Efficacy of ruthenium coordination complex-based Rutherrin in a preclinical rat glioblastoma model

Background

Glioblastoma is an aggressive brain cancer in adults with a grave prognosis, aggressive radio and chemotherapy provide only a 15 months median survival.

Methods

We evaluated the tolerability and efficacy of the Ruthenium-based photosensitizer TLD-1433 with apo-Transferrin (Rutherrin) in the rat glioma 2 (RG-2) model. The specific tumor uptake ratio and photodynamic therapy (PDT) threshold of the rat glioblastoma and normal brain were determined, survival and CD8⁺T-cell infiltration post-therapy were analyzed. Results were compared with those obtained for 5-aminolevulinic acid (ALA)-induced Protoporphyrin IX (PpIX)-mediated photodynamic therapy in the same animal model. As both photosensitizers have different photophysical properties, the number of absorbed photons required to achieve an equal cell kill was determined for in vitro and in vivo studies.

Results

A significantly lower absorbed energy was sufficient to achieve LD₅₀ with Rutherrin versus PpIX-mediated PDT. Rutherrin provides a higher specific uptake ratio (SUR) >20 in tumors versus normal brain, whereas the SUR for ALA-induced PpIX was 10.6. To evaluate the short-term tissue response in vivo, enhanced T2-weighted magnetic resonance imaging (MRI) provided the spatial extent of edema, post PpIX-PDT at twice the cross-section versus Rutherrin-PDT suggesting reduced nonspecific damage, typically associated with a secondary wave of neuronal damage. Following a single therapy, a significant survival increase was observed in rats bearing glioma for PDT mediated by Rutherrin versus PpIX for the selected treatment conditions. Rutherrin-PDT also demonstrated an increased CD8+T-cell infiltration in the tumors.

Conclusion

Rutherrin-PDT was well tolerated providing a safe and effective treatment of RG-2 glioma.

Transition Metal Complexes and Photodynamic Therapy from a Tumor-Centered Approach: Challenges, Opportunities, and Highlights from the Development of TLD1433

Transition metal complexes are of increasing interest as photosensitizers in photodynamic therapy (PDT) and, more recently, for photochemotherapy (PCT). In recent years, Ru(II) polypyridyl complexes have emerged as promising systems for both PDT and PCT. Their rich photochemical and photophysical properties derive from a variety of excited-state electronic configurations accessible with visible and near-infrared light, and these properties can be exploited for both energy- and electron-transfer processes that can yield highly potent oxygen-dependent and/or oxygen-independent photobiological activity. Selected examples highlight the use of rational design in coordination chemistry to control the lowest-energy triplet excited-state configurations for eliciting a particular type of photoreactivity for PDT and/or PCT effects. These principles are also discussed in the context of the development of TLD1433, the first Ru(II)-based photosensitizer for PDT to enter a human clinical trial. The design of TLD1433 arose from a tumor-centered approach, as part of a complete PDT package that includes the light component and the protocol for treating non-muscle invasive bladder cancer. Briefly, this review summarizes the challenges to bringing PDT into mainstream cancer therapy. It considers the chemical and photophysical solutions that transition metal complexes offer, and it puts into context the multidisciplinary effort needed to bring a new drug to clinical trial.

Metal-based antitumor compounds: beyond cisplatin

Despite improvements in the 5-year survival rate to over 80% in cancers, such as Hodgkin lymphoma and testicular cancer, more aggressive tumors including pancreatic and brain cancer still have extremely low survival rates. The establishment of chemoresistance, responsible for the reduction in treatment efficiency and cancer relapse, is one possible explanation for this setback. Metal-based compounds, a class of anticancer drugs, are largely used in the treatment of cancer. Herein, we will review the use of metal-based small molecules in chemotherapy, focusing on recent studies, and we will discuss how new nonplatinum-based agents are prompting scientists to increase drug specificity to overcome chemoresistance in cancer cells.

Functional Polymer Nanocarriers for Photodynamic Therapy

Photodynamic therapy (PDT) is an appealing therapeutic modality in management of some solid tumors and other diseases for its minimal invasion and non-systemic toxicity. However, the hydrophobicity and non-selectivity of the photosensitizers, inherent serious hypoxia of tumor tissues and limited penetration depth of light restrict PDT further applications in clinic. Functional polymer nanoparticles can be used as a nanocarrier for accurate PDT. Here, we elucidate the mechanism and application of PDT in cancer treatments, and then review some strategies to administer the biodistribution and activation of photosensitizers (PSs) to ameliorate or utilize the tumor hypoxic microenvironment to enhance the photodynamic therapy effect.

