Chlorin E6 Derivatives Research Articles

Isolation, Identification, and Biological Activities of a New Chlorin e6 Derivative.

Chlorin e6 is a well-known photosensitizer used in photodynamic diagnosis and therapy. A method for identifying and purifying a novel process-related impurity during the synthesis of chlorin e6 has been developed. Its structure was elucidated using NMR and HRMS. This new impurity is formed from chlorophyll b rather than chlorophyll a, which is the source of chlorin e6. The intermediates formed during chlorin e6 synthesis were monitored using HPLC-mass spectrometry. This new impurity was identified as rhodin g7 71-ethyl ester, the structure of which remains unknown to date. The cytotoxic effects of this novel compound in both dark and light conditions were studied against five cancer cell lines (HT29, MIA-PaCa-2, PANC-1, AsPC-1, and B16F10) and a normal cell line (RAW264.7) and compared to those of chlorin e6. Upon irradiation using a laser at 0.5 J/cm2, rhodin g7 71-ethyl ester demonstrated higher cytotoxicity (2-fold) compared to chlorin e6 in the majority of the cancer cell lines. Furthermore, this new compound exhibited higher dark cytotoxicity compared to chlorin e6. Studies on singlet oxygen generation, the accumulation in highly vascular liver tissue, and the production of reactive oxygen species in MIA-PaCa-2 cancer cells via rhodin g7 71-ethyl ester correspond to its higher cytotoxicity as a newly developed photosensitizer. Therefore, rhodin g7 71-ethyl ester could be employed as an alternative or complementary agent to chlorin e6 in the photodynamic therapy for treating cancer cells.

Fluorescence lifetime imaging and phasor analysis of intracellular porphyrinic photosensitizers applied with different polymeric formulations

The fluorescence lifetime of a porphyrinic photosensitizer (PS) is an important parameter to assess the aggregation state of the PS even in complex biological environments. Aggregation-induced quenching of the PS can significantly reduce the yield of singlet oxygen generation and thus its efficiency as a medical drug in photodynamic therapy (PDT) of diseased tissues. Hydrophobicity and the tendency to form aggregates pose challenges on the development of efficient PSs and often require carrier systems. A systematic study was performed to probe the impact of PS structure and encapsulation into polymeric carriers on the fluorescence lifetime in solution and in the intracellular environment. Five different porphyrinic PSs including chlorin e6 (Ce6) derivatives and tetrakis(m-hydroxyphenyl)-porphyrin and -chlorin were studied in free form and combined with polyvinylpyrrolidone (PVP) or micelles composed of triblock-copolymers or Cremophor. Following incubation of HeLa cells with these systems, fluorescence lifetime imaging combined with phasor analysis and image segmentation was applied to study the lifetime distribution in the intracellular surrounding. The data suggest that for free PSs, the structure-dependent cell uptake pathways determine their state and emission lifetimes. PS localization in the plasma membrane yielded mostly monomers with long fluorescence lifetimes whereas the endocytic pathway with subsequent lysosomal deposition adds a short-lived component for hydrophilic anionic PSs. Prolonged incubation times led to increasing contributions from short-lived components that derive from aggregates mainly localized in the cytoplasm. Encapsulation of PSs into polymeric carriers led to monomerization and mostly fluorescence emission decays with long fluorescence lifetimes in solution. However, the efficiency depended on the binding strength that was most pronounced for PVP. In the cellular environment, PVP was able to maintain monomeric long-lived species over prolonged incubation times. This was most pronounced for Ce6 derivatives with a logP value around 4.5. Micellar encapsulation led to faster release of the PSs resulting in multiple components with long and short fluorescence lifetimes. The hydrophilic hardly aggregating PS exhibited a mostly stable invariant lifetime distribution over time with both carriers. The presented data are expected to contribute to optimized PDT treatment protocols and improved PS-carrier design for preventing intracellular fluorescence quenching. In conclusion, amphiphilic and concurrent hydrophobic PSs with high membrane affinity as well as strong binding to the carrier have best prospects to maintain their photophysical properties in vivo and serve thus as efficient photodynamic diagnosis and PDT drugs.

