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Khan K.M.,University of Karachi | Khan M.,University of Karachi | Khan M.,Abdul Wali Khan University Mardan | Khan A.,University of Karachi | And 3 more authors.
Journal of the Chemical Society of Pakistan

Earlier 5-arylidene N,N-dimethylbarbiturates 1-24 were reported by our group as novel antioxidant, nevertheless, urease inhibitory activity of these compounds has not been investigated at all. In the present study, compounds 1-24 were synthesized by the reaction of N,N-dimethylbarbituric acid with different aromatic aldehydes, and screened for their in vitro urease inhibitory effects. Compound 7, was found to be most active urease inhibitor in the series. Nonetheless, compounds 11, 12, and 19 were also active against urease enzyme. Source

Mohammed Khan K.,University of Karachi | Alia M.,University of Karachi | Khana M.,University of Karachi | Taha M.,University of Karachi | Perveen S.,PCSIR Laboratories Complex Karachi
Letters in Organic Chemistry

Eco-benign method for synthesizing arylidene barbiturates has been developed by using ammonium chloride (NH 4Cl) in stoichiometric amount, as an enolization activator, in water. Execution of methodology is simple, products obtained in high yields and the reactions are completed within 30 min. The new methodology does not involve any solvent/solvent extraction while solid products were yielded in all cases which were filtered and washed. copy; 2011 Bentham Science Publishers Ltd. Source

Farooq M.,University of Karachi | Akhtar Z.,University of Karachi | Saad S.M.,University of Karachi | Ali S.I.,University of Karachi | And 3 more authors.
Journal of the Chemical Society of Pakistan

Summary: Disodium- 4,4 ′ - bis(1,3,5-triazinylamino)stilbene- 2,2 ′ - disulfonates 5a - 5d were synthesized by reacting 4,4′ -diaminostilbene-2- 2′ -disulfonic acid 1 with 2,4,6-trichloro-1,3,5-triazine 2 via the intermediacies of 3 and 4a-4d. The intermediate 3 was reacted with different amines at different temperature conditions to afford other intermediates 4a - 4d and finally the desired fluorescent brightener's 5a - 5d. The structures of the products were characterized by UV-visible, IR and H1 - NMR spectroscopy techniques. Elemental analyses were found to be in good agreement with the calculated values. These compounds were applied on cotton fiber as fluorescent brighteners and their physical properties were performed by wash-, chlorine-, and light-fastness. The whiteness of the fiber was measured by spectrophotometer. Fluorescent brightening agents UV-visible spectra Fastness properties Whiteness properties. Source

Sher N.,University of Karachi | Fatima N.,University of Karachi | Perveen S.,PCSIR Laboratories Complex Karachi | Siddiqui F.A.,University of Karachi | Wafa Sial A.,Ziauddin University
International Journal of Analytical Chemistry

This paper demonstrates colorimetric visible spectrophotometric quantification methods for amino acid, namely, tranexamic acid and pregabalin. Both drugs contain the amino group, and when they are reacted with 2,4-dinitrophenol and 2,4,6-trinitrophenol, they give rise to yellow colored complexes showing absorption maximum at 418 nm and 425 nm, respectively, based on the Lewis acid base reaction. Detailed optimization process and stoichiometric studies were conducted along with investigation of thermodynamic features, that is, association constant and standard free energy changes. The method was linear over the concentration range of 0.02-200 μgmL-1 with correlation coefficient of more than 0.9990 in all of the cases. Limit of detection was in range from 0.0041 to 0.0094 μgmL-1 and limit of quantification was in the range from 0.0137 to 0.0302 μgmL-1. Excellent recovery in Placebo spiked samples indicated that there is no interference from common excipients. The analytical methods under proposal were successfully applied to determine tranexamic acid and pregabalin in commercial products. t -test and F ratio were evaluated without noticeable difference between the proposed and reference methods. © 2015 Nawab Sher et al. Source

Khan K.M.,University of Karachi | Rahim F.,University of Karachi | Rahim F.,Hazara University | Shah S.A.A.,University Technology of MARA | And 5 more authors.
Journal of the Chemical Society of Pakistan

An effective and eco-friendly method for the bis(indolyl)methanes synthesis has been developed. A successive methodology involving sodium iodate/sodium hydrogen sulfite catalyzed reaction of indole with many aldehydes gave the resultant bis-indol in good yield. This method offers synthetically inexpensive alternate to the previously developed procedures for the bis-indol synthesis. The use of a low-cost and straightforwardly accessible catalyst, improved yields and a simple reaction process are the salient features of the current method. Source

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