram‐negative bacterial pathogens. In presence of CCafAgNPs the absorption spectra of BSA showed changes with increase in intensity around 280 nm of native BSA peak and appearance of a new band around 320 nm, indicating the possible binding interactions between BSA and CCafAgNPs. [ABSTRACT FROM AUTHOR]

Synthesis of uniform poly(glycidyl methacrylate-co-octadecyl methacrylate) (poly(GMA-co-OMA)) particles with smooth surfaces were carried out by dispersion copolymerization. Copolymeric particles with stable and smooth surfaces in the size range of 1.0–15 µm were obtained without any sign of coagulation. The effects of different reaction parameters in the preparation of uniform poly(GMA-co-OMA) particles were investigated. The reaction temperature as well as molar ratio of GMA to OMA has effect significantly on the formation of stable and uniform poly(GMA-co-OMA) particles. The final copolymeric particle sizes and stability increases from 2.4 µm to 10 µm with the increased temperature from 50 to 70 °C. For the formation of ideal spherical shape of poly(GMA-co-OMA) particles, ratio between GMA and OMA were optimized. Particle instabilities observed with the increase of hydrophobic OMA while particle sizes were found to be decreased with the increase of GMA content. This result suggests that the introduction of OMA in the dispersion copolymerization of GMA plays an important role for the synthesizing of uniform poly(GMA-co-OMA) microparticles with colloidal stability. [ABSTRACT FROM AUTHOR]

Abstract: Because of their numerous biological as well as industrial importance, the study of Schiff bases is an emerging field for the researchers, in recent time. In this study, we have designed some Schiff bases derived from biologically important precursors. The antioxidant activities of the designed compounds are thoroughly studied theoretically using density functional theory taking various parameters like bond dissociation enthalpy, ionization enthalpy, proton dissociation enthalpy, and electron transfer enthalpy followed by the study of effects of solvent, spin density, and molecular orbital on antioxidant activity of the compounds. The comparison of antioxidant activity of the compounds with that of phenol and their parent aldehydes reveals the superior antioxidant activity of the designed compounds. This study contributes towards the information of an important bridge between bioorganic and computational chemistry. [ABSTRACT FROM AUTHOR]

Phenolic compounds play a very crucial role as antioxidant that can prevent various diseases caused by free radicals in human body. Although, lots of natural phenolic compounds having antioxidant activity are available nowadays, the modeling of compounds with naturally available phenolics as building blocks is very important in order to get enhanced antioxidant activity. In this study, Ferulic acid (FA), one natural phenolic acid present in coffee, apples, orange, etc., is taken as building block and its ester derivatives with different alkyl groups are subjected to measure the antioxidant activity by using density functional theory (DFT). Various parameters like bond dissociation enthalpy (BDE), vertical ionization potential (IP), reactivity descriptors, metal chelation ability, etc. are used to measure the antioxidant activity. All the parameters suggest that the ester derivatives are superior antioxidants to the parent FA. Since FA has been reported to be present as esters in many herbs and plants, hence our study provides a route to study the structure activity relationship of this class of natural phenolics with antioxidant activity. Ferulic acid and its ester derivatives with different alkyl groups are studied by DFT to measure the antioxidant activity using various parameters like BDE, IPv, reactivity descriptors and metal chelation ability. All the parameters suggest that the ester derivatives are superior antioxidants to the parent ferulic acid. Since ferulic acid has been reported to be present as esters in many herbs and plants, hence this study provides a route to study the structure activity relationship of this class of natural phenolics. [ABSTRACT FROM AUTHOR]

We analyze the antioxidant property of four phenolic compounds i.e., gallic acid, methyl gallate, ethyl gallate, and 4, 5-dihydroxy 3-methoxy benzoic acid through the determination of bond dissociation enthalpy (BDE), vertical ionization potential (IPv) in gas phase as well as in six different solvent medium. The theoretical trends of these phenolic compounds, based on BDE and IP, is compared with the scavenging activity towards HOCl. In addition, we compute and analyze the values of the density-based reactivity descriptors such as chemical potential, hardness, electrophilicity, and local softness. [ABSTRACT FROM AUTHOR]

An abstract of the article " Synthesis and Electrochemical Behavior of Some Dendritic Polyphenols as Antioxidants" by Jyotirekha G. Handique, Dhrubajyoti Mahanta, Archana Devi, and Manas P. Boruah is presented.