Next Article in Journal
Naturally Occurring Microbiota-Accessible Borates: A Focused Minireview
Next Article in Special Issue
Analysis of Biomolecular Changes in HeLa Cervical Cancer Cell Line Induced by Interaction with [Pd(dach)Cl2]
Previous Article in Journal
Luminescent Materials with Advanced Properties and Applications
Previous Article in Special Issue
Comparative Study of Docking Tools for Evaluation of Potential Copper Metallodrugs and Their Interaction with TMPRSS2
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Inorganics
Volume 12
Issue 12
10.3390/inorganics12120307
inorganics-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Interaction of Phenanthroline-Containing Copper Complexes with Model Phospholipid Membranes

by
Priscilla Freddi
1,†,
Natalia Alvarez
2,†,
Gianella Facchin
2,* and
Antonio J. Costa-Filho
1,*
1
Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP, Brazil
2
Química Inorgánica, Departamento Estrella Campos, Facultad de Química, Universidad de la República, Av. General Flores 2124, Montevideo 11800, Uruguay
*
Authors to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Inorganics 2024, 12(12), 307; https://doi.org/10.3390/inorganics12120307
Submission received: 30 October 2024 / Revised: 19 November 2024 / Accepted: 23 November 2024 / Published: 26 November 2024
(This article belongs to the Special Issue Evaluation of the Potential Biological Activity of Metallo-Drugs)
Browse Figures
Versions Notes

Abstract

Medicinal Inorganic Chemistry has provided oncology with metallodrugs for cancer treatment, including several promising candidate drugs. In particular, copper(II) coordination compounds with phenanthroline stand out as potential anticancer agents. In this work, we used Differential Scanning Calorimetry and Electron Spin Resonance to investigate the interaction of the copper phenanthroline complexes [Cu(phen)]2+ and [Cu(L-dipeptide)(phenanthroline) (L-dipeptide: L-Ala-Gly and L-Ala-Phe)) with model lipid membranes (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC, and 1,2-dipalmitoyl-sn-glycero-3-phospho-(1′-rac-glycerol) sodium salt, DPPG). Our results showed that the complexes interact with the membrane models, fluidizing them. The [Cu(phen)]2+ presented a different localization than the free ligand phen. The dipeptide modulated the localization of the complex in the membrane and the modifications induced in the physicochemical properties of the lipid vesicles. A stronger interaction with DPPG anionic membranes was observed, which mimic membranes with negatively charged surfaces, as found on several tumor cells.

Graphical Abstract

1. Introduction

Medicinal Inorganic Chemistry has provided medicine with drugs widely and successfully used in oncology, such as Cisplatin, as well as a group of candidate compounds in different stages of research [1,2,3]. Elucidation of the interaction between metal complexes and cell membranes is a topic that has not yet been deeply explored, although it may be helpful for the rational design of anticancer drugs [1,2,3,4].
Copper coordination compounds are emerging as possible alternatives for the treatment of cancer [5,6,7,8,9]. Copper is an essential metal, and living organisms present metabolic routes to handle it. Consequently, copper complexes may present lower inherent toxicity than platinum-based compounds. In addition, the different coordination chemistry of copper in relation to platinum may give rise to different molecular mechanisms of action, therefore presenting different spectra of activity than Cisplatin and other Pt compounds. Several copper complexes have been reported to act as pharmacological agents, including potential anticancer drugs. Among the latter, multiple Cu(II) compounds containing phenanthroline, phen, were studied for their antitumor activity [6,9,10,11,12,13]. One complex of the family of Casiopeínas® reached clinical trials [14,15,16]. The molecular mechanism of action of Cu-phen-derived compounds is believed to include DNA binding and reactive oxygen species (ROS) production, leading to cellular death [6,15,16,17,18].
The interaction of biologically active compounds with cellular membranes influences their bioavailability, even when membranes are not considered the biological target of this type of compound [19,20,21,22]. The cell membrane can act as a barrier or a target for anticancer drugs. A compound localized in the membrane can modify its fluidity or promote chemical reactions. For instance, there is growing awareness of the importance of cellular uptake and efflux mechanisms as factors that control clinical resistance to platinum drugs [23,24,25]. For different coordination compounds that contain phen, a pronounced accumulation of the compound in the membrane fraction of the treated cells has been observed [26]. The interaction with the membrane may also be the determinant of the different antitumor activity as proposed for [Cu(5,6-dimethyl-phen)(acetylacetonate)]NO3 and [Cu(4,7-dimethyl-1,10-phen)(acetylacetonate)]NO3 of the Casiopeínas® family [27]. In this case, the position of the methyl groups on the phenanthroline ligand has proven to strongly influence in vivo activity, which seems modulated by the different abilities of the complexes to be retained in the cellular membrane. In contrast with a large number of studies of the interaction of coordination copper compounds with DNA, there are only a few reports of experimental studies on the interaction of these compounds with lipid model membranes [28,29,30,31,32,33].
As part of our studies on new copper compounds with potential applications in cancer treatment, we developed a series of heteroleptic copper compounds containing phen and L-dipeptides as ligands [34,35,36]. They present higher cytotoxic activity in tumor cell cultures than the reference drug Cisplatin. No direct relationship between the cytotoxicity and the DNA interaction or lipophilicity could be established. To understand the molecular basis that modulates their activity, in this work, we present our first results on the study of the interaction of [Cu(L-Ala-Gly)(phen)] and [Cu(L-Ala-Phe)(phen)] (Figure 1) with lipidic model membranes. Complexes were selected based on our previous studies, considering their different cytotoxic activity. On the other hand, the homoleptic [Cu(phen)]2+ species was also assessed for comparative purposes and because the [Cu(phen)]2+ moiety is a typical fragment of a myriad of other copper compounds with biological activity [37].
The membrane models used were 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (sodium salt) (DPPG). DPPC represents one of the most abundant lipid components of cell plasma membranes. The negatively charged DPPG allows the comparison with the effect on membranes with negatively charged surfaces, commonly found on the inside leaflet of the standard cell membrane and on both sides of several tumor cells [4,38]. The effect of introducing the selected compounds on the phase transitions of the lipid bilayer models was assessed using differential scanning calorimetry (DSC) and electron spin resonance (ESR).

