New porphyrin amino acid conjugates: Synthesis and photodynamic effect in human epithelial cells

The bromoporphyrins as promising anti-tumor photosensitizers in vitro

The synthesis of ideal photosensitizers (PSs) is considered to be the most significant bottleneck in photodynamic therapy (PDT). To discover novel PSs with excellent photodynamic anti-tumor activities, a series of novel photosensitizers 5,15-diaryl-10,20-dibromoporphyrins (I_1-6) were synthesized by a facile method. Compared with hematoporphyrin monomethyl ether (HMME) as the representative porphyrin-based photosensitizers, it is found that not only the longest absorption wavelength of all compounds was red-shifted to therapeutic window (660 nm) of photodynamic therapy, but also the singlet oxygen quantum yields were significantly increased. Furthermore, all compounds exhibited lower dark toxicity (except I₂) and stronger phototoxicity (except I₄) against Eca-109 tumor cells than HMME. Among them, I₃ possessed the highest singlet oxygen quantum yield (Φ_Δ = 0.205), the lower dark toxicity and the strongest phototoxicity (IC₅₀ = 3.5 μM) in vitro. The findings indicated the compounds I₃ had the potential to become anti-tumor agents for PDT.

The biological activities of 5,15-diaryl-10,20-dihalogeno porphyrins for photodynamic therapy

PURPOSE

Esophageal cancer is the most common gastrointestinal tumor and is difficult to be eradicated with conventional treatment. Porphyrin-based photosensitizers (PSs) mediated photodynamic therapy (PDT) could kill tumor cells with less damage to normal cells. As the most widely used porphyrin-based photosensitizer in clinics, Photofrin II has excellent anti-tumor effect. However, it has some disadvantages such as weak absorption at near infrared region, the complexity of components and prolonged skin photosensitivity. Here series novel 5,15-diaryl-10,20-dihalogeno porphyrin derivatives were afforded and evaluated to develop more effective and safer photosensitizers for tumor therapy.

METHODS

The photophysical properties and singlet oxygen generation rates of 5,15-diaryl-10,20-dihalogeno porphyrins (I_1-6, II_1-4) were tested. The cytotoxicity of I_1-6 and II_1-4 were measured by MTT assay. The pathway of cell death was studied by flow cytometry. In vivo photodynamic efficacy of I₃ and II_2-4 in Eca-109 tumor-bearing BABL/c nude mice were measured and histopathological analysis were examined.

RESULTS

5,15-Diaryl-10,20-dihalogeno porphyrins I_1-6 and II_1-4 were synthesized. The longest absorption wavelength of these halogenated porphyrins (λ_max = 660 nm) displayed a red shift around 30 nm compared to the unhalogenated porphyrins PS₁ (λ_max = 630 nm). The singlet oxygen generation rates of I_1-6 and II_1-4 were significantly higher than PS₁ and HMME. All PSs mediated PDT showed obvious cytotoxic effect against Eca-109 cells compared to HMME in vitro and in vivo. Among these PSs, II₄ exhibited appropriate absorption in the phototherapeutic window, higher ¹O₂ generation rate (k = 0.0061 s^-1), the strongest phototoxicity (IC₅₀ = 0.4 μM), lower dark toxicity, high generation of intracellular ROS in Eca-109 cells and excellent photodynamic anti-tumor efficacy in vivo. Besides, cell necrosis was induced by compound II₄ mediated PDT.

CONCLUSION

All new compounds have obvious photodynamic anti-esophageal cancer effects. Among them, the photosensitizer II₄ showed excellent efficacy in vitro and in vivo, which has the potential to become a photodynamic anti-tumor drug.

