M2L4 coordination capsules with tunable anticancer activity upon guest encapsulation.

Area of Science:

• Supramolecular Chemistry
• Medicinal Chemistry
• Nanotechnology

Background:

• Metallosupramolecular cages and capsules are increasingly recognized for their dual roles as molecular containers and therapeutic agents.
• Understanding how guest encapsulation influences the cytotoxic properties of these host structures is crucial for developing effective anticancer drugs.

Purpose of the Study:

• To investigate the modulation of cytotoxicity in Pt(II) and Pd(II)-linked M2L4 coordination capsules upon encapsulation of guest molecules (pyrene and caffeine).
• To correlate the observed anticancer activity with the stability of the capsules in the presence of glutathione.
• To elucidate the mechanism of action through cellular imaging studies.

Main Methods:

• Synthesis and characterization of M2L4 coordination capsules (Pt(II) and Pd(II)-linked).
• Encapsulation of guest molecules (pyrene, caffeine) within the capsules.
• In vitro cytotoxicity assays against various human cancer cell lines (HT-29, T-24, HL-60, HL-60/Dox, HL-60/CDDP).
• NMR-based kinetic experiments to assess stability towards glutathione.
• Fluorescence microscopy imaging of tumor cells.

Main Results:

• Guest encapsulation significantly altered the anticancer activity of both Pt(II) and Pd(II) capsules.
• Pyrene encapsulation decreased cytotoxicity more in Pt(II) than Pd(II) capsules.
• Caffeine-containing capsules showed lower cytotoxicity than empty capsules but remained superior to cisplatin.
• Capsule stability towards glutathione correlated with observed anticancer activity trends.
• Glutathione-triggered disassembly was identified as a potential activation pathway.

Conclusions:

• Metallosupramolecular capsules offer tunable anticancer properties based on encapsulated guests.
• The stability of these capsules, particularly towards glutathione, is a critical factor in their therapeutic efficacy.
• Glutathione-mediated disassembly represents a promising mechanism for targeted drug delivery and activation of these anticancer agents.