A Family of Potent Ru(II) Photosensitizers with Enhanced DNA Intercalation: Bimodal Photokillers

Ru(ii), Ir(iii), Re(i) and Rh(iii) based complexes as next generation anticancer metallopharmaceuticals

Several anticancer drugs such as cisplatin, and its analogues, epirubicin, and doxorubicin are well known for their anticancer activity but the therapeutic value of these drugs comes with certain side effects and they cannot distinguish between normal and cancer cells. Thus, a major challenge for researchers around the world is to develop an anticancer drug with the least toxicity and more target specificity. With the successful reporting of NAMI-A and KP1019, a new path has emerged in the anticancer field. Recently, several Ru(ii) complexes have been reported for their anticancer activity due to their enhanced cellular uptake and selectivity towards cancer cells. Apart from the Ru(ii) complexes, a large amount of research has been carried out with Ir(iii), Re(i), and Rh(iii) based complexes, which exhibited promising anticancer activity. The present review reports various Ru(ii), Ir(iii), Re(i), and Rh(iii) based complexes for their anticancer activity based on their cytotoxicity profiles, biological targets and mechanism of action.

A Novel Photosensitizer Znln2S4 Mediated Photodynamic Therapy Induced-HepG2 Cell Apoptosis

Photodynamic therapy (PDT) uses a combination of photosensitizers with visible light to generate reactive species and selectively kill tumor or unwanted tissue. Znln₂S₄ nanoparticles are widely implemented in photovoltaic device materials and photolysis water catalysts owing to their unique photoelectric properties. Whether Znln₂S₄ itself can be used as an effective dye in PDT is still unknown. To determine the effects and potential mechanism of Znln₂S₄PDT on HepG2 cell apoptosis, electron microscopic analysis was performed to monitor the apoptotic morphology of HepG2 cells upon exposure to Znln₂S₄-PDT. Flow cytometry was performed to measure the apoptosis rate and intracellular ROS production. Western blot and ELISA were performed to reveal the expression changes in Bax, caspase-3 and caspase-9. Data from this work suggested that cells exhibited the typical apoptotic morphology in response to Znln₂S₄-PDT, with high apoptotic rate. The intracellular ROS production after Znln₂S₄-PDT occurred in a dose-dependent manner. Moreover, Znln₂S₄-PDT augmented the expression levels of pro-apoptosis factors, especially, Bax, caspase-3 and caspase-9. Taken together, our novel findings, Znln₂S₄-PDT elicited HepG2 cell apoptosis, suggesting Znln₂S₄ as a promising photosensitizer candidate for cancer therapy.

Photocatalytic Atom Transfer Radical Addition to Olefins Utilizing Novel Photocatalysts

Photocatalysis is a rapidly evolving area of research in modern organic synthesis. Among the traditional photocatalysts, metal-complexes based on ruthenium or iridium are the most common. Herein, we present the synthesis of two photoactive, ruthenium-based complexes bearing pyridine-quinoline or terpyridine ligands with extended aromatic conjugation. Our complexes were utilized in the atom transfer radical addition (ATRA) of haloalkanes to olefins, using bromoacetonitrile or bromotrichloromethane as the source of the alkyl group. The tailor-made ruthenium-based catalyst bearing the pyridine-quinoline bidentate ligand proved to be the best-performing photocatalyst, among a range of metal complexes and organocatalysts, efficiently catalyzing both reactions. These photocatalytic atom transfer protocols can be expanded into a broad scope of olefins. In both protocols, the photocatalytic reactions led to products in good to excellent isolated yields.

Excited-State Dynamics of a Two-Photon-Activatable Ruthenium Prodrug

We present a new approach to investigate how the photodynamics of an octahedral ruthenium(II) complex activated through two-photon absorption (TPA) differ from the equivalent complex activated through one-photon absorption (OPA). We photoactivated a Ru(II) polypyridyl complex containing bioactive monodentate ligands in the photodynamic therapy window (620-1000 nm) by using TPA and used transient UV/Vis absorption spectroscopy to elucidate its reaction pathways. Density functional calculations allowed us to identify the nature of the initially populated states and kinetic analysis recovers a photoactivation lifetime of approximately 100 ps. The dynamics displayed following TPA or OPA are identical, showing that TPA prodrug design may use knowledge gathered from the more numerous and easily conducted OPA studies.

Ruthenium bistridentate complexes with non-symmetrical hexahydro-pyrimidopyrimidine ligands: a structural and theoretical investigation of their optical and electrochemical properties

The optical and electronic properties of six Ru complexes with non-symmetrical tridentate ligands have been investigated and, as corroborated by electrochemical data, the presence of the hpp ligand strongly affects the oxidation potential of the metal ion.