Mechanisms of action of Ru(ii) polypyridyl complexes in living cells upon light irradiation

The unique photophysical properties of Ru(ii) polypyridyl complexes make them very attractive candidates as photosensitisers in Photodynamic Therapy (PDT). However, to date, there are not many studies exploring in detail the mechanism(s) of action of such compounds in living systems upon light irradiation. This feature article provides an overview of the most in-depth biological studies on such compounds.

Catch and Release Photosensitizers: Combining Dual-Action Ruthenium Complexes with Protease Inactivation for Targeting Invasive Cancers

Dual action agents containing a cysteine protease inhibitor and Ru-based photosensitizer for photodynamic therapy (PDT) were designed, synthesized, and validated in 2D culture and 3D functional imaging assays of triple-negative human breast cancer (TNBC). These combination agents deliver and release Ru-based PDT agents to tumor cells and cause cancer cell death upon irradiation with visible light, while at the same time inactivating cathespin B (CTSB), a cysteine protease strongly associated with invasive and metastatic behavior. In total five Ru-based complexes were synthesized with the formula [Ru(bpy)₂(1)](O₂CCF₃)₂ (3), where bpy = 2,2'-bipyridine and 1 = a bipyridine-based epoxysuccinyl inhibitor; [Ru(tpy)(NN)(2)](PF₆)₂, where tpy = terpiridine, 2 = a pyridine-based epoxysuccinyl inhibitor and NN = 2,2'-bipyridine (4); 6,6'-dimethyl-2,2'-bipyridine (5); benzo[ i]dipyrido[3,2- a:2',3'- c]phenazine (6); and 3,6-dimethylbenzo[ i]dipyrido[3,2- a:2',3'- c]phenazine (7). Compound 3 contains a [Ru(bpy)₃]²⁺ fluorophore and was designed to track the subcellular localization of the conjugates, whereas compounds 4-7 were designed to undergo either photoactivated ligand dissociation and/or singlet oxygen generation. Photochemical studies confirmed that complexes 5 and 7 undergo photoactivated ligand dissociation, whereas 6 and 7 generate singlet oxygen. Inhibitors 1-7 all potently and irreversibly inhibit CTSB. Compounds 4-7 were evaluated against MDA-MB-231 TNBC and MCF-10A breast epithelial cells in 2D and 3D culture for effects on proteolysis and cell viability under dark and light conditions. Collectively, these data reveal that 4-7 potently inhibit dye-quenched (DQ) collagen degradation, whereas only compound 7 causes efficient cell death under light conditions, consistent with its ability to release a Ru(II)-based photosensitizer and to also generate ¹O₂.

Correlation of intracellular oxygen and cell metabolism by simultaneous PLIM of phosphorescent TLD1433 and FLIM of NAD(P)H

During photodynamic therapy (PDT), disruption of cell respiration and metabolic changes could be one of the first events. Photophysical characteristics of the photosensitizer (PS) and its specific redox potential define consumption of molecular oxygen followed by generation of reactive oxygen species. The potential PS TLD1433 is based on transition metal Ru(II) and possess an oxygen-dependent luminescence. This enables the study of oxygen consumption by PS-phosphorescence lifetime imaging (PLIM) and simultaneously changes the cellular metabolic state by nicotinamide adenine dinucleotide (NAD(P)H)-fluorescence lifetime imaging (FLIM). Within this study, localization and cellular function of TLD1433 is investigated in bladder carcinoma cells using time-resolved and confocal laser scanning microscopy. Simultaneous FLIM/PLIM of NAD(P)H and TLD1433 during PDT correlated oxygen consumption, redox state and cellular energy metabolism. Our investigations aimed to provide a personalized protocol in theranostic PDT procedures and demonstrate the potential use of TLD1433 PDT also under hypoxic conditions, which are otherwise difficult to treat.

