Cytotoxicity and mechanism of action of metal complexes: An overview.

After the discovery of cisplatin, many metal compounds were investigated for the therapy of diseases, especially cancer. The high therapeutic potential of metal-based compounds is related to the special properties of these compounds, such as their redox activity and ability to target vital biological sites. The overproduction of ROS and the consequent destruction of the membrane potential of mitochondria and/or the DNA helix is one of the known pathways leading to the induction of apoptosis by metal complexes. The apoptosis process can occur via the death receptor pathway and/or the mitochondrial pathway. The expression of Bcl2 proteins and the caspase family play critical roles in these pathways. In addition to apoptosis, autophagy is another process that regulates the suppression or promotion of various cancers through a dual action. On the other hand, the ability to interact with DNA is an important property found in several metal complexes with potent antiproliferative effects against cancer cells. These interactions were classified into two important categories: covalent/coordinated or subtle, and non-coordinated interactions. The anticancer activity of metal complexes is sometimes achieved by the simultaneous combination of several mechanisms. In this review, the anticancer effect of metal complexes is mechanistically discussed by different pathways, and some effective agents on their antiproliferative properties are explained.

Bis(2-amino-pyridinium) 2,5-dicarb-oxy-benzene-1,4-dicarboxyl-ate.

In the title compound, 2C(5)H(7)N(2) (+)·C(10)H(4)O(8) (2-), the 2-amino-pyridinium (2-apyH) cation and 2,5-dicarb-oxy-benzene-1,4-dicarboxyl-ate (btcH2) anion are both nearly planar, with r.m.s. deviations of 0.015 and 0.050 Å, respectively. The angle between the latter least-squares planes is 17.68 (9)°. The overall crystal structure results from the packing of two-dimensional networks, formed by alternating 2-apyH and btcH2 linked by hydrogen bonds, parallel to (100).

Hexaaqua-nickel(II) tetra-aqua-bis-(µ-pyridine-2,6-dicarboxyl-ato)bis-(pyridine-2,6-dicarboxyl-ato)trinickelate(II) octa-hydrate.

The title compound, [Ni(H(2)O)(6)][Ni(3)(C(7)H(3)NO(4))(4)(H(2)O)(4)]·8H(2)O, was obtained by the reaction of nickel(II) nitrate hexa-hydrate with pyridine-2,6-dicarb-oxy-lic acid (pydcH(2)) and 1,10-phenanothroline (phen) in an aqueous solution. The latter ligand is not involved in formation of the title complex. There are three different Ni(II) atoms in the asymmetric unit, two of which are located on inversion centers, and thus the [Ni(H(2)O)(6)](2+) cation and the trinuclear {[Ni(pydc)(2)](2)-µ-Ni(H(2)O)(4)}(2-) anion are centrosymmetric. All Ni(II) atoms exhibit an octa-hedral coordination geometry. Various inter-actions, including numerous O-H⋯O and C-H⋯O hydrogen bonds and C-O⋯π stacking of the pyridine and carboxyl-ate groups [3.570 (1), 3.758 (1) and 3.609 (1) Å], are observed in the crystal structure.

Phenyl-hydrazinium (6-carb-oxy-pyridine-2-carboxyl-ato)(pyridine-2,6-dicarboxyl-ato)cobaltate(II)-pyridine-2,6-dicarb-oxy-lic acid-water (1/1/3).

The asymmetric unit of the title compound, (C(6)H(9)N(2))[Co(C(7)H(3)NO(4))(C(7)H(4)NO(4))]·C(7)H(5)NO(4)·3H(2)O, contains one (6-carb-oxy-pyridine-2-carboxyl-ato)(pyridine-2,6-dicarboxyl-ato)cobaltate(II) anion, one phenyl-hydrazinium cation, one pyridine-2,6-dicarb-oxy-lic acid mol-ecule and three uncoordin-ated water mol-ecules, part of which are disordered. The Co(II) ion is coordinated by a pyridine-2,6-dicarboxyl-ate ion and a 6-carb-oxy-pyridine-2-carboxyl-ate ligand almost perpendicular to each other [the angle between the least-squares planes is 87.38 (4)°] and is surrounded by two O atoms and two N atoms in the equatorial plane and two O atoms in axial positions, resulting in a distorted octa-hedral coordination geometry. There is an extensive three-dimensional network of O-H⋯O and N-H⋯O hydrogen bonds, which link the components.