Synthesis and Photocatalytic Properties of Layered Magnesium Silicate Modified by Chlorin e6 Derivatives with Ethanolamine Fragments

Synthesis and Photocatalytic Properties of Layered Magnesium Silicate Modified by Chlorin e6 Derivatives with Ethanolamine Fragments

Chiral Macroheterocycles as Inducers of Helical Liquid Crystals: Molecular Design, Specialty of Functioning

AbstractThe mini‐review is devoted to the influence of the structure and properties of chiral macroheterocyclic dopants on the induction of helical liquid‐crystalline phases. Using the example of solutions of synthetic porphyrins, camphor substituted hemiporphyrazines and tetrapyrazinoporphyrazines, as well as chemically modified natural macrocycles based on chlorin e6 derivatives and their metal complexes in nematic liquid crystals, the features of the mesomorphic, dielectric and rheological properties of induced spiral mesophases are discussed.

Chiral induction of helical mesophase by amphiphilic chlorin e6 derivatives and their metal complexes: Effect of chiral and achiral aliphatic chains

An experimental and theoretical study of structure and properties of chiral amphiphilic chlorin e6 13(N)-methylamide-15-methyl,17-alkyl esters (17-pentadecyl 1 and 17-phytyl 2) and their Ni complexes (Ni-1 and Ni-2) and their helical twisting efficiency in liquid crystal were carried out. Quantum chemical simulation of their structure was performed, the adequacy of which was established by comparing the calculated and experimental UV/Vis, CD, 1H and 13C NMR spectra as well as optical rotation angles. Low values of g-factors of dissymmetry for macroheterocycle (MHC) with the phytol substituent were experimentally revealed. The reason for this effect, associated with the transfer of the chirality from the stereogenic centers of the substituent to macrocyclic chromophore in the associate, was established by quantum-chemical calculation. Using polarization microscopy, the formation of chiral nematic phases was detected by doping a mixture of cyanobiphenyls with macroheterocycles 1, 2, Ni-1 and Ni-2. The values of the clearance temperature and helical pitch were measured, the slopes of phase diagrams β and helical twisting power (HTP) were calculated. The orientation order parameters of dopants in liquid crystal (LC) were determined by polarization spectroscopy. The dielectric properties of LC–MHC systems were studied within the chiral nematics and isotropic phases, and the values of the Kirkwood’s correlation factors were calculated. Using quantum chemical simulation of MHC solvates, the features of the influence of aliphatic chains structure and complex formation on the physical properties of induced mesophases were established.

Effect of substituents in chlorin e6 derivatives on the loading efficiency of the photosensitizer into the liposome membrane and their biological activity

In this work, we incorporated the hydrophobic alkylamide and hydroxyalkylamide derivatives of chlorin e6 into the lipid bilayer of liposomes. We obtained the data on the effectiveness of incorporation of studied compounds and have determined the size of liposomes and their stability when stored in liquid form. We also investigated the bioactivity of chlorin photosensitizers and compared the photodynamic activity of studied compounds in free and liposomal forms.

Dual Sensitization Anti-Resistant Nanoparticles for Treating Refractory Breast Cancers via Apoptosis-Inducing.

Current chemotherapy fails to offer a desirable efficacy in clinical treatment against breast cancer due to the extensive multi-drug resistance. In this study, we developed dual sensitization anti-resistant nanoparticles to treat refractory breast cancer, aiming to benefit from photodynamic therapy and chemotherapy. Hyaluronic acid (HA) derivative and photosensitizer chlorin e6 (Ce6) derivative were synthesized and confirmed by mass spectrometry. These derivatives and the chemotherapy agent paclitaxel were incorporated into nanoparticles by an emulsion-solvent evaporation method. The prepared nanoparticles were characterized by dynamic laser scattering, atomic force microscopy, and high performance liquid chromatography (HPLC). The efficacy and mechanisms of the nanoparticles, both in vitroand in vivo, were investigated by flow cytometry, confocal/fluorescence microscopy, and a high-content screening system. The prepared dual sensitization anti-resistant nanoparticles were round with a diameter of ~ 100 nm, exhibiting high encapsulation efficiency for the anticancer agent paclitaxel. The nanoparticles demonstrated a robust inhibitory effect against drug-resistant breast cancer cells by enhanced uptake, synergistic effect of photodynamic therapy and chemotherapy, and apoptosis-inducing via multiple pathways. Invivoefficacy, biocompatibility and safety were further confirmed acceptable in tumor-bearing mice. The prepared dual sensitization anti-resistant nanoparticles were promising to treat refractory breast cancer with a controllable treatment site and minimal side effects.