2. Results and Discussion

2.1. DSC Measurements

Small molecules near the lipid bilayer are responsible for disrupting the long-range phase transitions of the lipid model membranes, as in the studies in this work. This effect was initially studied using DSC. Introducing a small molecule can alter the thermodynamic parameters associated with the phase transition (transition temperature—Tm, enthalpy H, and entropy S variations). The mechanisms underlying the interaction lead to different effects on the calorimetric profile.
The thermograms corresponding to DSC measurements of DPPC or DPPG bilayers in the absence and presence of the metal complexes are presented in Figure 2 and Figure 3, respectively. At the same time, Table 1 shows the respective thermodynamic parameters corresponding to the pre- and main transitions. Variations in the lipid phase transition temperature may indicate structural changes in the bilayer caused by the external agents, as well as alterations in the cooperativity of the transition and lipid packing, which can be observed through changes in entropy and/or the shape of the transition curve. As the temperature of DPPC bilayers increased, two thermal transitions were registered in measurements in the presence or absence of the studied compounds. The first weak broad peak corresponded to the pre-transition between the gel phase Lβ′ and the ripple phase Pβ′ (at around 35 °C). At higher temperatures, a sharp peak corresponding to the more energetic transition between the Pβ′ and the liquid-crystalline phase Lα (at approximately 41 °C) was observed.
In the presence of the complexes, the calorimetric profile of DPPC changed slightly. The main phase transition temperature was not modified, whereas its enthalpy variation was somewhat higher, indicating that the complexes likely established a slightly more effective interaction network. On the other hand, the cooperativity of the main phase transition was slightly reduced as measured by the increase in the transition’s width at half-height (ΔT1/2), indicating that the metal complexes decreased the size of the cooperative unit. The main phase transition temperature and the corresponding cooperativity (sharpness of the peak measured by the inverse of ΔT1/2) are believed to be regulated by interactions involving the acyl chains up to carbon 10 [39,40,41]. The low extent of alterations induced by the complexes on the DPPC main phase transition suggests that the compounds did not penetrate much into the bilayer. Among the various compounds, the one that induced the most significant changes was [Cu(L-Ala-Phe)(phen)]·4H2O, likely due to the presence of the dipeptide containing the hydrophobic amino acid phenylalanine, which is known to efficiently position in the membranes and increase its permeability [42].
The pre-transition peak observed for pure DPPC liposomes in DSC experiments has been attributed to the rotation of the phospholipid polar headgroups. Their hydration played a critical role in the formation of the rippled phase [43,44]. Therefore, the pre-transition is highly sensitive to the presence of foreign molecules on the bilayer surface. The reduction in both pre-transition temperature and enthalpy variation (Table 1) in the presence of the metal complexes suggests a direct interaction between them and the PC headgroup (membrane-solvent interface), in agreement with the minor alterations observed in the main phase transition parameters. Once again, the side chain of phenylalanine appears to be the critical factor responsible for the most significant changes induced by that compound.
DPPG bilayers presented only the sharp peak corresponding to the gel-to-liquid-crystalline phase transition around 39 °C (Figure 3). In contrast to the zwitterionic membrane, the negatively charged DPPG liposomes exhibited substantial changes upon adding the molecules of interest (Figure 3). Such more extensive modifications of the calorimetric behavior of DPPG membranes are consistent with an electrostatic interaction between the complex and the negatively charged surface of the membrane.
In the presence of the metal complexes, the main phase transition temperature decreased, as shown in Table 1, suggesting the compounds had a fluidizing effect on the lipid membrane. The [Cu(phen)]2+ complex has been reported to form a stable mixed ligand complex with phosphatidylglycerol of lipid membranes, neutralizing their charges and lowering the z potential of the membrane liposomes [45]. The observed behavior is different from that reported for Cisplatin, which increases transition temperature, decreasing membrane fluidity on anionic membrane models [23,24,46]. For the [Cu(Ala-Phe)(phen)] and [Cu(phen)]2+ complexes, the cooperative unit decreases, suggesting the complex localization allows it to interfere in the C1-C10 acyl chain region. In contrast, [Cu(Ala-Gly)(phen)] did not seem to disturb the cooperative unit. This behavior is different than that observed for the ligand phen alone in both membrane models [47].

