Synthesis, single crystal X-ray diffraction, Hirshfeld surface and biological activity of quinolone derivatives

Two new quinolone derivatives, 5-nitroquinolin-8-yl-3-bromobenzoate (1) and 5-nitroquinolin-8-yl-3-chlorobenzoate (2), were synthesized and their structures were elucidated using X-ray diffraction techniques. Both compounds crystallized in P21/n (monoclinic) space group having four independent molecules in asymmetric unit. The dihedral angle between benzene and planner quinoline rings in compounds 1 and 2 were found to be 117.7(2) and 117.4(2)ᵒ, respectively. No intermolecular hydrogen bonding was observed in compound 1. However, C-H···O intermolecular interaction was found to connect the molecules in crystal lattice of compound 2. Hirshfeld surfaces analysis was performed to evaluate the directions, and strength of interactions of molecules of compounds and 1 and 2 with neighbouring molecules, and the major contribution in the crystal packing was due to O-H (1, 24.6% and 2, 25.1%) interactions. The synthesized quinoline derivatives were found as potent anti-bacterial agents against E. coli reference (ATCC25922 and ATCC 35218) and multi-drug resistant strains (M2 and M3) with 91.42 to 94.72% inhibition. Both compounds 1 and 2 showed weak antileishmanial activity against L. Major promastigotes in vitro with IC50 values 73.2±3.1 and 72.2±2.3 mg/mL, respectively, and also found as cytotoxic in nature against 3T3 fibroblast cell line

Simian Virus 40 Large T Antigen as a Model to Test the Efficacy of Flouroquinolones against Viral Helicases

Simian virus 40 large T-antigen (SV40 LT-Ag) is a 708 amino acid nuclear phosphoprotein. Among many functions of LT-Ag is its ability to perform as an ATPase-helicase, catalyzing the unwinding of viral genome during replication. The LT-Ag has been employed in the studies of helicase structure and function, and has served as a model helicase for the screening of antiviral drugs that target viral helicase. In this study, using in vitro enzyme assays and in silico computer modeling, we screened a batch of 18 fluoroquinolones to assess their potential as antivirals by virtue of their inhibition of the LT-Ag helicase. We found all fluoroquinolones to be inhibitory to the helicase activity of LT-Ag. In our docking analysis, most of these tested drugs showed similarity in their interactions with LT-Ag. Our study shows the potential of fluoroquinolones as antiviral drugs and of SV40 LT-Ag as a model protein for screening drugs against viral helicases

N-(4-Methoxy-2-nitrophenyl)-N-(methylsulfonyl)methanesulfonamide

In the title compound, C9H12N2O7S2, the nitro substituent is slightly twisted from the benzene ring [dihedral angle = 14.69 (10)°]. The molecular geometry is stabilized by intramolecular C—H...O hydrogen bonds, forming S(6) ring motifs. In the crystal, molecules are linked by C—H...O hydrogen bonds into layers parallel to (10-2)

Immunohistochemical localization of G protein βγ subunits in the lateral wall of the rat cochlea

The role of G protein-mediated signal transduction in the production of endolymph, an extracellular fluid of unusual ionic composition, is beginning to be understood. The identity of Gα subunits in the stria vascularis and the spiral ligament of the lateral wall of the cochlear duct is well established. However, little is known about the presence of βγ subunits. This study used immunohistochemistry to investigate the distribution of G protein βγ subunits in the lateral wall of the cochlea. Temporal bones of 6- to 8-week-old rats were fixed in 4% paraformaldehyde and 0.1% glutaraldehyde and processed for embedding in paraffin wax. The dewaxed, midmodiolar sections of the cochlea were incubated with subunit-specific polyclonal antibodies. The results show that the pattern of immunoreactivity varies for the G protein β1–4 and γ1–3, 5 and 7 subunits in the stria vascularis and spiral ligament. In the stria vascularis, immunoreactivity was detected for β2, β3, β4, γ1, γ2 and γ7 subunits. All five types of fibrocytes in the spiral ligament exhibited positive staining for γ2 and γ7. However, immunoreactivity for β1–4 subunits was variable. Immunoreactivity for γ3 and γ5 subunits was not detected in the lateral cochlear wall. The expression pattern of G protein βγ subunits in lateral wall provides a basis for interpreting the functions of G protein-coupled receptors in cochlear fluid homeostasis

2-[3-(1,3-Benzothiazol-2-yl)-2,2-dimethylpropyl]-2-methyl-2,3-dihydro-1,3-benzothiazole

In the title compound, C20H22N2S2, the five-membered thiazole ring of the 2-methyl-2,3-dihydro-1,3-benzothiazole unit has an envelope conformation. The dihedral angle between the planar [maximum deviation of 0.014 (1) Å for the S atom] benzothiazole ring system and the benzene ring is 78.37 (12)°. Two intramolecular C—H...S hydrogen bonds are observed, forming rings of graph-set motif S(6). In the crystal, the molecules are consolidated in pairs through N—H...N hydrogen bonds and are arranged parallel to the b axis

Crystal structure of (3S*,4S*,4aS*,5R*,6R*,6aS*,7R*,11aS*,11bR*)-5,6-bis(benzoyloxy)-3,4a-dihydroxy-4,7,11b-trimethyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodecahydrophenanthro[3,2-b]furan-4-carboxylic acid methanol monosolvate

The title compound, C34H36O9·CH3OH, is a diterpenoid isolated from the roots of Caesalpinia pulcherrima (L.) Swartz. The three trans-fused six-membered rings are in chair, chair and half-chair conformations. The mean plane of this fused-ring system makes dihedral angles of 67.95 (15) and 83.72 (14)° with the two phenyl rings of the benzoyloxy groups. An intramolecular C—H...O hydrogen bond is observed. In the crystal, molecules are linked via O—H...O hydrogen bonds, forming an infinite chain along the b-axis direction