Merging Porphyrins with Gold Nanorods: Self Assembly Construct to High Fluorescent Polyelectrolyte Microcapsules

Dual probe porphyrin-gold nanorod polyelectrolyte microcapsules were developed to explore the enhancing effects of a plasmonic interface of self-assembled gold nanoparticles in the fluorescence emission from porphyrins loaded into the capsules’ core. An analysis of fluorescence lifetime imaging microscopy (FLIM) data reports a notable 10⁵–10⁶-fold increase in the maximum detected photon rates from diffraction-limited spots and an overall six-fold increase in fluorescence as averaged over the whole microcapsule area. Large emission enhancements were correlated with decreases in fluorescence lifetimes. The microcapsule’s design proved effective in achieving high fluorescent hybrids and may shed light on new possibilities for advanced materials imaging applications.

Tetracationic porphyrin derivatives against human breast cancer

Photodynamic therapy (PDT) is an approved therapeutic approach and an alternative to conventional chemotherapy for the treatment of several types of cancer with the advantages of reducing the side effects and developing resistance mechanisms. Here, was evaluated the photosensitization capabilities of 5,10,15,20-tetrakis[4-(pyridinium-1-yl-methyl)phenyl]porphyrin (3), its N-confused isomer (4) and of the neutral precursors (1) and (2) and the results were compared with the ones obtained with the cationic 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin (TMPyP). Both regular porphyrin derivatives 1 and 3 showed higher efficiency to generate singlet oxygen than TMPyP. The PDT assays towards MCF-7 cells under red light irradiation (λ > 640 nm, 23.7 mW cm^-2) demonstrated that the cationic porphyrin 3 is an efficient photosensitizer to kill MCF-7 breast cancer cells. The study of the cell death mechanisms induced by the photodynamic process showed that the studied porphyrin 3 and TMPyP caused cell death by autophagic flux and necrosis.

Design, synthesis and biological evaluation of novel 31-hexyloxy chlorin e6-based 152- or 131-amino acid derivatives as potent photosensitizers for photodynamic therapy

This study aimed to improve the biological effectiveness and pharmacokinetic properties of chlorin e₆, a second-generation photosensitizer (PS), for tumor photodynamic therapy (PDT). Herein, the novel 3¹-hexyloxy chlorin e₆-based 15²- or 13¹-amino acid derivatives 3a, 3b, 3c and 8 were synthesized and their photophysical properties and in vitro bioactivities such as phototoxicity against A549, HeLa and melanoma B16-F10 cells, reactive oxygen species (ROS) production and subcellular localization were evaluated. In addition, preferred target compounds were also investigated for their in vivo pharmacokinetic in SD rats and in vivo antitumor efficacies in C57BL/6 mice bearing melanoma B16-F10 cells. Apparently, simultaneous introduction of amino acid residue and n-hexyloxy chain in chlorin e₆ made a significant improvement in photophysical properties, ROS production, in vitro and in vivo PDT efficacy. Encouragingly, all target compounds showed higher in vitro phototoxicity than Talaporfin, and that 3c (15²-Lys) exhibited strongest phototoxicity and highest dark toxicity/phototoxicity ratio, followed by 8 (13¹-Asp), 3a (15²-Asp) and 3b (15²-Glu). Moreover, in vivo PDT antitumor efficacy of 3a, 3c and 8 was all better than that of Talaporfin, and that both 3c and 8 had stronger PDT antitumor efficiency than 3a. The overall results suggested that these novel 3¹-hexyloxy chlorin e₆-based 15²- or 13¹-amino acid derivatives, especially 3c and 8, might be potential antitumor candidate drugs for clinical treatment of melanoma by PDT.

Synthesis of amphiphilic meso-tetrasubstituted porphyrin-L-amino acid and -heterocyclic conjugates based on m-THPP

