Cationic octahedral molybdenum cluster complexes functionalized with mitochondria-targeting ligands: photodynamic anticancer and antibacterial activities.

Abstract

Octahedral molybdenum cluster complexes have recently come forth as pertinent singlet oxygen photosensitizers towards biological applications. Still, their phototoxic efficiency in the absence of nanocarriers remains limited due to their poor cellular uptake. Here, two cationic octahedral molybdenum cluster complexes, bearing carboxylate ligands with triphenylphosphonium (1) or N-methyl pyridinium (2) mitochondria-targeting terminal functions, have been designed and synthesized. Their photophysical properties in water and in vitro biological activity were investigated in the context of blue-light photodynamic therapy of cancer and photoinactivation of bacteria. Upon blue light irradiation, complex 1 displays red luminescence with a quantum yield of 0.24 in water, whereas complex 2 is much less emissive (ΦL < 0.01). Nevertheless, both complexes efficiently produce singlet oxygen, O2(1Δg). Complex 1 is rapidly internalized into HeLa cells and accumulated in mitochondria, followed by relocation to lysosomes and clearance at longer times. In contrast, the more hydrophilic 2 is not internalized into HeLa cells, highlighting the effect of the apical ligands on the uptake properties. The treatment with 1 results in an intensive phototoxic effect under 460 nm irradiation (IC50 = 0.10 ± 0.02 μM), which exceeds by far those previously reported for octahedral cluster-based molecular photosensitizers. The ratio between phototoxicity and dark toxicity is approximately 50 and evidences a therapeutic window for the application of 1 in blue-light photodynamic therapy. Complex 1 also enters and efficiently photoinactivates Gram-positive bacteria Enterococcus faecalis and Staphylococcus aureus, documenting its suitability as a blue-light photosensitizer for antimicrobial applications.

• Authors: Kaplan Kirakci , Jaroslav Zelenka , Michaela Rumlová , Josef Cvačka , Tomáš Ruml , Kamil Lang
• Journal: Biomaterials science (Biomater Sci) Vol. 7 Issue 4 Pg. 1386-1392 (Mar 26 2019) ISSN: 2047-4849 [Electronic] England
• PMID: 30656318 (Publication Type: Journal Article)

Chemical References

• Anti-Bacterial Agents
• Antineoplastic Agents
• Cations
• Ligands
• Organometallic Compounds
• Singlet Oxygen
• Molybdenum

Topics

• Anti-Bacterial Agents (chemical synthesis, chemistry, pharmacology)
• Antineoplastic Agents (chemical synthesis, chemistry, pharmacology)
• Cations (chemical synthesis, chemistry, pharmacology)
• Cell Proliferation (drug effects)
• Dose-Response Relationship, Drug
• Drug Screening Assays, Antitumor
• Gram-Negative Bacteria (drug effects)
• Gram-Positive Bacteria (drug effects)
• HeLa Cells
• Humans
• Ligands
• Microbial Sensitivity Tests
• Mitochondria (drug effects)
• Molecular Structure
• Molybdenum (chemistry, pharmacology)
• Organometallic Compounds (chemical synthesis, chemistry, pharmacology)
• Photochemotherapy
• Singlet Oxygen (chemistry, metabolism)
• Structure-Activity Relationship