2.2. ESR Measurements

To obtain molecular-level information regarding the interactions between the compounds and membrane mimetics, ESR measurements were performed on DPPC or DPPG liposomes containing the spin probes DOPTC, 5-PCSL or 16-PCSL, which monitor changes induced by the compounds on the membrane surface, the beginning of the acyl chain or the middle of the bilayer, respectively. The spectra were measured as a function of the temperature. The empirical parameters h+1, h0, h−1 (intensities of the ESR resonances) of the DOPTC and 16-PCSL or 2Amax (outer line separation) of the 5-PCSL were determined from the ESR spectra as described elsewhere [48]. These parameters are related to the mobility of the spin label in the membrane and can be linked to membrane fluidity. Higher ratios of the ESR line intensities (h+1/h0 or h−1/h0) indicate higher probe mobility. As for Amax, higher values point to lower mobilities (or higher order). The temperature variations of those parameters in the different lipid vesicles are shown in Figure 4, Figure 5 and Figure 6.
At the position of the polar headgroup of the membrane, monitored by the DOPTC probe, we observe more subtle effects in DPPC compared to DPPG (Figure 4), once again underscoring the relevance of the lipid charges (zwitterionic DPPC as compared to the negative DPPG) and in agreement with our DSC results. In DPPC, the most notable change arose from the presence of [Cu(Ala-Gly)(phen)] and [Cu(Ala-Phe)(phen)] that induced a slight increase in membrane fluidity as indicated by slightly higher h+1/h0 values in the fluid phase of DPPC (temperatures above ca. 39 °C). In DPPG, although inducing a more irregular pattern, all the compounds decreased the ordering at the polar headgroup region, likely due to their localization in this area of the lipid vesicle, as also suggested by our DSC data.
Moving down the acyl chain to the region monitored by the 5-PCSL probe, we observe that the metal compounds slightly altered the parameter related to this probe (Figure 5). Although these changes were subtle, they were noteworthy considering our DSC results as follows: (1) in DPPC, [Cu(Ala-Gly)(phen)] induced a discrete decrease in Tm and [Cu(Ala-Phe)(phen)] a decrease in the transition cooperativity (as seen in the slope of the curve); (2) in DPPG, a decrease in the phase transition temperature was observed, indicating a fluidizing effect of the DPPG membrane that agrees with the corresponding DSC data (Figure 3). Changes in the more ordered and less mobile region around C5 of the acyl chain are sometimes poorly reported by the 5-PCSL, whose naturally broader ESR spectra prevent observing more significant effects.
In the middle of the bilayer, the more fluid and dynamic environment results in sharper ESR spectra for the 16-PCSL probe compared to 5-PCSL. Therefore, changes are more easily detected in the 16-PCSL spectra even when the molecules are not located precisely halfway through the bilayer. This was the case observed in Figure 6. In DPPC, [Cu(Ala-Phe)(phen)] induced a shift of the transition curve to higher temperatures, showing that ESR can detect local alterations in the bilayer that are not seen in the overall heat exchange detected in DSC. In DPPG, the phase transition temperatures, as monitored by ESR (lower panel in Figure 6), were decreased in the presence of the compounds, which agrees with our DSC data (Figure 3). Moreover, we observe a significant increase in the dynamics of DPPG starting around the transition temperature and persisting in the fluid phase, which likely contributed to the membrane fluidization effect observed in the DSC experiments. This effect could contribute to the compound binding to the membrane and its subsequent passage through the lipid barrier. More studies will be required to validate this proposal fully.
All in all, our ESR data shows that DPPG membranes are more affected by the compounds than DPPC membranes and that in DPPC, the changes are mild, except for the increase in mobility of the middle of the bilayer induced by [Cu(Ala-Phe)(phen)]. In DPPG, the complexes promoted a decrease in the mobility of the headgroups and an increase in the mobility of the acyl chains, likely resulting from their location near the bilayer surface.
All these studies were performed at a concentration higher than those used to assess the cytotoxic activity (IC50 in the micromolar range) and observe the effects via the techniques used. Effects at micromolar concentrations can be more subtle but have similar characteristics. Taking into account the results obtained in this study and previous studies of cytotoxic activity, it can be observed that [Cu(Ala-Phe)(phen)], the complex that distributes more pronouncedly into the model membranes, is also the more cytotoxic. This can be related simply to better complex membrane permeation or this interaction being part of the mechanism of action. For a related complex, [Cu(Sal)(phen)] [49], it was found that treatment of tumor cells with phen-containing compounds induced marked membrane damage, which can be part of the mechanism of action.

2.3. Full Interaction Maps

As presented in Figure 7, the following features are standard in the Full Interaction Maps (FIM) of the studied structures. H- donor-acceptor regions surround the N atom in the phen ligand, the carbonyl group, aminic and amidic nitrogen atoms, as well as the aromatic C-H bonds. Hydrophobic interactions involving the phen group appear as central orange regions above and below the aromatic extended rings. These interactions mapped through the empiric information stored on the IsoStar library attest to the potential intermolecular interactions in which these molecules can participate.
The FIM of the phen ligand, Figure 7a, is in agreement with our previous experimental and theoretical studies of its interaction with DPPC, where the phenanthroline ligand is distributed throughout the DPPC bilayer interacting with the polar groups through a series of water molecule mediated hydrogen bonds and involving the N atom, as well as hydrophobic interactions involving the extended rings and the acyl chains in the bilayer [47].
For the studied copper complexes, the experimental evidence of an interaction with the PC headgroup can be explained in terms of the potential intermolecular interactions predicted both by the FIM analysis and the previously published results on the ligand. [47] In the case of [Cu(phen)]2+, in addition to the electrostatic interaction between the cationic complex and the phosphate groups, hydrogen bonds may be expected involving the coordinated water molecules in the complex and the oxygen atoms in the phosphate group in the DPPC. For the ternary complexes, direct hydrogen bonding involving the aminic and amidic N-H groups in the coordinated dipeptide is, as expected, predicted by the FIMs, Figure 7b, c, and d. Also, due to the electron density distribution expected for these types of complexes, where an electropositive region surrounding the copper center at the base of the square-based pyramid geometry [50] can also be expected to participate in polar interactions with the PC headgroup.
In addition, these complexes can interact hydrophobically with the acyl chains in the DPPC through the aromatic moieties within the structures as reported for phen [47]. In particular, for [Cu(Ala-Phe)(phen)], the benzyl group in the Phe aminoacid adds to the available interactions that can also participate in hydrophobic interactions as predicted by the FIM analysis, in agreement with the observed deeper distribution of this complex in the MLVs as previously discussed.

