Supramolecular organometallic chemistry: the platinum(IV) paradigm

Autophagy-targeted Pt(IV) agents: a new horizon in antitumor drug development

Pt(IV) complexes as prodrugs of Pt(II) drugs exhibit numerous advantages such as enhanced stability, reduced toxicity, increased oral bioavailability, and efficacy in overcoming the drug resistance of Pt(II) compounds, which underscore their significant potential in the advancement of novel Pt anticancer agents. Furthermore, protective autophagy is pivotal in sustaining tumor cell homeostasis and modulating the tumor microenvironment (TME), thereby representing a critical target for the development of antitumor drugs. Specific inhibition or activation of autophagy during chemotherapy would break the internal homeostasis in the TME and increase antitumor activities. Consequently, developing novel Pt(IV) antitumor agents with autophagy-targeting capabilities by incorporating autophagy-regulating moieties into the Pt(IV) framework has emerged as a hot topic in the discovery of novel Pt drugs. Herein, the research progress in novel Pt(IV) antitumor drugs with autophagy-targeted properties is systematically reviewed based on the literature. The future challenges and perspectives of this fascinating class of conjugates are also discussed, aiming to provide new insights and approaches for the future design and investigation of novel Pt antitumor drugs.

Transferrin-Modified Carprofen Platinum(IV) Nanoparticles as Antimetastasis Agents with Tumor Targeting, Inflammation Inhibition, Epithelial-Mesenchymal Transition Suppression, and Immune Activation Properties

The inflammatory microenvironment is a central driver of tumor metastasis, intimately associated with the promotion of epithelial-mesenchymal transition (EMT) and immune suppression. Here, transferrin-modified carprofen platinum(IV) nanoparticles Tf-NPs@CPF2-Pt(IV) with promising antiproliferative and antimetastatic properties were developed, which activated by inhibiting inflammation, suppressing EMT, and activating immune responses besides causing DNA injury. The nanoparticles released the active ingredient CPF2-Pt(IV) in a sustained manner and offered enhanced pharmacokinetic properties compared to free CPF2-Pt(IV) in vivo. Additionally, they possessed satisfactory tumor targeting effects via the transferrin motif. Serious DNA damage was induced with the upregulation of γ-H2AX and P53, and the mitochondria-mediated apoptotic pathway Bcl-2/Bax/caspase3 was initiated. Inflammation was alleviated by inhibiting COX-2 and MMP9 and decreasing inflammatory cytokines TNF-α and IL-6. Subsequently, the EMT was reversed by inhibiting the Wnt/β-catenin pathway. Furthermore, the antitumor immunity was provoked by blocking the immune checkpoint PD-L1 and increasing CD3+ and CD8+ T lymphocytes in tumors.

Responsive macrocyclic and supramolecular structures powered by platinum

Humankind's manipulation of platinum dates back more than two millennia to burial objects. Since then, its use has evolved from purely decorative purposes in jewelry to more functional applications such as in catalysts, pharmaceuticals, and bioimaging agents. Platinum offers a range of properties arguably unmatched by any other metal, including electroactivity, photoluminescence, chromic behaviour, catalysis, redox reactivity, photoreactivity, and stimuli-controlled intermetallic interactions. The vast body of knowledge generated by the exploration of these and other properties of platinum has recently merged with other areas of chemistry such as supramolecular and host-guest chemistry. This has shown us that platinum can incorporate its responsive character into supramolecular assemblies (e.g., macrocycles and polymers) to produce materials with tailorable functions and responses. In this Perspective Article, we cover some platinum-powered supramolecular structures reported by us and others, hoping to inspire new and exciting discoveries in the field.

Supramolecular chemistry of organoplatinum(IV) complexes: A syndiotactic polymer with uracil substituents

The reaction of RCH2X with [PtMe2(DPA)], 1, (DPA = di-2-pyridylamine) has given [PtXMe2(CH2R)(DPA)] by cis oxidative addition to give 2a, when R = 6-uracil, X = Cl, or 3a, when R = CO2H, X = Br, but by a mixture of cis and trans oxidative addition to give 4a/4b when R = 4-C6H4CO2H, X = Br. The unusual cis stereochemistry of oxidative addition is rationalized thermodynamically by the formation of an intramolecular hydrogen bond in 2a and 3a but not 4a, and kinetically by the role of the ligand DPA NH group in hydrogen bonding to halide. Complex 2a in the solid state forms an unusual supramolecular syndiotactic polymer by forming two different intermolecular NH..O=C hydrogen bonds to neighbouring molecules.