Benzamide porphyrins with directly conjugated and distal pyridyl or pyridinium groups substituted to the porphyrin macrocycles: Study of the photosensitising abilities as inducers of apoptosis in cancer cells under photodynamic conditions

Light exposure of tetra-cationic porphyrins containing peripheral Pd(II)-bipyridyl complexes and the induced effects on purified DNA molecule, fibroblast and melanoma cell lines

Photodynamic therapy (PDT) combines a light source, oxygen, and a photosensitizer (PS) to generate reactive oxygen species (ROS) for treating diseases. In this study, we evaluated two meso-tetra-pyridyl porphyrins with [Pd(bpy)Cl]+, namely 3-PdTPyP and 4-PdTPyP, as PS for PDT application. DNA interaction was assessed by spectroscopic measurements (UV-Vis and fluorescence emission), viscosity analysis, and molecular docking simulations. The results indicate that Pd(II)-porphyrins do not intercalate into DNA, suggesting that the minor groove is the primary interaction site, mainly through van der Waals forces. These metalloporphyrins effectively induced nitrogenous bases oxidation, particularly in purines, after white light irradiation. The induced DNA lesions were able to inactivate plasmid DNA metabolism (DNA replication and transcription) in a bacterial model. 3-PdTPyP and 4-PdTPyP significantly decreased the viability of treated melanoma cell lines (A375 and B16-F10), demonstrating that melanoma cell lines were more sensitive to these Pd(II)-porphyrins than the fibroblast cell line (L929). Moreover, 3-PdTPyP was more photototoxic to A375 cells (IC50 = 0.43 μM), whereas 4-PdTPyP was more photototoxic to B16-F10 cells (IC50 = 0.51 μM). These findings suggest that these porphyrins are promising PS for future PDT research focused on skin cancer.

Porphyrin-Based Nanoparticles: A Promising Phototherapy Platform

Phototherapy, including photodynamic therapy and photothermal therapy, is an emerging form of non-invasive treatment. The combination of imaging technology and phototherapy is becoming an attractive development in the treatment of cancer, as it allows for highly effective therapeutic results through image-guided phototherapy. Porphyrins have attracted significant interest in the treatment and diagnosis of cancer due to their excellent phototherapeutic effects in phototherapy and their remarkable imaging capabilities in fluorescence imaging, magnetic resonance imaging and photoacoustic imaging. However, porphyrins suffer from poor water solubility, low near-infrared absorption and insufficient tumor accumulation. The development of nanotechnology provides an effective way to improve the bioavailability, phototherapeutic effect and imaging capability of porphyrins. This review highlights the research results of porphyrin-based small molecule nanoparticles in phototherapy and image-guided phototherapy in the last decade and discusses the challenges and directions for the development of porphyrin-based small molecule nanoparticles in phototherapy.

An Anti-inflammatory Fe3 O4 -Porphyrin Nanohybrid Capable of Apoptosis through Upregulation of p21 Kinase Inhibitor Having Immunoprotective Properties under Anticancer PDT Conditions

We report the influence of Fe₃ O₄ nanoparticles (NPs) on porphyrins in the development of photosensitizers (PSs) for efficient photodynamic therapy (PDT) and possible post-PDT responses for inflicting cancer cell death. Except for Au, most metal-based nanomaterials are unsuitable for clinical applications. The US Food and Drug Administration and other agencies have approved Feraheme and a few other iron oxide NPs for clinical use, paving the way for novel biocompatible immunoprotective superparamagnetic iron oxide nanohybrids to be developed as nanotherapeutics. A water-soluble nanohybrid, referred to here as E-NP, comprising superparamagnetic Fe₃ O₄ NPs functionalised with tripyridyl porphyrin PS was introduced through a rigid 4-carboxyphenyl linker. As a PDT agent, the efficacy of E-NP toward the AGS cancer cell line showed enhanced photosensitising ability as determined through in vitro photobiological assays. The cellular uptake of E-NPs by AGS cells led to apoptosis by upregulating ROS through cell-cycle arrest and loss of mitochondrial membrane potential. The subcellular localisation of the PSs in mitochondria stimulated apoptosis through upregulation of p21, a proliferation inhibitor capable of preventing tumour development. Under both PDT and non-PDT conditions, this nanohybrid can act as an anti-inflammatory agent by decreasing the production of NO and superoxide ions in murine macrophages, thus minimising collateral damage to healthy cells.

