The Effect of Photosensitizer Metalation Incorporated into Arene-Ruthenium Assemblies on Prostate Cancer.

Prostate cancer is the second most common cancer for men and a major health issue. Despite treatments, a lot of side effects are observed. Photodynamic therapy is a non-invasive method that uses photosensitizers and light to induce cell death through the intramolecular generation of reactive oxygen species, having almost no side effects. However, some of the PSs used in PDT show inherent low solubility in biological media, and accordingly, functionalization or vectorization is needed to ensure internalization. To this end, we have used arene-ruthenium cages in order to deliver PSs to cancer cells. These metalla-assemblies can host PSs inside their cavity or be constructed with PS building blocks. In this study, we wanted to determine if the addition of metals (Mg, Co, Zn) in the center of these PSs plays a role. Our results show that most of the compounds induce cytotoxic effects on DU 145 and PC-3 human prostate cancer cells. Localization by fluorescence confirms the internalization of the assemblies in the cytoplasm. An analysis of apoptotic processes shows a cleavage of pro-caspase-3 and poly-ADP-ribose polymerase, thus leading to a strong induction of DNA fragmentation. Finally, the presence of metals in the PS decreases PDT's effect and can even annihilate it.

Dimethyl Sulfoxide: A Bio-Friendly or Bio-Hazard Chemical? The Effect of DMSO in Human Fibroblast-like Synoviocytes.

The effect of dimethyl sulfoxide (DMSO) in rheumatoid arthritis (RA) human fibroblast-like synoviocytes (FLSs) has been studied on five different samples harvested from the joints (fingers, hands and pelvis) of five women with RA. At high concentrations (>5%), the presence of DMSO induces the cleavage of caspase-3 and PARP-1, two phenomena associated with the cell death mechanism. Even at a 0.5% concentration of DMSO, MTT assays show a strong toxicity after 24 h exposure (≈25% cell death). Therefore, to ensure a minimum impact of DMSO on RA FLSs, our study shows that the concentration of DMSO has to be below 0.05% to be considered safe.

Ruthenium-based assemblies incorporating tetrapyridylporphyrin panels: a photosensitizer delivery strategy for the treatment of rheumatoid arthritis by photodynamic therapy.

Ruthenium-based assemblies containing tetrapyridylporphyrins (TPyP) in their structure have been evaluated as photosensitizers (PS) to treat rheumatoid arthritis (RA) by photodynamic therapy (PDT). TPyP is useless by itself as a PS due to its low solubility in biological media, however, incorporated in metallacages it can be internalized in cells. The study shows a cellular antiproliferative activity in fibroblast-like synoviocyte (FLS) in the lower nanomolar range in the presence of light, and no dark toxicity at 1 µM concentration, thus having an excellent photoactivity index. The presence of diamagnetic (Zn2+) and paramagnetic (Co2+) metals in the center of TPyP impairs the effectiveness of PDT, showing no (Co) or reduced (Zn) photoactivity. A total of five metallacages with different structural characteristics have been evaluated, and our results suggest that the incorporation of PS in metalla-assemblies is not only an elegant method to increase solubility in biological media for TPyP but also appears to be an efficient hybrid system to treat RA by PDT.

Evaluation of Ruthenium-Based Assemblies as Carriers of Photosensitizers to Treat Rheumatoid Arthritis by Photodynamic Therapy.

For the first time, ruthenium-based assemblies have been used as carriers for photosensitizers in the treatment of rheumatoid arthritis by photodynamic therapy (PDT). These metallacages are totally soluble in physiological media and can transport photosensitizers (PS) in their cavity. After an incubation period, the PS is released in the cytoplasm and irradiation can take place. This strategy allows photosensitizers with low or null solubility in biological media to be evaluated as PDT agents in rheumatoid arthritis. The systems in which 21H,23H-porphine and 29H,31H-phthalocyanine are encapsulated show excellent photocytotoxicity and no toxicity in the dark. On the other hand, systems in which metalated derivatives such as Mg(II)-porphine and Zn(II)-phthalocyanine are used show good photocytotoxicity, but to a lesser extent than the previous two. Furthermore, the presence of Zn(II)-phthalocyanine significantly increases the toxicity of the system. Overall, fifteen different host-guest systems have been evaluated, and based on the results obtained, they show high potential for treating rheumatoid arthritis by PDT.

Proton-responsive naphthyridinone-based RuII complexes and their reactivity with water and alcohols.

