Palladium (II) complexes based on Schiff base ligands derived from ortho-vanillin; synthesis, characterization and cytotoxic studies

Anticancer behaviour of 2,2'-(pyridin-2-ylmethylene)bis(5,5-dimethylcyclohexane-1,3-dione)-based palladium(II) complex and its DNA, BSA binding propensity and DFT study

Herein, we report the synthesis and biological evaluation of [Pd(L)(OH2)Cl] complex (where L = 2,2'-(pyridin-2-ylmethylene)bis(5,5-dimethylcyclohexane-1,3-dione) as a novel promising anticancer candidate. The complex was characterized by single-crystal X-ray diffraction and other various spectroscopic techniques. Besides, the optimized structure was determined through DFT calculations revealing that the coordination geometry of [Pd(L)(OH2)Cl] complex is square planar. The binding propensity of [Pd(L)(OH2)Cl] complex with DNA and BSA was assessed by the spectrophotometric method. The antimicrobial profile of the ligand and its [Pd(L)(OH2)Cl] complex was screened against clinically important bacterial strains. [Pd(L)(OH2)Cl] complex showed promising activity against these microorganisms. Pd(L)(OH2)Cl] complex exhibited a potent antiproliferative potential compared to its ligand against different human cancer cells (A549, HCT116, MDA-MB-231, and HepG2) with less toxic effect against normal cells (WI-38). Additionally, [Pd(L)(OH2)Cl] complex exerted its anticancer effects against the most responsive cells (HCT116 cells; IC50 = 11 ± 1 μM) through suppressing their colony-forming capabilities and triggering apoptosis and cell cycle arrest at S phase. Quantitative PCR analysis revealed a remarkable upregulation of the mRNA expression level of p53 and caspase-3 by 4.8- and 5.9-fold, respectively, relative to control. Remarkable binding properties and non-covalent interactions between L and its [Pd(L)(OH2)Cl] complex with the binding sites of different receptors including CDK2, MurE ligase, DNA, and BSA were established using molecular docking. Based on our results, [Pd(L)(OH2)Cl] complex is an intriguing candidate for future investigations as a potential anticancer drug for the treatment of colon cancer.

Cytotoxicity Induced by Newly Synthesized Palladium (II) Complexes Lead to the Death of MCF-7 and MDA-MB-435 Cancer Cell Lines

Purpose: Breast cancer is the most common female malignancy and melanoma is the most lethal type of skin cancer. Traditional therapy for cancer treatment is far from satisfactory due to drug resistance and side effects, thus a search for new medicines is being emphasized. Palladium(II) complexes have been reported as anticancer potential agents. In this work, the anticancer activities and cell death induction of a new series of square-planar Pd(II) complexes were evaluated against MCF-7 and MDA-MB-435 cancer cells. Methods: MCF-7 (breast carcinoma) and MDA-MB-435 (melanoma) cells were cultivated, and treated with ligand and Pd(II) complexes. Cell growth, migration and adhesion inhibition, morphological alterations, cell death induction and, DNA interaction upon treatment were studied. Results: Pd(II) complexes exhibited both short and long-term antiproliferative effects on both cell lines, reducing by 80% cell growth in the SRB assay and abolishing longterm proliferation, estimated by the clonogenic assay. Complexes reduced significantly (P<0.05) cell migration and adhesion when compared to the control group. Complexes induced morphological alterations in cell lines and significant (P<0.05) cellular shrinkage. Cell death was induced and the complexes were able to interact with DNA, inducing cleavage of double-stranded DNA, which may account for the complexes cytotoxic effects, observed against both MCF-7 and MDA-MB-435 cells. Conclusion: Overall, the complexes exhibited cytotoxic activities and induced cell death. These observations emphasize an anticancer role with a potential therapeutic value for Pd(II) complexes to improve the outcome of patients with breast cancer and melanoma.

Heteroleptic enantiopure Pd(ii)-complexes derived from halogen-substituted Schiff bases and 2-picolylamine: synthesis, experimental and computational characterization and investigation of the influence of chirality and halogen atoms on the anticancer activity

To investigate the effect of chirality and different halogen substituents on the anticancer activity, seven enantiomeric pairs of palladium complexes were synthesized and characterized.

