Photodamage in a Mitochondrial Membrane Model Modulated by the Topology of Cationic and Anionic Meso‐Tetrakis Porphyrin Free Bases

Abstract

The photodynamic effects of the cationic TMPyP (meso-tetrakis [N-methyl-4-pyridyl]porphyrin) and the anionic TPPS4 (meso-tetrakis[4-sulfonatophenyl]porphyrin) against PC/CL phosphatidylcholine/cardiolipin (85/15%) membranes were probed to address the influence of phorphyrin binding on lipid damage. Electronic absorption spectroscopy and zeta potential measurements demonstrated that only TMPyP binds to PC/CL large unilamellar vesicles (LUVs). The photodamage after irradiation with visible light was analyzed by dosages of lipid peroxides (LOOH) and thiobarbituric reactive substance and by a contrast phase image of the giant unilamellar vesicles (GUVs). Damage to LUVs and GUVs promoted by TMPyP and TPPS4 were qualitatively and quantitatively different. The cationic porphyrin promoted damage more extensive and faster. The increase in LOOH was higher in the presence of D2O, and was impaired by sodium azide and sorbic acid. The effect of D2O was higher for TPPS4 as the photosensitizer. The use of DCFH demonstrated that liposomes prevent the photobleaching of TMPyP. The results are consistent with a more stable TMPyP that generates long-lived singlet oxygen preferentially partitioned in the bilayer. Conversely, TPPS4 generates singlet oxygen in the bulk whose lifetime is increased in D2O. Therefore, the affinity of the porphyrin to the membrane modulates the rate, type and degree of lipid damage.

Metalloporphyrin Pd(T4) Exhibits Oncolytic Activity and Cumulative Effects with 5-ALA Photodynamic Treatment against C918 Cells

“…Considering these genes are typically overexpressed in cancer cells [45], their subsequent degradation after illumination [41] highlights another benefit of PDT against cancer. Our data further agreed with previous TMPyP findings [41,44,46], where results obtained with DNase and phospholipase ( Figure 6) led to the conclusion of a low level of complex formation with DNA and phospholipids, although most of the binding was with proteins. Together, these findings support using both 5-ALA and Pd(T4)-PDT simultaneously to target mitochondrial-and lysosomal-mediated death pathways, potentially leading to synergistic effects.…”

“…In our study, Pd(T4) exhibited oncolytic activity as soon as 5 min pre-illumination, which is significantly shorter than previously recorded at 2 h [41]. One of the facets contributing to the efficacy of TMPyP as a photosensitizer can be attributed to its diverse locations within the cell, accumulating primarily in the lysosome [42,43], as well as in the cytoplasm, phospholipid membrane [44], microtubules [31], and the G-rich sequences of DNA and mRNA [41]. The latter has been further characterized by Rapozzi et al, where TMPyP was intercalated with the G-rich 5 -untranslated region of ras genes [41] forming a G-quadruplex.…”

Not Only Oxidation of Cardiolipin Affects the Affinity of Cytochrome c for Lipid Bilayers

“…The GUVs were composed of monounsaturated lipids, POPC, DOPE, and TOCL, susceptible only to attack by singlet oxygen, to avoid the oxidation of the lipids caused by the applied electric field. 46 The images obtained in the absence of cyt c reveal that CL is clustered in particular domains rather than homogeneously distributed in the bilayer (mixed with PC and PE). The addition of cyt c to the GUV suspension led to two main effects: quenching of the fluorescence by Forster energy transfer and changes in the lipid domains.…”

Self assembled complexes of multibranched gold nanoparticles with porphyrins used in photodynamic therapy Spectral and structural characterization

“…The GNPs synthesized using 2.5 and 5.0 mM HEPES, pH 7.0 were associated with cationic and anionic meso-tetrakis porphyrins, TMPyP (5, 10, 15, 20 tetrakis(1-metyl-4-pyridinio) porphyrin tetra(p-toluenesulfonate) and TPPS4 ((4, 4', 4'', 4'''-(porphyrine-5, 10, 15, 20 tetrayl) tetrakis benzenesulfonic acid. These porphyrins were the choice because the wellknown application in photodynamic therapy (PDT) (21). The association of the porphyrins with GNPs was evidenced by changes of zeta potential (ζ).…”