Water-Soluble Mn(III)-Porphyrins with High Relaxivity and Photosensitization.

Area of Science:

• Coordination Chemistry
• Biomedical Imaging
• Photodynamic Therapy

Background:

• Development of novel contrast agents for Magnetic Resonance Imaging (MRI).
• Exploration of photosensitizers for Photodynamic Therapy (PDT).
• Need for multimodal agents combining diagnostic and therapeutic capabilities.

Purpose of the Study:

• Synthesize and characterize water-soluble Mn(III)-porphyrin complexes.
• Evaluate their potential as dual-action agents for MRI and PDT.
• Investigate their interaction with G4 DNA and photocytotoxicity.

Main Methods:

• Synthesis of three Mn(III)-porphyrin complexes with varying side chains.
• Measurement of water relaxivity at different frequencies and temperatures.
• Assessment of photoinduced DNA cleavage and singlet oxygen generation.
• G4 DNA binding studies and photocytotoxicity assays on HeLa cells.

Main Results:

• Synthesized water-soluble Mn(III)-porphyrin complexes (Mn-1, Mn-2, Mn-3) with high relaxivity (10-15 mM⁻¹s⁻¹), exceeding Gd(III) agents.
• Para-substituted complexes (Mn-2, Mn-3) showed efficient photoinduced DNA cleavage and singlet oxygen generation.
• Mn-3 demonstrated G4 DNA binding and stabilizing activity, with significant photocytotoxicity on HeLa cells in a light-dependent manner.

Conclusions:

• Water-soluble Mn(III)-porphyrins are promising multimodal agents for MRI and PDT.
• Complexes with para-substituted carboxylate or alcoholic side chains exhibit enhanced performance.
• Further development could lead to novel theranostic agents for cancer treatment.