Photodynamic activity attained through the ruptured π-conjugation of pyridyl groups with a porphyrin macrocycle: synthesis and the photophysical and photobiological evaluation of 5-mono-(4-nitrophenyl)-10,15,20-tris-[4-(phenoxymethyl)pyridine]-porphyrin and its Zn(ii) complex

This article compares a reported hydrophobic and photobiologically inert porphyrin synthon, (NPh)TPyP, bearing a single meso-4-nitrophenyl group and three meso-pyridyl groups (A₃B type) with a new photobiologically active metal-free porphyrin, P₃N, and its zinc-complex, P₃NZn, which bear a meso-4-nitrophenyl group along with three distal pyridyl groups. Both P₃N and P₃NZn experience ruptured π-conjugation with the porphyrin macrocycle and attain hydrophilicity, as indicated via density functional theory (DFT) calculations, becoming photobiologically active under in vitro conditions. The non-invasive photodynamic activity (PDA) predominantly shown by the zinc-complex P₃NZn (with higher hydrophilicity) towards KRAS-mutated human lung-cancer cells (A549) was studied. The results indicate the existence of intracellular singlet oxygen inflicted anticancer PDA, which is apparent through the upregulation of intracellular reactive oxygen species (ROS) and the downregulation of both intracellular superoxide dismutase (SOD) and intracellular reduced glutathione (GSH) levels. The trends obtained from both SOD and GSH assays were indicators of therapeutic defence against oxidative stress via neutralizing superoxide anions (SOA).

meso-Thiophenium Porphyrins and Their Zn(II) Complexes: A New Category of Cationic Photosensitizers

A new category of cationic meso-thiophenium porphyrins are introduced as possible alternatives to the popular meso-pyridinium porphyrins. Combinations of cationic porphyrins bearing meso-2-methylthiophenium and meso-4-hydroxyphenyl moieties T₂(OH)₂M (A₂B₂ type) and T(OH)₃M (AB₃ type) along with their zinc(II) complexes T₂(OH)₂MZn and T(OH)₃MZn, are reported. The increase in the number of thienyl groups attached to the meso-positions of the porphyrin derivatives (A₂B₂ frame) has been shown to impart longer fluorescence lifetimes and stronger photocytotoxicity toward A549 lung cancer cells, as evident with T₂(OH)₂M and its corresponding diamagnetic metal complex T₂(OH)₂MZn. The photoactivated T₂(OH)₂MZn imparts an early stage reactive oxygen species (ROS) upregulation and antioxidant depletion in A549 cells and contributes to the strongest oxidative stress-induced cell death mechanism in the series. The DFT calculations of the singlet-triplet energy gap (ΔE) of all the four hydrophilic thiophenium porphyrin derivatives establish the potential applicability of these cationic photosensitizers as PDT agents.

Enhanced photodynamic therapy and fluorescence imaging using gold nanorods for porphyrin delivery in a novel in vitro squamous cell carcinoma 3D model

Nanocomposites of gold nanorods (Au NRs) with the cationic porphyrin TMPyP (5,10,15,20-tetrakis(1- methyl 4-pyridinio)porphyrin tetra(p-toluenesulfonate)) were investigated as a nanocarrier system for photodynamic therapy (PDT) and fluorescence imaging. To confer biocompatibility and facilitate the cellular uptake, the NRs were encapsulated with polyacrylic acid (PAA) and efficiently loaded with the cationic porphyrin by electrostatic interaction. The nanocomposites were tested with and without light exposure following incubation in 2D monolayer cultures and a 3D compressed collagen construct of head and neck squamous cell carcinoma (HNSCC). The results showed that Au NRs enhance the absorption and emission intensity of TMPyP and improve its photodynamic efficiency and fluorescence imaging capability in both 2D cultures and 3D cancer constructs. Au NRs are promising theranostic agents for delivery of photosensitisers for HNSCC treatment and imaging.

Tetra-cationic platinum(II) porphyrins like a candidate photosensitizers to bind, selective and drug delivery for metastatic melanoma

Photodynamic therapy (PDT) is an expanding treatment modality due to its minimally invasive localized activity and few adverse effects. This therapy requires photosensitive compounds, which have high sensitivity to light exposure. Thus, in this work, the in vitro antitumor activity of meso-tetra(3- and 4-pyridyl)porphyrins (3-TPyP and 4-TPyP) in metastatic melanoma cell (WM1366 line) and non-tumoral Ovarian lineage Chinese Hamister (CHO) was evaluated using photodynamic process. Cell viability tests, molecular docking, annexin V, confocal microscopy and qRT-PCR were performed. Our results show that both porphyrins inhibited the viability of metastatic melanoma cells when exposed to light and did not alter viability in the dark. In addition, they did not demonstrate cytotoxicity in non-tumor cells. Molecular coupling demonstrated platinum porphyrin affinity for the N-terminal region of APO B-100, LDL receptor, and therefore of the cells under study. Genes such as Caspase 3 and 9, P21, Bax / BCL2, MnSod and GSH showed increased expression. For meta isomer 3-PtTPyP treatment, caspase-9 and caspase-3 expression levels showed a 4.89 and 3.23-fold increase, respectively, while for the para isomer 4-PtTPyP, this change was 3.77 and 12.16-fold, respectively. We also observed an upregulated expression of p21, a protein well-known by its action in cell cycle arrest in a p53-dependent manner. Conclusion: 3-PtTPyP and 4-PtTPyP demonstrated antitumor effect on WM1366 cells, inducing apoptosis and significant alteration of cell cytoskeleton actin. Our work shows that platinum(II) porphyrins may be promising photosensitizers for the treatment of metastatic melanoma by PDT.

