Copper(II) complexes inducing apoptosis in cancer cells, and demonstrating DNA and HSA interactions

Synthesis and Biological Activity of a New Indenoisoquinoline Copper Derivative as a Topoisomerase I Inhibitor

Topoisomerases are interesting targets in cancer chemotherapy. Here, we describe the design and synthesis of a novel copper(II) indenoisoquinoline complex, WN198. The new organometallic compound exhibits a cytotoxic effect on five adenocarcinoma cell lines (MCF-7, MDA-MB-231, HeLa, HT-29, and DU-145) with the lowest IC50 (0.37 ± 0.04 μM) for the triple-negative MDA-MB-231 breast cancer cell line. Below 5 µM, WN198 was ineffective on non-tumorigenic epithelial breast MCF-10A cells and Xenopus oocyte G2/M transition or embryonic development. Moreover, cancer cell lines showed autophagy markers including Beclin-1 accumulation and LC3-II formation. The DNA interaction of this new compound was evaluated and the dose-dependent topoisomerase I activity starting at 1 μM was confirmed using in vitro tests and has intercalation properties into DNA shown by melting curves and fluorescence measurements. Molecular modeling showed that the main interaction occurs with the aromatic ring but copper stabilizes the molecule before binding and so can putatively increase the potency as well. In this way, copper-derived indenoisoquinoline topoisomerase I inhibitor WN198 is a promising antitumorigenic agent for the development of future DNA-damaging treatments.

Copper (II) Species with Improved Anti-Melanoma and Antibacterial Activity by Inclusion in β-Cyclodextrin

To improve their biological activity, complexes [Cu(bipy)(dmtp)₂(OH₂)](ClO₄)₂·dmtp (1) and [Cu(phen)(dmtp)₂(OH₂)](ClO₄)₂·dmtp (2) (bipy 2,2'-bipyridine, phen: 1,10-phenantroline, and dmtp: 5,7-dimethyl-1,2,4-triazolo [1,5-a]pyrimidine) were included in β-cyclodextrins (β-CD). During the inclusion, the co-crystalized dmtp molecule was lost, and UV-Vis spectra together with the docking studies indicated the synthesis of new materials with 1:1 and 1:2 molar ratios between complexes and β-CD. The association between Cu(II) compounds and β-CD has been proven by the identification of the components' patterns in the IR spectra and powder XRD diffractograms, while solid-state UV-Vis and EPR spectra analysis highlighted a slight modification of the square-pyramidal stereochemistry around Cu(II) in comparison with precursors. The inclusion species are stable in solution and exhibit the ability to scavenge or trap ROS species (O₂·^- and HO·) as indicated by the EPR experiments. Moreover, the two inclusion species exhibit anti-proliferative activity against murine melanoma B16 cells, which has been more significant for (2)@β-CD in comparison with (2). This behavior is associated with a cell cycle arrest in the G0/G1 phase. Compared with precursors, (1a)@β-CD and (2a)@β-CD exhibit 17 and 26 times more intense activity against planktonic Escherichia coli, respectively, while (2a)@β-CD is 3 times more active against the Staphylococcus aureus strain.

Copper(ii) curcumin complexes for endoplasmic reticulum targeted photocytotoxicity

Three copper(ii) complexes viz. [Cu(cur)(L)(ClO4)] (1-3), where Hcur is curcumin and L is 1,10-phenanthroline (phen, 1), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 2), or dipyrido[3,2-a:2',3'-c]phenazine (dppz, 3) were synthesized, fully characterized by various physicochemical methods and evaluated for their light-assisted chemotherapeutic potential. The complexes [Cu(acac)(L)(ClO4)] (4-6), where Hacac is acetylacetone and L is phen (in 4), dpq (in 5) and dppz (in 6), were synthesized and used as controls. The solid state structures of complexes 4 and 5 were determined by single crystal X-ray diffraction. The curcumin complexes (1-3) were redox inactive at the copper centre, whereas the acetylacetonato complexes (4-6) displayed a Cu(ii)/Cu(i) couple at ∼0.1 V vs. Ag/AgCl reference electrode in DMF. Complexes 1-3 showed an intense curcumin-based band at ∼440 nm in DMF-Tris-HCl buffer (pH = 7.2) (1 : 9 v/v) which masks the copper based d-d band. The complexes bind to human serum albumin (HSA) with moderate efficacy. They also displayed significant binding affinity for calf-thymus (CT) DNA. The lipophilic curcumin complexes show remarkable visible light induced cytotoxicity (IC50 = ∼4 μM) with high phototoxic indices (PI) with low dark toxicity in human cervical carcinoma (HeLa) and human lung carcinoma (A549) cells. The corresponding acetylacetonato controls (4-6) did not show significant cytotoxicity in the dark or light. DCFDA and annexin V-FITC/PI assays using flow cytometry confirm the induction of significant apoptosis in cancer cells via generation of cytotoxic reactive oxygen species upon photoactivation. Confocal microscopic images using complex 3 demonstrate localization of the complexes predominantly in the endoplasmic reticulum of HeLa cells.

