Preparation and Characterization of Novel Poly(alkylidenamine) Nitrile Ruthenium Metallodendrimers

Biological Effects in Cancer Cells of Mono- and Bidentate Conjugation of Cisplatin on PAMAM Dendrimers: A Comparative Study

Cisplatin (cis-diamminedichloroplatinum(II)) is a potent chemotherapeutic agent commonly used to treat cancer. However, its use also leads to serious side effects, such as nephrotoxicity, ototoxicity, and cardiotoxicity, which limit the dose that can be safely administered to patients. To minimize these problems, dendrimers may be used as carriers for cisplatin through the coordination of their terminal functional groups to platinum. Here, cisplatin was conjugated to half-generation anionic PAMAM dendrimers in mono- and bidentate forms, and their biological effects were assessed in vitro. After preparation and characterization of the metallodendrimers, their cytotoxicity was evaluated against several cancer cell lines (A2780, A2780cisR, MCF-7, and CACO-2 cells) and a non-cancer cell line (BJ cells). The results showed that all the metallodendrimers were cytotoxic and that the cytotoxicity level depended on the cell line and the type of coordination mode (mono- or bidentate). Although, in this study, a correlation between dendrimer generation (number of carried metallic fragments) and cytotoxicity could not be completely established, the monodentate coordination form of cisplatin resulted in lower IC₅₀ values, thus revealing a more accessible cisplatin release from the dendritic scaffold. Moreover, most of the metallodendrimers were more potent than the cisplatin, especially for the A2780 and A2780cisR cell lines, which showed higher selectivity than for non-cancer cells (BJ cells). The monodentate G0.5COO(Pt(NH₃)₂Cl)₈ and G2.5COO(Pt(NH₃)₂Cl)₃₂ metallodendrimers, as well as the bidentate G2.5COO(Pt(NH₃)₂)₁₆ metallodendrimer, were even more active towards the cisplatin-resistant cell line (A2780cisR cells) than the correspondent cisplatin-sensitive one (A2780 cells). Finally, the effect of the metallodendrimers on the hemolysis of human erythrocytes was neglectable, and metallodendrimers' interaction with calf thymus DNA seemed to be stronger than that of free cisplatin.

New insights into ruthenium(ii) metallodendrimers as anticancer drug nanocarriers: from synthesis to preclinic behaviour

Pre-clinical results highlight the potential of the low-generation poly(alkylidenamine)-based dendrimers as ruthenium metallodrug nanocarriers.

Use of Half-Generation PAMAM Dendrimers (G0.5–G3.5) with Carboxylate End-Groups to Improve the DACHPtCl2 and 5-FU Efficacy as Anticancer Drugs

The DACHPtCl2 compound (trans-(R,R)-1,2-diaminocyclohexanedichloroplatinum(II)) is a potent anticancer drug with a broad spectrum of activity and is less toxic than oxaliplatin (trans-l-diaminocyclohexane oxalate platinum II), with which it shares the active metal fragment DACHPt. Nevertheless, due to poor water solubility, its use as a chemotherapeutic drug is limited. Here, DACHPtCl2 was conjugated, in a bidentate form, with half-generation PAMAM dendrimers (G0.5–G3.5) with carboxylate end-groups, and the resulting conjugates were evaluated against various types of cancer cell lines. In this way, we aimed at increasing the solubility and availability at the target site of DACHPt while potentially reducing the adverse side effects. DNA binding assays showed a hyperchromic effect compatible with DNA helix’s disruption upon the interaction of the metallodendrimers and/or the released active metallic fragments with DNA. Furthermore, the prepared DACHPt metallodendrimers presented cytotoxicity in a wide set of cancer cell lines used (the relative potency regarding oxaliplatin was in general high) and were not hemotoxic. Importantly, their selectivity for A2780 and CACO-2 cancer cells with respect to non-cancer cells was particularly high. Subsequently, the anticancer drug 5-FU was loaded in a selected metallodendrimer (the G2.5COO(DACHPt)16) to investigate a possible synergistic effect between the two drugs carried by the same dendrimer scaffold and tested for cytotoxicity in A2780cisR and CACO-2 cancer cell lines. This combination resulted in IC50 values much lower than the IC50 for 5-FU but higher than those found for the metallodendrimers without 5-FU. It seems, thus, that the metallic fragment-induced cytotoxicity dominates over the cytotoxicity of 5-FU in the set of considered cell lines.

Use of Half-Generation PAMAM Dendrimers (G0.5-G3.5) with Carboxylate End-Groups to Improve the DACHPtCl2 and 5-FU Efficacy as Anticancer Drugs

