LV^VO-Ethyl Maltol-Based Metallodrugs (L^2– = Tridentate ONO Ligands): Hydrophobicity, Hydrolytic Stability, and Cytotoxicity via ROS-Mediated Apoptosis

Abstract

Four new oxidovanadium [VVOL1–4(ema)] complexes (1–4) have been synthesized using tridentate binegative ONO donor ligands H2L1–4 [H2L1: (E)-N′-(2-hydroxybenzylidene)furan-2-carbohydrazide; H2L2: (E)-N′-(4-(diethylamino)-2-hydroxybenzylidene)thiophene-2-carbohydrazide; H2L3: (E)-2-(4-(diethylamino)-2-hydroxybenzylideneamino)-4-methylphenol; H2L4: (E)-2-(3-ethoxy-2-hydroxybenzylideneamino)-4-methylphenol] and ethyl maltol (Hema) as a bidentate uninegative coligand and characterized by CHNS analysis, IR, UV–vis, NMR, and HR–ESI–MS methods. The structures of 1, 3, and 4 are confirmed by single-crystal X-ray analysis. The hydrophobicity and hydrolytic stability of the complexes are tested using NMR and HR–ESI–MS and correlated with their observed biological activities. It is observed that 1 hydrolyzed into a penta-coordinated vanadium-hydroxyl species (VVOL1-OH) with the release of ethyl maltol, whereas 2–4 are found quite stable under the investigated time period. The biomolecular interaction of 1–4 with DNA and BSA was performed using absorbance, fluorescence, and circular dichroism techniques. The in vitro cytotoxicity activities of H2L1–4 and 1–4 were tested against A549, HT-29, and NIH-3T3 cell lines. Among complexes, 2 with an IC50 value of 4.4 ± 0.1 μM displayed maximum anticancer activity against the HT-29 cell line. Complexes induce cell cycle arrest at the G2/M phase and subsequently trigger dose-dependent cell apoptosis, which is obtained by the cell apoptosis analysis via flow cytometry and confocal microscopy assays. Being fluorescence active, 1–4 were observed to target the mitochondria and exhibit disruption of the mitochondrial membrane potential, which consequently causes overproduction of intracellular reactive oxygen species and induced cell apoptosis.

Hydrolytically Stable TiIV–Hydrazone-Based Metallodrugs: Protein Interaction and Anticancer Potential

“…Dual AO/EB fluorescence staining is an important technique to distinguish normal cells from early and late apoptotic and necrotic cells. AO dye can pass through intact cell membranes and exhibit green fluorescence, whereas EB only stains cells that have lost the integrity of their membranes and exhibit red fluorescence . As shown in Figure , the living cells (control) are seen as green, whereas the apoptotic cells (compound treated) displayed red fluorescence.…”

“…In addition, it is reported that anticancer activity increases with an increase in hydrophobicity. ,, As shown in Table S7, complexes with a high degree of hydrophobicity with log P ow values ranging from 0.643 to 0.588 for 1 – 3 have enhanced anticancer potentials as they facilitate improved cellular membrane crossing by making improved accessibility of compounds in its target. ,,, Also, the order of hydrophobicity correlates with a steady increase in the cytotoxicity against both cancer cell lines. In fact, 1 with a maximum log P ow value of 0.643 ± 0.01 exhibited maximum cytotoxicity results .…”

“…The cell viability of H 2 L 1–3 and 1 – 3 was determined by 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium (MTT, Sigma-Aldrich India) assay after the treatment of compounds with desired concentrations (0.1, 1, 5, 10, 20, 50, and 100 μM) against HeLa, A549, and NIH-3T3 cells for the treatment of 48 h by following the previously reported procedure …”

“…The differential uptake of AO and EB dyes was used for the identification of the apoptotic as well as necrotic cells from the live cells upon post treatment of 1 – 3 using live cell confocal microscopy assay by following previously reported procedure. , …”

“…Gathering the knowledge from the above discussion and expertise from our earlier research works on the development of metal-based anticancer agents, ,− herein, a series of new titanium­(IV)-hydrazone-based complexes ( 1 – 3 ) were reported and characterized by different physicochemical techniques. In this study, two units of dianionic tridentate ligands were purposefully implemented with the intention of achieving maximum hydrolytic stability of 1 – 3 in aqueous media.…”