New platinum(II)–bipyridyl corrole complexes: Synthesis, characterization and binding studies with DNA and HSA

DNA-Interactive and Damage Study with meso-Tetra(2-thienyl)porphyrins Coordinated with Polypyridyl Pd(II) and Pt(II) Complexes

We report the DNA-binding properties of three porphyrins with peripheral thienyl substituents (TThPor, PdTThPor and PtTThPor). The binding capacity of each porphyrin with DNA was determined by UV-Vis and steady-state fluorescence emission spectroscopy combined with molecular docking calculations. The results suggest that the interaction of these compounds probably occurs via secondary interactions via external grooves (minor grooves) around the DNA macromolecule. Moreover, porphyrins containing peripheral Pd(II) or Pt(II) complexes (PdTThPor and PtTThPor) were able to promote photo-damage in the DNA.

Photophysical, photobiological, and biomolecule-binding properties of new tri-cationic meso-tri(2-thienyl)corroles with Pt(II) and Pd(II) polypyridyl derivatives

We report the synthesis and characterization of new tri-cationic corrole derivatives, containing Pt(II) or Pd(II) complexes attached at the peripheral position of thienyl moieties. Corrole derivatives were characterized through microanalysis, electrochemical, spectrometry and spectroscopy analysis. Singlet and triplet excited-states are investigated by photophysical/theoretical calculation methods and photobiological parameters were also evaluated spectroscopic techniques (UV-Vis and EPR). Also, the binding capacity of each corrole derivative with nucleic acids (DNA) and human serum albumin (HSA) was determined by UV-Vis, steady-state, and time-resolved fluorescence spectroscopy, combined with molecular docking analysis. Moreover, the new corroles containing peripheral complexes improve their interactions with biomacromolecules, generate reactive oxygen species under light source irradiation studied and has potential for application in photodynamic therapeutic processes.

First report of trans-A2B-corrole derived from a lapachone derivative: photophysical, TD-DFT and photobiological assays

In this work, the synthesis, characterization and photophysical assays of a new trans-A₂B-corrole derivative from the naturally occurring quinone are described. β-Lapachone is a naturally occurring quinoidal compound that provides highly fluorescent heterocyclic compounds such as lapimidazoles. The new trans-A₂B-corrole compound was obtained from the reaction between 2,3,4,5,6-(pentafluorophenyl)dipyrromethane and the lapimidazole bearing an aldehyde group. The dyad was characterized by high-resolution mass spectrometry (HRMS), NMR spectroscopy (¹H, COSY 2D, HMBC, ¹⁹F), FT-IR, UV-vis, steady-state and time-resolved fluorescence, electrochemical studies (CV), TD-DFT analysis and photobiological experiments, in which includes aggregation, stability in solution, photostability and partition coefficients assays. Finally, ROS generation assays were performed using 1,3-diphenylisobenzofuran (DPBF) method and the presented compound showed significant photostability and singlet oxygen production.

Effects of Substituents on the Photophysical/Photobiological Properties of Mono-Substituted Corroles

The trans-A₂B-corrole series was prepared starting with 5-(pentafluorophenyl)dipyrromethene, which was then reacted with respective aryl-substituted aldehyde by Gryko synthesis. It was further characterized by HRMS and electrochemical methods. In addition, we investigated experimental photophysical properties (absorption, emission by steady-state and time-resolved fluorescence) in several solvents and TDDFT calculations, aggregation, photostability and reactive oxygen species generation (ROS), which are relevant when selecting photosensitizers used in photodynamic therapy and many other photo-applications. In addition, we also evaluated the biomolecule-binding properties with CT-DNA and HSA by spectroscopy, viscometry and molecular docking calculations assays.

Corroles at work: a small macrocycle for great applications

Corrole chemistry has witnessed an impressive boost in studies in the last 20 years, thanks to the possibility of preparing corrole derivatives by simple synthetic procedures. The investigation of a large number of corroles has highlighted some peculiar characteristics of these macrocycles, having features different from those of the parent porphyrins. With this progress in the elucidation of corrole properties, attention has been focused on the potential for the exploitation of corrole derivatives in different important application fields. In some areas, the potential of corroles has been studied in certain detail, for example, the use of corrole metal complexes as electrocatalysts for energy conversion. In some other areas, the field is still in its infancy, such as in the exploitation of corroles in solar cells. Herein, we report an overview of the different applications of corroles, focusing on the studies reported in the last five years.