In vivo acute toxicity and anti-gastric evaluation of a novel dichloro Schiff base: Bax and HSP70 alteration

Chlorine is shown to possess anti-gastric ulcer activity, since it can inactivate Helicobacter pylori, which is regarded as one of the most common risk factors for causing gastric problems. In the current study, the gastroprotective property of a novel dichloro-substituted Schiff base complex, 2, 2'- [-1, 2-cyclohexanediylbis(nitriloethylidyne)] bis(4-chlorophenol) (CNCP), against alcohol-induced gastric lesion in SD rats was assessed. SD rats were divided into four groups, i.e. normal, ulcer control, testing, and reference groups. Ulcer area, gastric wall mucus, and also gastric acidity of the animal stomachs were measured. In addition, antioxidant activity of CNCP was evaluated and its safe dose was identified. Immunohistochemistry staining was also carried to evaluate two important proteins, i.e. Bcl2-associated X protein (Bax) and heat shock protein 70 (HSP70). Moreover, the activities of super oxide dismutase and catalase, as well as the levels of prostaglandin E2 (PGE2) and malondialdehyde (MDA) were also measured. Antioxidant activity of CNCP was approved via the aforementioned experiments. Histological evaluations showed that the compound possesses stomach epithelial defense activity. Additionally, periodic acid-Schiff staining exhibited over-expression of HSP70 and down-expression of Bax protein in the CNCP-treated rats. Moreover, CNCP caused deceased MDA level and elevated PGE2 level, and at the same time increased the activities of the two enzymes.

Palladium(ii) complexes of tetradentate donor–acceptor Schiff base ligands: synthesis and spectral, structural, thermal and NLO properties

Structural and NLO behavior of push–pull palladium(ii) complexes of metallocenyl-containing asymmetric Schiff base ligands.

Gastroprotective activity of a novel Schiff base derived dibromo substituted compound against ethanol-induced acute gastric lesions in rats

BACKGROUND

Basic function of bromine in body is to activate pepsin production in gastritis with low acidity. The present study encompasses a broad in vivo study to evaluate gastroprotective activity of a novel dibromo substituted Schiff base complex against Sprague Dawley (SD) rats.

METHODS

2, 2'-[1, 2-cyclohexanediylbis (nitriloethylidyne)]bis(4-bromophenol) (CNBP) is synthesized via a Schiff base reaction, using the related ketone and diamine as the starting materials. SD rats are divided as normal, ulcer control (5 ml/kg of 10% Tween 20), testing (10 and 20 mg/kg of CNBP) and reference groups (omeprazole 20 mg/kg). Except for the normal group, the rest of the groups are induced gastric ulcer by ethanol 1 h after the pre-treatment. Ulcer area, gastric wall mucus, and acidity of gastric content of the animal stomachs are measured after euthanization. Antioxidant activity of the compound is tested by Ferric reducing antioxidant power (FRAP) test and safety of the compound is identified through acute toxicity by [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Moreover, activities of superoxide dismutase (SOD), catalase (CAT), levels of prostaglandins E₂ (PGE₂) and also malondialdehyde (MDA) are determined.

RESULTS

Antioxidant activity of CNBP was approved via FRAP assay. Vast shallow hemorrhagic injury of gastric glandular mucosa was observed in the ulcer group compared to the CNBP-treated animals. Histological evaluations confirmed stomach epithelial defense effect of CNBP with drastic decrease of gastric ulceration, edema and leucocytes penetration of submucosal stratum. Immunostaining exhibited over-expression in HSP70 protein in CNBP-treated groups compared to that of the ulcer group. Also, gastric protein analysis showed low levels of MDA, PGE₂ and high activity of SOD and CAT.

CONCLUSIONS

CNBP with noticeable antioxidant property showed gastroprotective activity in the testing rodents via alteration of HSP70 protein expression. Also, antioxidant enzyme activities which were changed after treatment with CNBP in the animals could be elucidated as its gastroprotective properties.