Taurine-modified Ru(ii)-complex targets cancerous brain cells for photodynamic therapy

Abstract

The precision and efficacy of photodynamic therapy (PDT) is essential for the treatment of brain tumors because the cancer cells are within or adjacent to the delicate nervous system. Taurine is an abundant amino acid in the brain that serves the central nervous system (CNS). A taurine-modified polypyridyl Ru-complex was shown to have optimized intracellular affinity in cancer cells through accumulation in lysosomes. Symmetrical modification of this Ru-complex by multiple taurine molecules enhanced the efficiency of molecular emission with boosted generation of reactive oxygen species. These characteristic features make the taurine-modified Ru-complex a potentially effective photosensitizer for PDT of target cancer cells, with outstanding efficacy in cancerous brain cells.

Selective Photoinactivation of Methicillin‐Resistant Staphylococcus aureus by Highly Positively Charged RuII Complexes

“…Using 3,3′‐(anthracene‐9,10‐diyl)‐dipropanoic acid (9,10‐ADPA) as 1 O 2 trapping agent, which reacts with 1 O 2 in a quantitative fashion to produce a non‐absorbing/emitting compound, the 1 O 2 quantum yields were measured to be 0.32±0.03 for Ru1 , 0.40±0.05 for Ru2 and 0.38±0.04 for Ru3 in H 2 O by monitoring the absorption decay of 9,10‐ADPA at 378 nm (Figure S5). The luminescence lifetimes in H 2 O were measured to be 566 ns for Ru0 , 282 ns for Ru1 , 517 ns for Ru2 and 847 ns for Ru3 , which is consistent with other reported Ru II complexes with similar structures . The lower 1 O 2 quantum yield of Ru1 may result from its shorter excited state lifetime.…”

“…The luminescence lifetimes in H 2 Ow ere measured to be 566 ns for Ru0,2 82 ns for Ru1,5 17 ns for Ru2 and 847 ns for Ru3,w hich is consistent with other reported Ru II complexes with similar structures. [34] The lower 1 O 2 quantum yield of Ru1 may result from its shorter excited state lifetime.…”

Development of Natural Product-Conjugated Metal Complexes as Cancer Therapies

“…Taurine is a typical amino acid existing in the brain and is involved in central nervous system (CNS) signaling. A taurine-bearing ruthenium(II) compound ( 5a ) has been reported by Zhang and coworkers for targeting brain cancer cells (Figure 6) [64]. Complex 5a showed lysosome-specific intracellular accumulation in cancer cells.…”

“…Ruthenium(II) complexes bearing proteinogenic α-amino acids exhibit potentially reduced cytotoxicity over cancer cells in contrast to anticancer platinum complexes [64]. In 2018, Santos and coworkers [65] developed thirteen amino acid conjugated ruthenium(II) complexes as cancer therapeutic drugs, including l -methionine (Met), l -histidine (His), l -tryptophan (Trp), l -tyrosine (Tyr), l -valine (Val), l -alanine (Ala), and glycine (Gly).…”

Polymeric Encapsulation of a Ruthenium Polypyridine Complex for Tumor Targeted 1- and 2-Photon Photodynamic Therapy

“…During the active targeting of a tumor, a specific interaction of a molecule, such as a signaling peptide, oligonucleotide, oligosaccharide, protein, receptor targeting moiety or an antibody, is used to transport the therapeutic molecule. [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] A large variety of transition metal complexes have been successfully coupled to peptides resulting in increased receptor selectivity. [48][49][50] As examples for Ru(II) polypyridine complexes, the conjugation to the peptide hormone somatostatin showed a 100-fold increased selectivity for somatostatin receptor-expressing cells relative to the free PS.…”