Catalytic Hydrogenation of CO to Higher Alcohols

The interest in converting synthesis gas to alcohols and oxygenated fuel additives via CO hydrogenation is growing rapidly due to the increasing rise in oil prices. Among the potential end products, ethanol is desirable since it serves as a clean alternative fuel, a gasoline blend, and a hydrogen carrier to supply fuel cells. The high cost and limited availability of the most active/selective Rh-based catalysts has led to the development of base metal catalysts such as modified Cu-based catalysts. Literature suggests that a combination of Co (or Mn) with Cu can facilitate higher alcohol formation by a non-dissociative adsorption of CO on the Cu sites, followed by insertion of CO into growing hydrocarbon chains formed from dissociated CO on the Co (or Mn) sites. The goal of this research work was to synthesize, characterize and test two types of copper-based catalysts – bimetallic nanoparticles and pyrochlores, for the hydrogenation of CO to higher alcohols, particularly ethanol. Copper-based bimetallic nanoparticles with core-shell morphologies synthesized using wet-chemical methods were the major focus of this dissertation. Uniformly dispersed and highly reproducible Cu core-Mn3O4 shell (Cu@Mn3O4) and Cu core-Co3O4 shell (Cu@Co3O4) nanoparticles were synthesized with a porous shell, thereby making the copper core accessible. DRIFTS (in-situ FTIR) showed that the Cu@Mn3O4 nanoparticles have a greater CO adsorption capacity and a lower CO dissociation activity, while the Cu@Co3O4 nanoparticles showed a higher selectivity towards alcohols and oxygenates, with the total alcohols/oxygenates being 48% of the total products. An ethanol selectivity of 15% (with a corresponding methane selectivity of 11%) was achieved at 10 bar, 270 °C and H2/CO=2. Another focus was on Cu-ZnO based catalysts supported on La2Zr2O7 pyrochlores which are believed to be promising candidates as supports for stable and active copper catalysts for CO hydrogenation. Mn or Co promoted Cu-ZnO-La2Zr2O7-Li2O catalysts were synthesized by coprecipitation. Addition of Mn or Co promoter increased the overall extent of reduction of the catalysts. DRIFTS studies showed increased CO chemisorption and negligible methanation on the Mn promoted catalyst under the conditions tested, while methane was the major product on the Co-promoted catalyst

SYNTHESIS AND EVALUATION OF ANTIDIABETIC PROPERTIES OF A ZINC MIXED LIGAND COMPLEX IN HIGH-FAT DIET - LOW-DOSE STREPTOZOTOCIN-INDUCED DIABETIC RATS

Objective: Due to the multifactorial and multisystemic nature of diabetes mellitus (DM), it is often treated with a combination of therapeutic agents. Earlier, we have synthesized and characterized several organozinc complexes and evaluated their safety and antidiabetic properties in experimental DM. In the present study, a new zinc mixed ligand (metformin-3-hydroxyflavone) was synthesized and characterized by various spectral studies and its antidiabetic properties were evaluated in high-fat diet (HFD) fed – low-dose streptozotocin (STZ)-induced Type 2 D (T2D) in rats.Methods: The zinc mixed ligand complex was characterized by spectral studies. The toxicity and dosage fixation studies were carried out as per OECD guidelines 423. HFD fed low-dose STZ-induced T2DM in rats was used as the experimental model. The hypoglycemic efficacy of the complex was evaluated through oral glucose tolerance test, homeostasis model assessment of insulin resistance (IR), QUICK I and by determining the status of important biochemical parameters. The activities of marker enzymes such as aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase were assayed. Metformin was used as a standard drug.Results: The spectral data evidenced the synthesis of a new zinc mixed ligand complex. The biochemical studies evidenced that the oral administration of the complex at a concentration of 10 mg/kg b.w/rat/day for 30 days to diabetic rats significantly improved the glucose homeostasis which was comparable to metformin treatment (50 mg/kg b.w).Conclusion: The zinc mixed complex possesses significant antidiabetic properties in ameliorating IR and stimulatory properties