3. Materials and Methods

3.1. Materials

Lipids 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (sodium salt) (DPPG) and spin label 1-palmitoyl-2-stearoyl-(n-doxyl)-s16-glycero-3-phosphocholine (16PC) were obtained from Avanti Polar Lipids, Inc. (Birmingham, AL, USA). Hepes buffer (4-(2-hydroxyethyl)-1-piperizineethanesulfonic) and phenanthroline (phen) were purchased from Sigma-Aldrich (São Paulo, Brazil). All reagents were used without further purification. Complexes [Cu2Cl4(phen)2], [Cu(L-Ala-Gly)(phen)]·5H2O, and [Cu(L-Ala-Phe)(phen)]·4H2O were synthesized as previously reported (purity was assessed by elemental analysis and infrared spectra) [36,51].

3.2. Methods

3.2.1. Sample Preparation

Lipid films were formed by drying chloroform/methanol (2/1, v/v) stock solutions of phospholipids under nitrogen flow, followed by centrifugation under vacuum for at least 2 h to ensure complete removal of the organic solvent. The films were hydrated by adding 20 mM Hepes buffer pH = 7.4, vortexed for 15 min, and sonicated to a final concentration of 5 mM. Complexes dissolved in the same buffer were added to the mixture to a final concentration of 0.5 mM and left for at least 15 min at 60 °C before measurements. For ESR measurements, 0.5 mol% of the spin labels were added to the initial chloroform/methanol lipid stock solution before film formation.

3.2.2. Calorimetric Measurements

Differential scanning calorimetry (DSC) experiments were performed in a VP-DSC MicroCal MicroCalorimeter (Malvern Panalytical, Westborough, MA, USA). To that end, a 5 mM lipid suspension in 20 mM Hepes buffer pH = 7.4 with 0.5 mM sample concentration was used to ensure a 10:1 lipid–compound relationship. The mixture was stabilized at 25 °C for 20 min before each measurement. Scans were recorded between 25 and 60 °C using a 20 °C/hour heating program, and scans were recorded only during the heating scans and at least twice to ensure reproducibility. Baseline correction and endotherm peak integration were performed on Microcal Origin 2022b software.

3.2.3. Electron Spin Resonance Measurements

ESR spectra were performed on an X-band E109 Varian spectrometer, and the temperature was controlled using an E257-X Varian temperature control unit. Samples were transferred into 1 mm inner diameter glass capillaries and then placed on a quartz tube containing mineral oil to help stabilize the sample temperature. Acquisition conditions were as follows: field modulation frequency: 100 kHz; field modulation amplitude: 1 G; sweep width: 160 G; microwave power: 20 mW.

3.2.4. Full Interaction Map

In order to further rationalize the intermolecular interactions possible between the studied molecules and the DPPC probe the crystal structure for phen, [CuCl2(phen)], [Cu(Ala-Gly)phen], and [Cu(Ala-Gly)phen] were recovered from the Cambridge Structural Databank (CSD) [52], refcodes OPENAN01, NUZPIH02, JABYER and LOPPEN, respectively. Their Full Interaction Maps (FIM) [53] were constructed using the CSD-Materials module in Mercury (v2024.2.0 build 415171). The construction of the FIM is based on the IsoStar library that gathers the information on intermolecular interactions in all the structures stored at the CSD Database and presents it as scatterplots related to pairs of functional groups [53]. The interactions can then be visualized as 3D scatterplots, including density maps that account for the relative chance of that particular intermolecular contact occurring. For the analysis in this article, we defined the central groups (about the studied molecule) as NH with uncharged nitrogen, carbonyl, and water oxygen atoms, methyl carbon, and aromatic carbon atoms. The obtained FIMs are represented in Figure 7, where the region is red for the acceptor of H bonds, blue for donor H bonds, and orange for hydrophobic groups.

4. Conclusions

All the complexes interacted with the studied model membranes as detected by DSC and ESR methods. The interaction was more pronounced with the negatively charged membrane model DPPG, fluidizing the membrane as a result of an increase in the mobility of the acyl chains and despite a decrease in the mobility of the headgroups and likely resulting from their location near the bilayer surface. In DPPC, the changes were mild, except for the increase in mobility of the middle of the bilayer induced by [Cu(Ala-Phe)(phen)].
With relation to the influence of the coordination on phen localization, the binary, cationic species [Cu(phen)]2+ was detected mainly in the polar zone of the bilayer, different from the phen ligand [47], which is located deeper into the bilayer. In ternary systems [Cu(dipeptide)(phen)], the dipeptide ligand influenced the localization of the complex in the membrane. The [Cu(Ala-phe)(phen)] complex was detected deep in the DPPC membrane bilayer. All the complexes seemed to localize around the polar head on the negatively charged membrane model.
This interaction might be part of the cytotoxic activity mechanism or influence the compounds’ availability inside the cell. The more robust interaction with negatively charged membranes may help to target cancer cells preferentially.

Author Contributions

Conceptualization, A.J.C.-F.; Data curation, P.F. and N.A.; Formal analysis, P.F.; Funding acquisition, A.J.C.-F.; Investigation, P.F. and N.A.; Methodology, A.J.C.-F.; Project administration, A.J.C.-F.; Resources, G.F. and A.J.C.-F.; Supervision, A.J.C.-F.; Validation, G.F. and A.J.C.-F.; Visualization, P.F. and N.A.; Writing—original draft, G.F. and A.J.C.-F.; Writing—review & editing, G.F. and A.J.C.-F. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) (Grant no. 2023/04532-9), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (Grant no. 306682/2018-4), Programa de Desarrollo de las Ciencias Básicas, (PEDECIBA, Uruguay), Comisión Sectorial de Investigación Científica (CSIC, Udelar, Uruguay) and Agencia Nacional de Investigación e Innovación (ANII, Uruguay).

