Terpyridine Oxovanadium(IV) Complexes of Phenanthroline Bases for Cellular Imaging and Photocytotoxicity in HeLa Cells

Phototherapeutic anticancer strategies with first-row transition metal complexes: a critical review

Photodynamic therapy (PDT) and photoactivated chemotherapy (PACT) are therapeutic techniques based on a photosensitizer (PS) and light. These techniques allow the spatial and temporal control of the activation of drugs with light. Transition metal complexes are attractive compounds as photoactivatable prodrugs since their excited states can be appropriately designed by subtle modifications of the ligands, the metal centre, or the oxidation state. However, most metal-based PSs contain heavy metals such as Ru, Os, Ir, Pt or Au, which are expensive and non-earth-abundant, contrary to first-row transition metals. In this context, the exploration of the photochemical properties of complexes based on first-row transition metals appears to be extremely promising. This did encourage several groups to develop promising PSs based on these metals. This review presents up-to-date state-of-the-art information on first-row-transition metal complexes, from titanium to zinc in regard to their application as PSs for phototherapeutic applications.

Effective topical treatments of innovative NNO-tridentate vanadium (IV) complexes-mediated photodynamic therapy in psoriasis-like mice model

Psoriasis is a chronic inflammatory skin disease that can significantly impact the quality of human life. Various drug treatments with long-term severe side effects limit those drugs usage. Photodynamic therapy...

Vanadium(IV) Complexes with Methyl-Substituted 8-Hydroxyquinolines: Catalytic Potential in the Oxidation of Hydrocarbons and Alcohols with Peroxides and Biological Activity

Methyl-substituted 8-hydroxyquinolines (Hquin) were successfully used to synthetize five-coordinated oxovanadium(IV) complexes: [VO(2,6-(Me)₂-quin)₂] (1), [VO(2,5-(Me)₂-quin)₂] (2) and [VO(2-Me-quin)₂] (3). Complexes 1-3 demonstrated high catalytic activity in the oxidation of hydrocarbons with H₂O₂ in acetonitrile at 50 °C, in the presence of 2-pyrazinecarboxylic acid (PCA) as a cocatalyst. The maximum yield of cyclohexane oxidation products attained was 48%, which is high in the case of the oxidation of saturated hydrocarbons. The reaction leads to the formation of a mixture of cyclohexyl hydroperoxide, cyclohexanol and cyclohexanone. When triphenylphosphine is added, cyclohexyl hydroperoxide is completely converted to cyclohexanol. Consideration of the regio- and bond-selectivity in the oxidation of n-heptane and methylcyclohexane, respectively, indicates that the oxidation proceeds with the participation of free hydroxyl radicals. The complexes show moderate activity in the oxidation of alcohols. Complexes 1 and 2 reduce the viability of colorectal (HCT116) and ovarian (A2780) carcinoma cell lines and of normal dermal fibroblasts without showing a specific selectivity for cancer cell lines. Complex 3 on the other hand, shows a higher cytotoxicity in a colorectal carcinoma cell line (HCT116), a lower cytotoxicity towards normal dermal fibroblasts and no effect in an ovarian carcinoma cell line (order of magnitude HCT116 > fibroblasts > A2780).

Theoretical study of the impact of metal complexation on the reactivity properties of Curcumin and its diacetylated derivative as antioxidant agents

The chemical behavior of Curcumin and its derivatives as antioxidant and metal chelator has become the subject of intense experimental research. In this work, a theoretical study was conducted with the aim to investigate whether the acetylation of the aromatic group in Curcumin, which makes it more lipophilic, will alter its biological activities. Also, we selected from the literature metal complexes of Curcumin and its diacetylated derivative with Ga(III) and In(III), in order to discriminate the molecular active sites of the investigated molecules in which the oxidative process occurs and to obtain information about their antioxidation mechanisms. The geometrical structures and electronic properties of these compounds have been obtained using the density functional theory (DFT) method, known for its accurate results. As our other objective is to understand the factors driving biological behavior of all the studied compounds as well as the impact of the metal complexation of Curcumin and its diacetylated derivative, we provided here evidences to explain experimental observations from a molecular reactivity perspective.

Structurally Characterized BODIPY-Appended Oxidovanadium(IV) β-Diketonates for Mitochondria-Targeted Photocytotoxicity