The DACHPtCl2 compound (trans-(R,R)-1,2-diaminocyclohexanedichloroplatinum(II)) is a potent anticancer drug with a broad spectrum of activity and is less toxic than oxaliplatin (trans-l-diaminocyclohexane oxalate platinum II), with which it shares the active metal fragment DACHPt. Nevertheless, due to poor water solubility, its use as a chemotherapeutic drug is limited. Here, DACHPtCl2 was conjugated, in a bidentate form, with half-generation PAMAM dendrimers (G0.5-G3.5) with carboxylate end-groups, and the resulting conjugates were evaluated against various types of cancer cell lines. In this way, we aimed at increasing the solubility and availability at the target site of DACHPt while potentially reducing the adverse side effects. DNA binding assays showed a hyperchromic effect compatible with DNA helix's disruption upon the interaction of the metallodendrimers and/or the released active metallic fragments with DNA. Furthermore, the prepared DACHPt metallodendrimers presented cytotoxicity in a wide set of cancer cell lines used (the relative potency regarding oxaliplatin was in general high) and were not hemotoxic. Importantly, their selectivity for A2780 and CACO-2 cancer cells with respect to non-cancer cells was particularly high. Subsequently, the anticancer drug 5-FU was loaded in a selected metallodendrimer (the G2.5COO(DACHPt)16) to investigate a possible synergistic effect between the two drugs carried by the same dendrimer scaffold and tested for cytotoxicity in A2780cisR and CACO-2 cancer cell lines. This combination resulted in IC50 values much lower than the IC50 for 5-FU but higher than those found for the metallodendrimers without 5-FU. It seems, thus, that the metallic fragment-induced cytotoxicity dominates over the cytotoxicity of 5-FU in the set of considered cell lines.

New anionic poly(alkylideneamine) dendrimers as microbicide agents against HIV-1 infection

Acquired immune deficiency syndrome (AIDS) due to human immunodeficiency virus type-1 (HIV-1) represents one of the most important sexually transmitted infections (STI) worldwide. Great international efforts have been made to stop new infections but, to date, several compounds failed as microbicides at different stages of clinical trials. The quest to design new molecules that could prevent these infections is essential. In this work, we synthesized the first, second and third generations of anionic dendrimers having carboxylate and sulfonate terminal groups, respectively named G1C, G2C, G3C and G1S, G2S, and G3S, starting from a family of poly(alkylideneamine) dendrimers with nitrile termini. The anionic terminal groups of these dendrimers were expected to prompt them to act against HIV-1 infection. All dendrimers were fully characterized by 1H- and 13C-NMR, FTIR, MS and zeta potential techniques. Importantly, they were able to remain stable in the solid state and aqueous solutions at least for one and a half years. Screening of these six new dendrimers was then performed to shed light on their potential anti-HIV-1 activity and their mechanism of action. Results showed that the dendrimers were cytocompatible and that G1C and G1S dendrimers had important activity against R5-HIV-1NLAD8 and X4-HIV-1NL4.3 isolates by acting directly on viral particles and blocking their entry in host cells. Additionally, G1C and G1S dendrimers maintained their inhibitory effect at different pH values. Through a vaginal irritation assay carried out in BALB/c mice, the safety of these new dendrimers for topical application was also shown. Taken together, our results clearly show that G1C and G1S dendrimers are strong candidates for developing an effective microbicide to prevent HIV-1 new infections.

Poly(alkylidenimine) Dendrimers Functionalized with the Organometallic Moiety [Ru(η⁵-C₅H₅)(PPh₃)₂]⁺ as Promising Drugs Against Cisplatin-Resistant Cancer Cells and Human Mesenchymal Stem Cells

Here and for the first time, we show that the organometallic compound [Ru(η⁵-C₅H₅)(PPh₃)₂Cl] (RuCp) has potential to be used as a metallodrug in anticancer therapy, and further present a new approach for the cellular delivery of the [Ru(η⁵-C₅H₅)(PPh₃)₂]⁺ fragment via coordination on the periphery of low-generation poly(alkylidenimine) dendrimers through nitrile terminal groups. Importantly, both the RuCp and the dendrimers functionalized with [Ru(η⁵-C₅H₅)(PPh₃)₂]⁺ fragments present remarkable toxicity towards a wide set of cancer cells (Caco-2, MCF-7, CAL-72, and A2780 cells), including cisplatin-resistant human ovarian carcinoma cell lines (A2780cisR cells). Also, RuCp and the prepared metallodendrimers are active against human mesenchymal stem cells (hMSCs), which are often found in the tumor microenvironment where they seem to play a role in tumor progression and drug resistance.

Advances in combination therapies based on nanoparticles for efficacious cancer treatment: an analytical report

The main objective of nanomedicine research is the development of nanoparticles as drug delivery systems or drugs per se to tackle diseases as cancer, which are a leading cause of death with developed nations. Targeted treatments against solid tumors generally lead to dramatic regressions, but, unfortunately, the responses are often short-lived due to resistant cancer cells. In addition, one of the major challenges of combination drug therapy (called "cocktail") is the crucial optimization of different drug parameters. This issue can be solved using combination nanotherapy. Nanoparticles developed in oncology based on combination nanotherapy are either (a) those designed to combat multidrug resistance or (b) those used to circumvent resistance to clinical cancer drugs. This review provides an overview of the different nanoparticles currently used in clinical treatments in oncology. We analyze in detail the development of combinatorial nanoparticles including dendrimers for dual drug delivery via two strategic approaches: (a) use of chemotherapeutics and chemosensitizers to combat multidrug resistance and (b) use of multiple cytotoxic drugs. Finally, in this review, we discuss the challenges, clinical outlook, and perspectives of the nanoparticle-based combination therapy in cancer.