Data Availability Statement

The dataset is available upon request from the authors.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Casini, A.; Vessières, A.; Meier-Menches, S.M. Metal-Based Anticancer Agents; Royal Society of Chemistry: London, UK, 2019; Volume 14. [Google Scholar]
  2. Abdolmaleki, S.; Aliabadi, A.; Khaksar, S. Riding the metal wave: A review of the latest developments in metal-based anticancer agents. Coord. Chem. Rev. 2024, 501, 215579. [Google Scholar] [CrossRef]
  3. Alassadi, S.; Pisani, M.J.; Wheate, N.J. A chemical perspective on the clinical use of platinum-based anticancer drugs. Dalton Trans. 2022, 51, 10835–10846. [Google Scholar] [CrossRef] [PubMed]
  4. Alves, A.C.; Ribeiro, D.; Nunes, C.; Reis, S. Biophysics in cancer: The relevance of drug-membrane interaction studies. Biochim. Biophys. Acta (BBA)-Biomembr. 2016, 1858, 2231–2244. [Google Scholar] [CrossRef] [PubMed]
  5. Balsa, L.M.; Baran, E.J.; León, I.E. Copper Complexes as Antitumor Agents: In vitro and In vivo Evidence. Curr. Med. Chem. 2023, 30, 510–557. [Google Scholar] [CrossRef]
  6. Santini, C.; Pellei, M.; Gandin, V.; Porchia, M.; Tisato, F.; Marzano, C. Advances in Copper Complexes as Anticancer Agents. Chem. Rev. 2014, 114, 815–862. [Google Scholar] [CrossRef]
  7. Ji, P.; Wang, P.; Chen, H.; Xu, Y.; Ge, J.; Tian, Z.; Yan, Z. Potential of Copper and Copper Compounds for Anticancer Applications. Pharmaceuticals 2023, 16, 234. [Google Scholar] [CrossRef]
  8. da Silva, D.A.; De Luca, A.; Squitti, R.; Rongioletti, M.; Rossi, L.; Machado, C.M.L.; Cerchiaro, G. Copper in tumors and the use of copper-based compounds in cancer treatment. J. Inorg. Biochem. 2022, 226, 111634. [Google Scholar] [CrossRef]
  9. Kumar Singh, A.; Kumar, A.; Singh, H.; Sonawane, P.; Pathak, P.; Grishina, M.; Pal Yadav, J.; Verma, A.; Kumar, P. Metal Complexes in Cancer Treatment: Journey So Far. Chem. Biodivers. 2023, 20, e202300061. [Google Scholar] [CrossRef]
  10. Kellett, A.; Molphy, Z.; McKee, V.; Slator, C. Recent Advances in Anticancer Copper Compounds. In Metal-Based Anticancer Agents; The Royal Society of Chemistry: London, UK, 2019; pp. 91–119. [Google Scholar]
  11. Golubeva, Y.A.; Lider, E.V. Copper(ii) Complexes Based on 2,2′-Bipyridine and 1,10-Phenanthroline as Potential Objects for Developing Antitumor Drugs. J. Struct. Chem. 2024, 65, 1159–1209. [Google Scholar] [CrossRef]
  12. Rani, J.J.; Roy, S. Recent Development of Copper (II) Complexes of Polypyridyl Ligands in Chemotherapy and Photodynamic Therapy. ChemMedChem 2023, 18, e202200652. [Google Scholar] [CrossRef]
  13. Naletova, I.; Satriano, C.; Curci, A.; Margiotta, N.; Natile, G.; Arena, G.; La Mendola, D.; Nicoletti, V.G.; Rizzarelli, E. Cytotoxic phenanthroline derivatives alter metallostasis and redox homeostasis in neuroblastoma cells. Oncotarget 2018, 9, 36289. [Google Scholar] [CrossRef] [PubMed]
  14. Figueroa-DePaz, Y.; Pérez-Villanueva, J.; Soria-Arteche, O.; Martínez-Otero, D.; Gómez-Vidales, V.; Ortiz-Frade, L.; Ruiz-Azuara, L. Casiopeinas of Third Generations: Synthesis, Characterization, Cytotoxic Activity and Structure-Activity Relationships of Mixed Chelate Compounds with Bioactive Secondary Ligands. Molecules 2022, 27, 3504. [Google Scholar] [CrossRef] [PubMed]
  15. Aguilar-Jiménez, Z.; Espinoza-Guillén, A.; Resendiz-Acevedo, K.; Fuentes-Noriega, I.; Mejía, C.; Ruiz-Azuara, L. The Importance of Being Casiopeina as Polypharmacologycal Profile (Mixed Chelate–Copper (II) Complexes and Their In Vitro and In Vivo Activities). Inorganics 2023, 11, 394. [Google Scholar] [CrossRef]
  16. Figueroa-DePaz, Y.; Resendiz-Acevedo, K.; Davila-Manzanilla, S.G.; Garcia-Ramos, J.C.; Ortiz-Frade, L.; Serment-Guerrero, J.; Ruiz-Azuara, L. DNA, a target of mixed chelate copper(II) compounds (Casiopeinas(R)) studied by electrophoresis, UV-vis and circular dichroism techniques. J. Inorg. Biochem. 2022, 231, 111772. [Google Scholar] [CrossRef]
  17. Ruiz, M.C.; Perelmulter, K.; Levín, P.; Romo, A.I.B.; Lemus, L.; Fogolín, M.B.; León, I.E.; Di Virgilio, A.L. Antiproliferative activity of two copper (II) complexes on colorectal cancer cell models: Impact on ROS production, apoptosis induction and NF-κB inhibition. Eur. J. Pharm. Sci. 2022, 169, 106092. [Google Scholar] [CrossRef]
  18. Shobha Devi, C.; Thulasiram, B.; Aerva, R.R.; Nagababu, P. Recent Advances in Copper Intercalators as Anticancer Agents. J. Fluoresc. 2018, 28, 1195–1205. [Google Scholar] [CrossRef]
