Zahid Hussain

Discovery of novel oxindole derivatives as potent α-glucosidase inhibitors.

A series of 6-chloro-3-oxindole derivatives 1-25 were synthesized in high yields by the reaction of 6-chlorooxindole with different aromatic aldehydes in the presence of piperidine. All the synthesized compounds were isolated with E configuration. The structures were confirmed using spectroscopic techniques, including (1)H NMR and EIMS. These compounds showed varying degree of yeast α-glucosidase inhibition and seven were found as potent inhibitors of the enzyme. Compounds 2, 3, 4, 5, 6, 23, and 25 exhibited IC50 values 2.71±0.007, 11.41±0.005, 37.93±0.002, 15.19±0.004, 24.71±0.007, 17.33±0.001, and 14.2±0.002μM, respectively, as compared to standard acarbose (IC50, 38.25±0.12μM). Docking studies helped to find interactions between the enzyme and the active compounds. As a result of this study, oxindoles have been discovered as a new class of α-glucosidase inhibitors which have not been reported earlier.

Development of microwave assisted spectrophotometric method for the determination of glucose

A spectrophotometric method was developed based on the microwave assisted synthesis of Maillard product. Various conditions of the reaction were optimized by varying the relative concentration of the reagents, operating temperature and volume of solutions used in the reaction in the microwave synthesizer. The absorbance of the microwave synthesized Maillard product was measured in the range of 360-740 nm using UV-Visible spectrophotometer. Based on the maximum absorbance, 370 nm was selected as the optimum wave length for further studies. The LOD and LOQ of glucose was found 3.08 μg mL(-1) and 9.33 μg mL(-1) with standard deviation of ±0.05. The developed method was also applicable to urine sample.

The Effect of Pretreatment of Juice on the Properties and Composition of Jaggery

Conservation of the sucrose contents of the jaggery helps to improve the color and shelf life. Light golden color jaggery is the demand of market these days. This color is developed by the chemicals which are hazardous. In the present work light golden color jaggery was prepared by the conservation of sucrose contents and minimization of the activity of the polyphenol oxidase. The activity of polyphenol oxidase was controlled by the interaction of juice with gases like carbon dioxide, nitric oxide, nitrogen dioxide, sulfur dioxide and hydrogen sulfide in separate experiments. These activities were monitored by the use of % pol, % brix and the color intensity of the jaggery. The reasons for these activities were also discussed in this communication.

The Effect of Contact Surface on the Properties of Jaggery

The composition of the products of the sugar cane mainly jaggery or gur is very important in term of their food value, color and shelf life. The juice passes through a number of changes up to the end products. The unwanted change is the darkening of the colour. In this work attempts were made to improve the colour and the sucrose contents of the jaggery by the use of different surfaces during its formation. The idea behind was the activity of these surfaces toward polyphenol colourants and the caramelisation. These activities were monitored by the use of % pol, % brix and the colour intensity of the jaggery. The reasons for these activities were also discussed in this communication.

Microwave-metal Interaction Pyrolysis of Waste Polystyrene in a Copper Coil Reactor

Waste polystyrene was pyrolyzed into substituted aromatic compounds in a microwave oven using a copper coil reactor. The copper coil acts as an antenna and heat-generating object. The rate of reaction was found to be dependent on the size, shape, and form of the metal antenna. The pyrolysis products were found to contain 85% oily liquid, 10–12% gases, and char residue. The amount of gas was calculated by taking the difference. The liquid products were analyzed by using gas chromatography-mass spectrometry and found that it contains substituted benzene in addition to polycyclic aromatics and condensed ring aromatic compounds.

Synthesis, molecular modeling and biological evaluation of 5-arylidene-N,N-diethylthiobarbiturates as potential α-glucosidase inhibitors

BACKGROUNDnBarbituric acid derivatives are a versatile group of compounds which are identified as potential pharmacophores for the treatment of anxiety, epilepsy and other psychiatric disorders. They are also used as anesthetics and have sound effects on the motor and sensory functions. Barbiturates are malonylurea derivatives with a variety of substituents at C-5 position showing resemblance with nitrogen and sulfur containing compounds like thiouracil which exhibited potent anticancer and antiviral activities. Recently, barbituric acid derivatives have also received great interest for applications in nanoscience.nnnOBJECTIVEnSynthesis of 5-arylidene-N,N-diethylthiobarbiturates, biological evaluation as potential α-glucosidase inhibitors and molecular modeling.nnnMETHODSnIn the present study, N,N-Diethylthiobarbituric acid derivatives were synthesized by refluxing of N,N-diethylthiobarbituric acid and different aromatic aldehydes in distilled water. In a typical reaction; a mixture of N,N-diethylthiobarbituric acid 0.20 g (1 mmol) and 5-bromo-2- hydroxybenzaldehyde 0.199 g (1 mmol) mixed in 10 mL distilled water and reflux for 30 minutes. After completion of the reaction, the corresponding product 1 was filtered and dried and yield calculated. It was crystallized from ethanol. The structures of synthesized compounds 1-25 were carried out by using 1H, 13C NMR, EI spectroscopy and CHN analysis used for the determination of their structures. The α-glucosidase inhibition assay was performed as given by Chapdelaine et al., with slight modifications and optimization.nnnRESULTSnOur newly synthesized compounds showed a varying degree of α-glucosidase inhibition and at least four of them were found as potent inhibitors. Compounds 6, 5, 17, 11 exhibited IC50 values (Mean±SEM) of 0.0006 ± 0.0002, 18.91 ± 0.005, 19.18 ± 0.002, 36.91 ± 0.003 µM, respectively, as compared to standard acarbose (IC50, 38.25 ± 0.12 µM).nnnCONCLUSIONnOur present study has shown that compounds 6, 5, 17, 11 exhibited IC50 values of 0.0006 ± 0.0002, 18.91 ± 0.005, 19.18 ± 0.002, 36.91 ± 0.003 µM, respectively. The studies were supported by in silico data analysis.

Production of highly upgraded bio-oil by microwave–metal interaction pyrolysis of biomass in a copper coil reactor

ABSTRACT In this study, highly upgraded bio-oil was produced by microwave–metal interaction pyrolysis of water hyacinth biomass. A copper coil was used as a microwave receiver and heat generating antenna. The pyrolysis of biomass was carried out with and without using a cement catalyst. The fractional amounts of the as-produced bio-oil, biogas, and biochar were determined in terms of catalyst mass, reaction time, and the gauge of the copper coil antenna. In cement catalyzed pyrolysis, the water hyacinth was converted into 20% bio-oil and 31% combustible gases with overall conversion efficiency of 66%. In the case of uncatalyzed pyrolysis, the overall conversion efficiency remained below 60% with 10% bio-oil. The biomass to catalyst ratio of 5:1, 25 min of reaction time and 2.5 mm gauge of wire were predicted as optimum conditions for the pyrolysis process. The bio-oil was further analyzed through chromatography–mass spectrometry (GC-MS) while the gaseous products were analyzed through chemical testing and combustibility analysis. Significant difference in the chemical composition of the bio-oils, produced using catalytic and noncatalytic microwave–metal interaction pyrolysis, was noticed in these investigations. The oil product of the catalyzed and uncatalyzed pyrolysis contained 11.6% and 9.418% hydrocarbons, respectively. Similarly, oxygen content in the oil was measured about 14.73% and 16.66%, respectively. Also, unlike the thermal or thermo-catalytic pyrolysis, the bio-oil product of the microwave–metal interaction pyrolysis was found immiscible with water.