Synthesis, Characterization, and Cytotoxic Activity of New Lanthanum(III) Complexes of Bis‐Coumarins

Abstract

Complexes of lanthanum(III) with bis-coumarins: 3,3′-benzylidene-bis(4-hydroxy-2H-1-benzopyran-2-one) (L1) and bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-(1H-pyrazol-3-yl)-methane (L2) were synthesized by reaction of lanthanum(III) salt and the ligands, in amounts equal to metal : ligand molar ratio of 1 : 2. The complexes were prepared by adding an aqueous solution of lanthanum(III) salt to an aqueous solution of the ligand subsequently raising the pH of the mixture gradually to circa 5.0 by adding dilute solution of sodium hydroxide. The lanthanum(III) complexes with bis-coumarins were characterized by different physicochemical methods—elemental analysis, IR-, -, and -NMR-spectroscopies, and mass spectral data. The spectral data of lanthanum(III) complexes were interpreted on the basis of comparison with the spectra of the free ligands. This analysis showed that in the complexes, the ligands coordinated to the metal ion through both deprotonated hydroxyl groups. On the basis of the ν(C=O) red shift observed, participation of the carbonyl groups in the coordination with the metal ion was also suggested. In the present study, we performed a cytotoxic-effects screening of the lanthanum complexes with L1 and L2 in a panel of human tumor cell lines, using the standard MTT-dye reduction assay for cell viability. The panel consisted of the acute myeloid leukemia-derived HL-60 and the chronic myeloid leukemia-derived BV-173. Following a 24- hour treatment of BV-173 cells with lanthanum complex of L1 at 100 or 200 μM led to a DNA-laddering. The findings suggest that the observed cytotoxicity of the lanthanum complex of L1 on BV-173 is at least partly mediated through induction of programmed cell death.

Synthesis, DNA-binding and antiproliferative activity of N-(Nitrogen heterocyclic) norcantharidin acylamide acid

“…2c, respectively. When DNA is present the intensity of the emission for HL 1 , HL 2 and HL 3 all decrease. This phenomenon of the luminescence property of compounds in presence of DNA strongly supports that the compounds bind to double-stranded DNA by intercalation.…”

“…The inhibition rate and IC 50 were calculated [13]. 1 and HL 2 The acylamide acids were prepared by direct reaction of norcantharidin with appropriate mole ratios of 2-aminopyrimidine, 2-aminopyridine and aniline in THF. The yields were good.…”

“…This phenomenon of the luminescence property of compounds in presence of DNA strongly supports that the compounds bind to double-stranded DNA by intercalation. The stacking of the compound with the base pairs of DNA leads to transfer of electron and energy from the aromatic ring of compound to the base pairs [18] and the nitrogen atoms of aromatic ring in HL 1 and HL 2 play a beneficial role in the accumulation. This maybe relative to the hydrogen bonds formed between nitrogen atoms of heterocycle and base pairs of the DNA.…”

“…Great interest is currently being focused on developing natural products due to their interesting anticancer activities [1][2][3][4]. Cantharidin has been used as a medicinal agent and shown to be active in cervical, leukaemia, bladder and colon cancer cell lines [5][6][7].…”

“…Two compounds containing heterocycle of HL 1 and HL 2 have been found to cleave pBR322 plasmid DNA at physiological pH and temperature. The test of antiproliferation activity showed that the compounds had moderate to strong antiproliferative ability against the tested cell lines except of HL 3 against the SMMC7721 cell line.…”