Nanoparticles of N-Vinylpyrrolidone Amphiphilic Copolymers and Pheophorbide a as Promising Photosensitizers for Photodynamic Therapy: Design, Properties and In Vitro Phototoxic Activity.

A series of nanoparticles (NPs) with a hydrodynamic radius from 20 to 100 nm in PBS was developed over the solubilization of hydrophobic dye methyl pheophorbide a (chlorin e6 derivative) by amphiphilic copolymers of N-vinylpyrrolidone with (di)methacrylates. Photophysical properties and biological activity of the NPs aqueous solution were studied. It was found that the dye encapsulated in the copolymers is in an aggregated state. However, its aggregation degree decreases sharply, and singlet oxygen quantum yield and the fluorescence signal increase upon the interaction of these NPs with model biological membranes-liposomes or components of a tissue homogenate. The phototoxic effect of NPs in HeLa cells exceeds by 1.5-2 times that of the reference dye chlorin e6 trisodium salt-one of the most effective photosensitizers used in clinical practice. It could be explained by the effective release of the hydrophobic photosensitizer from the NPs into biological structures. The demonstrated approach can be used not only for the encapsulation of hydrophobic photosensitizers for PDT but also for other drugs, and N-vinylpyrrolidone amphiphilic copolymers show promising potential as a modern platform for the design of targeted delivery vehicles.

Characterization of a Novel Amphiphilic Cationic Chlorin Photosensitizer for Photodynamic Applications.

A novel amphiphilic cationic chlorin e6 derivative was investigated as a promising photosensitizer for photodynamic therapy. Two cationic -N(CH3)3+ groups on the periphery of the macrocycle provide additional hydrophilization of the molecule and ensure its electrostatic binding to the mitochondrial membranes and bacterial cell walls. The presence of a hydrophobic phytol residue in the same molecule results in its increased affinity towards the phospholipid membranes while decreasing its stability towards aggregation in aqueous media. In organic media, this chlorin e6 derivative is characterized by a singlet oxygen quantum yield of 55%. Solubilization studies in different polymer- and surfactant-based supramolecular systems revealed the effective stabilization of this compound in a photoactive monomolecular form in micellar nonionic surfactant solutions, including Tween-80 and Cremophor EL. A novel cationic chlorin e6 derivative also demonstrates effective binding towards serum albumin, which enhances its bioavailability and promotes effective accumulation within the target tissues. Laser confocal scanning microscopy demonstrates the rapid intracellular accumulation and distribution of this compound throughout the cells. Together with low dark toxicity and a rather good photostability, this compound demonstrates significant phototoxicity against HeLa cells causing cellular damage most likely through reactive oxygen species generation. These results demonstrate a high potential of this derivative for application in photodynamic therapy.

Experience of using photodynamic therapy in early stages of penile cancer

Background. Penile cancer is a rare oncological pathology. Due to the intimate nature of the affected area and high significance of the organ for psycho-emotional state of the patient, at the early stages of the disease organ-sparing operations are preferred allowing to minimize the effect on patient’s quality of life without affecting oncological results.Aim. To evaluate the effectiveness of treatment of early stages penile cancer using photodynamic therapy (PDT) with chlorin E6 derivatives.Materials and methods. Between 2017 and 2021, PDT with chlorin E6 derivatives to treat early-stage penile cancer was performed in 15 patients between the ages of 29 and 84 years (mean age 56.4 years). Tumor stage was Tin situ–1bN0M0. PDT was performed with preliminary administration of Photolon and Photoran photosensitizers. Laser exposure on the tumor lesions was performed 3 hours after photosensitizer administration using laser device Latus-2 (662 nm), light dose 200–300 J/cm2, power density 0.21–0.41 mW/cm2.Results. After 1 PDT session, full regression was observed in 11 (73.3 %) patients, partial regression in 4 (26.7 %) patients who underwent 2nd session 2 months later with full effect. Therefore, in all patients full regression of the tumors was achieved. Follow-up duration was 6–56 months. Recurrence was diagnosed in 1 (6.7 %) patient 36 months after PDT, 14 (93.3 %) patients are under observation without signs of local recurrence, among them for more than 4 years – 3 men, more than 3 years – 1, more than 2 years – 3, more than 1 year – 4 and more than 6 months – 3. During the follow-up, no regional or distant metastases were observed in any of the patients.Conclusion. PDT with chlorin E6 derivatives is an effective organ-sparing treatment method for early-stage penile cancer with satisfactory oncological results without negative effect on patients’ quality of life. In 93.3 % of patients, local recurrence of the disease was not observed; during follow-up no distant metastases were diagnosed. It is necessary to point out satisfactory cosmetic results of the treatment: in all patients, elastic non-deforming scars were formed with full preservation of anatomical structures of the penis, no erectile dysfunction or disruption of urination were observed after PDT.

Study of acute toxicity of monocationic chlorin e6 derivative, a perspective photosensitizer for antimicrobial and antitumor photodynamic therapy

In this experimental work the acute toxicity of a chemically modified derivative of the natural pigment chlorophyll a called monocationic chlorin e6, which is a promising photosensitizer (PS) for antimicrobial and antitumor photodynamic therapy, was studied using white rats. The advantages of the PS under investigation are an intense absorption in the long-wavelength region of the visible spectrum, a sufficiently high quantum yield of singlet oxygen generation, pronounced amphiphilic properties along with an appropriate solubility in water, and a high level of photocytotoxic- ity in relation to both malignant HeLa cells and antibiotic-resistant hospital strains of E. сoli bacteria., P. aerugenosa and others. It has been shown that the value of LD 50 of the considered PS can be calculated as the value of 100 mg/kg. In the reproduced experimental model of acute toxicity, pathomorphological changes in the vital organs of laboratory animals indicate a pronounced vasopathic effect of the drug with the development of cerebral edema and respiratory distress syndrome, which have become the main signs of thanatogenesis.

A chlorin e6 derivative‐mediated photodynamic therapy for patients with cervical and vaginal low‐grade squamous intraepithelial lesions: a retrospective analysis

AbstractCervical and vaginal low‐grade squamous intraepithelial lesions (LSIL) are associated with persistent human papillomavirus infections, and require an efficacious non‐invasive treatment such as photodynamic therapy due to anatomical characteristics. In this study, we evaluated the clinical efficacy and safety of a chlorin e6 derivative named STBF‐mediated photodynamic therapy (STBF‐PDT) for patients with cervical and vaginal LSIL. A total of 18 patients received STBF‐PDT for 3 to 6 times and followed up for 6 to 12 months; among them, 6 had cervical and vaginal LSIL and 1 had vaginal stump LSIL after hysterectomy for cervical cancer. Results showed the complete remission (CR) rates were 72.22% (13/18), and the HPV remission rates and HPV clearance rates were 88.89% (16/18) and 83.33% (15/18), respectively at 1‐month follow‐up. The CR reached 88.89% and HPV remission rates got 94.44% at the 6‐month follow‐up. There were no recurrence cases so far, and no pain, heaving sensation, scar, deformity, and any other obvious adverse reactions occurred during treatment and follow‐up. In conclusion, STBF‐PDT is an effective, safe, and well‐tolerated method for the treatment of cervical and vaginal LSIL. It may have promising potential for applications in the future.

Photodynamic Therapy with Chlorin e6 Derivative for Chronic Central Serous Chorioretinopathy (Pilot Study).

Purpose: To evaluate the use of photodynamic therapy (PDT) with chlorin e6 (Ce6) derivative in patients with chronic central serous chorioretinopathy (CSC). Methods: Participants in this interventional, single-center clinical pilot study included 39 patients (39 eyes) with chronic CSC. Primary objectives were to assess safety and change in decimal best-corrected visual acuity (BCVA) during the 12-month follow-up. Secondary objectives were to evaluate change in central retinal thickness (CRT) in fovea area, maximal height of subretinal fluid (SRF), subfoveal choroidal thickness (SFCT) on spectral-domain optical coherence tomography, and number of treatments. Results: There were no systemic adverse events and ocular side effects. Mean decimal BCVA showed a significant increase from 0.49 ± 0.25 to 0.63 ± 0.28 (P = 0.001), mean CRT and maximal height of SRF decreased significantly from 335 ± 95 to 219 ± 69 μm and from 149 ± 84 to 32 ± 86 μm respectively (P = 0.001), comparing baseline and month 12. There was no significant difference between mean SFCT before PDT and at month 12. During all follow-up periods mean number of PDT treatments was 1.3 ± 0.7. Complete SRF resolution was observed in 82% (32 eyes) during observation period. Conclusion: Results of this pilot study demonstrate that PDT with Ce6 derivative is a safe method to treat eyes with chronic CSC. PDT with Ce6 derivative is the treatment option for chronic CSC. Further randomized controlled studies with a larger sample size and longer periods of follow-up are needed to assess the effectivity and safety of PDT with Ce6 derivative in chronic CSC.

Photodynamic Inactivation of plant pathogens part II: fungi

The constantly increasing demand for agricultural produce from organic and conventional farming calls for new, sustainable, and biocompatible solutions for crop protection. The overuse of fungicides leading to contamination of both produce and environment and the emergence of plant pathogenic fungi that are resistant to conventional treatments warrant the need for new methods to combat fungal infections in the field. We here deliver the follow-up study to our research on the Photodynamic Inactivation (PDI) of plant pathogenic bacteria (Glueck et al. in Photochem Photobiol Sci 18(7):1700–1708, 2019) by expanding the scope to fungal pathogens. Both fungal species employed in this study—Alternaria solani and Botrytis cinerea—cause substantial crop and economic losses. Sodium magnesium chlorophyllin (Chl, approved as food additive E140) in combination with Na2EDTA and the chlorin e6 derivative B17-0024 holding cationic moieties serve as eco-friendly photoactive compounds. Effectiveness of the antifungal PDI was measured by inhibition of growth of mycelial spheres (average diameter 2–3 mm) after incubation with the photosensitizer for 100 min and subsequent illumination using a LED array (395 nm, 106.6 J cm−2). One hundred micromolar Chl combined with 5 mM Na2EDTA was able to successfully photokill 94.1% of A. solani and 91.7% of B. cinerea samples. PDI based on B17-0024 can completely inactivate A. solani at 10 times lower concentration (10 µM); however, for B. cinerea, the concentration required for complete eradication was similar to that of Chl with Na2EDTA (100 µM). Using a plant compatibility assay based on Fragaria vesca, we further demonstrate that both photosensitizers neither affect host plant development nor cause significant leaf damage. The plants were sprayed with 300 µL of treatment solution used for PDI (one or three treatments on consecutive days) and plant growth was monitored for 21 days. Only minor leaf damage was observed in samples exposed to the chelators Na2EDTA and polyaspartic acid, but overall plant development was unaffected. In conclusion, our results suggest that sodium magnesium chlorophyllin in combination with EDTA and B17-0024 could serve as effective and safe photofungicides.Graphical abstract

Chlorin e6 13(N)-methylamide-15,17-dimethyl ester and its nickel complex as the inducers of chiral nematic liquid crystals

To search for new effective inducers of helical liquid-crystalline phases, chlorin e6 13 (N)-methylamide-15,17-dimethyl ester (MADMECl) and its nickel complex (Ni-MADMECl) were studied. An increase in the optical activity of the chlorin e6 derivative upon complexation with nickel, associated with a distortion of the macrocycle structure, was established by circular dichroism spectroscopy and quantum chemistry. The introduction of a macrocyclic complex into binary LC mixtures based on cyanobiphenyls (CB-2) and Schiff bases (SB-2), as well as the macrocyclic ligand MADMECl in CB-2, was shown to induce the formation of helical LC phases with high helical twisting power (maximum HTP = 409 μm−1 for the mixture CB-2 + Ni-MADMECl). The HTP decreases with an increase in the additive concentration. The assessment of the dopant influence on the LC thermal stability was carried out. The temperature dependences of the permittivity components of the studied liquid-crystalline solutions were obtained at different dopant concentrations. The relationship between the dielectric anisotropy and the helical pitch is established due to the 3D compensation of molecular dipoles. Quantum-chemical simulation of dopant-LC solvates was performed. The influence of the energy of intermolecular interaction on the efficiency of nematic phase twisting was ascertained. The contribution of supramolecular chirality to the process of chiral induction was detected.

Synthesis and biological evaluation of NO-donor containing photosensitizers to induce ferroptosis of cancer cells

Photodynamic therapy (PDT) is a non-invasive treatment method for tumors by exciting photosensitizers (PS) upon light irradiation to generate cytotoxic reactive oxygen species (ROS). However, the low oxygen concentration near the tumor tissue limits the therapeutic effect of PDT. Herein, we synthesized six chlorin e6 derivatives containing NO-donors to enhance their antitumor activity by synergistic effect of ROS and NO. The results revealed that the new NO-donor containing photosensitizers (PS-NO) exhibited more potent photodynamic activity than chlorin e6, and the introduction of NO donor moieties to chlorin e6 increased the level of NO and ROS in cells. The addition of Ferrostatin-1, a ferroptosis inhibitor, markedly reduced the photodynamic activity of PS-NO as well as the level of NO and ROS in cells. Mechanism studies further showed that PS-NO could reduce intracellular GSH level, inhibit GPX4 activity and promote malondialdehyde (MDA) accumulation upon light irradiation, which suggested the ferroptosis mechanism underlying the PDT effect of PS-NO.

Photodynamic antibacterial action of guanidine and biguanidine derivatives of chlorin e6

Photodynamic antibacterial action of guanidine and biguanidine derivatives of chlorin e6

Synthesis and Photocatalytic Properties of Magnesium Silicate Modified with Cationic Chlorin e6 Derivatives

Synthesis and Photocatalytic Properties of Magnesium Silicate Modified with Cationic Chlorin e6 Derivatives

Spectroscopic Investigation of Chlorin-Based Photosensitizers in Polymer Matrix

Chlorin e6 and its derivatives are the basis of a number of drugs used in medicine in the treatment of various diseases, including cancer, by photodynamic therapy. Nonpolar derivatives of Chlorin e6—dimethyl ether of Chlorin e6 (DME Ce6) and trimethyl ether of Chlorin e6 (TME Ce6)—are actively studied for application during photodynamic therapy. In this work, based on the electron optical absorption spectra, the interaction of photosensitizer molecules with branched star-like copolymer dextran-graft-polyacrylamide in anionic form was investigated and the possibility of using the latter as a carrier for drug delivery to tumor cells was suggested.

Nanoengineering of a newly designed chlorin e6 derivative for amplified photodynamic therapy via regulating lactate metabolism.

Chlorin e6 (Ce6) is a widely utilized photosensitizer in photodynamic therapy (PDT) against tumor growth, but its hydrophobic feature and the hypoxia in the tumor microenvironment greatly compromise its therapeutic efficacy. To address the issues, here we designed a new Ce6 derivative (TCe6) by coupling Ce6 with amphiphilic d-α-tocopherol polyethylene glycol 1000 succinate (TPGS), endowing Ce6 with an excellent amphiphilic feature. In particular, the overall reactive oxygen species (ROS) generation by TCe6 was significantly enhanced because TPGS could interact with mitochondrial complex II to induce extra ROS production, amplifying the total ROS production under PDT. Inspired by the unique property of α-cyano-4-hydroxycinnamate (CHC) in regulating lactate metabolism to spare more intracellular oxygen for PDT, TCe6 was further co-assembled with CHC to construct TCe6/CHC nanoparticles (NPs) for addressing the insufficient oxygen issue in PDT. The as-prepared TCe6/CHC NPs not only increased the efficiency of cell internalization but also improved the solubility and stability of Ce6 and CHC. Thanks to the extra ROS production by the TPGS unit, the amphiphilic feature of TCe6 and the CHC-mediated hypoxia microenvironment, the TCe6/CHC NPs demonstrated excellent PDT against tumor growth. This work provided a versatile strategy to solve the current bottleneck in photosensitizer-based PDT, holding great promise for the design of advanced photodynamic nanoplatforms.