New modulated design, docking and synthesis of carbohydrate-conjugate heterobimetallic CuII–SnIV complex as potential topoisomerase II inhibitor: In vitro DNA binding, cleavage and cytotoxicity against human cancer cell lines

Overview of the New Bioactive Heterocycles as Targeting Topoisomerase Inhibitors Useful Against Colon Cancer

Colorectal cancer (CRC) is the third most common cancer globally, with high mortality. Metastatic CRC is incurable in most cases, and multiple drug therapy can increase patients' life expectancy by 2 to 3 years. Efforts are being made to understand the relationship between topoisomerase enzymes and colorectal cancer. Some studies have shown that higher expression of these enzymes is correlated to a poor prognosis for this type of cancer. One of the primary drugs used in the treatment of CRC is Irinotecan, which can be used in monotherapy or, more commonly, in therapeutic schemes such as FOLFIRI (Fluorouracil, Leucovorin, and Irinotecan) and CAPIRI (Capecitabine and Irinotecan). Like Camptothecin, Irinotecan and other compounds have a mechanism of action based on the formation of a ternary complex with topoisomerase I and DNA providing damage to it, therefore leading to cell death. Thus, this review focused on the principal works published in the last ten years that demonstrate a correlation between the inhibition of different isoforms of topoisomerase and in vitro cytotoxic activity against CRC by natural products, semisynthetic and synthetic compounds of pyridine, quinoline, acridine, imidazoles, indoles, and metal complexes. The results revealed that natural compounds, semisynthetic and synthetic derivatives showed potential in vitro cytotoxicity against several colon cancer cell lines, and this activity was often accompanied by the ability to inhibit both isoforms of topoisomerase (I and II), highlighting that these enzymes can be promising targets for the development of new chemotherapy against CRC. Pyridine analogs were considered the most promising for this study, while the evaluation of the real potential of natural products was limited by the lack of information in their work. Moreover, the complexes, although promising, presented as the main limitation the lack of selectivity.

Synthesis and characterization of heterobimetallic SnIV-CuII/ZnII complexes: DFT studies, cleavage potential and cytotoxic activity

Heterobimetallic complexes [Cu(L)Sn(CH₃)₂(H₂O)(Cl)] (3) and [Zn(L)Sn(CH₃)₂(H₂O)(Cl)] (4) have been synthesized from their monometallic analogs [Cu(L)(H₂O)(Cl)] (1) and [Zn(L)(H₂O)(Cl)] (2) of Schiff base ligand (L) which were characterized by various spectroscopic and analytical methods. DFT calculations were carried out to simulate the vibrational spectra to support the anticipated structures. The interaction studies of ligand (L) and complexes (1-4) with CT-DNA were performed by employing UV-vis, and fluorescence spectroscopic techniques which revealed that heterobimetallic complexes 3 and 4 showed higher affinity with DNA due to dual mode of action as compared to monometallic complexes 1 and 2. Further, validation of the interaction studies was accomplished by carrying out molecular docking studies with DNA. Gel assay displayed that both the complexes have ability to cleave DNA efficiently and are specific minor groove binders. Cu^II-Sn^IV complex 3 cleaved pBR322 DNA via oxidative mechanism, while Zn^II-Sn^IV complex 4 followed hydrolytic cleavage pathway. In vitro cytotoxicity evaluation of complex 3 was tested on a different cancer cell lines showing promising antitumor activity.Communicated by Ramaswamy H. Sarma.

Design, synthesis and biological evaluation of 1,4-dihydroxyanthraquinone derivatives as anticancer agents

The novel hydroxyanthraquinone derivatives containing nitrogen-mustard and thiophene group were designed to covalently bind to topoisomerase II, and their structures were confirmed by nuclear magnetic resonance and high resolution mass spectrometer technologies in this article. The in vitro cytotoxicity against different cancer cell lines and one normal liver cell line (L02) was evaluated by MTT assay. Compound A1 was the most potent anti-proliferative agent against the human liver cancer HepG-2 cells (IC₅₀ = 12.5 μM), and there is no obvious growth inhibitory effect on normal liver tissue L02 cells. The good cytotoxicity and selectivity of compound A1 suggest that it could be a promising lead for further optimization. The mechanisms of action about compound A1 and A4 were further investigated through analysis of cell apoptosis. Confocal microscopy tracks the location of compound A1 in the cell, which could enter the cytoplasm and nucleus, and induce severe deformation of the nucleus. The docking study demonstrated that A1 could interact with the catalytic active site in topoisomerase II.

Dibutyltin(IV) Complexes Derived from L-DOPA: Synthesis, Molecular Docking, Cytotoxic and Antifungal Activity

A series of organotin(IV) complexes was herein prepared and characterized. A one-pot synthetic strategy afforded reasonable to high yields, depending on the nature of the ligand. All new complexes were fully characterized by spectroscopic techniques, consisting of IR, MS and NMR (¹H, ¹³C and ¹¹⁹Sn). The in vitro cytotoxicity tests demonstrated that the organotin complexes produced a greater inhibition, versus cisplatin (the positive control), of the growth of six human cancer cell lines: U-251 (glioblastoma), K-562 (chronic myelogenous leukemia), HCT-15 (colorectal), MCF-7 (breast), MDA-MB-231 (breast) and SKLU-1 (non-small cell lung). The potency of this cytotoxic activity depended on the nature of the substituent bonded to the aromatic ring. All complexes exhibited excellent IC₅₀ values. The test compounds were also screened in vitro for their antifungal effect against Candida glabrata and Candida albicans, showing minimum inhibitory concentration (MIC) values lower than those obtained for fluconazole. A brine shrimp bioassay was performed to examine the toxic properties. Molecular docking studies demonstrated that the organotin(IV) complexes bind at the active site of topoisomerase I in a similar manner to topotecan, sharing affinity for certain amino acid side chains (Ile535, Arg364 and Asp533), as well as for similar DNA regions (DA113, DC112 and DT10).

