Synthesis, X-ray studies, electrochemical properties, evaluation as in vitro cytotoxic and antibacterial agents of two antimony(III) complexes with dipicolinic acid
“…The presence of water molecules in this structure increases the probability of the formation of hydrogen bonds and also has a significant role to create water clusters, three-dimensional networks, and following the stability of the crystal lattice. The views of (H 2 O) n tetrameric and pentameric water clusters are shown for C3 in Figures S7 and S8 27 .…”
Section: Resultsmentioning
confidence: 99%
“…The investigations indicated that ligands do not have remarkable electrochemical reactivity. Therefore, redox couples are related to only the metal centers in complexes 27 , 28 . Figure 4 Cyclic voltammogram of complexes c = 4 × 10 –3 mol/dm 3 in H 2 O medium, KCl (0.1 M) at GCE, scan rate 50 V/s.…”
Three novel Tl(III) complexes (C1), (C2) and (C3) were synthesized using the one-pot reactions of pyridine dicarboxylic acid derivatives, 2-aminobenzimidazole and/or 4-aminopyridine, and also thallium(III) nitrate trihydrate metal salt. The structure of all three complexes was determined by the single-crystal X-ray diffraction. C1 and C2 were realized to be isostructural with disordered square anti-prismatic geometry and for C3 arrangement of the distorted tricapped triangular prism was proposed. Cyclic voltammetry measurements on the complexes exhibited that formal potential values are more positive for C1 (E0ˊ 0.109 V) and C3 (E0ˊ 0.244 V) compared to C2 (E0ˊ –0.051 V), versus Ag/AgCl under argon. Moreover, cytotoxicity of the compounds was evaluated in vitro against two cancer cell lines including a human melanoma (A375), a human colon adenocarcinoma (HT29), and also one normal cell human foreskin fibroblast (HFF). The selective and potent cytotoxicity effect was exhibited by C1 and C3 on cancer cell lines. The apoptosis through a caspase-dependent mitochondrion pathway was confirmed by ROS production, MMP reduction, p53 activation, Bax up-regulation, and Bcl-2 down-regulation, cytochrome c release, procaspase-9, and 3 expression, for A375 cells treated to C1 and C3. According to similar cellular uptake of the complexes in A375 cell line, the generation of ROS was considered as an effective agent to justify the inhibition effect C1 and C3 on mentioned cells. Furthermore, arresting the cell cycle in the G2-M phase and inducing apoptosis were indicated by these two complexes.
“…The presence of water molecules in this structure increases the probability of the formation of hydrogen bonds and also has a significant role to create water clusters, three-dimensional networks, and following the stability of the crystal lattice. The views of (H 2 O) n tetrameric and pentameric water clusters are shown for C3 in Figures S7 and S8 27 .…”
Section: Resultsmentioning
confidence: 99%
“…The investigations indicated that ligands do not have remarkable electrochemical reactivity. Therefore, redox couples are related to only the metal centers in complexes 27 , 28 . Figure 4 Cyclic voltammogram of complexes c = 4 × 10 –3 mol/dm 3 in H 2 O medium, KCl (0.1 M) at GCE, scan rate 50 V/s.…”
Three novel Tl(III) complexes (C1), (C2) and (C3) were synthesized using the one-pot reactions of pyridine dicarboxylic acid derivatives, 2-aminobenzimidazole and/or 4-aminopyridine, and also thallium(III) nitrate trihydrate metal salt. The structure of all three complexes was determined by the single-crystal X-ray diffraction. C1 and C2 were realized to be isostructural with disordered square anti-prismatic geometry and for C3 arrangement of the distorted tricapped triangular prism was proposed. Cyclic voltammetry measurements on the complexes exhibited that formal potential values are more positive for C1 (E0ˊ 0.109 V) and C3 (E0ˊ 0.244 V) compared to C2 (E0ˊ –0.051 V), versus Ag/AgCl under argon. Moreover, cytotoxicity of the compounds was evaluated in vitro against two cancer cell lines including a human melanoma (A375), a human colon adenocarcinoma (HT29), and also one normal cell human foreskin fibroblast (HFF). The selective and potent cytotoxicity effect was exhibited by C1 and C3 on cancer cell lines. The apoptosis through a caspase-dependent mitochondrion pathway was confirmed by ROS production, MMP reduction, p53 activation, Bax up-regulation, and Bcl-2 down-regulation, cytochrome c release, procaspase-9, and 3 expression, for A375 cells treated to C1 and C3. According to similar cellular uptake of the complexes in A375 cell line, the generation of ROS was considered as an effective agent to justify the inhibition effect C1 and C3 on mentioned cells. Furthermore, arresting the cell cycle in the G2-M phase and inducing apoptosis were indicated by these two complexes.