Photophysical and Photobiological Properties of Dinuclear Iridium(III) Bis-tridentate Complexes

A series of cationic dinuclear iridium(III) complexes (Ir1-Ir5) bearing terpyridine-capped fluorenyl bridging ligands and different polypyridyl or cyclometalating terminal tridentate ligands were synthesized, characterized, and evaluated for their photophysical and photobiological activities. The influence of the bridging and terminal ligands on the photophysical properties of the complexes was investigated by UV-vis absorption, emission, and transient absorption spectroscopy and simulated by TDDFT calculations. All of the complexes displayed strong bridging-ligand localized visible 1π,π* absorption and red- or near-infrared phosphorescence as well as broad triplet excited-state absorption across both visible and NIR wavelengths. These triplet states were assigned as predominantly 3π,π* for Ir1 (τ = 3.1 μs) and Ir4 (τ = 48 μs) and 3CT (charge transfer) for Ir2, Ir3, and Ir5 (τ = 1.7-2.7 μs). Complexes Ir1-Ir5 acted as in vitro photodynamic therapy (PDT) agents toward human SK-MEL-28 melanoma cells when activated with visible light, with submicromolar photocytotoxicity and phototherapeutic indices ranging from 20 to almost 300. The in vitro PDT effects with visible light did not correlate with singlet oxygen (1O2) quantum yields or DNA photocleaving capacity probed under cell-free conditions. All of the Ir(III) complexes phosphoresced brightly when associated with compromised cells (with or without light treatment) and exhibited photoactivated cellular uptake, highlighting the theranostic potential of this new class of Ir(III) complex photosensitizers.

In vitro anticancer activities of Withania coagulans against HeLa, MCF-7, RD, RG2, and INS-1 cancer cells and phytochemical analysis

BACKGROUND

The Pakistani Salt Range has a rich floral diversity including Withania coagulans from the Solanaceae family.

METHODS

The crude methanolic extracts of the root, leaf, leaf stalk, and fruit of this plant were screened for their cytotoxic activity against human (HeLa, MCF-7, RD) and rat (RG2 and INS-1) cancer cell lines at 20 μg/mL and compared to methotrexate. The IC50 values indicated that leaf stalk and fruit extracts exert an 80% or higher cytotoxic activity against all cell lines at 24 hours.

RESULTS

The leaf stalk extract showed the highest cytotoxic efficacy against all tested cell lines, with IC50 values ranging from 0.96 ± 0.01 μg/mL to 4.73 ± 0.05 μg/mL followed by the fruit extract with IC50 values of 0.69 ± 0.01-6.69 ± 0.06 μg/mL after 48-72 hours incubation. The leaf stalk and seed extracts were analyzed for polyphenols and flavonoids using RP-HPLC. The total flavonoid content (TFC) was calculated for all tested samples, and the highest TFC was recorded for the root extract (394.34 ± 1.26 μg/g). The total phenolic content (TPC) was found in the seed extract (307.86 ± 9.42 μg/g) of W. coagulans. The highest contents of myricetin (358.46 ± 2.91 μg/g) were noted in the leaf extract, and highest quercetin was recorded in the seed extract (21.43 ± 0.13 μg/g). The highest gallic acid concentration (83.62 ± 0.71 μg/g) was recorded in leaf stalk extract and p-hydroxybenzoic acid in the seed extract (157.46 ± 1.43 μg/g).

CONCLUSION

The present study gives a scientific insight and comparative analysis of various plant parts in this medicinally important plant species from the Salt Range of Pakistan against both human and rat cancer cells.

Photodynamic inactivation assisted by localized surface plasmon resonance of silver nanoparticles: In vitro evaluation on Escherichia coli and Streptococcus mutans

Localized surface plasmon resonance (LSPR) of gold nanoparticles has been reported to increase the antimicrobial effect of the photodynamic therapy. Although silver nanoparticles (AgNPs) are an efficient growth inhibitor of microorganisms, no studies exploring LSPR of AgNPs to enhance the photodynamic inactivation (PDI) have been related. In this work, we described the LSPR phenomenon of AgNP sand investigated its interaction with riboflavin, a natural photosensitizer. We evaluated the use of AgNPs coated with pectin (p-AgNP) in riboflavin (Rb)-mediated PDI of Escherichia coli (Gram- bacteria) and Streptococcus mutans (Gram + bacteria) using a blue light-emitting diode (λ = 455 ± 20 nm) of optical power 200 mW. Irradiance was 90 mW/cm² and radiant exposure varied according to the time exposure. Uptake of Rb and p-AgNP by the cells was evaluated by measuring the supernatant absorption spectra of the samples. We observed that LSPR of p-AgNPs was able to enhance the riboflavin photodynamic action on S. mutans but not on E. coli, probably due to the lower uptake of Rb by E. coli. Taken together, our results provide insights to explore the use of the LPRS promoted by silver nanostructures to optimize antimicrobial PDI protocols.