  19. Lopes, D.; Jakobtorweihen, S.; Nunes, C.; Sarmento, B.; Reis, S. Shedding light on the puzzle of drug-membrane interactions: Experimental techniques and molecular dynamics simulations. Prog. Lipid Res. 2017, 65, 24–44. [Google Scholar] [CrossRef]
  20. Peetla, C.; Bhave, R.; Vijayaraghavalu, S.; Stine, A.; Kooijman, E.; Labhasetwar, V. Drug resistance in breast cancer cells: Biophysical characterization of and doxorubicin interactions with membrane lipids. Mol. Pharm. 2010, 7, 2334–2348. [Google Scholar] [CrossRef]
  21. Wang, K.; Lu, J.; Li, R. The events that occur when cisplatin encounters cells. Coord. Chem. Rev. 1996, 151, 53–88. [Google Scholar] [CrossRef]
  22. Róg, T.; Girych, M.; Bunker, A. Mechanistic Understanding from Molecular Dynamics in Pharmaceutical Research 2: Lipid Membrane in Drug Design. Pharmaceuticals 2021, 14, 1062. [Google Scholar] [CrossRef]
  23. Martinho, N.; Marquês, J.M.T.; Todoriko, I.; Prieto, M.; de Almeida, R.F.M.; Silva, L.C. Effect of Cisplatin and Its Cationic Analogues in the Phase Behavior and Permeability of Model Lipid Bilayers. Mol. Pharm. 2023, 20, 918–928. [Google Scholar] [CrossRef] [PubMed]
  24. Martinho, N.; Santos, T.C.B.; Florindo, H.F.; Silva, L.C. Cisplatin-Membrane Interactions and Their Influence on Platinum Complexes Activity and Toxicity. Front. Physiol. 2019, 9, 01898. [Google Scholar] [CrossRef] [PubMed]
  25. Liu, Q.; Qu, Y.; Van Antwerpen, R.; Farrell, N. Mechanism of the Membrane Interaction of Polynuclear Platinum Anticancer Agents. Implications for Cellular Uptake. Biochemistry 2006, 45, 4248–4256. [Google Scholar] [CrossRef]
  26. Marques, F.; Matos, A.P.; Matos, C.P.; Correia, I.; Pessoa, J.C.; Campello, M.P. Ultrastructural features of cells following incubation with metal complexes using Phenantroline-based ligands: The influence of the metal center. Ultrastruct. Pathol. 2017, 41, 128–129. [Google Scholar] [CrossRef]
  27. García-Ramos, J.C.; Vértiz-Serrano, G.; Macías-Rosales, L.; Galindo-Murillo, R.; Toledano-Magaña, Y.; Bernal, J.P.; Cortés-Guzmán, F.; Ruiz-Azuara, L. Isomeric Effect on the Pharmacokinetic Behavior of Anticancer CuII Mixed Chelate Complexes: Experimental and Theoretical Approach. Eur. J. Inorg. Chem. 2017, 2017, 1728–1736. [Google Scholar] [CrossRef]
  28. Selvaraj, S.; Krishnaswamy, S.; Devashya, V.; Sethuraman, S.; Krishnan, U.M. Investigations on membrane perturbation by chrysin and its copper complex using self-assembled lipid bilayers. Langmuir 2011, 27, 13374–13382. [Google Scholar] [CrossRef]
  29. Bal, W.; Kozlowski, H.; Lisowski, M.; Pettit, L.; Robbins, R.; Safavi, A. A dramatic change in the interaction of Cu (II) with bio-peptides promoted by SDS—A model for complex formation on a membrane surface. J. Inorg. Biochem. 1994, 55, 41–52. [Google Scholar] [CrossRef]
  30. Subczynski, W.K.; Pasenkiewicz-Gierula, M.; Antholine, W.E.; Hyde, J.S. Oriented self-association of copper (II) tetraphenylporphine in liquid-crystalline lipid bilayer membranes: An EPR study. J. Am. Chem. Soc. 1999, 121, 4054–4059. [Google Scholar] [CrossRef]
  31. Pasenkiewicz-Gierula, M.; Subczynski, W.K.; Antholine, W.E. Rotational motion of square planar copper complexes in solution and phospholipid bilayer membranes. J. Phys. Chem. B 1997, 101, 5596–5606. [Google Scholar] [CrossRef]
  32. Subczynski, W.K.; Antholine, W.E.; Hyde, J.S.; Petering, D.H. Orientation and mobility of a copper square-planar complex in a lipid bilayer. J. Am. Chem. Soc. 1987, 109, 46–52. [Google Scholar] [CrossRef]
  33. Castillo, I.; Suwalsky, M.; Gallardo, M.J.; Troncoso, V.; Sánchez-Eguía, B.N.; Santiago-Osorio, E.; Aguiñiga, I.; González-Ugarte, A.K. Structural and functional effects of benzimidazole/thioether–copper complexes with antitumor activity on cell membranes and molecular models. J. Inorg. Biochem. 2016, 156, 98–104. [Google Scholar] [CrossRef] [PubMed]
  34. Muñoz Garzón, K.S.; Álvarez, N.; Facchin, G.; Soria, B.D.; Di Virgilio, A.L. Actividad antitumoral de complejos de cobre(II) con fenantrolina y dipéptidos en células de cáncer de mama. Rev. Colomb. Hematol. Y Oncol. 2024, 11, 14–30. [Google Scholar] [CrossRef]
  35. Facchin, G.; Veiga, N.; Kramer, M.G.; Batista, A.A.; Várnagy, K.; Farkas, E.; Moreno, V.; Torre, M.H. Experimental and theoretical studies of copper complexes with isomeric dipeptides as novel candidates against breast cancer. J. Inorg. Biochem. 2016, 162, 52–61. [Google Scholar] [CrossRef] [PubMed]