Synthesis of Carvacrol Derivatives as Potential New Anticancer Agent against Lung Cancer

Lung cancer remains a major public health concern among all cancer diseases due to the toxicity and side-effects of the available commercially synthesized drugs. Natural product-derived synthesized anticancer drugs are now of promising interest to fight against cancer death. Carvacrol is a major component of most essential oil-bearing plants with potential pharmacological activity, especially against various cancer cell lines. Among the other organometallic compounds, copper complexes have been reported to be effective anticancer agents against various cancer cell lines, especially lung and leukemia cancers, due to the nontoxic nature of copper in normal cells since it is an endogenic metal. In this study, we synthesized three carvacrol derivatives, i.e., carvacrol aldehyde, Schiff base, and copper–Schiff base complex, through an established synthesis protocol and characterized the synthesized product using various spectroscopic techniques. The synthesized derivatives were evaluated for in vitro cytotoxic activity against different cancer cell lines, including human lung cancer (A549) and human fibroblast (BALB-3T3). Our findings showed that the copper–Schiff base complex derived from carvacrol inhibited the proliferation and migration of the A549 cell lines in a dose-dependent manner. This activity might be due to the inhibition of cell proliferation and migration at the G₂/M cell-cycle phase, as well as apoptosis, possibly through the activation of the mitochondrial apoptotic pathway. To our knowledge, this is the first report on the activity of the copper–Schiff base complex of carvacrol against A549 cell lines. Our result highlights that a new synthesized copper complex from carvacrol could be a novel potential drug in the treatment of lung cancer.

A selective CuII complex with 4-fluorophenoxyacetic acid hydrazide and phenanthroline displays DNA-cleaving and pro-apoptotic properties in cancer cells

The thin line between efficacy and toxicity has challenged cancer therapy. As copper is an essential micronutrient and is important to tumor biology, CuII complexes emerged as an alternative to chemotherapy; however, its biological properties need to be better understood. Thus, we report in vitro the antitumor effects of two CuII complexes named [Cu(4-fh)(phen)(ClO4)2] (complex 1) and [Cu(4-nh)(phen)(ClO4)2]·H2O (complex 2), in which 4-fh = 4-fluorophenoxyacetic acid hydrazide; 4-nh = 4-nitrobenzoic hydrazide and phen = 1,10-phenanthroline. Both complexes presented cytotoxic activity against tumor cells, but only complex 1 showed significant selectivity. Complex 1 also induced DNA-damage, led to G0/G1 arrest and triggered apoptosis, which was initiated by an autophagy dysfunction. The significant in vitro selectivity and the action mechanism of complex 1 are noteworthy and reveal this prodrug as promising for anticancer therapy.

Ternary Copper (II) Complex Induced Apoptosis and Cell Cycle Arrest in Colorectal Cancer Cells

BACKGROUND

The lack of specificity, severe side effects, and development of drug resistance have largely limited the use of platinum-based compounds in cancer treatment. Therefore, copper complexes have emerged as potential alternatives to platinum-based compounds.

OBJECTIVE

Ternary copper (II) complex incorporated with 1-10-phenanthroline and L-tyrosine was investigated for its anti-cancer effects in HT-29 colorectal cancer cells.

METHODS

Cytotoxic effects of ternary copper (II) complex in HT-29 cells were evaluated using MTT assay, Real-Time Cell Analysis (RTCA), and lactate dehydrogenase (LDH) assay. Cell cycle analysis was performed using flow cytometry. Apoptosis induction was studied by Annexin V-FITC/propidium iodide (PI) staining and mitochondrial membrane potential analysis (JC-10 staining) using flow cytometry. Intracellular reactive oxygen species (ROS) were detected by DCFH-DA assay. The expression of proteins involved in the apoptotic signalling pathway (p53, caspases, and PARP-1) was evaluated by western blot analysis.