“…The inactivity of HL 1 and its complex, compared with the activities of HL 2 and C2, is probably due to their higher nitrogen content, as nitrogen is a vital element required for the growth of the microorganisms [42]. Indeed, metal complexes have been reported in several papers as long-acting drugs with slow releases in the cells, and the higher activities given by complexes relative to those of their ligands have been documented in several papers that concluded that upon coordination, the ligands bio-active or -inactive improved their antimicrobial activities or attained some pharmacological action [43,44].…”
New complexes of trivalent cobalt with substituted thiosemicarbazone ligands having an NNS donor system {HL1 = 4-(4-nitrophenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide and HL2 = 4-(2,5-dimethoxyphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide} were synthesized via the in situ oxidation of divalent cobalt chloride accompanying its addition to the ligands. The complexes C1 and C2 were characterized via elemental (CHNS) analysis and 1H NMR, FT-IR and UV-Vis. spectroscopic data. Further, conductometric studies on the DMF solutions of the complexes indicated their 1:1 nature, and their diamagnetism revealed the low-spin trivalent oxidation state of the cobalt in the complexes. The X-ray diffraction analysis of complex C1 indicated that it crystallizes in the triclinic space group P-1. The metal exhibits an octahedral environment built by two anionic ligands bound via pyridine nitrogen, imine nitrogen and thiol sulfur atoms. The complex is counterbalanced by a chloride ion. In addition, two lattice water molecules were detected in the asymmetric unit of the unit cell. The ligand HL2 (20 mg/mL in DMSO) displayed inhibition zones of 10 mm against both S. aureus and E. coli, and the same concentration of the respective complex raised this activity to 15 and 12 mm against these bacterial strains, respectively. As a comparison, ampicillin inhibited these bacterial strains by 21 and 25 mm, respectively. Screening assay by HL1 on four human cancer cells revealed the most enhanced activity against the breast MCF-7 cells. The induced growth inhibitions in the MCF-7 cells by all compounds (0–100 μg/mL) have been detected. The ligands {HL1 and HL2} and complex C2 gave inhibitions with IC50 values of 52.4, 145.4 and 49.9 μM, respectively. These results are more meaningful in comparison with similar cobalt complexes, but less efficient compared with the inhibition with IC50 of 9.66 μM afforded by doxorubicin. In addition, doxorubicin, HL1 and HL2 induced cytotoxicity towards healthy BHK cells with IC50 values of 36.42, 54.8 and 110.6 μM, but surviving fractions of 66.1% and 62.7% of these cells were detected corresponding to a concentration of 100 μg/mL of the complexes (136.8 μM of C1 and 131.4 μM of C2).
“…Indeed, for the To conclude, it is clear that complexation with trivalent antimony enhanced the antimicrobial effect of the ligands to the limit that exceeded the effect of the antibacterial standard and that, often, equaled the effect of the antifungal reference. Indeed, for the enhancement in the bioactivity profile of ligands in coordination with metals, it was previously documented that bioactive ligands could improve their bioactivities and inactive ligands could attain pharmacological properties [35,36]. In addition, it is well known that metal coordination is an efficient strategy in designing slow-release and long-acting chemotherapeutics [35,36].…”
Section: Antibacterial and Antifungal Activity Screeningmentioning
confidence: 99%
“…Indeed, for the enhancement in the bioactivity profile of ligands in coordination with metals, it was previously documented that bioactive ligands could improve their bioactivities and inactive ligands could attain pharmacological properties [35,36]. In addition, it is well known that metal coordination is an efficient strategy in designing slow-release and long-acting chemotherapeutics [35,36].…”
Section: Antibacterial and Antifungal Activity Screeningmentioning
Two antimony complexes {[Sb(L1)Cl2] C1 and [Sb(L2)Cl2] C2} with the thiosemicarbazone ligands {HL1 = 4-(2,4-dimethylphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide and HL2 = 4-(2,5-dimethoxyphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide} were introduced. The structures were elucidated on the basis of a CHNS analysis, spectroscopic techniques (UV-Vis and FT-IR), and DMF solution electrical conductivities. Single crystal X-ray diffraction analysis of complex C1 assigned the complex pseudo-octahedral geometry and triclinic P-1 space group. Only the ligand HL1 and its derived complex C1 displayed antifungal activities against Candida albicans and this activity was enhanced from 10 mm to 21 mm for the respective complex, which is the same activity given by the drug “Amphotericin B”. The ligands HL1 and HL2 gave inhibitions, respectively, of 14 and 10 mm against Staphylococcus aureus and 15 and 10 mm against Escherichia coli; however, complexes C1 and C2 increased these inhibitions to 36 and 32 mm against Staphylococcus aureus and 35 and 31 mm against Escherichia coli exceeding the activities given by the ampicillin standard (i.e., 21 mm against Staphylococcus aureus and 25 mm against Escherichia coli). Against MCF-7 human breast cancer cells, the IC50 values of HL1 (68.9 μM) and HL2 (145.4 μM) were notably enhanced to the values of 34.7 and 37.4 μM for both complexes, respectively. Further, the complexes induced less toxicity in normal BHK cells (HL1 (126.6 μM), HL2 (110.6 μM), C1 (>210.1 μM), and C2 (160.6 μM)). As a comparison, doxorubicin gave an IC50 value of 9.66 μM against MCF-7 cells and 36.42 μM against BHK cells.
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