Design,synthesis and evaluation against Mycobacterium tuberculosis of azole piperazine derivatives as dicyclotyrosine (cYY) mimics

Three series of azole piperazine derivatives that mimic dicyclotyrosine (cYY), the natural substrate of the essential Mycobacterium tuberculosis cytochrome P450 CYP121A1, were prepared and evaluated for binding affinity and inhibitory activity (MIC) against M. tuberculosis. Series A replaces one phenol group of cYY with a C3-imidazole moiety, series B includes a keto group on the hydrocarbon chain preceding the series A imidazole, whilst series C explores replacing the keto group of the piperidone ring of cYY with a CH₂-imidazole or CH₂-triazole moiety to enhance binding interaction with the heme of CYP121A1. The series displayed moderate to weak type II binding affinity for CYP121A1, with the exception of series B 10a, which displayed mixed type I binding. Of the three series, series C imidazole derivatives showed the best, although modest, inhibitory activity against M. tuberculosis (17d MIC?=?12.5?μg/mL, 17a 50?μg/mL). Crystal structures were determined for CYP121A1 bound to series A compounds 6a and 6b that show the imidazole groups positioned directly above the haem iron with binding between the haem iron and imidazole nitrogen of both compounds at a distance of 2.2?Å. A model generated from a 1.5?Å crystal structure of CYP121A1 in complex with compound 10a showed different binding modes in agreement with the heterogeneous binding observed. Although the crystal structures of 6a and 6b would indicate binding with CYP121A1, the binding assays themselves did not allow confirmation of CYP121A1 as the target.     

The relative efficacy of aminoguanidine and pentoxifylline in modulating endotoxin-induced cardiac stress

This study investigates the effect of aminoguanidine (AG), a selective inducible nitric oxide synthase (iNOS) inhibitor, and pentoxifylline (PTX), a tumour necrosis factor–alpha (TNF‐α) inhibitor, on lipopolysaccharide (LPS)‐induced cardiac stress. Rats were divided into four groups: group I served as a control, group II (LPS) received a single intraperitoneal injection of LPS (10 mg·kg^–1), group III (LPS+AG) and group IV (LPS+PTX) were injected with either AG (100 mg·kg^–1) or PTX (150 mg·kg^–1) intraperitoneally 10 days prior to LPS administration. Normalization of cardiac levels of nitrite/nitrate (NO_X), malondialdehyde (MDA), glutathione (GSH), heme oxygenase‐1 (HO‐1), glutathione peroxidase (GPx) and Na⁺, K⁺‐ATPase activities was evident in the AG group. Both AG and PTX decreased the elevated serum TNF‐α levels, the activities of lactate dehydrogenase (LDH), creatine kinase (CK) and cardiac myeloperoxidase (MPO). The levels of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and phosphocreatine (PCr) were enhanced following AG and PTX pretreatments. Calcium (Ca²⁺) levels were altered, and the histopathological observations supported the described results. Conclusively, the study highlights the cardioprotective potential of AG and PTX with superior results from AG. These findings reveal the relative contribution of nitric oxide and TNF‐α to oxidative stress and energy failure during endotoxemia. Copyright © 2011 John Wiley & Sons, Ltd.     

Microsatellite marker based genetic diversity analysis among cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis>) accessions differing for their response to drought stress

Genetic diversity is an essential input for any plant breeding programme. To assess the genetic divergence among the newly identified drought tolerant lines and elite cotton genotypes including popular varieties, a total of 51 distinctly polymorphic markers were identified after screening 142 genome-wide SSR markers. The identified polymorphic markers detected a total of 140 alleles with a mean of 2.75 alleles per loci and average polymorphism information content of 0.45. Jaccard coefficient based dissimilarity index between the genotypes ranged from 0.18 to 0.82 indicating existence of wide variation between and within the drought tolerant and susceptible genotypes at the DNA level. Cluster and factorial analyses have provided the structure of genetic diversity present and clearly distinguished the drought tolerant and susceptible cotton genotypes. Clustering pattern was in congruence with the source or pedigree of genotypes. The information generated in the present study on genetic divergence among genotypes having differential response to drought will help in selection of suitable lines as parents for developing drought tolerant cultivars in cotton. The polymorphic markers and diverse lines identified in the study will be of immense utility in molecular mapping and marker assisted breeding to achieve drought tolerance in cotton.     

