ascorbic-acid and 2-mercaptoacetate

Antibacterial activity of ZnO nanoparticles (NPs) triggered by generation of reactive oxygen species (ROS) depends on the fate of photoexcited charge carriers. Batches of wide band gap ZnO NPs of 7-9nm sizes, capped with polyethylene glycol (PEG), ascorbic acid (AsA), mercaptoacetic acid (MAA) and polysorbate 80 (T-80) were synthesized by precipitation method. These capped ZnO NPs exhibited ROS induced antibacterial activity, where the ROS was measured by TBARS assay. The PEG capped and AsA capped ZnO NPs exhibited weaker antibacterial activity and were correlated with strong and broad green emission peak owing to oxygen vacancies. The oxygen vacancies were trap sites of photoexcited electrons which inhibited interaction between the photoexcited electrons and oxygen on the surface of the ZnO NPs and accounted for lesser ROS generation and subsequently weaker antibacterial activity. Contrastingly MAA capped and T-80 capped ZnO NPs did not exhibit significant green emission peak, but exhibited 13% and 43% inhibition of growth of E. coli, respectively. The lack of oxygen vacancy defects in MAA capped and T-80 capped ZnO NPs perhaps led to lesser trapping of charge carriers, which is favorable for higher ROS generation and consequently higher antibacterial activity.

Topics: Anti-Bacterial Agents; Ascorbic Acid; Escherichia coli K12; Lipid Peroxidation; Nanoparticles; Optical Phenomena; Polyethylene Glycols; Polysorbates; Reactive Oxygen Species; Structure-Activity Relationship; Thiobarbituric Acid Reactive Substances; Thioglycolates; Zinc Oxide

The green chemoselective synthesis of thiazolo[3,2-a]pyridine derivatives was achieved in water via microwave-assisted three-component reactions of malononitrile, aromatic aldehydes and 2-mercaptoacetic acid with molar ratios of 2:1:1.5 and 2:2.2:1, respectively. These compounds were subject to the experiments of antioxidant activity and cytotoxicity to carcinoma HCT-116 cells and mice lymphocytes. Nearly all of the tested compounds possessed potent capacities for scavenging free radicals. In addition, most of these compounds showed cytotoxicity to HCT-116 cells and mice lymphocytes with no selectivity. Of these, only thiazolo[3,2-a]pyridine derivative 5d suggested selective cytotoxicity to tumor cell line HCT-116 cells.

Topics: Aldehydes; Animals; Free Radical Scavengers; HCT116 Cells; Humans; Lymphocytes; Mice; Microwaves; Nitriles; Pyridines; Thioglycolates

Topics: Anaerobiosis; Ascorbic Acid; Bacteria, Anaerobic; Clostridium; Cysteine; Electron Transport; Ferredoxins; Oxidation-Reduction; Paraquat; Sulfides; Thioglycolates

Topics: Acetates; Ascorbic Acid; Curare; Cysteine; Reducing Agents; Thioglycolates; Vitamins; X-Rays