We report the synthesis and reactivity of RuII complexes with a new naphthyridinone-substituted phosphine ligand, 7-(diisopropylphosphinomethyl)-1,8-naphthyridin-2(1H)-one (L-H), which contains two reactive sites that can potentially be deprotonated by a strong base: an NH proton of naphthyridinone and a methylene arm attached to the phosphine. In the absence of a base, the stable bis-ligated complex Ru(L-H)2Cl2 (1) containing two NH groups in the secondary coordination sphere is formed. Upon further reaction with a base, a doubly deprotonated, dimeric complex is obtained, [Ru2(L*-H)2(L)2] (2), in which two of the four ligands undergo deprotonation at the NH (L), while the other two ligands are deprotonated at the methylene groups (L*-H) as confirmed by an X-ray diffraction study; intramolecular hydrogen bonding is present between the NH group of one ligand and an O-atom of another ligand in the dimeric structure, which stabilizes the observed geometry of the complex. Complex 2 reacts with protic solvents such as water or methanol generating aqua Ru(L)2(OH2)2 (3) or methanol complexes Ru(L)2(MeOH)2 (4), respectively, both exhibiting intramolecular H-bonded patterns with surrounding ligands at least in the solid state. These complexes react with benzyl alcohols to give aldehydes via base-free acceptorless dehydrogenation.

Photosensitizers Used in the Photodynamic Therapy of Rheumatoid Arthritis.

Photodynamic Therapy (PDT) has become one of the most promising treatment against autoimmune diseases, such as rheumatoid arthritis (RA), as well as in the treatment of different types of cancer, since it is a non-invasive method and easy to carry out. The three main ingredients of PDT are light irradiation, oxygen, and a photosensitizer (PS). Light irradiation depends on the type of molecule or compound to be used as a PS. The concentration of O2 fluctuates according to the medium where the target tissue is located and over time, although it is known that it is possible to provide oxygenated species to the treated area through the PS itself. Finally, each PS has its own characteristics, the efficacy of which depends on multiple factors, such as solubility, administration technique, retention time, stability, excitation wavelength, biocompatibility, and clearance, among others. Therefore, it is essential to have a thorough knowledge of the disease to select the best PS for a specific target, such as RA. In this review we will present the PSs used in the last three decades to treat RA under PDT protocol, as well as insights on the relevant strategies.

Aluminium(iii) dialkyl 2,6-bisimino-4R-dihydropyridinates(-1): selective synthesis, structure and controlled dimerization.

A family of stable and otherwise selectively unachievable 2,6-bisimino-4-R-1,4-dihydropyridinate aluminium (III) dialkyl complexes [AlR'2(4-R-iPrBIPH)] (R = Bn, Allyl; R' = Me, Et, iBu) have been synthesized, taking advantage of a method for the preparation of the corresponding 4-R-1,4-dihydropiridine precursors developed in our group. All the dihydropyrdinate(-1) dialkyl aluminium complexes have been fully characterized by 1H- 13C-NMR, elemental analysis and in the case 2'a, also by X-ray diffraction studies. Upon heating in toluene solution at 110 °C, the dimethyl derivatives 2a and 2'a dimerize selectively through a double cycloaddition. This reaction leads to the formation of two new C-C bonds that involve the both meta positions of the two 4-R-1,4-dihydropyridinate fragments, resulting the binuclear aluminium species [Me2Al(4-R-iPrHBIP)]2 (R = Bn (3a); allyl (3'a)). Experimental kinetics showed that the dimerization of 2'a obeys second order rate with negative activation entropy, which is consistent with a bimolecular rate-determining step. Controlled methanolysis of both 3a and 3'a release the metal-free dimeric bases, (4-Bn-iPrHBIPH)2 and (4-allyl-iPrHBIPH)2, providing a convenient route to these potentially useful ditopic ligands. When the R' groups are bulkier than Me (2b, 2'b and 2'c), the dimerization is hindered or fully disabled, favoring the formation of paramagnetic NMR-silent species, which have been identified on the basis of a controlled methanolysis of the final organometallic products. Thus, when a toluene solution of [AlEt2(4-Bn-iPrBIPH)] (2b) was heated at 110 °C, followed by the addition of methanol in excess, it yields a mixture of the dimer (4-Bn-iPrHBIPH)2 and the aromatized base 4-Bn-iPrBIP, in ca. 1 : 2 ratio, indicating that the dimerization of 2b competes with its spontaneous dehydrogenation, yielding a paramagnetic complex containing a AlEt2 unit and a non-innocent (4-Bn-iPrBIP)˙- radical-anion ligand. Similar NMR monitoring experiments on the thermal behavior of [AlEt2(4-allyl-iPrBIPH)] (2'b) and [AliBu2(4-allyl-iPrBIPH)] (2'c) showed that these complexes do not dimerize, but afford exclusively NMR silent products. When such thermally treated samples were subjected to methanolysis, they resulted in mixtures of the alkylated 4-allyl-iPrBIP and non-alkylated iPrBIP ligand, suggesting that dehydrogenation and deallylation reactions take place competitively.