Phylogenetic diversity and genome sizes of Astragalus (Fabaceae) in the Lebanon biogeographical crossroad

The Lebanese mountain range is an important zone of plant species richness and endemism where the genus Astragalus constitutes a principal component of plant biodiversity. Most of endemic Astragalus taxa, living in mountains and arid zones of Mounts Lebanon and anti-Lebanon, are characterized by a cushion, spiny vegetative form, named “tragacanthic”, which is a remarkable example of vegetative convergence evolution. Because of determination difficulties, taxonomic uncertainties, and discrepancy in the number of taxa listed according to authors, new data are hardly needed to improve systematics of Astragalus and to investigate the role of the Lebanese mountain range as refugia of biodiversity. Before this study only two values on the genome size of Astragalus were reported in the literature and no previous molecular studies had been carried out on Astragalus genus in Lebanon. We examined the utility of rDNA ITS molecular markers to distinguish Astragalus species of Lebanese mountain range and the variation range of their genome size. The main results revealed a striking diversity in Lebanese Astragalus species with the emphasis of a huge variation of genome sizes, an important inter-specific chromosome polymorphism and the existence of a high phylogenetic diversity. The strict endemic species of the Lebanese mountains are positioned throughout the phylogeny. These results confirm that the Lebanon and anti-Lebanon mounts constitute a third diversity center for Astragalus and that high altitude areas are important refugia of plant biodiversity despite centuries of exploitation by humans.     

The Impact of a One-Dose versus Two-Dose Oral Cholera Vaccine Regimen in Outbreak Settings: A Modeling Study

BackgroundIn 2013, a stockpile of oral cholera vaccine (OCV) was created for use in outbreak response, but vaccine availability remains severely limited. Innovative strategies are needed to maximize the health impact and minimize the logistical barriers to using available vaccine. Here we ask under what conditions the use of one dose rather than the internationally licensed two-dose protocol may do both.ConclusionsReactive vaccination campaigns using a single dose of OCV may avert more cases and deaths than a standard two-dose campaign when vaccine supplies are limited, while at the same time reducing logistical complexity. These findings should motivate consideration of the trade-offs between one- and two-dose campaigns in resource-constrained settings, though further field efficacy data are needed and should be a priority in any one-dose campaign.     

Thioxanthene-derived analogs as sigma(1) receptor ligands

An investigation of the structure-affinity relationships for the binding of thioxanthene-related structures indicates that an intact thioxanthene ring is not required for binding at sigma(1) receptors, and that with the appropriate structural modifications, affinity can be enhanced to the subnanomolar level. Certain of the analogs displayed sigma(1)-fold selectivity for sigma(1) versus sigma(2) receptors.     

Synthesis and antimicrobial activity of meso-substituted polymethine cyanine dyes

The condensation reaction of equivalent amounts of 2-cyanomethyl benzooxazole or its derivatives with variously substituted aromatic aldehydes gave 2-cyano-styryl benzooxazole or its derivatives. The subsequent reaction of the 2-cyano-styryl benzooxazoles with 2(4)-methyl substituted heterocyclic quaternary salts afforded meso-substituted styryl-2(4)-polymethine cyanines. The condensation reaction of 2-cyanomethyl benzooxazole or its derivatives with alpha-nitroso-beta-naphthol followed by reaction with 2(4)-methyl substituted heterocyclic quaternary salts gave meso-substituted aza-2(4)-polymethine cyanines. The reaction of 2-cyanomethyl benzooxazole or its derivatives with N-methyl heterocyclic quaternary salts followed by the reaction with 2-methylquinolinium methiodide afforded the corresponding meso-substituted trimethine cyanine dyes. Elemental analyses, visible absorption, IR, (1)H NMR spectroscopy, and mass spectra established the structures of these compounds. The relationship between the structure and properties of these dyes has been studied and the solvatochromic behavior of some selected cyanine dyes in organic solvents is discussed. Finally, the antimicrobial activity of selected novel dyes was investigated in vitro using a wide spectrum of microbial strains.