Two series of amphiphilic meso-tetrasubstituted porphyrin conjugates based on 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin ([Formula: see text]-THPP) covalently linked to L-amino acids and heterocycles were synthesized efficiently in the context of a program targeting new photosensitizers for PDT. 5,10,15-Tris(3-hydroxyphenyl)-20-(3-oxyacetic acid)phenyl]porphyrin and the respective trihexyl ether derivatives were conjugated with polar and non-polar natural L-amino acids such as glycine, L-proline, and L-tyrosine via an amide bond linker using [Formula: see text]-tetramethyl-[Formula: see text]-(1H-benzotriazol-1-yl)uroniumhexafluorophosphate in diisopropylethylamine (HBTU/DIPEA). [Formula: see text]-THPP was also conjugated with heterocyclic systems such as indole 3-acetic acid, 4-methylthiazole-5-carboxylic acid, and thiophene-2-carboxylic acid via ester linker using [Formula: see text]-(3-dimethylaminopropyl)-[Formula: see text]-ethylcarbodiimide hydrochloride in [Formula: see text]-hydroxysuccinamide or 1-hydroxybenzotriazole (EDCI, NHS or HOBt). The members of the two series were obtained in good yields and characterized by UV-vis, HRMS MALDI-TOF, 1H NMR and 13C NMR spectroscopy.

Porphyrinoid biohybrid materials as an emerging toolbox for biomedical light management

The present article reviews the most important developing strategies in light-induced nanomedicine, based on the combination of porphyrinoid photosensitizers with a wide variety of biomolecules and biomolecular assemblies.

Synthesis, characterisation and catalytic use of iron porphyrin amino ester conjugates

This study described the synthesis and characterisation of C₂-symmetrical chiral Fe(iii)(porphyrin)(OMe) complexes, whose activity as cyclopropanation catalysts was investigated from both experimental and theoretical viewpoints.

Synthesis and photodynamic activity of unsymmetrical A3B tetraarylporphyrins functionalized with l-glutamate and their Zn(II) and Cu(II) metal complex derivatives

Four novel unsymmetrical A3B porphyrins 1, 2, 3 and 4 were synthesized following Lindsey procedure. Porphyrins 3 and 4 include one and three l-glutamate groups, respectively, and all porphyrins were metallated with Zn(II) (1a-4a) or Cu(II) (1b-4b). Porphyrins and metalloporphyrins presented values of singlet oxygen quantum yields (ΦD) ranging from 0.21 to 0.67. The tetraaryl derivatives in this study showed phototoxicity in SiHa cells with IC50 values ranging from <0.01 to 6.56±0.11μM, the metalloporphyrin 4a showed the lowest IC50 value. Comparing the phototoxic activity between all porphyrins, functionalization of porphyrins with glutamate increased 100 times phototoxic activity (1 (IC50 4.81±0.34μM) vs. 3 (IC50 0.04±0.02μM) and 2 (IC50 5.19±0.42μM) vs. 4 (IC50 0.05±0.01μM)). This increased activity could be attributed to reduced hydrophobicity and increased ΦΔ, given by functionalization with l-glutamate. Metalloporphyrins 3a (IC50 0.04±0.01μM) and 4a (IC50<0.01μM) presented the best values ​​of phototoxic activity. Therefore, functionalization and zinc metalation increased the phototoxic activity. SiHa cells treated with porphyrins 3, 4, 3a and 4a at a final concentration of 10μM, showed increased activity of caspase-3 enzyme compared to the negative control; indicating the induction of apoptosis. Differential gene expression pattern in SiHa cells was determined; treatments with metalloporphyrins 4a and 4b were performed, respectively, comparing the expression with untreated control. Treatments in both cases showed similar gene expression pattern in upregulated genes, since they share about 25 biological pathways and a large number of genes. According to the new photophysical properties related to the structural improvement and phototoxic activity, these molecules may have the potential application as photosensitizers in the photodynamic therapy.

Chlorin p6-Based Water-Soluble Amino Acid Derivatives as Potent Photosensitizers for Photodynamic Therapy

The development of novel photosensitizer with high phototoxicity, low dark toxicity, and good water solubility is a challenging task for photodynamic therapy (PDT). A series of chlorin p6-based water-soluble amino acid conjugates were synthesized and investigated for antitumor activity. Among them, aspartylchlorin p6 dimethylester (7b) showed highest phototoxicity against melanoma cells with weakest dark toxicity, which was more phototoxic than verteporfin while with less dark toxicity. It also exhibited better in vivo PDT antitumor efficacy on mice bearing B16-F10 tumor than verteporfin. The biological assays revealed that 7b was localized in multiple subcellular organelles and could cause both cell necrosis and apoptosis after PDT in a dose-dependent manner, resulting in more effective cell destruction. As a result, 7b represents a promising photosensitizer for PDT applications because of its strong absorption in the phototherapeutic window, relatively high singlet oxygen quantum yield, highest dark toxicity/phototoxicity ratio, good water solubility, and excellent in vivo PDT antitumor efficacy.

Glucose-functionalized amino-OPEs as biocompatible photosensitizers in PDT

Photodynamic therapy (PDT) is a minimally invasive procedure that can provide a selective eradication of neoplastic diseases by the combined effect of a photosensitizer, light and oxygen. New amino oligo(phenylene-ethynylene)s (OPEs), bearing hydrophilic glucoside terminations, have been prepared, characterized and tested as photosensitizers in PDT. The effectiveness of these compounds in combination with UVA light has been checked on two tumor cell lines (HEp-2 and HeLa cells, derived from a larynx carcinoma and a cervical carcinoma, respectively). The compounds triggered a mitotic blockage that led to the cell death, being the effect active up to 3 μm concentration. The photophysical properties of OPEs, such as high quantum yield, stability, singlet oxygen production, biocompatibility, easy cell-internalization and very good response even at low concentration, make them promising photosensitizers in the application of PDT.

meso-Mono-[4-(1,4,7-triazacyclononanyl)]-tri(phenyl)]porphyrin and the respective zinc(ii)-complex: complete characterization and biomolecules binding abilities

We aimed to synthesize a new series of triazacyclononanyl-porphyrins (4and5) with the potential ability to bind DNA.

Novel porphyrin–Schiff base conjugates: synthesis, characterization and in vitro photodynamic activities

Three novel porphyrin–Schiff base conjugates were synthesized and characterized. Their phototoxic activities were improved after irradiation and increased significantly with the increase of doses against A431 cells.

Antibodies armed with photosensitizers: from chemical synthesis to photobiological applications

Targeting photosensitizers to cancer cells by conjugating them with specific antibodies, able to recognize and bind to tumor-associated antigens, is today one of the most attractive strategies in photodynamic therapy (PDT). This comprehensive review updates on chemical routes available for the preparation of photo-immunoconjugates (PICs), which show dual chemical and biological functionalities: photo-properties of the photosensitizer and the immunoreactivity of the antibody. Moreover, photobiological results obtained with such photo-immunoconjugates using in vitro and in vivo cancer models are also discussed.

Photodynamic effect of glycochlorin conjugates in human cancer epithelial cells

The effect of glycochlorins in HeLa cells shows that the galactose conjugate is the most efficient photosensitizer.

The near-mid-IR HOMO-LUMO gap in amide linked porphyrin-rhodamine dyads

Novel amide linked porphyrin-rhodamine dyads yield utmost intense red-shifted electronic transitions beyond the near-infrared region.

Synthesis of three novel imidazolyl-appended porphyrins and their cytostatic and phototoxic activity on A431 cells

Three imidazolyl-appended porphyrins were synthesized and characterized by 1 H NMR, elemental analyses, MS and UV-vis spectra. Anticancer activities of porphyrins have been evaluated against cutaneous squamous cell carcinoma (A431 cells) in vitro. The results indicate that the porphyrins have high selective cytotoxicity towards A431 cells in the absence of light and improved phototoxic activity upon exposure to UV light. The yield of singlet oxygen generated by porphyrins were also evaluated by measuring the absorption decay of 1,3-diphenylisobenzofuran (DPBF) in DMF. The phototoxicities of porphyrins against A431 cells were enhanced along with the increase of singlet oxygen.

Star-shaped polymer consisting of a porphyrin core and poly(L-lysine) dendron arms: synthesis, drug delivery, and in vitro chemo/photodynamic therapy

A novel star-shaped polymer, porphyrin-poly(L-lysine) dendrons (PP-PLLD), is synthesized by the click reaction between azido-modified porphyrin and propargyl focal point poly(L-lysine) dendrons. Its chemical structure is characterized by (1) H nuclear magnetic resonance, Fourier transform infrared spectroscopy, and gel permeation chromatography (GPC) is analyses etc. Due to its amphiphilic property, the obtained PP-PLLD has a low critical micelle concentration in an aqueous solution, and can load doxorubicin (DOX) with a loading amount of 64 μg mg(-1) . By in vitro toxicity assay, PP-PLLD has no dark cytotoxicity but has significant phototoxicity. Moreover, DOX-loaded PP-PLLD shows a higher cytotoxicity under the light condition than PP-PLLD or DOX alone, suggesting PP-PLLD has a potential application in combined photodynamic therapy and chemotherapy.

Reorganization of self-assembled dipeptide porphyrin J-aggregates in water-ethanol mixtures

The self-assembly of a neutral meso-methoxyphenylporphyrin functionalized with a dipeptide glycilglycine substituent (MGG) in water and in water-ethanol mixtures was studied by absorption and fluorescence spectroscopy. In water, hydrophobic interactions and the noncovalent intermolecular hydrogen bonding between the terminal carboxylate group of one porphyrin and the hydrogen atoms of the pyrrolic nitrogens of another porphyrin originate nonspecific disorganized H- and J-aggregates. The addition of ethanol (0.1-25% v/v) to the water creates small clusters within which porphyrin J-aggregates reorganize as revealed by a narrow intense band detected by the Rayleigh light scattering (RLS) at 443 nm. Similar phenomenology is detected in SDS premicellar aggregates. Computational DFT calculations of a model dimer formation stabilized via intermolecular hydrogen bonding estimate an energy gain of -22 kJ mol(-1) and a center-to-center and interplane distances between porphyrin moieties of 16.8 and 3.7 Å, respectively. The kinetics of the J-aggregate formation could be fitted with a time-dependent model, and an activation energy of 96 kJ mol(-1) was estimated. The aggregate's morphology of MGG was followed by transmission electron microscopy (TEM) which showed rod-type structures of 5-8 μm evolving to spherical particles with increased ethanol content. Similar images and sizes were obtained in analogous samples using fluorescence lifetime imaging microscopy (FLIM) and dynamic light scattering (DLS). The formation of excitonically coupled supramolecular MGG structures of brickwork or staircase types is proposed in these water-ethanol mixtures.

Chlorosulfonated corrole: a versatile synthon for advanced materials

The easily accessible 2,17-bis-chlorosulfonated 5,10,15-trispentafluorophenylcorrole is demonstrated as a highly versatile synthon for the preparation of corroles with functional groups that may be used for advanced applications and materials. Examples presented here are useful for donor-acceptor dyads, water-solubility inducing carbohydrates, chirality-inducing sugars and amino acids, and biotin-avidin technology.

Study of the interaction between N-confused porphyrin and bovine serum albumin by fluorescence spectroscopy

The fluorescence and ultraviolet spectroscopy were explored to study the interaction between N-confused porphyrins (NCP) and bovine serum albumin (BSA) under imitated physiological condition. The experimental results indicated that the fluorescence quenching mechanism between BSA and NCP was static quenching procedure at low NCP concentration at 293 and 305 K or a combined quenching (static and dynamic) procedure at higher NCP concentration at 305 K. The binding constants, binding sites and the corresponding thermodynamic parameters ΔH, ΔS, and ΔG were calculated at different temperatures. The comparison of binding potency of the three NCP to BSA showed that the substituting groups in benzene ring could enhance the binding affinity. From the thermodynamic parameters, we concluded that the action force was mainly hydrophobic interaction. The binding distances between NCP and BSA were calculated using Förster non-radiation energy transfer theory. In addition, the effect of NCP on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy.