Synthesis and photophysical properties of sulfonamidophenyl porphyrins as models for activatable photosensitizers

A novel porphyrin-based theranostic agent activated by cysteine over-expressed in cancer cells shows promise for tumour-targeted monitoring and phototherapy

l-Cysteine (Cys) is a tumor-related biomarker. The photo- and Cys-activatable theranostic agent 4 was designed and synthesized based on 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin (3). Compound 4 exhibited negligible fluorescence and photosensitizing activity in the absence of Cys. However, when activated by Cys, 3 was released, resulting in fluorescence and photosensitization. Moreover, upon irradiation with 660 nm light, 4 displayed selective and effective fluorescence and photo-cytotoxicity exclusively against cancer cells, such as HeLa and A549 cells, which express high levels of Cys. This wavelength of light falls within the phototherapeutic window.

Tetramethyl Cucurbit[6]uril-Porphyrin Supramolecular Polymer Enhances Photosensitization

Porphyrins serve as photosensitizers (PS) in the realm of cancer photodynamic therapy (PDT). Upon excitation by laser light, porphyrins are capable of converting molecular oxygen into highly cytotoxic singlet oxygen (1O2). However, the rigid π-conjugated structure of porphyrins frequently results in the formation of aggregates in aqueous solutions, which leads to the self-quenching of the excited state. Cucurbit[n]urils exhibit the capacity to stably bind with porphyrins via host-guest interactions, effectively inhibiting their aggregation and potentially enhancing the therapeutic efficacy of PDT. In this study, water-soluble tetramethyl cucurbit[6]uril (TMeQ[6]) was selected as the host, while four propionic acid group-appended porphyrin cationic (TPPOR) was utilized as guests to construct a supramolecular photosensitizer (TPPOR-2TMeQ[6]) in a molar ratio of 2:1. Further experimental findings demonstrate that the presence of TMeQ[6] inhibits the aggregation of TPPOR through non-covalent interactions. This inhibition reduces the energy difference between the excited singlet and triplet states, thereby enhancing the conversion efficiency of 1O2. Moreover, TPPOR-2TMeQ[6] exhibits favorable biocompatibility and minimal dark toxicity against breast cancer cells (4T1). Upon intracellular excitation, the levels of reactive oxygen species (ROS) significantly increase, inducing oxidative stress in 4T1 cells and leading to apoptosis. Consequently, the findings of this study suggest that the enhanced photosensitization achieved through this supramolecular approach is likely to promote the anticancer therapeutic effects of PDT, thereby broadening the application prospects of porphyrins within PDT systems.

Fluorinated High-Valent Sn(IV) Porphyrins Show Remarkable Photodynamic Activity in Cancer Cells

In recent years, Sn(IV) porphyrins have proven to be excellent choice as photosensitizers for photodynamic therapy. This work reports the synthesis, characterization and photodynamic activity of four high-valent fluorinated Sn(IV) porphyrins having different numbers of F-atoms in the peripheral of meso-phenyl groups viz. (Dichloro)meso-tetrakis(4-fluorophenylporphyrinato)stannic(IV), [Sn(IV)FTPP(Cl)2] or Sn1; (Dichloro)meso-tetrakis(2,4-difluorophenylporphyrinato)stannic(IV), [Sn(IV)2,4-FTPP(Cl)2] or Sn2; (Dichloro)meso-tetrakis(2,6-difluorophenylporphyrinato)stannic(IV), [Sn(IV)2,6-FTPP(Cl)2] or Sn3 and (Dichloro)meso-tetrakis(4-trifluoromethylphenylporphyrinato)stannic(IV), [Sn(IV)CF3TPP(Cl)2] or Sn4. The solid-state structure of Sn1 has been determined by single crystal X-ray diffraction analysis. The increasing number of F-atoms attached to the meso-phenyl positions of the porphyrin framework results in increase of their lipophilicity, singlet oxygen quantum yield (ΦΔ) and photocytotoxicity in A549 (human lung adenocarcinoma cells), MCF-7 and MDA-MB-231 (human breast adenocarcinoma) cells. Sn4 predominantly localize in the mitochondria of A549 cells. The light-induced cell death by the Sn(IV) porphyrins in A549 cells occur primarily via apoptosis.