The development of ruthenium(ii) polypyridyl complexes and conjugates for in vitro cellular and in vivo applications

Ruthenium(ii) [Ru(ii)] polypyridyl complexes have been the focus of intense investigations since work began exploring their supramolecular interactions with DNA. In recent years, there have been considerable efforts to translate this solution-based research into a biological environment with the intention of developing new classes of probes, luminescent imaging agents, therapeutics and theranostics. In only 10 years the field has expanded with diverse applications for these complexes as imaging agents and promising candidates for therapeutics. In light of these efforts this review exclusively focuses on the developments of these complexes in biological systems, both in cells and in vivo, and hopes to communicate to readers the diversity of applications within which these complexes have found use, as well as new insights gained along the way and challenges that researchers in this field still face.

Effective phthalocyanines mediated photodynamic therapy with doxorubicin or methotrexate combination therapy at sub-micromolar concentrations in vitro

To improve a cancer patient's quality of life, short treatment duration resulting in rapid tumour removal while sparing normal tissue are highly desirable. Photodynamic therapy (PDT) commonly applied in a single treatment, while often effective can be limited at low photosensitizer or light doses. Combination therapies can overcome the efficacy limitations while not increasing treatment-associated morbidity. Here the efficacy of combination therapy comprised of doxorubicin (DOX) or methotrexate (MTX) with Photosens mediated PDT was investigated in three cell lines in vitro, employing multiple incubation sequences. Photosense is a mixture of aluminium phthalocyanines with different sulfonation. The results demonstrated higher synergistic effects when DOX or MTX-mediated chemotherapy preceded PDT light activation by 24 h. MTX is marginally more cytotoxic than DOX, when combined with Photosens (AlPcS_2-4) mediated PDT. While MTX and DOX exposure prior to AlPcS_2-4 incubation may enhance mitochondrial localisation photosensitizer, the simultaneous targeting of DNA, proteins, and lipids of the combination therapies leads to the observed high cytotoxicity at sub μM drug doses.

Photoactivated in Vitro Anticancer Activity of Rhenium(I) Tricarbonyl Complexes Bearing Water-Soluble Phosphines

Fifteen water-soluble rhenium compounds of the general formula [Re(CO)3(NN)(PR3)]+, where NN is a diimine ligand and PR3 is 1,3,5-triaza-7-phosphaadamantane (PTA), tris(hydroxymethyl)phosphine (THP), or 1,4-diacetyl-1,3,7-triaza-5-phosphabicylco[3.3.1]nonane (DAPTA), were synthesized and characterized by multinuclear NMR spectroscopy, IR spectroscopy, and X-ray crystallography. The complexes bearing the THP and DAPTA ligands exhibit triplet-based luminescence in air-equilibrated aqueous solutions with quantum yields ranging from 3.4 to 11.5%. Furthermore, the THP and DAPTA complexes undergo photosubstitution of a CO ligand upon irradiation with 365 nm light with quantum yields ranging from 1.1 to 5.5% and sensitize the formation of 1O2 with quantum yields as high as 70%. In contrast, all of the complexes bearing the PTA ligand are nonemissive and do not undergo photosubstitution upon irradiation with 365 nm light. These compounds were evaluated as photoactivated anticancer agents in human cervical (HeLa), ovarian (A2780), and cisplatin-resistant ovarian (A2780CP70) cancer cell lines. All of the complexes bearing THP and DAPTA exhibited a cytotoxic response upon irradiation with minimal toxicity in the absence of light. Notably, the complex with DAPTA and 1,10-phenanthroline gave rise to an IC50 value of 6 μM in HeLa cells upon irradiation, rendering it the most phototoxic compound in this library. The nature of the photoinduced cytotoxicity of this compound was explored in further detail. These data indicate that the phototoxic response may result from the release of both CO and the rhenium-containing photoproduct, as well as the production of 1O2.

