Simultaneous Determination of Ofloxacin and Ornidazole in Solid Dosage Form by RP-HPLC and HPTLC Techniques

The objective of this work was to develop and validate simple, rapid and accurate chromatographic methods for simultaneous determination of ofloxacin and ornidazole in solid dosage form. The first method was based on reversed phase high performance liquid chromatography, on Intersil C18 column (250 mm, 4.6 i.d.), using acetonitrile:methanol: 0.025M phosphate buffer, pH 3.0 (30:10:60 % v/v/v) as the mobile phase, at a flow rate of 1 ml/min at ambient temperature. Quantification was achieved with UV detection at 318 nm over a concentration range of 2-40 µg/ml for ofloxacin and 5-100 µg/ml for ornidazole. The mean retention time of ofloxacin and ornidazole was found to be 4.04 min and 5.83 min, 6.77 min (isomers), respectively. The amount of ofloxacin and ornidazole estimated as percentage of label claimed was found to be 100.23 and 99.61%, with mean percent recoveries 100.20 and 100.93%, respectively. The second method was based on TLC separation of these drugs using silica gel 60F254 aluminium sheets and dichloromethane:methanol:25% ammonia solution (9.5:1:3 drops v/v) as mobile phase. Detection was carried out at 318 nm over the concentration range of 20-100 ng/spot for ofloxacin and 50-250 ng/spot for ornidazole. The mean Rf value of ofloxacin and ornidazole was found to be 0.16 and 0.56, 0.78 (isomers), respectively. The amount of ofloxacin and ornidazole estimated as percentage of label claimed was found to be 100.23 and 99.61% with mean percent recoveries 100.47 and 99.32%, respectively. Both these methods were found to be simple, precise, accurate, selective and rapid and could be successfully applied for the determination of pure laboratory prepared mixtures and tablets

A draft of the genome and four transcriptomes of a medicinal and pesticidal angiosperm <it>Azadirachta indica</it>

<p>Abstract</p> <p>Background</p> <p>The <it>Azadirachta indica</it> (neem) tree is a source of a wide number of natural products, including the potent biopesticide azadirachtin. In spite of its widespread applications in agriculture and medicine, the molecular aspects of the biosynthesis of neem terpenoids remain largely unexplored. The current report describes the draft genome and four transcriptomes of <it>A. indica</it> and attempts to contextualise the sequence information in terms of its molecular phylogeny, transcript expression and terpenoid biosynthesis pathways. <it>A. indica</it> is the first member of the family <it>Meliaceae</it> to be sequenced using next generation sequencing approach.</p> <p>Results</p> <p>The genome and transcriptomes of <it>A. indica</it> were sequenced using multiple sequencing platforms and libraries. The <it>A. indica</it> genome is AT-rich, bears few repetitive DNA elements and comprises about 20,000 genes. The molecular phylogenetic analyses grouped <it>A. indica</it> together with <it>Citrus sinensis</it> from the <it>Rutaceae</it> family validating its conventional taxonomic classification. Comparative transcript expression analysis showed either exclusive or enhanced expression of known genes involved in neem terpenoid biosynthesis pathways compared to other sequenced angiosperms. Genome and transcriptome analyses in <it>A. indica</it> led to the identification of repeat elements, nucleotide composition and expression profiles of genes in various organs.</p> <p>Conclusions</p> <p>This study on <it>A. indica</it> genome and transcriptomes will provide a model for characterization of metabolic pathways involved in synthesis of bioactive compounds, comparative evolutionary studies among various <it>Meliaceae</it> family members and help annotate their genomes. A better understanding of molecular pathways involved in the azadirachtin synthesis in <it>A. indica</it> will pave ways for bulk production of environment friendly biopesticides.</p

Suspensions of titania nanoparticle networks in nematic liquid crystals: rheology and microstructure

We study the influence of confinement on the rheology and structure of nematic liquid crystals (NLCs). NLCs get confined in networks of titania (TiO2, primary particle size = 21 nm) nanoparticles in suspensions of TiO2 and NLC, N-(4-methoxybenzylidene)-4-butylaniline (MBBA). Suspensions with TiO2 nanoparticle volume fraction (ϕ) of 0.006–0.017, form viscoelastic solids with low elastic modulus (G′) of 101 Pa–102 Pa and short relaxation times. Increase in TiO2 nanoparticle ϕ leads to a rise in G′ with TiO2 nanoparticles forming a percolating network at a critical volume fraction (ϕ c) = 0.023, and G′ of ~103 Pa. TiO2/MBBA NLC suspensions at and above ϕ c = 0.023 show G′ ~ ω x−1 scaling, where ω is the angular frequency and the minimum in loss modulus (G′′) with ω. The effective noise temperature, x decreases and approaches 1 with the increase in the TiO2 nanoparticle ϕ from 0.023–0.035, is indicative of an increase in the glassy dynamics. Through the polarized light microscopy and differential scanning calorimetry experiments, we propose that the progressive addition of TiO2 nanoparticles introduces a quenched random disorder (QRD) in the NLC medium which disturbs the nematic order. This results in metastable TiO2/MBBA NLC suspensions in which NLC domains get confined in the network of flocs of TiO2 nanoparticles. We also show that the salient rheological signatures of soft glassy rheology develop only in the presence of NLC MBBA and are absent in the isotropic phase of MBBA.by Siddharth Kulkarni and Prachi Tharej

The critically endangered forest owlet <i>Heteroglaux blewitti</i> is nested within the currently recognized <i>Athene</i> clade: A century-old debate addressed

<div><p>Range-restricted species generally have specific niche requirements and may often have unique evolutionary histories. Unfortunately, many of these species severely lack basic research, resulting in poor conservation strategies. The phylogenetic relationship of the Critically Endangered Forest Owlet <i>Heteroglaux blewitti</i> has been the subject of a century-old debate. The current classifications based on non-phylogenetic comparisons of morphology place the small owls of Asia into three genera, namely, <i>Athene</i>, <i>Glaucidium</i>, and <i>Heteroglaux</i>. Based on morphological and anatomical data, <i>H</i>. <i>blewitti</i> has been alternatively hypothesized to belong within <i>Athene</i>, <i>Glaucidium</i>, or its own monotypic genus <i>Heteroglaux</i>. To test these competing hypotheses, we sequenced six loci (~4300 bp data) and performed phylogenetic analyses of owlets. Mitochondrial and nuclear trees were not congruent in their placement of <i>H</i>. <i>blewitti</i>. However, both mitochondrial and nuclear combined datasets showed strong statistical support with high maximum likelihood bootstrap (>/ = 90) and Bayesian posterior probability values (>/ = 0.98) for <i>H</i>. <i>blewitti</i> being nested in the currently recognized <i>Athene</i> group, but not sister to Indian <i>A</i>. <i>brama</i>. The divergence of <i>H</i>. <i>blewitti</i> from its sister taxa was between 4.3 and 5.7 Ma coinciding with a period of drastic climatic changes in the Indian subcontinent. This study presented the first genetic analysis of <i>H</i>. <i>blewitti</i>, a Critically Endangered species, and addressed the long debate on the relationships of the <i>Athene</i>-<i>Heteroglaux</i>-<i>Glaucidium</i> complex. We recommend further studies with more data and complete taxon sampling to understand the biogeography of Indian <i>Athene</i> species.</p></div