The inner oxygen-substituted strategy effects on structure, aromaticity and absorption spectra of corrole isomers: A theoretical study

Corrole and oxaporphyrin have been successfully synthesized and applied in many research fields such as organic photoelectronics and sensors with the unique photophysical and chemical properties. However, the low synthesis yields of oxacorrole drive researchers turning their attention to theoretical studies for more reasonable molecular structure as the appeal of energy conservation and green chemistry. Corroles, oxacorroles (OC) and dioxacorroles (DOC), a total of 14 molecules, are calculated to systematically explore their structures, intramolecular hydrogen bonds, molecular aromatic and absorption spectral properties influenced by the inner O atoms positions with density functional theory (DFT) and time-dependent density functional theory (TDDFT). The smaller NICS(1)_ZZ values of oxacorrole (-35.23 ppm to -33.54 ppm) and dioxacorrole (-34.91 ppm to -33.24) than these of corroles (-32.97 ppm and -33.12 ppm) indicate that the O atoms attendances can increase the molecular aromaticity. The gradually increasing energy gaps of H-8 to H-3 from Corrole1 and Corrole2 to DOC series and the larger charge of C_O (+0.208e-+0.380e) than that of C_N (+0.065e-+0.177e) illustrate that the substitution of O can reduce the degeneracy degree of energy levels and change the charge distributions. With Hirshfeld method, the molecular orbital contributions of H-1, HOMO, LUMO and L+1 exhibit the regular effects of O atoms positions on orbital energy and electron absorption spectra. For series 1, 23O is beneficial to the red shift of electron absorption spectra. These theoretical conclusions manifest that OC1-23 and DOC1-1 possess the excellent absorption characteristics in the visible region, which can be used as potential materials in the fields of photoelectric materials.

Anticancer activity and cell death mechanism of Pt(II) complexes: Their in vitro bio-transformation to Pt(II)-DNA adduct formation and BSA binding study by spectroscopic method

Pt(II) complex cis-[Pt(PEA)(OH₂)₂] X₂, C-2 (where, PEA = 2-Pyridylethylamine and X  = ClO₄^- or NO₃^-) was synthesized by hydrolysis of cis-[Pt(PEA)Cl₂] C-1. Glutathione (GSH) and DL-penicilamine (DL-pen) substituted complexes cis-[Pt(PEA)(GSH)],C-3 and cis-[Pt(PEA)DL-pen)]X C-4 were synthesized and characterized by spectroscopic methods. Kinetic studies were traced on complex C-2 with the thiols, GSH and DL-pen. Pt(II)-Sulfur adduct formation mechanisms of the substituted products C-3 and C-4 were established from the kinetic investigation. At pH 4.0, C-2 - thiols interactions follow two consecutive steps: the first step is dependent, and the second is independent of [thiol]. The association equilibrium constant (K_E), substitution rate constants for both steps (k₁ & k₂), and activation parameters (ΔH^‡ and ΔS^‡) have been assessed to propose the mechanism. Agarose gel electrophoresis mobilization pattern of DNA with complexes was performed to visualize the interaction nature. CT-DNA and BSA binding activities of the complexes have been executed by electronic, fluorescence spectroscopy, and viscometric titration methods. Evaluation of thermodynamic parameters (ΔH⁰, ΔS⁰, and ΔG⁰) from BSA binding constants was executed to propose the driving forces of interaction between these species. A molecular docking study was performed to evaluate the binding mode of complexes with BDNA strands. Anticancer activity of the complexes C-1 to C-4 was explored on both A549 and HEp-2 cell lines, compared with approved anticancer drugs cisplatin, carboplatin, and oxaliplatin. All these complexes were tested by NBT assay on normal cell line skeletal muscle cells (L6 myotubes) to observe the adverse effects compared to recognized anticancer medications. The ultimate aim is to explore the role of anticancer agents on cell death mechanism, which has been performed by flow-cytometer on HEp-2 cell lines.

Unraveling the Photodynamic Activity of Cationic Benzoporphyrin-Based Photosensitizers against Bladder Cancer Cells

In this study, we report the preparation of new mono-charged benzoporphyrin complexes by reaction of the appropriate neutral benzoporphyrin with (2,2'-bipyridine)dichloroplatinum(II) and of the analogs' derivatives synthesized through alkylation of the neutral scaffold with iodomethane. All derivatives were incorporated into polyvinylpyrrolidone (PVP) micelles. The ability of the resultant formulations to generate reactive oxygen species was evaluated, mainly the singlet oxygen formation. Then, the capability of the PVP formulations to act as photosensitizers against bladder cancer cells was assessed. Some of the studied formulations were the most active photosensitizers causing a decrease in HT-1376 cells' viability. This creates an avenue to further studies related to bladder cancer cells.