Asymmetrically meso-substituted porphyrin derivative containing the triazole group: Synthesis, characterization and photo-physicochemical properties

In this study, a novel asymmetrically meso-substituted AB3 porphyrins derivative including one triazole group to enhance the anticancer activity of the molecule and three bromophenyl groups to improve photochemical properties has been synthesized and characterized. Our objectives were to generate a system with triazole and bromophenyl groups that enhance the singlet oxygen generation and exhibits an anti-cancer effect. Therefore, photophysical and photochemical properties of this asymmetric porphyrin derivative (AB[Formula: see text] and the symmetric derivative (B[Formula: see text] were investigated in THF. The substituent effect on fluorescence quantum yield and singlet oxygen generation was evaluated for efficiency in photodynamic therapy (PDT) as a photosensitizer. The molecules exhibited no aggregation tendency, solubility in common organic solvents and high singlet oxygen quantum yield in THF therefore these favorable properties make them good candidates as a photosensitizer for PDT.

Comparison of the Photodynamic Action of Porphyrin, Chlorin, and Isobacteriochlorin Derivatives toward a Melanotic Cell Line

Melanoma is the most dangerous form of skin cancer, with an abrupt growth of its incidence over the last years. It is extremely resistant to traditional treatments such as chemotherapy and radiotherapy, but therapies for this cancer are gaining attention. Photodynamic therapy (PDT) is considered an effective modality to treat several types of skin cancers and can offer the possibility to treat one of the most aggressive ones: melanoma. In this work, the effect of PDT on a melanotic cell line (B16F10 cells) was assessed by exposing cultured cells to 5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)porphyrin (PS1) and to its chlorin (PS2) and isobacteriochlorin (PS3) corresponding derivatives and red LED light (λ = 660 ± 20 nm). The PDT effect in the cells' viability was measured using the MTT assay. The cell apoptosis was quantified by flow cytometry, and the subcellular localization of the photosensitizer was determined by fluorescence microscopy. In addition, the ability of PS2 to generate superoxide radicals was qualitatively assessed by tyrosine nitration. The results show that the efficiency of the PDT process is dependent on the structure of the PS and on their ability to produce singlet oxygen. Besides that, the photoactivation efficiency is highly dependent on the cellular sublocalization of the PS and on its cellular uptake and singlet oxygen production. We also found that the resistant cell line B16F10 has distinctive chlorin, isobacteriochlorin, or porphyrin-specific resistance profiles. Furthermore, it is shown that the highly fluorescent chlorin derivative PS2 can also be considered in imaging diagnostics.

Light-assisted anticancer photodynamic therapy using porphyrin-doped nanoencapsulates

Light activatable porphyrinic photosensitizers (PSs) are essential components of anticancer and antimicrobial therapy and diagnostic imaging. However, their biological applications are quite challenging due to the lack of hydrophilicity and biocompatibility. To overcome such drawbacks, photosensitizers can be doped into a biocompatible polymer such as gelatin and further can be used for biomedical applications. Herein, first, a novel A4 type porphyrin PS [5,10,15,20-tetrakis(4-pyridylamidephenyl)porphyrin; TPyAPP] was synthesized via a rational route with good yield. Further, this porphyrin was encapsulated into the gelatin nanoparticles (GNPs) to develop hydrophilic phototherapeutic nanoagents (PTNAs, A4por-GNPs). Notably, the synthesis of such porphyrin-doped GNPs avoids the use of any toxic chemicals or solvents. The nanoprobes have also shown good fluorescence quantum yield demonstrating their applicability in bioimaging. Further, the mechanistic aspects of the anticancer and antimicrobial efficacy of the developed A4por-GNPs were evaluated via singlet oxygen generation studies. Overall, our results indicated porphyrin-doped biodegradable polymeric nanoparticles act as effective phototherapeutic agents against a broad range of cancer cell lines and microbes upon activation by the low-cost LED light.

Ubiquinone-BODIPY nanoparticles for tumor redox-responsive fluorescence imaging and photodynamic activity

Successful applications of photodynamic therapy (PDT) in cancer treatment require the development of effective photosensitizers with controllable singlet oxygen generation. Here we report a ubiquinone-BODIPY photosensitizer that self-assembles into nanoparticles (PS-Q-NPs) and undergoes selective activation and deaggregation within the highly reductive intracellular environment of tumor cells. PS-Q-NPs are highly stable in aqueous buffer solution, and exhibit minimal fluorescence and photosensitization due to a rapid non-radiative relaxation process. Upon endocytosis by cancer cells, reduction of the ubiquinone moiety by intracellular glutathione (GSH) triggers the conversion of the aggregated hydrophobic precursor into the active hydrophilic carboxylate derivative PS-A. The conversion results in enhanced fluorescence and therapeutic singlet oxygen generation, portending to its application as an activatable photosensitizer for fluorescence imaging-guided photodynamic cancer therapy.

Novel sulfonamide porphyrin TBPoS-2OH used in photodynamic therapy for malignant melanoma

The application of photodynamic therapy (PDT) for the treatment of skin diseases has been receiving much attention. Here, we examined the anti-tumor effect of a novel porphyrin-based photosensitizer TBPoS-2OH in the malignant melanoma A375 and B16 cells. TBPoS-2OH has obvious cell photo-cytotoxicity, but it has low cell dark-cytotoxicity. Further research showed that TBPoS-2OH is enriched in lysosomes after being taken up by cells. Subsequently, the apoptotic rates were significantly increased in TBPoS-2OH-treated A375 and B16 cells. The specific mechanism may be that after receiving light stimulation, TBPoS-2OH could effectively increase the level of intracellular reactive oxygen species (ROS), thereby activating mitochondrial apoptosis pathway-related proteins in A375 and B16 cells. We found an increase in the content of cytochrome C in the cytoplasm, and the levels of related proteins, such as cleaved caspase-3, cleaved caspase-9, and cleaved PARP1, were significantly increased in TBPoS-2OH-treated cells. These results indicated that the new compound TBPoS-2OH could be developed and become an alternative drug for the treatment of melanoma. Some reference ideas for the development of new photosensitizers are also provided.

Photodynamic treatment of melanoma cells using aza-dipyrromethenes as photosensitizers

In this study, we report for the first time the use of four aza-dipyrromethenes (ADPMs) as photosensitizers for cancer PDT. The synthesis and characterization of the ADPMs and their photodynamic action against B16F10 melanoma cells were assessed. ADPM 2 is the best singlet oxygen generator and the most phototoxic (at 2.5 μM) towards B16F10 cells.

(Aminophenyl)porphyrins as precursors for the synthesis of porphyrin-modified siloxanes

The present research reports the efficient synthesis of mono- and di-(aminophenyl)porphyrins and their metalation with Zn(II) using microwave irradiation. The subsequent reaction of amino-functionalized porphyrins with siloxane moieties bearing epoxy or carboxyl functional groups provided four new porphyrin-modified siloxanes. The structure of the resulting derivatives was established by 1H-NMR and MALDI-TOF-MS. The optical properties of the porphyrin chromophores were preserved, as proven by comparing the absorption and emission spectra of the initial porphyrins to those of the porphyrin-modified siloxanes.

Synthesis, Photophysical Properties and Application of New Porphyrin Derivatives for Use in Photodynamic Therapy and Cell Imaging

New derivatives of tetrakis(4-carboxyphenyl) porphyrin were designed, synthesized and characterized by IR, proton NMR and mass spectroscopy. The ground and excited state nature of new derivatives were examined using UV-Vis. absorption and fluorescence spectroscopy, fluorescence quantum yield and fluorescence lifetime studies. The singlet oxygen quantum yield of each synthesized derivative of porphyrin was estimated for their further efficacy as potential photosensitizer in biological studies. The significant photophysical data of all synthesized derivatives was supplementary accessed to examine the cell imaging and cytotoxicity against two cancer cell lines viz. MBA-MD-231 and A375. The fluorescence lifetime, fluorescence quantum yield and efficiency of singlet oxygen generation suggests alkyl amine and alkyl hydrazide linked new porphyrin photosensitizers can be useful for PDT agent in cancer treatment.

