In-silico docking based design and synthesis of [1H,3H] imidazo[4,5-b] pyridines as lumazine synthase inhibitors for their effective antimicrobial activity.

PURPOSE: The imidazopyridine moiety is important pharmacophore that has proven to be useful for a number of biologically relevant targets, also reported to display antibacterial, antifungal, antiviral properties. Riboflavin biosynthesis involving catalytic step of Lumazine synthase is absent in animals and human, but present in microorganism, one of marked advantage of this study. Still, this path is not exploited as antiinfective target. Here, we proposed different interactions between [1H,3H] imidazo[4,5-b] pyridine test ligands and target protein Lumazine synthase (protein Data Bank 2C92), one-step synthesis of title compounds and further evaluation of them for in vitro antimicrobial activity. MATERIALS AND METHODS: Active pocket of the target protein involved in the interaction with the test ligands molecules was found using Biopredicta tools in VLifeMDS 4.3 Suite. In-silico docking suggests H-bonding, hydrophobic interaction, charge interaction, aromatic interaction, and Vanderwaal forces responsible for stabilizing enzyme-inhibitor complex. Disc diffusion assay method was used for in vitro antimicrobial screening. RESULTS AND DISCUSSION: Investigation of possible interaction between test ligands and target lumazine synthase of Mycobacterium tuberculosis suggested 1i and 2f as best fit candidates showing hydrogen bonding, hydrophobic, aromatic and Vanderwaal's forces. Among all derivatives 1g, 1j, 1k, 1l, 2a, 2c, 2d, 2e, 2h, and 2j exhibited potent activities against bacteria and fungi compared to the standard Ciprofloxacin and Fluconazole, respectively. The superiority of 1H imidazo [4,5-b] pyridine compounds having R' = Cl >No2 > NH2 at the phenyl/aliphatic moiety resident on the imidazopyridine, whereas leading 3H imidazo[4,5-b] pyridine compounds containing R/Ar = Cl > No2 > NH2> OCH3 substituents on the 2(nd) position of imidazole.

Proteasome inhibitors mechanism; source for design of newer therapeutic agents.

The proteasome was first identified as a high MW protease complex that gets resolved into a series of low MW protein species upon denaturation. As the dominant protease dedicated to protein turnover, the proteasome shapes the cellular protein repertoire. Our knowledge of proteasome regulation and activity has improved considerably over the past decade. Novel inhibitors, in particular, have helped to advance our understanding of proteasome biology. They range from small peptide-based structures that can be modified to vary target specificity to large macromolecular inhibitors that include proteins. Although these reagents have an important role in establishing our current knowledge of the proteasome's catalytic mechanism, many questions remain. The future lies in designing compounds that can function as drugs to target processes involved in disease progression. Our focus in this chapter is to highlight the use of various classes of inhibitors to probe the mechanism of the proteasome and to identify its physiological significance in the cell, so that the mechanism of inhibition of proteasome will work as a definite source for design of protocols for newer therapeutic agents for the treatment of inflammation and in cancer therapy.

Purification and partial characterization of thermostable serine alkaline protease from a newly isolated Bacillus species HSRB08 from hotspring.

The purpose of the research was to study the purification and partial characterization of thermostable serine alkaline protease from a newly isolated Bacillus species HSRB08, which was isolated from hotspring. The enzyme was purified in a 2-step procedure involving ammonium sulfate precipitation and Sephadex G-200 chromatography. The enzyme was shown to have molecular weight of 66 kD by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and Gelatin Zymogram and was purified 15.3-fold with a yield of 7.5%. It was most active at 45 degrees C, pH 9.0, with casein as substrate. It was strongly activated by metal ions such as Ca2+, Mg2+, and Mn2+. Enzyme activity was inhibited strongly by phenylmethyl sulphonyl fluoride (PMSF) but was not inhibited by ethylene diamine tetra acetic acid (EDTA), while a slight inhibition was observed with beta-mercaptoethanol (beta-ME). The compatibility of the enzyme was studied with commercial and local detergents in the presence of 10 mM CaCl2. The addition of 10 mM CaCl2 individually and in combination, was found to be very effective in improving the enzyme stability. This enzyme improved the cleansing power of various detergents. It removed blood stains completely when used with detergents in the presence of 10 mM CaCl2.