TITLE:
SARs Investigation of α-, β-, γ-, δ-, ε-RuCl2(Azpy)2 Complexes as Antitumor Drugs
AUTHORS:
Kafoumba Bamba, Ouattara Wawohinlin Patrice, N’Guessan Kouakou Nobel, Nahossé Ziao
KEYWORDS:
Structure Activity-Relationship (SARs), Ru (II) Complexes, Azpy, DFT, Lanl2dz, DNA-Binding
JOURNAL NAME:
Computational Chemistry,
Vol.4 No.1,
January
6,
2016
ABSTRACT: Structure Activity-Relationships (SARs) of the five possible isomers of RuCl2(Azpy)2 were predicted
thanks to DFT method. Azpy stands for 2-phenylazopyridine and the structure of the isomers
α-RuCl2(Azpy)2, β-RuCl2(Azpy)2, γ-RuCl2(Azpy)2, δ-RuCl2(Azpy)2 and ε-RuCl2(Azpy)2 call respectively α-Cl, β-Cl, γ-Cl, δ-Cl and ε-Cl are defined according to chlorine atoms orientations. Hence,
they are divided into two groups. In the first group comprising α-Cl, β-Cl and ε-Cl, both chlorine
atoms are in cis position and Azpy ligands are intervertical. Whereas the two others isomers (γ-Cl
and δ-Cl), they form the second group. Here, both chlorine are in trans position and Azpy are planar.
The five synthesized isomers were investigated as potential antitumor agents. Then, regarding
the DNA, its bases are stacked by pair. Therefore, complexes are assumed to insert and to stack
on them through intercalative mode. So the electronic and geometric structures become more
important to describe their SARs. Consequently, group 2 regarding γ-Cl and δ-Cl presents the best
structure to allow intercalation between DNA base-pairs. Besides, the energy order of the lower
unoccupied molecular orbital (LUMO) of the isomers is ELUMO(β-Cl) > ELUMO(α-Cl) > ELUMO(ε-Cl) >
ELUMO(γ-Cl) > ELUMO(δ-Cl). The energy gap between LUMO and HOMO was also sorted as Δ(L-H)(β-Cl) >
Δ(L-H)(α-Cl) > Δ(L-H)(ε-Cl) > Δ(L-H)(γ-Cl) > Δ(L-H)(δ-Cl). In addition, the total dipole moment was classified
as μ(ε-Cl) > μ(β-Cl) > μ(α-Cl) > μ(γ-Cl) > μ(δ-Cl). Finally, net charge of the ligand Azpy was also
classified as QL(δ-Cl) > QL(γ-Cl) > QL(ε-Cl) > QL(α-Cl) > QL(β-Cl). All those parameters show that δ-Cl
isomer displays the highest activity as antitumor drug when intercalating between the DNA basepairs
Cytosine-Guanine/Cytosine-Guanine (CG/CG).