Pyrazole appended quinoline-BODIPY based arene ruthenium complexes: their anticancer activity and potential applications in cellular imaging

Synthesis of four arene ruthenium complexes [Ru(η⁶-C₆H₆)(L1)Cl]PF₆, (1), [Ru(η⁶-C₁₀H₁₄)(L1)Cl]PF₆ (2), [Ru(η⁶-C₆H₆)(L2)Cl]PF₆ (3) and [Ru(η⁶-C₁₀H₁₄)(L2)Cl]PF₆ (4) based on quinoline-BODIPY were described and their photocytotoxicity was evaluated.

A novel photosensitizer based on a ruthenium(ii) phenanthroline bis(perylenediimide) dyad: synthesis, generation of singlet oxygen andin vitrophotodynamic therapy

In this study, a novel photosensitizer having two perylenediimide units and a phenanthroline ruthenium(ii) coordination moiety (Ru-BP)has been developed for photodynamic therapy (PDT) of cancer cells.

Critical Overview of the Use of Ru(II) Polypyridyl Complexes as Photosensitizers in One-Photon and Two-Photon Photodynamic Therapy

Photodynamic Therapy (PDT) is an emerging technique to treat certain types of cancer, bacterial, fungal, and viral infections, and skin diseases. In past years, different research groups developed new ruthenium-containing photosensitizers (PSs) with tuned photophysical and biological properties to better fit the requirements of PDT. In this Account, we report and discuss the latest results in this research area, emphasizing particularly our own research. For example, inspired by the DNA intercalating complex [Ru(bpy)₂(dppz)]²⁺ (bpy = 2,2'-bipyridine; dppz = (dipyrido[3,2-a:2',3'-c]phenazine), a series of ruthenium complexes bearing differently functionalized dppz ligands were synthesized to target DNA. The introduction of the substituents on the dppz ligand did not reduce much the affinity of the complexes to DNA but highly affected their cellular uptake. The most effective complex in this series, [Ru(bpy)₂(dppz-7-OMe)]²⁺, showed IC₅₀ values in the low micromolar range against several types of cancer cells upon light irradiation and, importantly, a high phototoxic index (PI) of >150. This value is comparable to or even better than several PSs used in clinics under comparable experimental conditions. This compound was found to localize in the nucleus and to induce DNA damage in HeLa cells upon light irradiation. Interestingly, cells in the mitotic phase were found to be more affected and to have a different mechanism of cell death (apoptosis) upon light irradiation than those in the interphase (paraptosis). To take advantage of that, the PS was combined with a cell cycle inhibitor to synchronize cells in the mitotic phase, further improving the phototoxicity by a factor of 3.6. In addition, our group recently demonstrated that [Ru(bphen)₂(benzene-1,2-dislufinate)] (bphen = 4,7-diphenyl-1,10-phenanthroline) localizes in mitochondria and has an IC₅₀ value of 0.62 μM with a PI of over 80 in HeLa cells upon light irradiation at 420 nm. Interestingly, this complex was also found to efficiently kill Gram-positive Staphylococcus aureus under light irradiation. Antimicrobial PDT (aPDT) is another field of research where Ru(II) polypyridyl complexes can play an interesting role to fight antibiotics resistance. [Ru(dqpCO₂Me)(ptpy)]²⁺ (dqpCO₂Me = 4-methylcarboxy-2,6-di(quinolin-8-yl)pyridine), ptpy = 4'-phenyl-2,2':6',2″-terpyridine) is additionally efficient against Gram-negative Escherichia coli. The efficacy of positively charged Ru(II) PSs is related to their affinity to the negatively charged membrane of Gram-negative bacteria. A drawback of many Ru(II) polypyridyl PSs is their low absorption in the biological optical window (600-900 nm) where light penetration depth into tissue is the highest. The lowest energy transition in the UV/Vis spectra of Ru(II) polypyridyl complexes is usually a metal-to-ligand charge-transfer band. To shift the absorption into this range, tuning of the ligand system, for example, by extending π-systems, has been described in the literature. Another approach to make excitation in the optical biological window possible is Two-Photon Absorption (2PA). High photon density is needed and usually confocal laser beams are used for excitation. In collaboration with the Chao group, a series of homoleptic Ru(II) complexes bearing tertiary alkyl ammonium substituted bipyridine ligands with two photon cross sections between 185 and 250 GM at around 800 nm was tested in vitro. They showed IC₅₀ values in the micromolar range and PIs between 103 and 313. The highly positive-charged complexes were found to enter the cell via endocytosis and to target lysosomes. Studies on 3D tumor cell spheroids, a model closer to real tumors than commonly used 2D cell monolayers, were also performed. It could be demonstrated that 2P-PDT treatment with 800 nm laser irradiation was significantly more effective than that with 450 nm laser irradiation.

