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  • Author or Editor: S. S. Bhatt x
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Abstract  

The thermal decomposition of the complexes [Vcl (acac)2(OAr)] (where acac=2,4-pentanedionato anion; OAr=–OC6H4O-M-4, OC6H4OBut-4) has been studied using non-isothermal techniques (DTA and TG). The TGA indicate that the substitution of chlorine in VCl2(acac)2 with aryloxide ligands results in an increase in the initial temperature of decomposition (IDT) of the new complexes. The role of the substituent at the aryloxide ring on the thermal stability of the complexes is depicted and hence described. The ultimate decomposition product in all the complexes has been identified as V2O5. The kinetic and thermodynamic parameters namely, the energy of activation E, the frequency factor A, entropy of activation S and specific reaction rate constant k r etc. have been rationalized in relation to the bonding aspect of the aryloxide ligands.

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Abstract  

Thermal decomposition of di- and triphenyltin(IV) complexes derived from potassium salicylhydroxamate (KSHA) of compositions Ph2SnCl(SHA), Ph2Sn(SHA)2 and Ph3Sn(SHA) has been studied by TG, DTG and DTA. Based upon thermal mass losses the transitory formation of diphenyltin oxide, Ph2SnO as the possible intermediate from the decomposition pattern of all the three complexes has been proposed. Both DTG and DTA give well-defined peaks in the appropriate regions. These studies reveal the formation of SnO2 as the ultimate product.

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Summary

An isocratic reversed-phase liquid chromatograpic assay method was developed for the quantitative determination of atorvastatin and aspirin (ASP) in combined dosage form. A Phenomenex Gemini C-18, 5-μm column with mobile phase containing 0.02 M potassium dihydrogen phosphate-acetonitrile-methanol (30:30:40, v/v/v) adjusted to pH 3 using o-phosphoric acid was used. The flow rate was 1.0 mL min−1 and effluents were monitored at 240 nm. The retention times (RTs) of atorvastatin calcium (ATV) and ASP were 10.5 and 3.8 min, respectively. ATV and ASP stock solutions were subjected to acid and alkali hydrolysis, chemical oxidation, and dry heat degradation. The degraded product peaks were well resolved from the pure drug peak with significant difference in their RT values. Stressed samples were assayed using developed LC method. The proposed method was validated with respect to linearity, accuracy, precision, and robustness. The method was successfully applied to the estimation of ATV and ASP in combined capsule dosage forms.

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Abstract

The square-pyramidal copper(II) complexes with ciprofloxacin in the presence of bipyridine derivatives have been synthesized and characterized using elemental analysis, magnetic moment measurement, thermal analysis (TG), IR, mass and reflectance spectra. The thermal denaturation study has been used for evaluating calf thymus DNA interaction activity. Spectral and hydrodynamic measurements have been used for validating the DNA interaction study. The thermodynamic profile was established for proper understanding of DNA binding Gibbs free energy.

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Thermal behaviour of aryloxides of titanium(IV) of composition TiCln(OAr)4−n (wheren=0→3 and OAr=OC6But-4, OC6H4OMe-4 and OC6H2-Bu2 t-2,6−Me-4) has been studied by DTA and TG analysis. Multiple decomposition steps have been indicated by thermal weight losses which are both exothermic and endothermic as shown by DTA curves. Based upon the total % loss in weight; during entire decomposition titanium dioxide has been found to be the final residue in each case.

