dc.description.abstract |
Two series of substituted guanidines (a 1 -a 32 & b 1 -b 32 ) and their copper(II) complexes of
general formula [κ 2 (O, N)-C 6 H 5 CONHC(NHR 1 )NR 2 ] 2 Cu(II) where, R 1 = phenyl (A 1 -
A 32 ), 2-chlorophenyl (B 1 -B 32 ) and R 2 = alkyl/aryl groups, have been synthesized and
characterized by using elemental analysis, FT-IR, multinuclear ( 1 H and
13
C) NMR
spectroscopy and magnetic susceptibility measurements. Single crystal XRD was used
for structural elucidation of some of the synthesized guanidine ligands and their
copper(II) complexes. Based on the single crystal X-ray analysis most of the synthesized
guanidine ligands were stabilized by intermolecular as well as intramolecular hydrogen
bonding. All the complexes are mononuclear in solid state and copper adopts a regular
square planar geometry with slight distortion in few cases, while N,N',N"-trisubstituted
guanidine ligands chelate the Cu(II) atom through oxygen and nitrogen with ligand to
metal ratio 2:1. DFT studies have been used to assess the location of the protons in free
ligands, however calculations have shown that in all cases, hydrogen bonding from either
of the N-H groups gives conformations that are very similar in energy.
The synthesized guanidines and their complexes were also screened for urease
inhibition, antileishmanial, anticancer and antifungal activities. The complexes exhibited
a better usease inhibition activity than the respective guanidines and compound A 7 was
found to be the most active with IC 50 = 4.8 ± 0.05 μM (IC 50 for standard thiourea is 21.0
± 0.1 μM). These compounds were also screened for their brine shrimp lethality assay, a 1
and A 28 were found to be more toxic with the ID 50 value 1.701 ppm. In potato disc
antitumour assay guanidines and complexes have shown the excellent activity
comparable with the vincristine, used as standard drug while, in vitro cytotoxicity against
human cell lines carcinomas A498, EVSAT, H226, IGROV, M19, MCF-7 and WIDR
these compounds show moderate cytotoxicity against these cell lines as compared to the
standard chemotherapeutic drugs. These compounds were also tested for antifungal and
antileishmanial activities and show moderate to good antifungal activity but no
significant antileishmanial activity. |
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