Synthesis, X-ray studies, electrochemical properties, evaluation as in vitro cytotoxic and antibacterial agents of two antimony‌(III) complexes with dipicolinic acid

Structural investigations and antibacterial, antifungal and anticancer studies on zinc salicylaldimine complexes

Aim: Zinc salicylaldimines may act as multidrug agents. Results: Three zinc salicylaldimines C1-C3 and respective ligands HL1-HL3 were examined for antimicrobial/anticancer drug action and C3 was structurally analyzed (tetrahedral, triclinic). Against two fungi, C1 inhibited Candida albicans with 12 mm (21 mm for amphotericin B). Among four bacteria, two ligands inhibited Staphylococcus aureus and Escherichia coli (9-10 mm), but the complexes inhibited all bacteria with 10-14 mm (21-26 mm for ampicillin). The half-maximal inhibitory concentrations for the ligands, complexes and doxorubicin were 195.5-310.7, 22.18-70.05 and 9.66 μM against cancerous MCF-7 cells and 186.4-199.9, 14.95-18.87 and 36.42 μM against normal BHK cells. Conclusion: The complexation produced pronounced enhancement in the ligand antimicrobial/anticancer activities, despite these activities are moderate comparing with standards.

Unveiling the promising anticancer effect of copper-based compounds: a comprehensive review

Copper is a necessary micronutrient for maintaining the well-being of the human body. The biological activity of organic ligands, especially their anticancer activity, is often enhanced when they coordinate with copper(I) and (II) ions. Copper and its compounds are capable of inducing tumor cell death through various mechanisms of action, including activation of apoptosis signaling pathways by reactive oxygen species (ROS), inhibition of angiogenesis, induction of cuproptosis, and paraptosis. Some of the copper complexes are currently being evaluated in clinical trials for their ability to map tumor hypoxia in various cancers, including locally advanced rectal cancer and bulky tumors. Several studies have shown that copper nanoparticles can be used as effective agents in chemodynamic therapy, phototherapy, hyperthermia, and immunotherapy. Despite the promising anticancer activity of copper-based compounds, their use in clinical trials is subject to certain limitations. Elevated copper concentrations may promote tumor growth, angiogenesis, and metastasis by affecting cellular processes.

Effect of the extra-nuclear cation on the cytotoxicity and mechanism of action of pyridine-2,6-dicarboxylate Ga(III) complexes

Two Ga(III) complexes (C1) and (C2) were prepared by the one-pot reaction of pyridine-2,6-dicarboxylic acid and aminopyridine derivatives with gallium(III) nitrate octahydrate. The compounds were characterized by single-crystal X-ray diffraction. The distorted octahedral geometry was confirmed by crystallographic data for both complexes. The study of the in vitro cytotoxicity of the compounds showed that the presence of different extra-nuclear cations can affect the cytotoxicity of the same anionic complexes. The most significant antiproliferative activity was observed for C1 (IC50 = 0.69 μM, MAE = 73.96%) and C2 (IC50 = 3.78 μM, MAE = 60.35%) (where MAE represents the maximal antiproliferative effect) against A431 cell line. The mechanistic study evidenced the same pathway for the death of A431 cells treated with the complexes, although the results for C2 were obtained at approximately five times the concentration of C1. According to the study, both complexes induced cell cycle arrest in G2/M phase in A431 cells by upregulating the levels of p21, p27, p-cdc25C, and p-cdc2 and downregulating the levels of cdc25C, cdc2, and cyclin B1. In addition, apoptosis via a caspase-dependent mitochondrial pathway was confirmed by a decrease in Bcl-2 family proteins and an increase in the expression of procaspase-9 and 3. Also, the complexes induced autophagic cell death by activating the RAGE /PI3KC3/Beclin 1 pathway in A431 cells. DATA AVAILABILITY: CCDC 874052 and 874055 contain the supplementary crystallographic data for C1 and C2, respectively. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/services/structures?pid=ccdc:874052,874055&sid=CCDCManual, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.

In vitro biological activity of cobalt(II) complexes with salicylaldimine ligands in microbial and cancer cells

Background: More studies using cobalt complexes as drugs are needed. Results: The drug action of two cobalt salicylaldimines was determined. The complexes and amphotericin B (20 mg/ml) inhibited Candida albicans at 9-15 and 21 mm. This concentration of both ligands inhibited Staphylococcus aureus at 10 mm and one ligand inhibited Escherichia coli at 9 mm, but the complexes and ampicillin inhibited four bacteria at 9-20 and 21-26 mm. The ligands were inactive against cancer and normal cells, but the complexes and doxorubicin provided IC50 values of 28.18-54.19 and 9.66 μM against MCF-7 cells and 15.76-20.49 and 36.42 μM against BHK cells. Conclusion: The ligands' activity was much improved by complexation, although they remained substandard.

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.

Thiosemicarbazones and Derived Antimony Complexes: Synthesis, Structural Analysis, and In Vitro Evaluation against Bacterial, Fungal, and Cancer Cells

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.

Trivalent Cobalt Complexes with NNS Tridentate Thiosemicarbazones: Preparation, Structural Study and Investigation of Antibacterial Activity and Cytotoxicity against Human Breast Cancer Cells

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).

Novel Tl(III) complexes containing pyridine-2,6-dicarboxylate derivatives with selective anticancer activity through inducing mitochondria-mediated apoptosis in A375 cells

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 (E⁰' 0.109 V) and C3 (E⁰' 0.244 V) compared to C2 (E⁰' -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.