PHYTOCHEMICAL SCREENING AND EVALUATION OF IN VITRO ANTIOXIDANT POTENTIAL OF IMMATURE PALMYRA PALM (BORASSUS FLABELLIFER LINN.) FRUITS

Objective: The present study was aimed to evaluate the in vitro antioxidant properties of immature Palmyra palm fruits which have been traditionally used for the treatment of diabetes. The qualitative phytochemical screening and quantitative estimation of total phenolic and flavonoids contents in the ethanolic extract were performed to substantiate the antioxidant and medicinal claims.Methods: Immature palmyra palm fruits were collected, authenticated, dried and powdered in an electrical grinder. The powdered fruits were delipidated in petroleum ether and soxhilation using ethanol to extract the active ingredients. Qualitative phytochemical screening, total phenolic and flavonoid contents were carried out by established methods. The in vitro antioxidant potentials were performed by diphenyl-2-picrylhydrazyl, azino-bis(3-ethylbenzothiazoline-6-sulphonic acid, nitric oxide and superoxide anion scavenging assays.Results: The phytochemical screening showed the presence of alkaloids, flavonoids, glycosides, saponins, tannins, phytosterols, triterpenoids and phenols in the immature palmyra palm fruits extract. The total phenolic and flavonoid contents in the fruits extract was found to be 104.00±0.02 μg gallic acid equivalents/100 mg of fruits extract and 98.45±0.03 μg quercetin equivalents/100 mg, respectively. The percentage inhibition of DPPH radicals range from 35 to 70% at a concentration ranges from 200-1000μg/ml. Similarly, the percentage of inhibition of ABTS radicals was found to be in the range of 40 to 75.5%. The nitric oxide scavenging activity of the fruits extract ranges from 45 to 76% whereas the superoxide radical scavenging activity ranges from 43 to 83%.Conclusion: The observed significant free radical scavenging activity along with increased total phenolic as well as flavonoid contents suggest that the immature fruits may be considered as a potential source for the identification of pharmacologically active phytochemicals capable of controlling oxidative stress

3D-QSAR studies on the inhibitory activity of trimethoprim analogues against Escherichia coli dihydrofolate reductase

Three-dimensional quantitative structure activity relationship (3D-QSAR) study has been carried out on the Escherichia coli DHFR inhibitors 2,4-diamino-5-(substituted-benzyl)pyrimidine derivatives to understand the structural features responsible for the improved potency. To construct highly predictive 3D-QSAR models, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) methods were used. The predicted models show statistically significant cross-validated and non-cross-validated correlation coefficient of r2CV and r2nCV, respectively. The final 3D-QSAR models were validated using structurally diverse test set compounds. Analysis of the contour maps generated from CoMFA and CoMSIA methods reveals that the substitution of electronegative groups at the first and second position along with electropositive group at the third position of R2 substitution significantly increases the potency of the derivatives. The results obtained from the CoMFA and CoMSIA study delineate the substituents on the trimethoprim analogues responsible for the enhanced potency and also provide valuable directions for the design of new trimethorpim analogues with improved affinity

Growth and Mass Spectrometry Profile of Alternaria Alternata Pigment Grown in Maize Grain extract

Alternaria species are common saprophytes found in a variety of habitats as ubiquitous agents of decay. Alternaria spp. produces about sixty different secondary metabolites. In the present investigation, growth and production of pigment from Alternaria alternata was studied in maize grain extract at pH 4-9. The reddish brown pigment was extracted, estimated and partially purified by fractionation. Through mass spectrometry, major constituents of pigment from Alternaria alternata such as Tenuazoic acid (m/z 198), Stemphyperylenol (m/z 253), Alterperylenol (m/z 351), Alternariol (m/z 259.200), Altenuene (m/z 292), Alternarienoic acid (m/z 279.35) and Alternariol 5 methyl ether (m/z 273.20) were identified. The bio-prospecting of these secondary metabolites in industrial applications is also discussed