Mixed-ligand oxidovanadium(IV) β-diketonates having NNN-donor dipicolylamine-conjugated to boron-dipyrromethene (BODIPY in L₁) and diiodo-BODIPY (in L₂) moieties, namely, [VO(L₁)(acac)]Cl (1), [VO(L₂)(acac)]Cl (2), and [VO(L₁)(dbm)]Cl (3), where acac and dbm are monoanionic O,O-donor acetylacetone and 1,3-diphenyl-1,3-propanedione, were prepared, characterized, and tested for their photoinduced anticancer activity in visible light. Complexes 1 and 2 were structurally characterized as their PF₆ ^- salts (1a and 2a) by X-ray crystallography. They showed V^IVN₃O₃ six-coordinate geometry with dipicolylamine base as the facial ligand. The non-iodinated BODIPY complexes displayed absorption maxima at ∼501 nm, while it is ∼535 nm for the di-iodinated 2 in 10% DMSO-PBS buffer medium (pH = 7.2). Complexes 1 and 3 being green emissive (λ_em, ∼512 nm; λ_ex, 470 nm; Φ_F, ∼0.10) in 10% aqueous DMSO were used for cellular imaging studies. Complex 3 localized primarily in the mitochondria of the cervical HeLa cells with a co-localization coefficient value of 0.7. The non-emissive diiodo-BODIPY complex 2 showed generation of singlet oxygen (Φ_Δ ≈ 0.47) on light activation. Annexin-V assay showed singlet oxygen-mediated cellular apoptosis, making this complex a targeted PDT agent.

Novel blue-green emitting NLOphoric triphenylamine-imidazole based donor-π-acceptor compound: Solvatochromism, DFT, TD-DFT and non-linear optical studies

Novel Donor (D)-π-Acceptor (A) NLOphoric triphenylamine-imidazole based dye 9 was designed, synthesized, and confirmed by Mass, ¹³C NMR, and ¹H NMR analysis. Photophysical properties of 9 were studied in solvents of different polarities and compared with analogues compounds 7 and 8. Phenonthroline acceptor based dye 9 shows highly bathochromic shifted absorption and emission compared to dyes 7 and 8. Positive solvatochromism was noticed in 7, 8, and 9 which was supported by the linear (i.e. Lippert-Mataga and Mac-Rae polarity functions) and multi-linear (i.e. Kamlet-Taft and Catalan parameters) analysis. Moreover, solvent polarizability (d_SP) and solvent dipolarity (C_SdP) are the major factors responsible for red shift in absorption as well as in emission spectra. Charge transfer descriptors as well as the polarity graphs are in good relation with Generalized Mulliken-Hush (GMH) parameters. NLO properties of 7, 8, and 9 were studied by using solvatochromic and computational methods. The static first hyperpolarizability (β₀) and relevant microscopic parameters (μ,α₀,α,β,γ) were determined using DFT with B3LYP, BHHLYP, and CAM-B3LYP functionals. Third-order NLO properties of nitrogen containing phenanthroline based compound 9 were observed to be several times higher than those of the compounds 7 and 8, justify the design approach.

Terpyridyl oxovanadium(IV) complexes for DNA crosslinking and mito-targeted photocytotoxicity

Oxovanadium(IV) complexes [VO(L¹/L²)Cl₂]ⁿ⁺ (1,2) of (anthracenyl)terpyridine (An-tpy as L¹ in 1, n=0) and triphenylphosphonium-appended (anthracenyl)terpyridine (An-tpy-TPP⁺ as L² in 2, n=1) were synthesized, characterized and their DNA crosslinking ability, photocytotoxicity in visible light and cellular localization in cancer cells studied. The bromide derivative of 2, viz. [VO(An-tpy-TPP)Br₂]Br (3) is structurally characterized. The structure showed trans disposition of two halides in the coordination sphere and the TPP⁺ unit is a pendant to the terpyridyl ligand. The DNA melting and comet assay studies on the complexes suggest the formation of DNA crosslinks. Complexes 1 and 2 displayed ~10 fold increase in cytotoxicity on exposure to visible light (400-700nm) when compared to those in dark in HeLa and MCF-7 cells. FACScan (Fluorescence Associated Cell Sorter Scan) analysis showed cellular apoptosis when treated with the complex in visible light in comparison to their dark controls. Fluorescence microscopic studies using complex 2 revealed its mitochondrial localization within the cancer cells.

DNA photo-cleaving agents in the far-red to near-infrared range – a review

Ideal photonucleases for clinical applications cleave DNA upon activation with deeply penetrating far-red to near-infrared light.

Oxovanadium(IV) complexes of curcumin for cellular imaging and mitochondria targeted photocytotoxicity

Oxovanadium(IV) complexes [VO(R-tpy)(cur)](ClO4) (1, 2) of curcumin (Hcur) and terpyridine ligands (R-tpy) where R is phenyl (phtpy in 1) or p-triphenylphosphonium methylphenyl bromide (C6H4CH2PPh3Br) (TPP-phtpy in 2) were prepared and characterized and their DNA photocleavage activity, photocytotoxicity and cellular localization in cancer cells (HeLa and MCF-7) were studied. Acetylacetonate (acac) complexes [VO(R-tpy)(acac)](ClO4) of phtpy (3) and TPP-phtpy (4) were prepared and used as the control species. These complexes showed efficient cleavage of pUC19 DNA in visible light of 454 nm and near-IR light of 705 nm. Complexes 1 and 2 showed significant photocytotoxicity in visible light of 400-700 nm. FACS analysis showed sub-G1/G0 phase cell-cycle arrest in cancer cells when treated with 1 and 2 in visible light in comparison with the dark controls. Fluorescence microscopic studies revealed specific localization of the p-triphenylphosphonium complex 2 in the mitochondria of MCF-7 cancer cells whereas no such specificity was observed for complex 1.

