Crystal structure, infrared and EPR spectra and anticancer activity in vitro of the novel manganese(II) complexes of indolecarboxylic acids

The new complexes of 5-methoxyindole-2-carboxylic acid (5-MeOI2CAH) and indole-2-carboxylic acid (I2CAH) with manganese(II): catena-poly[diaquamanganese(II)-bis(μ2-5-methoxyindole-2-carboxylato-O:O′)], [Mn(5-MeOI2CA)2(H2O)2]n (1) and catena-poly[diaquamanganese(II)-bis(μ2-indole-2-carboxylato-O:O′)], [Mn(I2CA)2(H2O)2]n (2) have been prepared. A single crystal X-ray analysis of 1 shows that the complex crystallizes in the monoclinic system, space group P21/c. The 5-MeOI2CA anion acts as a bidentate bridging ligand coordinated to Mn(II) in an abnormal non-planar skew–skew mode, which differs from the coplanar syn–syn, syn–anti and anti–anti bridging modes commonly occurring in metal carboxylates. The FTIR and EPR spectroscopic studies of Mn(II) complexes are reported. In vitro cytotoxicities of 1, 2, 5-MeOI2CAH, I2CAH and their Zn(II) complexes have been evaluated by an MTT assay against the selected human leukemia cell lines: HL-60, MV-4-11, U937, Jurkat, KG-1, U2932 and murine melanoma B16-F0. The results have revealed that the two manganese(II) complexes are cytotoxic and their antiproliferative activity against some cell lines (e.g. Jurkat derived from an acute T cell leukemia) is similar to that of cisplatin.

Indole-2-carboxylic acids act as bidentate bridging ligands binding Mn(II) in an abnormal non-planar skew-skew mode.The Mn-O(carboxyl) stretching vibrations are in the range 288-245 cm−1, Mn-O(water) at 416 and 381 cm−1, the in FT-IR.Mn(II) complexes with indole-2-carboxylic acids exhibit significant cytotoxicity against six leukemia cell lines, comparable to cisplatin.Figure optionsDownload as PowerPoint slide