RESULTS

Ternary copper (II) complex reduced the cell viability of HT-29 cells in a time- and dose-dependent manner, with IC50 of 2.4 ± 0.4 and 0.8 ± 0.04 µM at 24 and 48 hours, respectively. Cell cycle analysis demonstrated induction of S-phase cell cycle arrest. Morphological evaluation and Annexin V-FITC/PI flow cytometry analysis confirmed induction of apoptosis that was further supported by cleavage and activation of caspase-8, caspase-9, caspase-3, and PARP-1. Mutant p53 was also downregulated in a dose-dependent manner. No LDH release, mitochondrial membrane potential disruption, and ROS production were observed.

CONCLUSION

Ternary copper (II) complex holds great potential to be developed for colorectal cancer treatment.

Cell apoptosis induced by ciprofloxacin based Cu(II) complexes: cytotoxicity, SOD mimic and antibacterial studies

The current cancer research focuses on the design and synthesis of chemical compounds that can modulate cell apoptosis or programmed cell death. So we synthesized and characterized ciprofloxacin based copper(II) complexes and studied their anticancer activity against HCT 116 cancer cells by MTT assay. We further investigated the influence of compound-2 (better IC₅₀ value than cisplatin) on cancer cells to know the exact mechanism of anticancer activity. The distinct morphological change of cells due to compound-2 was observed in bright field microscopy. The trypan blue assay clearly demonstrated inhibition of cell viability. The clonogenic ability inhibition assay showed a low percentage of the plating efficiency of HCT 116 cells. The mechanism of cell death, either apoptotic or necrotic was distinguished by annexin V-FITC/PI (propidium iodide) staining assay and LDH (lactate dehydrogenase) release assay. The positive annexinV/PI cells in presence of compound-2 and absence of LDH in the LDH release assay confirmed the cell apoptotic mechanism of cell death. We also checked in vitro antibacterial activity of compounds against Gram^(-ve) and Gram^(+ve) bacteria in terms of MIC (minimum inhibitory concentration) and the data were in good agreement with the standard drug data. SOD mimic activity of synthesized Cu(II) complexes was also studied in terms of IC₅₀ value. The brine shrimp lethality bioassay was also performed to evaluate the cytotoxic properties of the Cu(II) complexes.Communicated by Ramaswamy H. Sarma.

Ultrasonic synthesis of Oct. trans-Br2Cu(N ∩ N)2 Jahn-Teller distortion complex: XRD-properties, solvatochromism, thermal, kinetic and DNA-binding evaluations

Under mode of ultrasonic vibration, the neutral octahedral mononuclear [trans-CuBr₂(N ∩ N)₂]·3H₂O complex with N ∩ N = 2,2-dimethylpropane-1,3-diamine was obtained. The structure of the desired complex was characterized by UV-Vis. spectroscopy, FT-IR, EDX, MS, SEM, TG/DTA and CHN-analysis. The octahedral-structure of the desired Cu(II) complex was proven via XRD single-crystal diffraction and its molecular interactions were computed by Hirschfeld surface analysis. Alcohol (as solvent) and short ultrasonic vibration dose period played a critical role in sonochemistry synthesis of octahedral neutral trans-CuBr₂(N ∩ N)₂ complex instead of trigonal bi-pyramidal monocation [CuBr(N ∩ N)₂]Br one. Due to the Jahn-Teller effect, the complex exhibited a trans bonds elongation along Br-Cu-Br axis originating a distorted-octahedral Cu(II), as revealed by the XRD measurements (Br-Cu = 3.04 Å). Therefore, the Solvatochromic behavior of the complex was successfully performed since the trans di-bromide ions are loosely coordinated to Cu(II) center, the change in complex solutions colors by using different solvents which can be detected even by naked-eye supported atypical Jahn-Teller elongation effect formation. TG/DTA and Flynn Wall Ozawa (FWO) isoconversional kinetic methods were applied for the complex to figure out the thermal behavior, kinetic of the ligands de-structured and estimate its Ea/α relation. The complex binding mode to the CT-DNA was examined by UV-vis. spectroscopic, melting curve, CV and viscosity tests. The complex exhibited very strong DNA binding via an intercalation mode of coordination with K_b = 6.5 × 10⁵ value.