New Oxidovanadium Complexes Incorporating Thiosemicarbazones and 1, 10-Phenanthroline Derivatives as DNA Cleavage, Potential Anticancer Agents, and Hydroxyl Radical Scavenger

Four novel oxidovanadium(IV) complexes, [VO(hntdtsc)(PHIP)] (1) (hntdtsc = 2-hydroxy-1-naphthaldehyde thiosemicarbazone, PHIP= 2-phenyl-imidazo[4,5-f]1,10-phenanthroline), [VO(hntdtsc)(DPPZ)](2)(DPPZ= dipyrido[3,2-a:2',3'-c]phenazine), [VO(satsc)(PHIP)](3) (satsc=salicylaldehyde thiosemicarbazone), and [VO(satsc)(DPPZ)](4), have been prepared and characterized. The chemical nuclease activities and photocleavage reactions of the complexes were tested. All four complexes can efficiently cleave pBR322 DNA, and complex 1 has the best cleaving ability. The antitumor properties of these complexes were examined with three different tumor cell lines using MTT assay. Their antitumor mechanism has been analyzed using cell cycle analysis, fluorescence microscopy of apoptosis, and Annexin V-FITC/PI assay. The results showed that the growth of human neuroblastoma (SH-SY5Y, SK-N-SH) and human breast adenocarcinoma (MCF-7) cells were inhibited significantly with very low IC50 values. Complex 1 was found to be the most potent antitumor agent among the four complexes. It can cause G0/G1 phase arrest of the cell cycle and exhibited significant induced apoptosis in SK-N-SH cells and displayed typical morphological apoptotic characteristics. In addition, they all displayed reasonable abilities to scavenge hydroxyl radical, and complex 1 was the best inhibitor.

Enhancing the photocytotoxic potential of curcumin on terpyridyl lanthanide(III) complex formation

Lanthanide(III) complexes [Ln(R-tpy)(cur)(NO3)2] (Ln = La(III) in 1, 2; Gd(III) in 5, 6) and [Ln(R-tpy)(scur)(NO3)2] (Ln = La(III) in 3, 4; Gd(III) in 7, 8), where R-tpy is 4′-phenyl-2,2′:6′,2′′-terpyridine (ph-tpy in 1, 3, 5, 7), 4′-(1-pyrenyl)-2,2′:6′,2′′-terpyridine (py-tpy in 2, 4, 6, 8), Hcur is curcumin (in 1, 2, 5, 6) and Hscur is diglucosylcurcumin (in 3, 4, 7, 8), were prepared and their DNA photocleavage activity and photocytotoxicity studied. Complexes [La(ph-tpy)(cur)(NO3)2] (1) and [Gd(ph-tpy)(cur)(NO3)2] (5) were structurally characterized. The complexes in aqueous-DMF showed an absorption band near 430 nm and an emission band near 515 nm when excited at 420 nm. The complexes are moderate binders to calf-thymus DNA. They cleave plasmid supercoiled DNA to its nicked circular form in UV-A (365 nm) and visible light (454 nm) via (1)O2 and ˙OH pathways. The complexes are remarkably photocytotoxic in HeLa cells in visible light (λ = 400–700 nm) and are non-toxic in the dark. FACScan analysis of the HeLa cells treated with 2 and 4 showed cell death via an apoptotic pathway. Nuclear localization of 1–4 is evidenced from confocal imaging on HeLa cells. The hydrolytic instability of curcumin gets significantly reduced upon binding to the lanthanide ions while retaining its photocytotoxic potential.

Synthesis and In Vitro Antitumor Activity of Two Mixed-Ligand Oxovanadium(IV) Complexes of Schiff Base and Phenanthroline

Two oxovanadium(IV) complexes of [VO(msatsc)(phen)], (1) (msatsc = methoxylsalicylaldehyde thiosemicarbazone, phen = phenanthroline) and its novel derivative [VO (4-chlorosatsc)(phen)], (2) (4-chlorosatsc = 4-chlorosalicylaldehyde thiosemicarbazone), have been synthesized and characterized by elemental analysis, IR, ES-MS, (1)H NMR, and magnetic susceptibility measurements. Their antitumor effects on BEL-7402, HUH-7, and HepG2 cells were studied by MTT assay. The antitumor biological mechanism of these two complexes was studied in BEL-7402 cells by cell cycle analysis, Hoechst 33342 staining, Annexin V-FITC/PI assay, and detection of mitochondrial membrane potential (ΔΨm). The results showed that the growth of cancer cells was inhibited significantly, and complexes 1 and 2 mainly caused in BEL-7402 cells G0/G1 cell cycle arrest and induced apoptosis. Both 1 and 2 decreased significantly the ΔΨm, causing the depolarization of the mitochondrial membrane. Complex 2 showed greater antitumor efficiency than that of complex 1.