  36. Iglesias, S.; Alvarez, N.; Torre, M.H.; Kremer, E.; Ellena, J.; Ribeiro, R.R.; Barroso, R.P.; Costa-Filho, A.J.; Kramer, M.G.; Facchin, G. Synthesis, structural characterization and cytotoxic activity of ternary copper (II)–dipeptide–phenanthroline complexes. A step towards the development of new copper compounds for the treatment of cancer. J. Inorg. Biochem. 2014, 139, 117–123. [Google Scholar] [CrossRef]
  37. Hachey, A.C.; Havrylyuk, D.; Glazer, E.C. Biological activities of polypyridyl-type ligands: Implications for bioinorganic chemistry and light-activated metal complexes. Curr. Opin. Chem. Biol. 2021, 61, 191–202. [Google Scholar] [CrossRef]
  38. Szlasa, W.; Zendran, I.; Zalesińska, A.; Tarek, M.; Kulbacka, J. Lipid composition of the cancer cell membrane. J. Bioenerg. Biomembr. 2020, 52, 321–342. [Google Scholar] [CrossRef]
  39. Jain, M.K.; Wu, N.M. Effect of small molecules on the dipalmitoyl lecithin liposomal bilayer: III. Phase transition in lipid bilayer. J. Membr. Biol. 1977, 34, 157–201. [Google Scholar] [CrossRef]
  40. McElhaney, R.N. The use of differential scanning calorimetry and differential thermal analysis in studies of model and biological membranes. Chem. Phys. Lipids 1982, 30, 229–259. [Google Scholar] [CrossRef]
  41. Basso, L.G.M.; Rodrigues, R.Z.; Naal, R.M.Z.G.; Costa-Filho, A.J. Effects of the antimalarial drug primaquine on the dynamic structure of lipid model membranes. Biochim. Biophys. Acta (BBA)-Biomembr. 2011, 1808, 55–64. [Google Scholar] [CrossRef]
  42. Perkins, R.; Vaida, V. Phenylalanine Increases Membrane Permeability. J. Am. Chem. Soc. 2017, 139, 14388–14391. [Google Scholar] [CrossRef]
  43. Janiak, M.J.; Small, D.M.; Shipley, G.G. Nature of the thermal pretransition of synthetic phospholipids: Dimyristoyl- and dipalmitoyllecithin. Biochemistry 1976, 15, 4575–4580. [Google Scholar] [CrossRef] [PubMed]
  44. Cevc, G. Polymorphism of the bilayer membranes in the ordered phase and the molecular origin of the lipid pretransition and rippled lamellae. Biochim. Biophys. Acta (BBA)-Biomembr. 1991, 1062, 59–69. [Google Scholar] [CrossRef]
  45. Mlakar, M.; Cuculić, V.; Frka, S.; Gašparović, B. Copper-phospholipid interaction at cell membrane model hydrophobic surfaces. Bioelectrochemistry 2018, 120, 10–17. [Google Scholar] [CrossRef]
  46. Speelmans, G.; Sips, W.H.; Grisel, R.J.; Staffhorst, R.W.; Fichtinger-Schepman, A.M.J.; Reedijk, J.; de Kruijff, B. The interaction of the anti-cancer drug cisplatin with phospholipids is specific for negatively charged phospholipids and takes place at low chloride ion concentration. Biochim. Biophys. Acta (BBA)-Biomembr. 1996, 1283, 60–66. [Google Scholar] [CrossRef]
  47. Alvarez, N.; Freddi, P.; Castellani, S.; Veiga, N.; Facchin, G.; Costa-Filho, A.J. New Insights into the Biophysical Behavior of an Old Molecule: Experimental and Theoretical Studies of the Interaction Between 1,10-Phenanthroline and Model Phospholipid Membranes. Braz. J. Phys. 2022, 52, 111. [Google Scholar] [CrossRef]
  48. Basso, L.G.M.; Zeraik, A.E.; Felizatti, A.P.; Costa-Filho, A.J. Membranotropic and biological activities of the membrane fusion peptides from SARS-CoV spike glycoprotein: The importance of the complete internal fusion peptide domain. Biochim. Biophys. Acta (BBA)-Biomembr. 2021, 1863, 183697. [Google Scholar] [CrossRef]
  49. Nunes, P.; Yildizhan, Y.; Adiguzel, Z.; Marques, F.; Costa Pessoa, J.; Acilan, C.; Correia, I. Copper(II) and oxidovanadium(IV) complexes of chromone Schiff bases as potential anticancer agents. JBIC J. Biol. Inorg. Chem. 2022, 27, 89–109. [Google Scholar] [CrossRef]
  50. Veiga, N.; Alvarez, N.; Castellano, E.E.; Ellena, J.; Facchin, G.; Torre, M.H. Comparative Study of Antioxidant and Pro-Oxidant Properties of Homoleptic and Heteroleptic Copper Complexes with Amino Acids, Dipeptides and 1,10-Phenanthroline: The Quest for Antitumor Compounds. Molecules 2021, 26, 6520. [Google Scholar] [CrossRef]
  51. Viossat, B.; Gaucher, J.F.; Mazurier, A.; Selkti, M.; Tomas, A. Crystals tructure of bis(μ-chloro)bis[chloro-(o-phenanthroline-N,N′)-copper(II)], Cu2(C12H8N2)2(Cl2)2. Z. Für Krist.-New Cryst. Struct. 1998, 213, 343–344. [Google Scholar] [CrossRef]
  52. Groom, C.R.; Bruno, I.J.; Lightfoot, M.P.; Ward, S.C. The Cambridge Structural Database. Acta Crystallogr. Sect. B 2016, 72, 171–179. [Google Scholar] [CrossRef]
