Organotin(IV) complexes derived from 2,6-diacetylpyridine bis(2-hydroxybenzoylhydrazone) as prospective anti-proliferative agents: Synthesis, characterization, structures and in vitro anticancer activity

Six organotin(IV) complexes, viz., [Me2Sn(L)] (1), [n-Bu2Sn(L)] (2), [n-Oct2Sn(L)] (3), [Bz2Sn(L)]·0.5C7H8 (4), [n-BuSn(L)Cl] (5), and [PhSn(L)Cl] (6), were synthesized using a 2,6-diacetylpyridine bis(2-hydroxybenzoylhydrazone), H2L. Compounds were characterized by Fourier transform infrared (FT-IR), High-resolution mass spectrometry (HRMS), and solutions Fourier transform nuclear magnetic resonance (FT-NMR) spectroscopies. The structures 1-6 were established by single-crystal X-ray diffraction (SC-XRD) analysis. Diffraction results evidenced that complexes 1-6 were seven-coordinated mononuclear species with the equatorial plane comprising the pentagonal N3O2 chelate ring of the doubly deprotonated L and two axial ligands, either R (R = Me, n-Bu, n-Oct, Bz) or R (n-Bu or Ph) and Cl ligands. Additionally, the photophysical properties were examined due to the enhanced conjugation and rigidity of the molecules while thermogravimetric analysis was carried out to evaluate the thermal stabilities of compounds. The anti-proliferative activity of the complexes 1-6 was tested against prostate cancer cells (DU-145) and normal human embryonic kidney cells (HEK-293). Among the compounds, dibutyltin compound 2 exhibited increased anti-proliferative activity, with an IC50 value of 6.16 ± 1.56 μM. The investigation of its mechanism of action involves using AO/EB (acridine orange/ethidium bromide) and ROS (reactive oxygen species) generation assays. This likely detects apoptotic morphological alterations in the nucleus of the cells, with ROS generation ultimately leading to apoptosis and cell death. The superior activity of 2 may be attributed to the C···H contacts and respective higher de outside and di inside distances from the Hirshfeld surface. Thus, these compounds could be a promising alternative to classical chemotherapy agents.

Recent Development on Copper-Sensor and its Biological Applications: A Review

Metal ion recognition is one of the most prospective research topics in the field of chemical sensors due to its wide range of clinical, biological and environmental applications. In this context, hydrazones are well known compounds that exhibit metal sensing and several biological properties due to the presence of N=CH- bond. Some of the biological properties includes anti-cancer, anti-tumor, anti-oxidant, anti-microbial activities. Hydrazones are also used as a ligand to detect metal ion as well as to generate metal complexes that exhibit medicinal properties. Thus, in recent years, many attempts were made to develop novel ligands with enhanced metal sensing and medicinal properties. In this review, some of the recent development on the hydrazones and their copper complexes are covered from the last few years from 2015-2023. These includes significance of copper ions, synthesis, biological properties, mechanism and metal sensing properties of some of the copper complexes were discussed.

Intercalation of anticancer drug Palbociclib with calf-thymus DNA: new insights from molecular spectroscopic, molecular dynamic simulations and cleavage studies

The interaction between the anti-cancer drug Palbociclib (PAL) and calf-thymus DNA (CT-DNA) was investigated using various biophysical techniques in a physiological buffer (pH 7.4). It was found that PAL intercalated into the base pairs of CT-DNA as evidenced from the results of UV-Vis, fluorescence, circular dichroism (CD), competitive binding assay with ethidium bromide (EB) and Hoechst 33258, KI quenching study, the effect of denaturing agent and viscosity measurements. The magnitude of binding constants (106 M-1) at different temperatures suggested strong binding between PAL and CT-DNA during complexation. The observed ΔHo > 0 and ΔSo > 0 indicated that the binding process is primarily driven by hydrophobic interactions. Molecular docking studies indicated partial intercalation of pyridopyrimidine ring between the base pairs of DNA. Free energy surface (FES) analysis derived from metadynamics simulation studies revealed the PAL-induced cleavage of DNA, which was confirmed by gel electrophoresis experiments.Communicated by Ramaswamy H. Sarma.