Cellular and cell-free studies of catalytic DNA cleavage by ruthenium polypyridyl complexes containing redox-active intercalating ligands

The ruthenium(ii) polypyridyl complexes (RPCs), [(phen)2Ru(tatpp)]2+ (32+ ) and [(phen)2Ru(tatpp)Ru(phen)2]4+ (44+ ) are shown to cleave DNA in cell-free studies in the presence of a mild reducing agent, i.e. glutathione (GSH), in a manner that is enhanced upon lowering the [O2]. Reactive oxygen species (ROS) are involved in the cleavage process as hydroxy radical scavengers attenuate the cleavage activity. Cleavage experiments in the presence of superoxide dismutase (SOD) and catalase reveal a central role for H2O2 as the immediate precursor for hydroxy radicals. A mechanism is proposed which explains the inverse [O2] dependence and ROS data and involves redox cycling between three DNA-bound redox isomers of 32+ or 44+ . Cultured non-small cell lung cancer cells (H358) are sensitive to 32+ and 44+ with IC50 values of 13 and 15 μM, respectively, and xenograft H358 tumors in nude mice show substantial (∼80%) regression relative to untreated tumors when the mice are treated with enantiopure versions of 32+ and 44+ (Yadav et al. Mol Cancer Res, 2013, 12, 643). Fluorescence microscopy of H358 cells treated with 15 μM 44+ reveals enhanced intracellular ROS production in as little as 2 h post treatment. Detection of phosphorylated ATM via immunofluorescence within 2 h of treatment with 44+ reveals initiation of the DNA damage repair machinery due to the ROS insult and DNA double strand breaks (DSBs) in the nuclei of H358 cells and is confirmed using the γH2AX assay. The cell data for 32+ is less clear but DNA damage occurs. Notably, cells treated with [Ru(diphenylphen)3]2+ (IC50 1.7 μM) show no extra ROS production and no DNA damage by either the pATM or γH2AX even after 22 h. The enhanced DNA cleavage under low [O2] (4 μM) seen in cell-free cleavage assays of 32+ and 44+ is only partially reflected in the cytotoxicity of 32+ and 44+ in H358, HCC2998, HOP-62 and Hs766t under hypoxia (1.1% O2) relative to normoxia (18% O2). Cells treated with RPC 32+ show up to a two-fold enhancement in the IC50 under hypoxia whereas cells treated with RPC 44+ gave the same IC50 whether under hypoxia or normoxia.

Interaction and oxidative damage of DVDMS to BSA: a study on the mechanism of photodynamic therapy-induced cell death

Photodynamic therapy (PDT) is a promising method for neoplastic and nonneoplastic diseases. In this study, we utilized sinoporphyrin sodium (DVDMS) as a sensitizer combined with light to investigate its cytotoxic effect on different cell lines. For this purpose, we chose bovine serum albumin (BSA) as a model to explore the mechanism of PDT-induced cell death at a molecular level. Our findings indicated that the combined treatment significantly suppressed cell survival. Fluorescence spectroscopy revealed a strong interaction between DVDMS and BSA molecules in aqueous solution, affecting DVDMS’ targeting distribution and metabolism. Spectroscopic analysis and carbonyl content detection indicated that DVDMS-PDT significantly enhanced the damage of BSA at a higher extent than Photofrin II-PDT under similar experimental conditions. Our observations were consistent with the cytotoxicity results. Excessive reactive oxygen species (ROS) were induced by the synergy effect of the sensitizer and light, which played an important role in damaging BSA and tumor cells. These results suggested that the interaction and oxidative damage of protein molecules by DVDMS were the main reasons to cell death and constitute a valuable reference for future DVDMS-PDT investigations.

New cyclometalated Ir(iii) complexes with NCN pincer and meso-phenylcyanamide BODIPY ligands as efficient photodynamic therapy agents

A new class of cyclometalated iridium(iii) with NCN pincer andmeso-phenylcyanamide BODIPY ligands has been synthesized and studied for photodynamic therapy.