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Trikatu Churna is an important formulation in Ayurveda — the Traditional System of Indian Medicine. It consists of fine powders of fruits of Piper nigrum L., Piper longum L., and rhizomes of Zingiber officinale Roscoe in equal proportions. Piperine, present in both P. nigrum and P. longum, is considered to be responsible for the improvement of digestion and bioavailability enhancement of many medicaments. Gingerols and 6-shogaol are key chemical molecules in Z. officinale. Piperlongumine is present in P. longum fruits but absent in the fruits of P. nigrum. We report a validated high-performance thin-layer chromatography (HPTLC) method for the determination of piperine, piperlongumine, and 6-shogaol in these herbs and in Trikatu Churna. Piperine, piperlongumine, and 6-shogaol resolved well in n-hexane—ethyl acetate (8:2) on precoated silica gel 60 F254 plates. The absorption maxima for piperine, piperlongumine, and 6-shogaol were found to be 327, 272 and 235 nm, respectively. Linearity for the corresponding markers was observed between 0.1–0.5, 0.2–1.0, and 0.1–1.6 μg spot−1, respectively. The limit of detection (LOD) and limit of quantification (LOQ) were 28 and 100, 56 and 200, and 32 and 100 ng for piperine, piperlongumine, and 6-shogaol, respectively. Recovery experiments showed 99.6%, 99.5%, and 99.7% recoveries for piperine, piperlongumine, and 6-shogaol, respectively. P. nigrum fruits from Delhi and Ahmedabad had around 2.0% w/w piperine, while fruits of P. longum from these markets were analyzed for 0.8% and 0.6% w/w piperine. Piperlongumine was not found in both samples of P. nigrum, while the fruits of P. longum had 0.36% and 0.26% w/w piperlongumine. Z. officinale from Delhi had 0.19% w/w of 6-shogaol as against 0.16% w/w found in the sample from Ahmedabad. Plant materials procured from Delhi were employed for the preparation of Trikatu Churna which showed 96.5%, 95%, and 103% w/w of the expected values of piperine, piperlongumine, and 6-shogaol, respectively. The present method is simple, reproducible, and reliable which can be applied for the routine analysis of Trikatu Churna and its ingredients in polyherbal formulations.

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The investigation was undertaken at two different climatic regimens of NW Himalayas, to determine the response of diverse genotypes of triticale and wheat and environment on their crossability as well as to evaluate the efficiency of Imperata cylindrica-mediated chromosome elimination approach for haploid induction in triticale × wheat (Triticum aestivum) hybrids. The experimental material included three elite hexaploid triticale genotypes (DT123, DT126 and TL9335) and five bread wheat genotypes (DH40, HPW155, HS295, VL829 and C306). Significant genotypic and environmental variations were observed for seed setting at two agroclimatic zones. Among parental genotypes, DT126 (triticale) and C306, HPW155 and HS295 (wheat) responded significantly better for seed setting due to significant positive GCA effects at both locations. Maximum seed set of 39.53% and 45.37% was recorded at short day and long day climates, respectively, proving later as the better location for seed setting in most of the crosses. For all the three parameters of haploid induction, viz. pseudoseed formation, embryo formation and regeneration, significant differences were recorded in all the triticale × wheat hybrids depicting the potential of I. cylindrica-mediated approach for haploid induction. Triticale × wheat cross DT126 × HS295 followed by DT126 × HPW155 were found to be significantly more responsive towards embryo formation and regeneration.

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In the present study, a simple and effcient high-performance thin-layer chromatographic (HPTLC) method was developed for the separation and quantitation of three proton-pump inhibitors, omeprazole, pantoprazole, and rabeprazole, from their binary combinations with diclofenac. Using a “quality by design” approach, preliminary trials were performed on pre-coated silica gel HPTLC plates using toluene together with various alcohols (methanol, ethanol, iso-propanol, n-butanol) as the mobile phase. For better peak symmetry, ammonia was added in different volumes, and its effect on analyte retention and separation was also assessed. The mobile phase consisting of toluene–n-butanol-25% ammonia (3:7:0.2, v/v) afforded excellent separation of proton-pump inhibitors from diclofenac as well as from each other. The retardation factor (R F) for all the separated compounds was between 0.20 and 0.80. The developed method was successfully validated as per the International Conference on Harmonization (ICH) guidelines, and the selected drugs were determined simultaneously from dosage forms without any interference from the excipients.

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The present paper reports that significant genetic variability was evident in Fe, Zn, β-carotene, and phytic acid (phytate, PA) contents in a set of 39 diverse maize genotypes collected from maize breeding programme of hill agriculture, India. The Fe, Zn, β-carotene, and PA concentrations were found to be in the range 19.31–50.64 mg kg−1, 12.60–37.18 mg kg−1, 0.17–8.27 µg g−1, and 6.59–7.13 g kg−1, respectively. The genotypes V335, V420, V393, V416, V414, V372, and V351 were identified to have higher concentration of β-carotene, Fe, and Zn but lower amount of PA. Possible availability of the minerals Fe and Zn was determined using molar ratio between PA as inhibitor and β-carotene as promoter for their absorption. The micronutrient molar ratio showed that Fe and Zn traits could be dependent of each other. Low R2 value revealed relation between β-carotene and kernel colour. The selected genotypes could be considered as potential sources of favourable genes for further breeding programs to develop micronutrient enriched maize cultivars.

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