Head and neck cancer susceptibility: a genetic marker in the methylenetetrahydrofolate reductase gene

Progress in the elucidation of molecular genetic changes that lead to the development of tumors should soon bring novel diagnostic and therapeutic procedures into clinical practice. In this respect, methylenetetrahydrofolate reductase (MTHFR) plays a central role in folate metabolism that affects DNA methylation and synthesis. DNA methylation is an epigenetic feature that influences cellular development and function. Germ line mutation C\u3eT at nucleotide 677 of the MTHFR gene, which results in increased thermolability and diminished enzyme activity, is oncogenic, i.e. should be a contributor to molecular changes leading to cancerous phenotypes (it has also been shown independently to be implicated in cardiovascular disease phenotypes). Interestingly, it has been shown that MTHFR T677 allele homozygosity confers a sixfold increased risk for esophageal squamous cell carcinoma in Northern China. The purpose of this study was twofold: (1) to evaluate the putative association of MTHFR C677T and epithelial squamous cell carcinoma (ESCC) in Pakistan, and (2) to investigate whether de novo MTHFR C677T mutations are involved in the determination of ESCC phenotypes. We recruited 50 ESCC patients referred to the Otolaryngology Clinic of the Aga Khan University Hospital, and 54 age- and gender-matched control (disease-free) subjects. Our results show that T allele frequencies were 0.18 +/- 0.05 in cases vs. 0.24 +/- 0.05 in controls (as compared with 0.63 vs. 0.41 in the report from China). Although the association is not statistically significant, T alleles are actually more common amongst controls in the Pakistani population, which is the opposite of what would be expected and what has been reported amongst Chinese. Yet the frequency of deleterious T alleles is lower in Pakistan (range 0.18-0.24) than in other parts of the world. Our results indicate that MTHFR C677T cannot form the basis for a genetic test aimed at evaluating an individual\u27s genetic susceptibility to ESCC in Pakistan. As the conversion of precancerous submucous fibrosis into overt cancer is a frequent occurrence in Pakistan, we proceeded to extract DNA samples in all ESCC patients, from whole blood, cancerous tissues and neighboring normal tissues. We sought to determine whether C677T genotypes were different in the three tissue samples from each ESCC patient. In all patients, identical genotypes (and therefore allele frequencies) were systematically observed in all three samples. This indicates that de novo MTHFR 677TC\u3eT mutations are not part of the molecular etiology of ESCC. In conclusion, we can rule out a major involvement of the MTHFR gene in the determination of ESCC in Pakistan

Temporal expression of calcium/calmodulin-dependent adenylyl cyclase isoforms in rat articular chondrocytes: RT-PCR and immunohistochemical localization

A multitude of signalling cascades are implicated in the homeostasis of articular chondrocytes. However, the identity of these signalling pathways is not fully established. The 3, 5\u27-cyclic AMP-mediated signalling system is considered to be a prototype. Adenylyl cyclase (AC) is an effector enzyme responsible for the synthesis of cAMP. There are 10 mammalian AC isoforms and some of these are differentially regulated by calcium/calmodulin (Ca2+/CaM). Ca2+ is known to play an important role in the development and maintenance of skeletal tissues. Ca2+/CaM-dependent AC isoforms and their temporal expression in articular chondrocytes in rats were identified using RT-PCR and immunohistochemistry techniques. All Ca2+/CaM-dependent AC isoforms were expressed in chondrocytes from all age groups examined. Each isoform was differentially expressed in developing and adult articular chondrocytes. Generally, expression of AC isoforms was observed to increase with age, but the increase was not uniform for all Ca2+/CaM-dependent AC isoforms. Expression of Ca2+/CaM-dependent AC isoforms along with other signalling molecules known to be present in articular chondrocytes indicate complicated and multifactorial signalling cascades involved in the development and homeostasis of articular cartilage. The significance of these findings in terms of articular chondrocyte physiology is discussed

Fluoroquinolones inhibit HCV by targeting its helicase

Background: HCV has infected \u3e170 million individuals worldwide. Effective therapy against HCV is still lacking and there is a need to develop potent drugs against the virus. In the present study, we have employed two culture models to test the activity of fluoroquinolone drugs against HCV: a subgenomic replicon that is able to replicate independently in the cell line Huh-8 and the Huh-7 cell culture model that employs cells transfected with synthetic HCV RNA to produce the infectious HCV particles. Fluoroquinolones have also been shown to have inhibitory activity against certain viruses, possibly by targeting the viral helicase. To tease out the mechanism of the antiviral activity of fluoroquinolones, their effect on HCV NS3 helicase protein was also tested. Methods: Huh-7 cells producing the HCV virion as well as Huh-8 cells were grown in the presence or absence of 12 different fluoroquinolones. Afterwards, Huh-7 and Huh-8 cells were lysed and viral RNA was extracted. The extracted RNA was reverse transcribed and quantified by real-time quantitative PCR. Fluoroquinolones were also tested on purified NS3 protein in a molecular-beacon-based in vitro helicase assay. Results: To varying degrees, all of the tested fluoroquinolones effectively inhibited HCV replication in both Huh-7 and Huh-8 culture models. The inhibition of HCV NS3 helicase activity was also observed with all 12 of the fluoroquinolones. Conclusions: Fluoroquinolones inhibit HCV replication possibly by targeting the HCV NS3 helicase. These drugs hold promise for the treatment of HCV infection