Therapeutic Study of Cinnamic Acid Derivative for Oxidative Stress Ablation: The Computational and Experimental Answers

This study aimed to examine the therapeutic activity of the cinnamic acid derivative KAD-7 (N'-(2,4-dichlorobenzylidene)-3-(4-methoxyphenyl) acrylohydrazide) on Fe2+-induced oxidative hepatic injury via experimental and computational models. In addition, the role of ATPase and ectonucleoside triphosphate diphosphohydrolase (ENTPDase) in the coordination of cellular signals is speculated upon to proffer suitable therapeutics for metabolic stress disorder upon their inhibition. While we know little about therapeutics with flexible dual inhibitors for these protein targets, this study was designed to screen KAD-7's (N'-(2,4-dichlorobenzylidene)-3-(4-methoxyphenyl) acrylohydrazide) inhibitory potential for both protein targets. We induced oxidative hepatic damage via the incubation of hepatic tissue supernatant with 0.1 mM FeSO4 for 30 min at 37 °C. We achieved the treatment by incubating the hepatic tissues with KAD-7 under the same conditions. The catalase (CAT), glutathione (GSH), malondialdehyde (MDA), ATPase, and ENTPDase activity were all measured in the tissues. We predicted how the drug candidate would work against ATPase and ENTPDase targets using molecular methods. When hepatic injury was induced, there was a significant decrease in the levels of the GSH, CAT, and ENTPDase (p < 0.05) activities. In contrast, we found a noticeable rise in the MDA levels and ATPase activity. KAD-7 therapy resulted in lower levels of these activities overall (p < 0.05), as compared to the control levels. We found the compound to have a strong affinity for ATPase (-7.1 kcal/mol) and ENTPDase (-7.4 kcal/mol), and a better chemical reactivity than quercetin. It also met all drug-likeness parameters. Our study shows that KAD-7 can protect the liver from damage caused by FeSO4 by reducing oxidative stress and purinergic actions. Our studies indicate that KAD-7 could be developed as a therapeutic option since it can flexibly inhibit both ATPase and ENTPDase.

Docking Studies, Cytotoxicity Evaluation and Interactions of Binuclear Copper(II) Complexes with S-Isoalkyl Derivatives of Thiosalicylic Acid with Some Relevant Biomolecules

The numerous side effects of platinum based chemotherapy has led to the design of new therapeutics with platinum replaced by another transition metal. Here, we investigated the interactions of previously reported copper(II) complexes containing S-isoalkyl derivatives, the salicylic acid with guanosine-5'-monophosphate and calf thymus DNA (CT-DNA) and their antitumor effects, in a colon carcinoma model. All three copper(II) complexes exhibited an affinity for binding to CT-DNA, but there was no indication of intercalation or the displacement of ethidium bromide. Molecular docking studies revealed a significant affinity of the complexes for binding to the minor groove of B-form DNA, which coincided with DNA elongation, and a higher affinity for binding to Z-form DNA, supporting the hypothesis that the complex binding to CT-DNA induces a local transition from B-form to Z-form DNA. These complexes show a moderate, but selective cytotoxic effect toward colon cancer cells in vitro. Binuclear complex of copper(II) with S-isoamyl derivative of thiosalicylic acid showed the highest cytotoxic effect, arrested tumor cells in the G2/M phase of the cell cycle, and significantly reduced the expression of inflammatory molecules pro-IL-1β, TNF-α, ICAM-1, and VCAM-1 in the tissue of primary heterotopic murine colon cancer, which was accompanied by a significantly reduced tumor growth and metastases in the lung and liver.

