Abstract
An efficient synthesis of new A-2, A-3, and A-4 analogues from amlodipine (A-1) has been achieved. All synthesized compounds were investigated by elemental analysis, FTIR, EIMS, and H-1 NMR techniques. Crystal structures of A-2 and A-3 were determined by single crystal X-ray diffraction method. Compound A-2 crystallizes in a monoclinic space group C2/c having unit cell parameters alpha = 23.8754(9) angstrom, b = 8.6725(3) angstrom, c = 30.5777(12) angstrom, beta = 90.673(2)degrees, and V = 6331.0(4) angstrom(3), whereas A-3 crystallizes in a triclinic space group P (1) over bar having unit cell parameters a = 8.2968(3) angstrom, b = 9.3112(4) angstrom, c = 18.1359(7) angstrom, alpha = 100.692(2)degrees, beta = 98.316(3)degrees, gamma = 102.747(2)degrees, and V = 1317.39(9) angstrom(3). These compounds showed that C-H center dot center dot center dot 0 and N-H center dot center dot center dot O hydrogen bonds stabilize the crystal packing. The results of thermal analysis of all products were consistent with the proposed stoichiometry and compounds were found thermally stable up to 200 degrees C. The compounds were tested for direct free radical scavenging effect toward alpha, alpha-Dipheny1-1-picryl hydrazide (DPPH center dot) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS center dot+) radical cation in aqueous phosphate-buffered saline of pH 7.4 and showed significant in vitro antioxidant potential. Antiurease activity was also performed; A-2 and A-4 showed excellent results with dose independency. (C) 2016 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.