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valsartan
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Structure and Conformational Study of Drug Compounds using NMR and Ab-initio Calculations
, Ph.D. Dissertation Sharif University of Technology ; Tafazzoli, Mohsen (Supervisor)
Abstract
NMR spectroscopy as a powerful technique is often used to investigate on structural and conformational studies on proteins and drug compounds. In this work, conformations and structural properties of drug compounds and some nucleoside derivations have been studied using advanced NMR techniques including H-H COSY, HMQC, HMBC and NOESY and quantum based calculations.Experimental analysis on Valsartan show that there are two simultaneous conformers (M and m) with unequal population in M-m type solvents and two stable conformers (N and n) in the N-n type solvents. As the results show, different intramolecular hydrogen bond is the reason for stability af all available conformers. In the...
NMR investigation and theoretical calculations of the solvent effect on the conformation of valsartan
, Article Journal of Molecular Structure ; Volume 1148 , 2017 , Pages 73-80 ; 00222860 (ISSN) ; Tafazzoli, M ; Sharif University of Technology
Abstract
Structure and conformational properties of valsartan were studied by advanced NMR techniques and quantum calculation methods. Potential energy scanning using B3LYP/6-311++g** and B3LYP-D3/6-311++g** methods were performed and four conformers (V1-V4) at minimum points of PES diagram were observed. According to the NMR spectra in acetone-d6, there are two conformers (M and m) with mM = 0.52 ratio simultaneously and energy barriers of the two conformers were predicted from chemical shifts and multiplicities. While, intramolecular hydrogen bond at tetrazole ring and carboxylic groups prevent the free rotation on N6[sbnd]C11 bond in M-conformer, this bond rotates freely in m-conformer. On the...
Preparation of amine–modified lignin and its applicability toward online micro–solid phase extraction of valsartan and losartan in urine samples
, Article Journal of Chromatography A ; Volume 1643 , 2021 ; 00219673 (ISSN) ; Zeinali, S ; Bagheri, H ; Sharif University of Technology
Elsevier B.V
2021
Abstract
In the present work, with the focus on an environmentally–friendly approach, some gels were prepared by synthesizing amine–modified lignin, extracted from sugarcane bagasse, and further esterification and subsequent freeze–drying. These lignin–based gels were implemented as extractive phases in an online micro–solid phase extraction (μSPE) setup in conjunction with high performance liquid chromatography (HPLC) with UV detector. The developed method was used for analytical determination of valsartan and losartan in urine samples. To study the effect of the functionalization process, the efficiency of the unmodified lignin and the functionalized lignin were compared both in the absence and the...