[Cu(TPMA)(Phen)](ClO₄)₂: Metallodrug Nanocontainer Delivery and Membrane Lipidomics of a Neuroblastoma Cell Line Coupled with a Liposome Biomimetic Model Focusing on Fatty Acid Reactivity

Abstract

The use of copper complexes for redox and oxidative-based mechanisms in therapeutic strategies is an important field of multidisciplinary research. Here, a novel Cu(II) complex [Cu(TPMA)(Phen)](ClO4)2 (Cu-TPMA-Phen, where TPMA = tris-(2-pyridylmethyl)amine and Phen = 1,10-phenanthroline) was studied using both the free and encapsulated forms. A hollow pH-sensitive drug-delivery system was synthesized, characterized, and used to encapsulate and release the copper complex, thus allowing for the comparison with the free drug. The human neuroblastoma-derived cell line NB100 was treated with 5 μM Cu-PMA-Phen for 24 h, pointing to the consequences on mono- and polyunsaturated fatty acids (MUFA and PUFA) present in the membrane lipidome, coupled with cell viability and death pathways (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium viability assay, flow cytometry, microscopy, caspase activation). In parallel, the Cu-TPMA-Phen reactivity with the fatty acid moieties of phospholipids was studied using the liposome model to work in a biomimetic environment. The main results concerned: (i) the membrane lipidome in treated cells, involving remodeling with a specific increase of saturated fatty acids (SFAs) and a decrease of MUFA, but not PUFA; (ii) cytotoxic events and lipidome changes did not occur for the encapsulated Cu-TPMA-Phen, showing the influence of such nanocarriers on drug activity; and (iii) the liposome behavior confirmed that MUFA and PUFA fatty acid moieties in membranes are not affected by oxidative and isomerization reactions, proving the different reactivities of thiyl radicals generated from amphiphilic and hydrophilic thiols and Cu-TPMA-Phen. This study gives preliminary but important elements of copper(II) complex reactivity in cellular and biomimetic models, pointing mainly to the effects on membrane reactivity and remodeling based on the balance between SFA and MUFA in cell membranes that are subjects of strong interest for chemotherapeutic activities as well as connected to nutritional strategies.

The Entrapment of Somatostatin in a Lipid Formulation: Retarded Release and Free Radical Reactivity

“…Lipid peroxidation and isomerization have been already evidenced for antitumoral drugs [20], and nowadays the oxidative aspect is considered not only as a side effect induced by anticancer therapy, but also as a condition to create oxidant-antioxidant unbalance in cancer cells [30]. This is connected with the metal redox state of the cellular environment that can be an important trigger of radical reactions, as shown for the reactivity of copper complexes [31,32]. Thiol compounds are reactive species in this context as in the new model here proposed for SST, expanding the actual knowledge of the molecular properties of this peptide for pharmacological applications.…”

Polypyridyl‐Based Copper Phenanthrene Complexes: Combining Stability with Enhanced DNA Recognition

“…In that work, the caging system was tris-(2-pyridylmethyl)amine (TPMA)-at etradentatec helatorw ith three pyridine groups-and although DNA binding affinity was moderate, they displayed excellent solution stability and provided chemicaln uclease activity departing from classical Fenton chemistry.T he cytotoxicity of one complex, Cu-TPMA-Phen, was subsequently tested in neuroblastoma cells (NB100) with activity in the low micromolar range (EC 50 = 4.2 mm). [24] The current study set out to establish if the DNA binding affinity and cytotoxicity of this chemotype could be enhanced whilem aintaining( a) high solution stability and (b) appropriate redox chemistry neededf or DNA oxidation. Therefore, we selected DPA[ di-(2-pycolylamine)])-a less sterically hindered tris chelator with two pyridine groups,a nd coordinated this to specific Cu II phenanthrenes.…”

“…This design yielded a new type of AMN with DNA oxidation chemistry departing substantially from Cu‐Phen or simple Fenton reagents [23] . The complexes showed promising preclinical chemotherapeutic activity against human neuroblastoma‐derived cells (NB100) with EC 50 values falling in the micromolar range [24] . The presence of TPMA enhanced complex stability and facilitated rearrangement of the coordination sphere during redox cycles.…”

“…[23] The complexes showedp romising preclinical chemotherapeutic activity againsth uman neuroblastoma-derived cells (NB100) with EC 50 values falling in the micromolar range. [24] The presence of TPMA enhanced complex stabilitya nd facilitated rearrangement of the coordination sphere during redox cycles. However,D NA binding and oxidative cleavage were nonethelessh ampered by the steric bulk of TPMA which contains three pyridine groups.…”

Copper bis-Dipyridoquinoxaline Is a Potent DNA Intercalator that Induces Superoxide-Mediated Cleavage via the Minor Groove

“…In recent years, we have focused on introducing modifications to the Cu-Phen scaffold to enhance DNA recognition, oxidative damage and cytotoxicity [11]. Approaches including inner sphere modifications using coordinated carboxylate groups [13]; dicarboxylate groups (e.g., o-phthalate or octanedioate) [26,27,28,29,30,31]; designer phenazine intercalators [32,33]; tris-(2-pyridylmethyl)amine (TPMA) caging ligands [34,35]; and the introduction of a binuclear di -cation have been undertaken [26,30,36]. Previously, we reported a series of phenazine-functionalized Cu(II) phenanthroline complexes—with general formula [Cu(N,N′)(Phen)] 2+ (where N,N′ = dipyridoquinoxaline (DPQ) or dipyridophenazine (DPPZ))—that offered a significant enhancement of DNA binding affinity relative to Cu–Phen [32].…”