Dual activity of amphiphilic Zn(II) nitroporphyrin derivatives as HIV-1 entry inhibitors and in cancer photodynamic therapy

Two Zn(II) nitro porphyrin derivatives bearing combinations of meso-4-nitrophenyl and meso-4-methylpyridinium moieties and their free-base precursors were synthesized through one-pot microwave process, purified and characterized. The biological activity of these nitroporphyrins was assessed under both photodynamic and non-photodynamic conditions to correlate their structure-activity relationship (SAR). Unlike, the free-base precursors, Zn(II) complexes of these nitroporphyrins displayed nearly complete inhibition in the entry of lentiviruses such as HIV-1 and SIVmac under non-photodynamic conditions. In addition, the Zn(II) complexes also exhibited a higher in vitro photodynamic activity towards human lung cancer cell-line A549 than their free-base precursors. Our results strongly suggest that incorporation of Zn(II) has improved the antiviral and anticancer properties of the nitroporphyrins. To the best of our knowledge, this is the first report demonstrating the dual activity of nitroporphyrin-zinc complexes as antiviral and anti-cancer, which will aid in their development as therapeutics in clinics.

Multimodal use of the porphyrin TMPyP: From cancer therapy to antimicrobial applications

The cationic porphyrin meso-tetra(4-[Formula: see text]-methylpyridyl)porphine (TMPyP) has a high yield of singlet oxygen generation upon light activation and a strong affinity for DNA. These advantageous properties have turned it into a promising photosensitizer for use in photodynamic therapy (PDT). In this review, we have summarized the current state-of-the-art applications of TMPyP for the treatment of cancer as well as its implementation in antimicrobial PDT. The most relevant studies reporting its pharmacokinetics, subcellular localization, mechanism of action, tissue biodistribution and dosimetry are discussed. Combination strategies using TMPyP-PDT together with other photosensitizers and chemotherapeutic agents to achieve synergistic anti-tumor effects and reduce resistance to therapy are also explored. Finally, we have addressed emerging applications of this porphyrin, including nanoparticle-mediated delivery, controlled drug release, biosensing and G-quadruplex stabilization for tumor growth inhibition. Altogether, this work highlights the great potential and versatility that TMPyP can offer in different fields of biomedicine such us cancer treatment or antimicrobial therapy.

Novel 1,4‑naphthoquinone derivatives induce reactive oxygen species‑mediated apoptosis in liver cancer cells

Derivatives of 1,4-naphthoquinone have excellent anti-cancer effects, but their use has been greatly limited due to their serious side effects. To develop compounds with decreased side effects and improved anti-cancer activity, two novel types of 1,4-naphthoquinone derivatives, 2,3-dihydro-2,3-epoxy-2-propylsulfonyl-5,8-dimethoxy-1,4-naphthoquinone (EPDMNQ) and 2,3-dihydro-2,3-epoxy-2-nonylsulfonyl-5,8-dimethoxy-1,4-naphthoquinone (ENDMNQ) were synthesized and their anti-tumor activities were investigated. The effects of EPDMNQ and ENDMNQ on cell viability, apoptosis and accumulation of reactive oxygen species (ROS) in liver cancer cells were determined by MTT cell viability assay and flow cytometry. The expression levels of mitochondrial, mitogen activated protein kinase (MAPK) and signal transducer and activator of transcription 3 (STAT3) signaling pathway-associated proteins in Hep3B liver cancer cells were analyzed by western blot analysis. The results demonstrated that EPDMNQ and ENDMNQ inhibited the proliferation of liver cancer Hep3B, HepG2, and Huh7 cell lines but not that of normal liver L-02, normal lung IMR-90 and stomach GES-1 cell lines. The number of apoptotic cells and ROS levels were significantly increased following treatment with EPDMNQ and ENDMNQ, and these effects were blocked by the ROS inhibitor N-acetyl-L-cysteine (NAC) in Hep3B cells. EPDMNQ and ENDMNQ induced apoptosis by upregulating the protein expression of p38 MAPK and c-Jun N-terminal kinase and downregulating extracellular signal-regulated kinase and STAT3; these effects were inhibited by NAC. The results of the present study demonstrated that EPDMNQ and ENDMNQ induced apoptosis through ROS-modulated MAPK and STAT3 signaling pathways in Hep3B cells. Therefore, these novel 1,4-naphthoquinone derivatives may be useful as anticancer agents for the treatment of liver cancer.