Applications of Fluorous Porphyrinoids: An Update†

Porphyrins and related macrocycles have been studied broadly for their applications in medicine and materials because of their tunable physicochemical, optoelectronic and magnetic properties. In this review article, we focused on the applications of fluorinated porphyrinoids and their supramolecular systems and summarized the reports published on these chromophores in the past 5-6 years. The commercially available fluorinated porphyrinoids: meso-perfluorophenylporphyrin (TPPF₂₀ ) perfluorophthalocyanine (PcF₁₆ ) and meso-perfluorophenylcorrole (CorF₁₅ ) have increased photo and oxidative stability due to the presence of fluoro groups. Because of their tunable properties and robustness toward oxidative damage these porphyrinoid-based chromophores continue to gain attention of researchers developing advanced functional materials for applications such as sensors, photonic devices, component for solar cells, biomedical imaging, theranostics and catalysts.

In vitro and in silico assessment of antitumor properties and biomolecular binding studies for two new complexes based on NiII bearing k2N,S-donor ligands

This work deals with two new molecule-based materials, namely Ni^II-complexes of general formulae [Ni(L1)₂] (Ni1) and [Ni(L2)₂] (Ni2), where L1 = trans-cinnamaldehyde-N(4)-methyl thiosemicarbazone and L2 = trans-cinnamaldehyde-N(4)-ethyl thiosemicarbazone, as potential antitumor agents. Both compounds were characterized by elemental analysis, molar conductivity and spectroscopic techniques (FTIR and NMR). Their molecular structures were obtained by single-crystal X-ray diffraction analysis. Each one crystallizes in a monoclinic space group P 2₁/c, also the asymmetric unit comprises of one Ni^II ion located on an inversion centre and one anionic ligand, which acts as a κ²N,S-donor affording a five-membered metallaring. The compounds were screened against two selected tumour cell lines (MCF-7 and A549) and non-tumour fibroblasts cell line (MRC-5) via MTT assays. In both tumour cells, all compounds exhibited higher cytotoxicity than the control drug (cisplatin). The IC₅₀ values ranges of 3.70 - 41.37 μM and 1.06 - 14.91 μM were found for MCF-7 and A549, respectively. Importantly, all of them were less toxicity than cisplatin in MRC-5 with SI values ranged at 11.80 - 86.60. The red blood cell (RBC) assay revealed Ni2 as non-toxic due to its reduced haemolytic effect (0--9% at 1--10 μM). The DNA binding was investigated through a combination of spectrophotometric absorption and emission titrations, electrophoresis, and circular dichroism experiments. As a result, these metal complexes were not able to strongly binding to DNA (K_b values ~10⁴ mol L^--1) but suggesting groove-binding interactions. The scavenging ability of them towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical was also evaluated in this work, but no important antioxidant behaviour was detected. Further, the interaction of Ni1 and Ni2 to human serum albumin (HSA) was explored by quenching of tryptophan emission, warfarin competitive assay, and molecular docking protocols. The HSA binding analyses indicated good affinity of both complexes to Sudlow site I (K_b values ⁓10³ mol L^-1).

Fluorescent pyrene moiety in fluorinated C6F5-corroles increases the interaction with HSA and CT-DNA

Two fluorinated meso-C6F5-corroles (5,15-bis(pentafluorophenyl)-10-(phenyl)corrole and 5,15-bis(pentafluorophenyl)-10-(1-pyrenyl)corrole) were biologically evaluated in terms of binding affinity to human serum albumin (HSA) and calf-thymus DNA (CT-DNA) via multiple spectroscopic techniques under physiological conditions combined with molecular docking calculations. The HSA:corrole interaction is spontaneous and moderate via static binding, disturbing both secondary and tertiary albumin structures at high fluorinated corrole concentrations. The competitive binding studies indicated positive cooperativity or allosteric activation, while molecular docking calculations suggested that both fluorinated corroles bind preferentially inside subdomains IIA and IB (sites I and III, respectively). The experimental CT-DNA binding assays indicated that fluorinated corroles interact spontaneously by non-classical modes in the minor groove of the CT-DNA strands via static fluorescence quenching mechanism. Molecular docking results also showed the minor groove as the main binding site for CT-DNA. Overall, the pyrene moiety increased the interaction with HSA and CT-DNA, which is probably due to the planarity and volume that favors the pyrene unit to be buried inside the biomacromolecule pockets.

Peripheral tetra-cationic Pt(II) porphyrins photo-inactivating rapidly growing mycobacteria: First application in mycobacteriology

In this manuscript, we report, for the first time, the photoinactivation evaluation of tetra-cationic porphyrins with peripheral Pt (II)-bpy complexes in the photodynamic inactivation (PDI) of rapidly growing mycobacterial strains (RGM). Two different isomeric Pt (II)-porphyrins were synthetized and applied. PDI experiments in the strains of Mycobacteroides abscessus subsp. Abscessus (ATCC 19977), Mycolicibacterium fortuitum (ATCC 6841), Mycobacteroides abscessus subsp. Massiliense (ATCC 48898), and Mycolicibacterium smegmatis (ATCC 700084) conducted with adequate concentration (without aggregation) of photosensitizers (PS) under white-light illumination for 90 min showed that the most effective PS significantly reduced the concentration of viable mycobacteria. The present results show that positively charged porphyrins at the meta position (3-PtTPyP) are more efficient PS against M. abscessus, M. fortuitum, M. massiliense, and M. smegmatis. The effectiveness of the molecule as PS for PDI studies is also clear with mycobacteria, which is strongly related with the porphyrin peripheral charge and coordination platinum (II) compounds and consequently their solubility in physiological media. Tetra-cationic PS may be promising anti-mycobacterial PDI agents with potential applications in medical clinical cases and bioremediation.

Water-soluble tetra-cationic porphyrins display virucidal activity against Bovine adenovirus and Bovine alphaherpesvirus 1

Porphyrins are photoactive compounds that can absorb the energy of light and transfer it to oxygen molecules, producing reactive oxygen species (ROS). Once produced, ROS may alter biological molecules and cellular mechanisms, leading to cell apoptosis or inactivation of microorganisms, such as bacteria, fungi, and viruses. Therefore, the objective of this study was to evaluate the in vitro virucidal activity of six tetra-cationic porphyrins against two bovine viruses (Bovine alphaherpesvirus 1, BoHV-1, enveloped; and Bovine adenovirus, BAV, non-enveloped). For this, viral suspensions were incubated with each porphyrin (H₂TMeP, ZnTMeP, and CuTMeP at 4.0 μM, NiTMeP at 5.0 μM, and CoClTMeP and MnClTMeP at 1.0 μM) and exposed to white-light irradiation for 0, 60, 120, and 180 min (BAV) or 0, 30, 60, 90, and 120 min (BoHV-1). Then, the remaining viral titers were determined by limiting dilution and compared with the control (virus + porphyrins without light exposition). The porphyrins H₂TMeP and ZnTMeP showed the highest virucidal activity against both viruses. ZnTMeP inactivated BoHV-1 after 30 min of photoactivation and H₂TMeP after 60 min. The BAV was photo-inactivated by both porphyrins at 180 min of white-light exposition. CuTMeP, NiTMeP, and CoClTMeP porphyrins had weak virucidal activity against BoHV-1 and MnClTMeP showed no virucidal activity against both viruses. These results indicated that free-base H₂TMeP and ZnTMeP porphyrins present virucidal activity against non-enveloped and enveloped viruses, opening the possibility for their use to inactivate viruses on surfaces, biological substrates, and solutions.

The post-functionalization of Co(iii)PPh3 triarylcorroles through Suzuki-Miyaura couplings and their tunable electrochemically-catalyzed hydrogen evolution and oxygen reduction

The post-functionalization of six novel symmetric and asymmetric meso-expanded Co(iii) corroles through Suzuki-Miyaura coupling reactions has been successfully accomplished and is reported along with their structural characterization. An analysis of the structure-property relationships of the optical and redox properties of the corroles has been carried out by comparing their optical spectra and their electrochemical properties. The results demonstrate that post-functionalized meso-expanded Co(iii) triarylcorroles exhibit enhanced electrocatalyzed oxygen reduction reaction (ORR) activity and that their reactivity can be controlled by modulating the electronic structure, the functionalization and the number of coupled meso-substituents.

Photophysical and electrochemical properties of two trans-A2B-corroles: differences between phenyl or pyrenyl groups at the meso-10 position

The photophysical properties of two meso–trans-A₂B-type corroles containing phenyl or pyrenyl units were reported in this study. TD-DFT calculations and electrochemical analysis were conducted to better understand the corrole molecular structures.

Developing novel zinc(ii) and copper(ii) Schiff base complexes: combined experimental and theoretical investigation on their DNA/protein binding efficacy and anticancer activity

Zn(ii) and Cu(ii) Schiff base complexes having DNA and HSA binding efficacy have been exploited as cancer therapeutic agents.

Antimicrobial activity and safety applications of meso-tetra(4-pyridyl)platinum(II) porphyrin

Tetra-platinated(II) porphyrin hexafluorophosphate compound (4-PtTPyPor) was synthetized and along 5,10,15,20-tetrakis(4-pyridyl)porphyrin (4-TPyPor), evaluated about the antimicrobial activity and safety. The effect was evaluated with and without light exposition. The antimicrobial activity was analyzed by microdilution and growth curve method. The assays showed an increase of antimicrobial potential caused by porphyrins with light exposition comparing the treatment without light irradiation. The biocompatibility was tested by MTT, ROS production, dsDNA on culture medium and hemolysis. All platinum porphyrin concentrations showed hemolytic activity under light exposition. The ROS measurement doesn't showed statistic difference between treatments and control. The picogreen assay demonstrates a reduction of dsDNA on culture medium with cells treated with porphyrins under light irradiation. The study demonstrated that the platinated porphyrins might be promising microbial photodynamic inactivation with potential applications in wastewater treatment, biofilm control and bioremediation.

Evaluation of meso-substituted cationic corroles as potential antibacterial agents

Cationic derivatives of 5,10,15-tris[4-(pyridin-4-ylsulphanyl)-2,3,5,6-tetrafluorophenyl]-corrolategallium(III)pyridine and 5,10,15-tris[4-(pyridin-2-ylsulfanyl)-2,3,5,6-tetrafluorophenyl]-correlategallium(III)pyridine were synthesized and their photosensitizing properties against the naturally bioluminescent Gram-negative bacterium Allivibrio fischeri were evaluated. The cationic corrole derivatives exhibited antibacterial activity at micromolar concentrations against this Gram-negative bacterium strain.

VP, Misini B, Das P, Dasgupta S, Linert W, Moi SC. Synthesis, biological evaluation, substitution behaviour and DFT study of Pd(ii) complexes incorporating benzimidazole derivative

Pd(ii) complexes with good DNA/BSA binding ability exhibit cytotoxicity comparable to cisplatin on different cancer cells along with reduced toxicity towards normal cells.

Photoactive meso-tetra(4-pyridyl)porphyrin-tetrakis-[chloro(2,2′bipyridine)platinum(ii) derivatives recognize and cleave DNA upon irradiation

Photoactive platinum porphyrins may be interesting as photosensitizers in photodynamic therapy and photochemotherapy, and we demonstrate their activity towards DNA cleavage under exposure to light.

Isomeric effect on the properties of tetraplatinated porphyrins showing optimized phototoxicity for photodynamic therapy

The design of new photosensitizers (PS) with improved properties is essential for the development of photodynamic therapy as an alternative therapeutic method.

Strategies for Corrole Functionalization

This review covers the functionalization reactions of meso-arylcorroles, both at the inner core, as well as the peripheral positions of the macrocycle. Experimental details for the synthesis of all known metallocorrole types and for the N-alkylation reactions are presented. Key peripheral functionalization reactions such as halogenation, formylation, carboxylation, nitration, sulfonation, and others are discussed in detail, particularly the nucleophilic aromatic substitution and the participation of corroles in cycloaddition reactions as 2π or 4π components (covering Diels-Alder and 1,3-dipolar cycloadditions). Other functionalizations of corroles include a large diversity of reactions, namely Wittig reactions, reactions with methylene active compounds, formation of amines, amides, and imines, and metal catalyzed reactions. At the final section, the reactions involving oxidation and ring expansion of the corrole macrocycle are described comprehensively.

Novel mononuclear ruthenium(ii) complexes as potent and low-toxicity antitumour agents: synthesis, characterization, biological evaluation and mechanism of action

The ruthenium(ii) complex, [Ru(dmb)₂(salH)]PF₆(Ru-2), is considered a potential antitumour agent that could avoid the side-effects of platinum-based anti-cancer drugs, such as cisplatin, carboplatin or oxaliplatin.