Discovery and structure–activity relationships of a novel series of benzopyran-based KATP openers for urge urinary incontinence

A novel series of benzopyran derivatives were synthesized and evaluated as K_ATP channel openers. Structure–activity relationships were investigated around 4-position of the benzopyran nucleus. Optimization of 4-substituent with some heterocyclic rings led to compound 13b bearing a benzo[d]isoxazol-3-one moiety as a potent and selective K_ATP channel opener in vitro. In two anesthetized rat models of myogenic bladder overactivity, compound 13b was found to inhibit spontaneous bladder contractions.     

In vivo protein tyrosine nitration in S. cerevisiae: Identification of tyrosine-nitrated proteins in mitochondria

Protein tyrosine nitration (PTN) is a selective post-translational modification often associated with pathophysiological conditions. Although yeast cells lack of mammalian nitric oxide synthase (NOS) orthologues, still it has been shown that they are capable of producing nitric oxide (NO). Our studies showed that NO or reactive nitrogen species (RNS) produced in flavohemoglobin mutant (Δyhb1) strain along with the wild type strain (Y190) of Saccharomyces cerevisiae can be visualized using specific probe 4,5-diaminofluorescein diacetate (DAF-2DA). Δyhb1 strain of S. cerevisiae showed bright fluorescence under confocal microscope that proves NO or RNS accumulation is more in absence of flavohemoglobin. We further investigated PTN profile of both cytosol and mitochondria of Y190 and Δyhb1 cells of S. cerevisiae using two-dimensional (2D) gel electrophoresis followed by western blot analysis. Surprisingly, we observed many immunopositive spots both in cytosol and in mitochondria from Y190 and Δyhb1 using monoclonal anti-3-nitrotyrosine antibody indicating a basal level of NO or nitrite or peroxynitrite is produced in yeast system. To identify proteins nitrated in vivo we analyzed mitochondrial proteins from Y190 strains of S. cerevisiae. Among the eight identified proteins, two target mitochondrial proteins are aconitase and isocitrate dehydrogenase that are involved directly in the citric acid cycle. This investigation is the first comprehensive study to identify mitochondrial proteins nitrated in vivo.     

Antikinetoplastid antimitotic activity and metabolic stability of dinitroaniline sulfonamides and benzamides

N(1)-Phenyl-3,5-dinitro-N(4),N(4)-di-n-propylsulfanilamide (1) and N(1)-phenyl-3,5-dinitro-N(4),N(4)-di-n-butylsulfanilamide (2) show potent in vitro antimitotic activity against kinetoplastid parasites but display poor in vivo activity. Seventeen new dinitroaniline sulfonamide and eleven new benzamide analogs of these leads are reported here. Nine of the sulfonamides display in vitro IC(50) values under 500 nM against African trypanosomes, and the most active antikinetoplastid compounds also inhibit the in vitro assembly of purified leishmanial tubulin with potencies similar to that of 2. While several of the potent compounds are rapidly degraded by rat liver S9 fractions in vitro, N(1)-(3-hydroxy)phenyl-3,5-dinitro-N(4),N(4)-di-n-butylsulfanilamide (21) displays an IC(50) value of 260 nM against African trypanosomes in vitro and is more stable than 2 in the in vitro metabolism assay.     

Biogenic synthesis of <Emphasis Type="Italic">Marsilea quadrifolia</Emphasis> gold nanoparticles: a study of improved glucose utilization efficiency on 3T3-L1 adipocytes

This study aims mainly to provide an insight and understanding of the effect of glucose utilization efficiency of biogenic gold nanoparticles (GNPs) synthesized through the mediation of Marsilea quadrifolia (M. quadrifolia) methanol extract on 3T3-L1 adipocytes. The biosynthesized GNPs were characterized by UV visible spectrophotometry and FTIR. Simultaneously, the nature, stability, and morphological characteristics were analyzed by XRD, TG-DTA, SEM-EDS, HRTEM, and SAED. The results of characterization studies were used to assess the properties of GNPs. The in vitro cytotoxicity screening indicates that 100 μM of biogenic GNPs were displayed 71.23 ± 1.56% of cellular viability in 3T3-L1 adipocyte cells. Subsequently, increased glucose utilization of biosynthesized GNPs based on a dose-dependent manner on 3T3-L1 has also been demonstrated. The effect of GNPs (30 μg) on glucose uptake was higher than that of insulin and metformin. Moreover, the observed results clearly highlight that the biogenic GNPs have higher efficiency of glucose utilization and cellular viability in 3T3-L1 adipocytes with lower toxicity.     

Molecular characterization of the interaction between sialylated Neisseria gonorrhoeae and factor H

Human factor H (HufH), a key inhibitor of the alternative pathway of complement, binds to Neisseria gonorrhoeae and constitutes an important mechanism of human-specific complement evasion. The C-terminal domain 20 of HufH contains the binding site for sialylated gonococci. We exploited differences in amino acid sequences between human and non-binding chimpanzee fH domain 20 to create cross-species mutations to define amino acids important for binding to sialylated gonococci. We used fH/Fc fusion constructs that contained contiguous fH domains 18-20 fused to Fc fragments of murine IgG2a. The Fc region was used both as a tag for detection of each fusion molecule on the bacterial surface and as an indicator for complement-dependent killing. Arg-1203 was critical for binding to both porin (Por) B.1A and PorB.1B strains. Modeling of the R1203N human-to-chimpanzee mutation using the crystal structure of HufH19-20 as a template showed a loss of positive charge that protrudes at the C terminus of domain 20. We tested the functional importance of Arg-1203 by incubating sialylated gonococci with normal human serum, in the presence of wild-type HufH18-20/Fc or its R1203A mutant. Gonococci bound and were killed by wild-type HufH18-20/Fc but not by the R1203A mutant. A recombinant fH/Fc molecule that contained chimpanzee domain 20, humanized only at amino acid 1203 (N1203R) also bound to sialylated gonococci and restored killing. These findings provide further insights into the species specificity of gonococcal infections and proof-of-concept of a novel therapeutic approach against gonorrhea, a disease rapidly becoming resistant to conventional antibiotics.