Remdesivir for 5 or 10 Days in Patients With Severe Covid-19

Background: Remdesivir is an RNA polymerase inhibitor with potent antiviral activity in vitro and efficacy in animal models of coronavirus disease 2019 (Covid-19). Methods: We conducted a randomized, open-label, phase 3 trial involving hospitalized patients with confirmed SARS-CoV-2 infection, oxygen saturation of 94% or less while they were breathing ambient air, and radiologic evidence of pneumonia. Patients were randomly assigned in a 1:1 ratio to receive intravenous remdesivir for either 5 days or 10 days. All patients received 200 mg of remdesivir on day 1 and 100 mg once daily on subsequent days. The primary end point was clinical status on day 14, assessed on a 7-point ordinal scale. Results: In total, 397 patients underwent randomization and began treatment (200 patients for 5 days and 197 for 10 days). The median duration of treatment was 5 days (interquartile range, 5 to 5) in the 5-day group and 9 days (interquartile range, 5 to 10) in the 10-day group. At baseline, patients randomly assigned to the 10-day group had significantly worse clinical status than those assigned to the 5-day group (P = 0.02). By day 14, a clinical improvement of 2 points or more on the ordinal scale occurred in 64% of patients in the 5-day group and in 54% in the 10-day group. After adjustment for baseline clinical status, patients in the 10-day group had a distribution in clinical status at day 14 that was similar to that among patients in the 5-day group (P = 0.14). The most common adverse events were nausea (9% of patients), worsening respiratory failure (8%), elevated alanine aminotransferase level (7%), and constipation (7%). Conclusions: In patients with severe Covid-19 not requiring mechanical ventilation, our trial did not show a significant difference between a 5-day course and a 10-day course of remdesivir. With no placebo control, however, the magnitude of benefit cannot be determined. (Funded by Gilead Sciences; GS-US-540-5773 ClinicalTrials.gov number, NCT04292899.)

NALP3 inflammasome upregulation and CASP1 cleavage of the glucocorticoid receptor cause glucocorticoid resistance in leukemia cells

Glucocorticoids are universally used in the treatment of acute lymphoblastic leukemia (ALL), and resistance to glucocorticoids in leukemia cells confers poor prognosis. To elucidate mechanisms of glucocorticoid resistance, we determined the prednisolone sensitivity of primary leukemia cells from 444 patients newly diagnosed with ALL and found significantly higher expression of CASP1 (encoding caspase 1) and its activator NLRP3 in glucocorticoid-resistant leukemia cells, resulting from significantly lower somatic methylation of the CASP1 and NLRP3 promoters. Overexpression of CASP1 resulted in cleavage of the glucocorticoid receptor, diminished the glucocorticoid-induced transcriptional response and increased glucocorticoid resistance. Knockdown or inhibition of CASP1 significantly increased glucocorticoid receptor levels and mitigated glucocorticoid resistance in CASP1-overexpressing ALL. Our findings establish a new mechanism by which the NLRP3-CASP1 inflammasome modulates cellular levels of the glucocorticoid receptor and diminishes cell sensitivity to glucocorticoids. The broad impact on the glucocorticoid transcriptional response suggests that this mechanism could also modify glucocorticoid effects in other diseases

New Insights into the Mechanism of Visible Light Photocatalysis

ABSTRACT: In recent years, the area of developing visible-lightactive photocatalysts based on titanium dioxide has been enormously investigated due to its wide range of applications in energy and environment related fields. Various strategies have been designed to efficiently utilize the solar radiation and to enhance the efficiency of photocatalytic processes. Building on the fundamental strategies to improve the visible light activity of TiO2-based photocatalysts, this Perspective aims to give an insight into many contemporary developments in the field of visible-light-active photocatalysis. Various examples of advanced TiO2 composites have been discussed in relation to their visible light induced photoconversion efficiency, dynamics of electron− hole separation, and decomposition of organic and inorganic pollutants, which suggest the critical need for further development of these types of materials for energy conversion and environmental remediation purposes