Hybrid pharmacophore approach for bio-relevant di-imines based homobimetallic complexes incorporating functionalized dicarboxylates as co-ligands: Synthesis, spectral and structural activity dependent biological insights (in-vitro DNA and HSA binding, antioxidant and cytotoxicity)

Synthesis of bio-efficient homobimetallic complexes, [Cu₂(L¹)₂(dipic)](NO₃)₂.3H₂O (1), [Zn₂(L¹)₂(dipic)](NO₃)₂.4H₂O (2), [Cu₂(L²)₂(oxa)](NO₃)₂.4H₂O (3) and [Zn₂(L²)₂(oxa)] (NO₃)₂.5H₂O (4) was carried out using Schiff bases [(N¹E,N²E)-N¹,N²-bis(5-chlorothiophen-2-ylmethylene)-4-chlorobenzene-1,2-diamine; L¹] and [(N¹E,N²E)-N¹,N²-bis(5-chlorofuran-2-ylmethylene)-4-chlorobenzene-1,2-diamine; L²] as main ligands and dicarboxylate moieties of 2,6-pyridine dicarboxylic acid (H₂-dipic) and oxalic acid (H₂-oxa) as co-ligands, respectively in order to apprehend their structure activity relationships on the basis of pharmacophore hybrid approach. The stoichiometry, geometry, thermal stability, morphology and crystallite size of the compounds were inferred by analytical, spectral (FT-IR, ¹H NMR and ¹³C NMR and Mass), thermal (TGA/DTA), SEM and XRD studies. In-vitro DNA and HSA binding profiles of complexes were analysed by different biophysical measurements. The absorption study divulged that the observed alterations in the physico-chemical properties of complexes upon binding with DNA connoted their intercalative binding mode while fluorescence quenching mechanism was quantified by using Stern Volmer constant (K_SV)_; 1.73×10⁴ (1), 1.47×10⁴ (2), 5.65×10³ (3) and 3.60×10³M^-1 (4) which discerned that hybrid pharmacophore active metal complexes (1 and 2) exhibited efficient quenching effect with Ct-DNA in comparison to complexes (3 and 4) due to greater planarity and extent of conjugation (π-π interactions). The intercalative binding mode of complexes is further supported by competitive displacement assay by using fluorogenic dyes (EtBr and Hoechst 33258). The results of HSA fluorescence study divulged static quenching of the complexes (1-4) with K_SV values of 7.24×10⁴ (1), 6.03×10⁴ (2), 5.06×10⁴ (3) and 2.85×10⁴ (4) while K_b values; 1.16×10⁵ (1), 2.01×10⁴ (2), 5.84×10³ (3) and 8.60×10² (4) suggested them potent avid binder of HSA. Additionally, comparative estimation of scavenging properties using DPPH, superoxide(O₂^.-), hydroxyl (OH^-) and ABTS method and in-vitro cytotoxicity against different cell lines (MCF-7, HeLa and Hep G2) brought out distinct biopotency of complexes due to diverse structural features and chelation effect.

The structural characterization and biological activity of sulfamethoxazolyl-azo-p-cresol, its copper(ii) complex and their theoretical studies

Sulfonamide-azophenol and its copper(ii) complex exhibit antimicrobial activity and interaction with DNA. Molecular docking was used to determine the mechanism of drug action.

Structural, spectral, NLO and MEP analysis of the [MgO₂Ti₂(OPr(i)ⁱⁱ)₆], [MgO₂Ti₂(OPr(i)ⁱ)₂(acac)₄] and [MgO₂Ti₂(OPr(i)ⁱ)2(bzac)₄] by DFT method

Quantum chemical calculations are performed on [MgO2Ti2(OPr(i))6] and [MgO2Ti2(OPr(i))2(L)4] complexes. L is acetylacetonate (acac) and benzoylacetonate (bzac) anion. The crystal structures of these complexes have not been obtained as experimentally but optimized structures of these complexes are obtained as theoretically in this study. Universal force field (UFF) and DFT/B3LYP method are used to obtain optimized structures. Theoretical spectral analysis (IR, (1)H and (13)C NMR) is compared with their experimental values. A good agreement is found between experimental and theoretical spectral analysis. These results mean that the optimized structures of mentioned complexes are appropriate. Additionally, the active sites of mentioned complexes are determined by molecular electrostatic potential (MEP) diagrams and non-linear optical (NLO) properties are investigated.

The crystal structure of sulfamethoxazole, interaction with DNA, DFT calculation, and molecular docking studies

Sulfamethoxazole (SMX) [4-amino-N-(5-methyl-1,2-oxazol-3-yl)benzenesulfonamide] is structurally established by single crystal X-ray diffraction measurement. The crystal packing shows H-bonded 2D polymer through N(7)-H(7A)-O(2), N(7)-H(7B)-O(3), N(1)-H(1)-N(2), C(5)-H(5)-O(3)-S(1) and N(7)-(H7A)-O(2)-S(1). Density Functional Theory (DFT) and Time Dependent-DFT (TD-DFT) computations of optimized structure of SMX determine the electronic structure and has explained the electronic spectral transitions. The interaction of SMX with CT-DNA has been studied by absorption spectroscopy and the binding constant (Kb) is 4.37×10(4)M(-1). The in silico test of SMX with DHPS from Escherichia coli and Streptococcus pneumoniae helps to understand drug metabolism and accounts the drug-molecule interactions. The molecular docking of SMX-DNA also helps to predict the interaction feature.