Transition metal complexes as self-activating chemical nucleases: proficient DNA cleavage without any exogenous redox agents

Chemical nucleases have found potential applications in the research fields of chemistry, biotechnology and medicine. A variety of metal complexes have been explored as good to outstanding therapeutic agents for DNA cleavage activity most likely via hydrolytic, oxidative or photoinduced cleavage pathways. However, most of these DNA cleaving agents lack their utility in in vivo applications due to their dependence on exogenous oxidants or reductants to achieve successful DNA damage. In view of addressing these issues, the development of metal complexes/organic molecules serving as self-activating chemical nucleases has received growing attention from researchers. In only the last decade, this field has dramatically expanded for the usage of chemical nucleases as therapeutic agents for DNA damage. The present study provides an overview of the opportunities and challenges in the design and development of self-activating chemical nucleases as improved DNA therapeutic candidates in the absence of an external redox agent. The reports on DNA nuclease activity via self-activation, especially with copper, zinc and iron complexes, and their mechanistic investigation have been discussed in this review article.

DNA-binding, cleavage, antibacterial and in vitro anticancer activity of copper(II) mixed ligand complexes of 2-(((6-chloro-1H-benzo[d]imidazol-2-yl)methyl)amino)aceticacid and polypyridyl ligands

A tridentate ligand(A), 2-(((6-chloro-1H-benzo[d]imidazol-2-yl)methyl)amino) aceticacid (Cl-BIGH) was synthesised by the Phillips condensation of 4-chlorobenzene-1,2-diamine and iminodiaceticacid in 1:2 molar ratio. Its Cu(II) mixed ligand complexes[Cu(II)-A-L] were obtained by involving other co-ligands(L): 2,2΄-bipyridine(L₁), 4,4΄-dimethyl-2,2΄-bipyridyl(L₂), 5,5΄-dimethyl-2,2΄-bipyridyl(L₃) and 1,10 phenanthroline(L₄). The complexes were characterized by elemental analysis, thermal analysis, molar conductance, magnetic moment measurements, X-ray diffraction, FTIR, UV-Visible, ESR spectroscopy, mass spectrometry and cyclic voltammetry. From the spectral and analytical data, the ternary complexes [Cu(Cl-BIGH)(L_1-4)]ClO₄ were found to form in 1:1:1(Cu(II): Cl-BIGH: L) molar ratio. The geometry of the mixed-ligand complexes were found to be 5-coordinated square pyramidal or trigonal bipyramidal with polycrystalline natures. The DNA binding and cleaving abilities, antibacterial and the in vitro cytotoxicity of the complexes were explored. The molecular docking was used to predict the efficiency of binding of the metal complexes with COX- 2.Communicated by Ramaswamy H. Sarma.

Green carbon-carbon homocoupling of terminal alkynes by a silica supported Cu(II)-hydrazone coordination compound

A Cu(II) complex, [Cu(HL)(NO₃)(CH₃OH)]·CH₃OH (1), was obtained by the reaction of Cu(NO₃)₂·3H₂O and H2L in methanol solvent (H2L is (E)-4-amino-N'-(2-hydroxy-3-methoxybenzylidene)benzohydrazide). H2L and compound 1 were characterized by various spectroscopic analyses and the molecular structure of [Cu(HL)(NO₃)(CH₃OH)]·CH₃OH was determined by single-crystal X-ray analysis. The results indicated the product is a mononuclear Cu(II) complex and contains a free NH₂ functional group on the structure of the ligand. [Cu(HL)(NO₃)(CH₃OH)]·CH₃OH was used for the preparation of a heterogeneous catalyst by supporting it on functionalized silica gel. The heterogeneous catalyst (Si-Cu) was prepared by an amidification reaction of [Cu(HL)(NO₃)(CH₃OH)]·CH₃OH with functionalized silica gel. The resulting silica-supported catalyst (Si-Cu) was characterized by TGA, FT-IR, EPR, DRS, EDS, XRD, SEM and XPS analyses. Si-Cu was employed in a carbon-carbon coupling reaction and the effects of the amount of Si-Cu and temperature were investigated in the catalytic coupling. The structure of one of the products of the catalytic reactions (C₁₆H₂₂O₂, CP1) was determined by single-crystal X-ray analysis, which proved the formation of a C-C bond and the production of di-acetylene by homocoupling of terminal alkyne. This catalytic system is stable and it can be reused for a coupling reaction without a significant change in its catalytic activity.

Evaluation of the antitumor activity of a series of the pincer-type metallocomplexes produced from isonicotinohydrazide derivative

In this work we report on the antitumor properties of a series of pincer-type metallocomplexes [Hg₂(HL-keto)Cl₄]_n (1), [Hg(HL-keto)I₂] (2) and [Mn(HL-zwitterion)Cl₂]∙MeOH (3∙MeOH), derived from N'-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide (HL) and corresponding metal salts. The Hg(II) and Mn(II) salts are chelated by the keto (HL-keto) or zwitterionic (HL-zwitterion) form of HL, respectively. The cytotoxic effects of these compounds have been accessed against lung adenocarcinoma (A549) and hepatocellular carcinoma (HepG2 and Huh7) cell lines. Complexes 1 and 2 were found to be most efficient against the cell line Huh7 with IC₅₀ value of 2.56 and 9.90 μM, respectively, while they exhibit moderate activity towards cell lines A549 and HepG2, as evidenced from IC₅₀ values in the range 27.98-56.99 μM. Complex 3∙MeOH is less efficient towards all the three cell lines with relatively high IC₅₀ values. The mechanisms of the metallocomplexes killing the aforementioned cells were elucidated by flow cytometry, colony formation and polymerase chain reaction (PCR) analysis of apoptosis related expression of the genes. The results of the cytotoxic effects and antitumor activity on different cell lines are affected by the metal nature and the presence of the coordinated halide.

Antitumor activity of tridentate pincer and related metal complexes

Pincer complexes featuring tunable tridentate ligand frameworks are one of the most actively studied classes of metal-based complexes. Currently, growing attention is devoted to the cytotoxicity of pincer and related metal complexes. The antiproliferative activity of numerous pincer complexes has been reported. Pincer tridentate ligand scaffolds show different coordination modes and offer multiple options for directed structural modifications. This review summarizes the significant progress in the research studies of the antitumor activity of pincer and related platinum(ii), gold(iii), palladium(ii), copper(ii), iron(iii), ruthenium(ii), nickel(ii) and some other metal complexes, in order to provide a reference for designing novel metal coordination drug candidates with promising antitumor activity.

Dithiocarbazate-Copper Complexes for Bioimaging and Treatment of Pancreatic Cancer

Anticancer agents that present nonapoptotic cell death pathways are required for treating apoptosis-resistant pancreatic cancer. Here, we synthesized three fluorescent dithiocarbazate-copper complexes, {[Cu^II(L)(Cl)] 1, [Cu^II₂(L)₂(NO₃)₂] 2, and [Cu^II₂Cu^I(L)₂(Br)₃] 3}, to assess their antipancreatic cancer activities. Complexes 1-3 showed significantly greater cytotoxicity toward several pancreatic cancer cell lines with better IC₅₀ than those of the HL ligand and cisplatin. Confocal fluorescence imaging showed that complex 3 was primarily localized in the mitochondria. Primarily, compound 3 also can be applied to in vivo imaging. Further studies revealed that complex 3 kills pancreatic cancer cells by triggering multiple mechanisms, including ferroptosis. Complex 3 is the first copper complex to evoke cellular events consistent with ferroptosis in cancer cells. Finally, it significantly retarded the ASPC-1 cells' growth in a mouse xenograft model.

Quinoline Functionalized Schiff Base Silver (I) Complexes: Interactions with Biomolecules and In Vitro Cytotoxicity, Antioxidant and Antimicrobial Activities

A series of fifteen silver (I) quinoline complexes Q1-Q15 have been synthesized and studied for their biological activities. Q1-Q15 were synthesized from the reactions of quinolinyl Schiff base derivatives L1-L5 (obtained by condensing 2-quinolinecarboxaldehyde with various aniline derivatives) with AgNO₃, AgClO₄ and AgCF₃SO₃. Q1-Q15 were characterized by various spectroscopic techniques and the structures of [Ag(L1)₂]NO₃Q1, [Ag(L1)₂]ClO₄Q6, [Ag(L2)₂]ClO₄Q7, [Ag(L2)₂]CF₃SO₃Q12 and [Ag(L4)₂]CF₃SO₃Q14 were unequivocally determined by single crystal X-ray diffraction analysis. In vitro antimicrobial tests against Gram-positive and Gram-negative bacteria revealed the influence of structure and anion on the complexes' moderate to excellent antibacterial activity. In vitro antioxidant activities of the complexes showed their good radical scavenging activity in ferric reducing antioxidant power (FRAP). Complexes with the fluorine substituent or the thiophene or benzothiazole moieties are more potent with IC₅₀ between 0.95 and 2.22 mg/mL than the standard used, ascorbic acid (2.68 mg/mL). The compounds showed a strong binding affinity with calf thymus-DNA via an intercalation mode and protein through a static quenching mechanism. Cytotoxicity activity was examined against three carcinoma cell lines (HELA, MDA-MB231, and SHSY5Y). [Ag(L2)₂]ClO₄Q7 with a benzothiazole moiety and [Ag(L4)₂]ClO₄Q9 with a methyl substituent had excellent cytotoxicity against HELA cells.

Regulation of π⋯π stacking interactions between triimidazole luminophores and comprehensive emission quenching by coordination to Cu(ii)

Pioneering work demonstrating coordination preferences towards Cu(ii) of unexplored cyclic triimidazole-based luminophores and their favorable stacking patterns in coordination compounds.

Copper (II)-based halogen-substituted chromone antitumor drug entities: Studying biomolecular interactions with ct-DNA mediated by sigma hole formation and cytotoxicity activity

Copper-based antitumor drug entities 1-3 derived from substituted (F^-, Br^-, -CH₃) 3-formylchromone pharmacophore were synthesized and thoroughly characterized by spectroscopic and single X-ray crystallographic studies. These complexes show structural novelty due to presence of the X-bonds in chromone scaffold which could facilitate higher propensity for nucleic acids via sigma σ-hole interactions. Therefore, structure-activity relationship of 1-3 was studied by performing ct-DNA binding, pBR322 cleavage and cytotoxicity activity to validate their potential to act as chemotherapeutic drug entities. The binding studies of 1-3 with ct- DNA were carried out employing many biophysical techniques and the corroborative results of these experiments showed intercalation mode of binding and the order of binding was found to be 2 > 1 > 3. The structure of drug entities could facilitated strong halogen bonding interaction (in case of 1 &2) and stability of X bond was rationalized by sigma hole region of positive electrostatic potential on the surface of C-X covalent bond, as determined by gas phase B3LYP computational DFT studies. Interestingly, 2 exhibited most avid binding affinity due to presence of Br^- electron withdrawing and polarizable group. Further, cleavage studies of 1-3 with pBR322 plasmid DNA were performed which demonstrated significant cleavage activity, the supercoiled form (Form I) of plasmid DNA was converted to nicked form (Form II) with the appearance of linearized form (Form III) in between two, implicating lethal double strand breaks of DNA. 2 showed predominantly higher cleavage activity following the similar trend as observed for binding studies. The cytotoxicity of the complexes 1-3 was evaluated by MTT assay against the human liver carcinoma (Huh-7) and prostate cancer (DU-145) cell lines; complex 2 exhibited specific and selective cytotoxicity for the DU-145 cancer cell line with LC₅₀ value of 1.6 μM.

Synthesis and Structure-Activity Relationship Studies of Hydrazide-Hydrazones as Inhibitors of Laccase from Trametes versicolor

A series of hydrazide-hydrazones 1-3, the imine derivatives of hydrazides and aldehydes bearing benzene rings, were screened as inhibitors of laccase from Trametes versicolor. Laccase is a copper-containing enzyme which inhibition might prevent or reduce the activity of the plant pathogens that produce it in various biochemical processes. The kinetic and molecular modeling studies were performed and for selected compounds, the docking results were discussed. Seven 4-hydroxybenzhydrazide (4-HBAH) derivatives exhibited micromolar activity Ki = 24-674 µM with the predicted and desirable competitive type of inhibition. The structure-activity relationship (SAR) analysis revealed that a slim salicylic aldehyde framework had a pivotal role in stabilization of the molecules near the substrate docking site. Furthermore, the presence of phenyl and bulky tert-butyl substituents in position 3 in salicylic aldehyde fragment favored strong interaction with the substrate-binding pocket in laccase. Both 3- and 4-HBAH derivatives containing larger 3-tert-butyl-5-methyl- or 3,5-di-tert-butyl-2-hydroxy-benzylidene unit, did not bind to the active site of laccase and, interestingly, acted as non-competitive (Ki = 32.0 µM) or uncompetitive (Ki = 17.9 µM) inhibitors, respectively. From the easily available laccase inhibitors only sodium azide, harmful to environment and non-specific, was over 6 times more active than the above compounds.

Novel 2,4-Disubstituted-1,3-Thiazole Derivatives: Synthesis, Anti-Candida Activity Evaluation and Interaction with Bovine Serum Albumine

Herein we report the synthesis of two novel series of 1,3-thiazole derivatives having a lipophilic C4-substituent on account of the increasing need for novel and versatile antifungal drugs for the treatment of resistant Candida sp.-based infections. Following their structural characterization, the anti-Candida activity was evaluated in vitro while using the broth microdilution method. Three compounds exhibited lower Minimum Inhibitory Concentration (MIC) values when compared to fluconazole, being used as the reference antifungal drug. An in silico molecular docking study was subsequently carried out in order to gain more insight into the antifungal mechanism of action, while using lanosterol-C14α-demethylase as the target enzyme. Fluorescence microscopy was employed to further investigate the cellular target of the most promising molecule, with the obtained results confirming its damaging effect towards the fungal cell membrane integrity. Finally, the distribution and the pharmacological potential in vivo of the novel thiazole derivatives was investigated through the study of their binding interaction with bovine serum albumin, while using fluorescence spectroscopy.

Structural-Dependent N,O-Donor Imine-Appended Cu(II)/Zn(II) Complexes: Synthesis, Spectral, and in Vitro Pharmacological Assessment

Four mononuclear bioefficient imine-based coordination complexes, [(L ¹ ) ₂ Cu], [(L ¹ ) ₂ Zn], [(L ² )Cu(H ₂ O)], and [(L ² )Zn(H ₂ O)], were synthesized using ligands [L ¹ = 2-(((3-hydroxynaphthalen-2-yl)methylene)amino)-2-methylpropane-1,3-diol and L ² = 4-(1-((1,3-dihydroxy-2-methylpropan-2-yl)imino)ethyl)benzene-1,3-diol]. The formation of the complexes was ascertained by elemental analysis, Fourier transform infrared, ¹H NMR, ¹³C NMR, electrospray ionization-mass spectroscopy, electron paramagnetic resonance, and thermogravimetric analysis. The comparative binding propensity profiles of the above-synthesized complexes with the DNA/human serum albumin (HSA) were investigated via UV absorption, fluorescence, and Förster resonance energy-transfer studies. On the basis of extended conjugation and planarity, L ¹ complexes exhibited superior bioactivity with greater calculated DNA binding constant values, (K _b) 2.9444 × 10³ [(L ¹ ) ₂ Cu] and 2.2693 × 10³ [(L ¹ ) ₂ Zn], as compared to L ² complexes, 1.793 × 10³ [(L ² )Cu(H ₂ O)] and 9.801 × 10² [(L ² )Zn(H ₂ O)]. The competitive displacement assay of complexes was performed by means of fluorogenic dyes (EtBr and Hoechst), which corroborates the occurrence of minor groove binding because of the enhanced displacement activity with Hoechst 33258. The minor groove binding of the [(L ¹ ) ₂ Cu] complex is further confirmed by the molecular docking study. Moreover, the HSA study demonstrated effective static quenching of complexes with substantial K _sv values. The [(L ¹ ) ₂ Cu] complex was found to have pronounced cleavage efficiency as evaluated from sodium dodecyl sulfate polyacrylamide gel electrophoresis electrophoresis. Furthermore, in vitro antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl and superoxide radicals further proclaimed the remarkable bioefficiency of compounds, which make them promising as active chemotherapeutic agents.