  53. Wood, P.A.; Olsson, T.S.G.; Cole, J.C.; Cottrell, S.J.; Feeder, N.; Galek, P.T.A.; Groom, C.R.; Pidcock, E. Evaluation of molecular crystal structures using Full Interaction Maps. CrystEngComm 2013, 15, 65–72. [Google Scholar] [CrossRef]
Inorganics 12 00307 g001
Figure 1. [Cu(dipeptide)(phen)] complex scheme.
Figure 1. [Cu(dipeptide)(phen)] complex scheme.
Inorganics 12 00307 g001
Inorganics 12 00307 g002
Figure 2. DSC traces from MLVs of DPPC in the absence and the presence of the complexes. The insets show the zoomed-in regions around the pre-transition at 35 °C and the main phase transition at 41 °C.
Figure 2. DSC traces from MLVs of DPPC in the absence and the presence of the complexes. The insets show the zoomed-in regions around the pre-transition at 35 °C and the main phase transition at 41 °C.
Inorganics 12 00307 g002
Inorganics 12 00307 g003
Figure 3. DSC traces from MLVs of DPPG in the absence and the presence of the complexes.
Figure 3. DSC traces from MLVs of DPPG in the absence and the presence of the complexes.
Inorganics 12 00307 g003
Inorganics 12 00307 g004
Figure 4. Temperature variation of h+1/h0 for the spin probe DOPTC in MLVs of DPPC (upper panel) and DPPG (lower panel) in the absence and presence of the complexes. The solid lines are guides for the eyes only.
Figure 4. Temperature variation of h+1/h0 for the spin probe DOPTC in MLVs of DPPC (upper panel) and DPPG (lower panel) in the absence and presence of the complexes. The solid lines are guides for the eyes only.
Inorganics 12 00307 g004
Inorganics 12 00307 g005
Figure 5. Temperature variation AMAX for the spin probe 5-PCSL in MLVs of DPPC (upper panel) and DPPG (lower panel) in the absence and presence of the complexes. The solid lines are guides for the eyes only.
Figure 5. Temperature variation AMAX for the spin probe 5-PCSL in MLVs of DPPC (upper panel) and DPPG (lower panel) in the absence and presence of the complexes. The solid lines are guides for the eyes only.
Inorganics 12 00307 g005
Inorganics 12 00307 g006
Figure 6. Temperature variation of h−1/h0 for the spin probe 16-PCSL in MLVs of DPPC (upper panel) and DPPG (lower panel) in the absence and presence of the complexes. The solid lines are guides for the eyes only.
Figure 6. Temperature variation of h−1/h0 for the spin probe 16-PCSL in MLVs of DPPC (upper panel) and DPPG (lower panel) in the absence and presence of the complexes. The solid lines are guides for the eyes only.
Inorganics 12 00307 g006
Inorganics 12 00307 g007
Figure 7. FIMs for (a) phen, (b) [CuCl2(phen)], (c) [Cu(Ala-Gly)phen] and (d) Cu(Ala-Phe)phen].
Figure 7. FIMs for (a) phen, (b) [CuCl2(phen)], (c) [Cu(Ala-Gly)phen] and (d) Cu(Ala-Phe)phen].
Inorganics 12 00307 g007
Table 1. Thermodynamical parameters obtained from the DSC data for (a) DPPC and (b) DPPG membranes. The subscripts refer to P—pre-transition and M—main transition.
Table 1. Thermodynamical parameters obtained from the DSC data for (a) DPPC and (b) DPPG membranes. The subscripts refer to P—pre-transition and M—main transition.
TP (°C)ΔT1/2P (°C)ΔHP (kcal/mol)TM (°C)ΔHM (kcal/mol)ΔT1/2 M (°C)ΔSM (cal/mol.K)
(a) DPPC35.01.21.2141.07.990.1025.4
+[Cu(phen)]2+33.52.00.8941.08.660.1527.6
+[Cu(Ala-Gly)(phen)]34.11.90.8341.18.640.1927.5
+[Cu(Ala-Phe)(phen)]33.72.10.7341.09.020.1928.7
(b) DPPG---39.65.760.64018.4
+[Cu(phen)]2+---38.49.440.87930.3
+[Cu(Ala-Gly)(phen)]---38.38.980.61628.8
+[Cu(Ala-Phe)(phen)]---38.59.570.77330.7
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Freddi, P.; Alvarez, N.; Facchin, G.; Costa-Filho, A.J. Interaction of Phenanthroline-Containing Copper Complexes with Model Phospholipid Membranes. Inorganics 2024, 12, 307. https://doi.org/10.3390/inorganics12120307

AMA Style

Freddi P, Alvarez N, Facchin G, Costa-Filho AJ. Interaction of Phenanthroline-Containing Copper Complexes with Model Phospholipid Membranes. Inorganics. 2024; 12(12):307. https://doi.org/10.3390/inorganics12120307

Chicago/Turabian Style

Freddi, Priscilla, Natalia Alvarez, Gianella Facchin, and Antonio J. Costa-Filho. 2024. "Interaction of Phenanthroline-Containing Copper Complexes with Model Phospholipid Membranes" Inorganics 12, no. 12: 307. https://doi.org/10.3390/inorganics12120307

APA Style

Freddi, P., Alvarez, N., Facchin, G., & Costa-Filho, A. J. (2024). Interaction of Phenanthroline-Containing Copper Complexes with Model Phospholipid Membranes. Inorganics, 12(12), 307. https://doi.org/10.3390/inorganics12120307

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop