Khalid Mohammad Khan

Synthesis and In Vitro Leishmanicidal Activity of Some Hydrazides and Their Analogues

Twenty-one hydrazides were synthesized by treating different esters with hydrazine hydrate. Substituted hydrazides were obtained by treating hydrazides with alkyl/aryl/acyl halides. Some of these compounds exhibit potential in vitro leishmanicidal activity. The structures of all the synthesized compounds were confirmed by spectroscopic analysis.

6-Nitrobenzimidazole derivatives: Potential phosphodiesterase inhibitors: Synthesis and structure-activity relationship

6-Nitrobenzimidazole derivatives (1-30) synthesized and their phosphodiesterase inhibitory activities determined. Out of thirty tested compounds, ten showed a varying degrees of phosphodiesterase inhibition with IC(50) values between 1.5±0.043 and 294.0±16.7 μM. Compounds 30 (IC(50)=1.5±0.043 μM), 1 (IC(50)=2.4±0.049 μM), 11 (IC(50)=5.7±0.113 μM), 13 (IC(50)=6.4±0.148 μM), 14 (IC(50)=10.5±0.51 μM), 9 (IC(50)=11.49±0.08 μM), 3 (IC(50)=63.1±1.48 μM), 10 (IC(50)=120.0±4.47 μM), and 6 (IC(50)=153.2±5.6 μM) showed excellent phosphodiesterase inhibitory activity, much superior to the standard EDTA (IC(50)=274±0.007 μM), and thus are potential molecules for the development of a new class of phosphodiesterase inhibitors. A structure-activity relationship is evaluated. All compounds are characterized by spectroscopic parameters.

Synthesis of some N4-substituted isatin-3-thiosemicarbazones

In this article, we describe a simple and new method for the synthesis of some N4-substituted isatin-3-thiosemicarbazones based on the reactions of the common intermediate, methyl 2-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)-1-hydrazinecarbodithioate, prepared by condensing isatin with methyl 1-hydrazinecarbodithioate, and the readily available amines in essentially a one-step reaction. The synthesized thiosemicarbazones were fully characterized by their physical, analytical, and spectral (IR, 1H-NMR, EIMS) data.

Determination of nicotinamide and 4-aminobenzoic acid in pharmaceutical preparation by LC

A rapid, precise and time saving high performance liquid chromatographic method has been developed and validated for the simultaneous determination of nicotinamide and 4-aminobenzoic acid in pharmaceutical preparation. The method involves isocratic elution of mobile phase through column in a reverse phase chromatography with UV detection at 254 nm. The ranges of quantification for nicotinamide and 4-aminobenzoic acid were 11-34 microg ml(-1) and 37-113 microg ml(-1), respectively. Investigating specificity, linearity, precision, accuracy, robustness and ruggedness performed the validation of the method.

Development of new UV-vis spectroscopic microwave-assisted method for determination of glucose in pharmaceutical samples.

A new UV-Visible spectroscopic method assisted with microwave for the determination of glucose in pharmaceutical formulations was developed. In this study glucose solutions were oxidized by ammonium molybdate in the presence of microwave energy and reacted with aniline to produce a colored solution. Optimum conditions of the reaction including wavelength, temperature, and pH of the medium and relative concentration ratio of the reactants were investigated. It was found that the optimal wavelength for the reaction is 610 nm, the optimal reaction time is 80s, the optimal reaction temperature is 160°C, the optimal reaction pH is 4, and the optimal concentration ratio aniline/ammonium molybdate solution was found to be 1:1. The limits of detection and quantification of the method are 0.82 and 2.75 ppm for glucose solution, respectively. The use of microwaves improved the speed of the method while the use of aniline improved the sensitivity of the method by shifting the wavelength.

Synthesis, phytotoxic, cytotoxic, acetylcholinesterase and butrylcholinesterase activities of N,N'-diaryl unsymmetrically substituted thioureas.

Fourteen N,N′-diaryl unsymmetrically substituted thioureas were synthesised and their cytotoxic (in vitro), phytotoxic (in vitro), acetylcholinesterase and butrylcholinesterase activities were determined. Thiourea 16 exhibited high, and 1 and 3 showed significant phytotoxic activity. Thioureas 1, 3, 4, 6 and 10 showed significant activity and 2, 6 and 7 indicated moderate cytotoxic activities. Compound 12 exhibited butrylcholinesterase activity higher than a standard reference.

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.

Erratum to: Three-dimensional quantitative structure–activity relationship (CoMSIA) analysis of bis-coumerine analogues as urease inhibitors

As a basis for predicting structural features that may lead to the design of more potent and selective inhibitors of urease, the three-dimensional quantitative structure–activity relationship (3D-QSAR) studies were carried out on a series of 30 bis-coumerine analogs, which are known urease inhibitors. Five different properties: steric, electrostatic, hydrophobic, H-bond donor, and H-bond acceptor, assumed to cover the major contributions to ligand binding, were used to generate the 3D-QSAR model. A significant cross-validated correlation coefficient q2 (0.51), r2 (0.962) for CoMSIA were obtained, indicating the statistical significance of this class of compounds. Actual urease inhibitory activities of this class, and the predicted values were in good agreement with the experimental results. This model offer insight into the structural requirements for activity of bis-coumerine analogues as urease inhibitors, since there is only speculative knowledge of their target in protein.

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.