Copper(ii) complexes with NNO ligands: synthesis, crystal structures, DNA cleavage, and anticancer activities

Three novel copper(ii) complexes, Cu(L1)₂ (1), Cu(L2)₂·2DMF (2), and Cu(L3)₂·2DMF (3), were synthesized using three aroylhydrazone ligands, (E)-2-hydroxy-N'-(1-(pyrazin-2-yl)ethylidene)benzohydrazide (HL1), (E)-3-hydroxy-N'-(1-(pyrazin-2-yl)ethylidene)benzohydrazide (HL2) and (E)-4-hydroxy-N'-(1-(pyrazin-2-yl)ethylidene)benzohydrazide (HL3). The complexes were characterized by elemental analysis, infrared (IR), and Ultraviolet-visible light (UV-vis) spectroscopy. The X-ray crystal structures of the complexes all possess a distorted octahedral coordination geometry. Both an absorption spectral titration and a competitive binding assay (ethidium bromide, 4',6-diamidino-2-phenylindole (DAPI), and methyl green) revealed that complexes 2 and 3 bind readily to calf thymus DNA (ctDNA) through intercalative and minor groove binding modes. Complexes 2 and 3 also exhibited oxidative cleavage of supercoiled plasmid DNA (pUC19) in the presence of ascorbic acid as an activator. Cytotoxicity studies showed that complexes 2 and 3 possessed high cytotoxicities toward the HeLa human cervical cancer cell line, but weak toxicities toward the L929 normal mouse fibroblast cell line. We therefore have reason to believe that complexes 2 and 3 both show potential as promising anticancer candidate drugs.

Zirconia-Cu(I) stabilized copper oxide mesoporous nano-catalyst: Synthesis and DNA reactivity of 1,2,4-oxadiazole-quinolinepeptidomimetics-based metal(II) complexes

Contemporary research reveals an undemanding protocol for the catalytic synthesis of 1,2,4-oxadiazole-quinolinepeptide in the incidence of a cost-effective and reusable mesoporous ZrO₂-supported Cu₂O (Cu₂ZrO₃) catalyst. This paper depicts a unique system for peptide bond synthesis staying away from toxic solvents and reactants. The catalyst was reused for four cycles without noteworthy loss in the activity, and the catalyst was genuinely heterogeneous. The method followed a simple workup procedure, and no column chromatography was needed. Further, the synthesized 1,2,4-oxadiazole-quinolinepeptide ligand (L), and its complexes of type, [FeLCl₂] and [CuL]Cl₂ were synthesized and characterized by spectral and analytical techniques. An octahedral geometry has been projected for Fe(II) complexes, while the Cu(II) complex exhibits a square planar geometry. The binding properties of the complexes with CT-DNA were studied by absorption spectral analysis, followed by viscosity measurement and thermal denaturation studies. The photo-induced cleavage studies revealed that the complexes possess photonuclease activity against pUC19 DNA under UV-visible irradiation.