The discovery of half-sandwich iridium complexes containing lidocaine and (pyren-1-yl)ethynyl derivatives of phenylcyanamide ligands for photodynamic therapy

The new design of two cyclopentadienyl iridium(iii) complexes with (pyren-1-yl)ethynyl derivatives of phenylcyanamide and lidocaine ligands, have been studied for photodynamic therapy.

Transition Metal Intercalators as Anticancer Agents-Recent Advances

The diverse anticancer utility of cisplatin has stimulated significant interest in the development of additional platinum-based therapies, resulting in several analogues receiving clinical approval worldwide. However, due to structural and mechanistic similarities, the effectiveness of platinum-based therapies is countered by severe side-effects, narrow spectrum of activity and the development of resistance. Nonetheless, metal complexes offer unique characteristics and exceptional versatility, with the ability to alter their pharmacology through facile modifications of geometry and coordination number. This has prompted the search for metal-based complexes with distinctly different structural motifs and non-covalent modes of binding with a primary aim of circumventing current clinical limitations. This review discusses recent advances in platinum and other transition metal-based complexes with mechanisms of action involving intercalation. This mode of DNA binding is distinct from cisplatin and its derivatives. The metals focused on in this review include Pt, Ru and Cu along with examples of Au, Ni, Zn and Fe complexes; these complexes are capable of DNA intercalation and are highly biologically active.

Combining Ruthenium(II) Complexes with Metal-Organic Frameworks to Realize Effective Two-Photon Absorption for Singlet Oxygen Generation

Singlet oxygen ((1)O2), as a reactive oxygen species, has garnered serious attention in physical, chemical, and biological studies. In this paper, we designed and synthesized a new type of singlet-oxygen generation system by exchanging cationic ruthenium complexes (RCs) into anionic bio-MOF-1. The resulting bio-MOF-1&RCs can be used as effective photocatalysts for generation of singlet oxygen under both single-photon and two-photon excitation. Especially, the excellent two-photon absorption (TPA) behavior of bio-MOF-1&RCs aroused our interest greatly because their two-photon absorption band lies in the optical window of biological tissue. Here, we measured the ability of bio-MOF-1&RCs to generate (1)O2 by irradiation under both 490 and 800 nm wavelength light in DMF. 1,3-Diphenylisobenzofuran (DPBF) and 2',7'-dichlorofluorescein (DCFH) were used as typical (1)O2 traps to detect and evaluate the efficiency of generation of (1)O2 under single-photon and two-photon excitation, respectively. Results indicated that bio-MOF-1&[Ru(phen)3](2+) was able to effectively generate (1)O2 under both conditions. Our work creates a novel synergistic TPA system with the excellent photophysical properties of RCs and the unique microporous structure benefit of MOFs, which may open a new avenue for creation of a cancer treatment system with both photodynamic therapy and chemotherapy.

Murine Model Imitating Chronic Wound Infections for Evaluation of Antimicrobial Photodynamic Therapy Efficacy

It is generally acknowledged that the age of antibiotics could come to an end, due to their widespread, and inappropriate use. Particularly for chronic wounds alternatives are being thought. Antimicrobial Photodynamic Therapy (APDT) is a potential candidate, and while approved for some indications, such as periodontitis, chronic sinusitis and other niche indications, its use in chronic wounds is not established. To further facilitate the development of APDT in chronic wounds we present an easy to use animal model exhibiting the key hallmarks of chronic wounds, based on full-thickness skin wounds paired with an optically transparent cover. The moisture-retaining wound exhibited rapid expansion of pathogen colonies up to 8 days while not jeopardizing the host survival. Use of two bioluminescent pathogens; methicillin resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa permits real time monitoring of the pathogens. The murine model was employed to evaluate the performance of four different photosensitizers as mediators in Photodynamic Therapy. While all four photosensitizers, Rose Bengal, porphyrin TMPyP, New Methylene Blue, and TLD1411 demonstrated good to excellent antimicrobial efficacy in planktonic solutions at 1 to 50 μM concentrations, whereas in in vivo the growth delay was limited with 24–48 h delay in pathogen expansion for MRSA, and we noticed longer growth suppression of P. aeruginosa with TLD1411 mediated Photodynamic Therapy. The murine model will enable developing new strategies for enhancement of APDT for chronic wound infections.