Endosome Targeting meso-Tetraphenylchlorin-Chitosan Nanoconjugates for Photochemical Internalization

Four amphiphilic covalently linked meso-tetraphenylchlorin-chitosan nanoconjugates were synthesized and evaluated for use in photochemical internalization (PCI) in vitro and in vivo. The synthetic protocol for the preparation of two different hydrophobic chlorin photosensitizers, 5-(4-aminophenyl)-10,15,20-triphenylchlorin and 5-(4-carboxyphenyl)-10,15,20-triphenylchlorin, was optimized. These monofunctional photosensitizers were covalently attached to carrier chitosan via silyl-protected 3,6-di-O-tert-butyldimethylsilyl-chitosan (Di-TBDMS-chitosan) with 0.10 degree of substitution per glucosamine (DS). Hydrophilic moieties such as trimethylamine and/or 1-methylpiperazine were incorporated with 0.9 DS to give fully water-soluble conjugates after removal of the TBDMS groups. A dynamic light scattering (DLS) study confirmed the formation of nanoparticles with a 140-200 nm diameter. These nanoconjugates could be activated at 650 nm (red region) light, with a fluorescence quantum yield (Φ_F) of 0.43-0.45, and are thus suitable candidates for use in PCI. These nanoconjugates were taken up and localized in the endocytic vesicles of HCT116/LUC human colon carcinoma cells, and upon illumination they substantially enhanced plasmid DNA transfection. The nanoconjugates were also evaluated in preliminary in vivo experiments in tumor-bearing mice, showing that the nanoconjugates could induce a strong photodynamic therapy (PDT) and also PCI effects in treatment with bleomycin.

Bioinspired nanophotosensitizers: synthesis and characterization of porphyrin–noble metal nanoparticle conjugates

Conjugatable and compact porphyrinic photosensitizer nanoparticle conjugates were developed through rational synthesis followed by conjugation with noble metal nanoparticles.

Anion exchange nanofiber materials activated by daylight with a dual antibacterial effect

Anion exchange polystyrene nanofiber materials (AE) were prepared by electrospinning followed by two-step functionalization of the nanofiber surface by chlorosulfonic acid and ethylendiamine. The photoactive character of these materials was introduced through adsorption of the tetra-anionic 5,10,15,20-tetrakis-(4-sulfonatophenyl)porphyrin photosensitizer (TPPS-AE) on the nanofiber surface or by encapsulation of the nonpolar 5,10,15,20-tetraphenylporphyrin photosensitizer (AE(TPP)) into the nanofibers. Anion exchange nanofiber materials with porphyrins are characterized by a high ion-exchange capacity, photogeneration of singlet oxygen O2((1)Δg), and singlet oxygen-sensitized delayed fluorescence. Due to the photogeneration of cytotoxic O2((1)Δg), the nanofibers exhibited oxidation of the external substrates in aqueous solution and an efficient antibacterial effect when activated by simulated daylight. Adsorption of both TPPS and I(-) on the surface of AE led to the formation of more efficient I-TPPS-AE materials. Rapid photooxidation of I(-) by O2((1)Δg), and the formation of another cytotoxic species, I3(-), on the surface of the nanofibers were responsible for the increased antibacterial properties of I-TPPS-AE and the prolonged antibacterial effect in the dark.

Selective photosensitization through an AND logic response: optimization of the pH and glutathione response of activatable photosensitizers

A series of pH and GSH responsive photosensitizers were designed and synthesized. pKa values were optimized by adjusting the inductive contribution of substituents to reach a pH range (6.0-7.4) relevant to the tumour microenvironment. pH-Activatable behaviour and redox mediated release of the quencher from the PS by GSH allow the construction of an AND logic operator for selective photodynamic action in aqueous solutions.

Synthesis and photodynamic activity of new meso-tetranaphthylporphyrins derivatives

The meso-tetranaphthylporphyrins (TNP) derivatives, 5-(2-hydroxy-1-naphthaldehyde-4-naphthyleneimine)-10,15,20-trinaphthylporphyrin 3, 5-(salicylidene-4-naphthyleneamine)-10,15,20- trinaphthylporphyrin 4 and 5-(thiophene-2-carboxaldehyde-4-naphthyleneimine)-10,15,20-trinaphthylporphyrin 5, were synthesized by the reaction of 5-(4-aminonaphthyl)-l0,15,20-trinaphthylporphyrin 2 with different aldehydes. Their photodynamic activity against K562 cells were evaluated in vitro. They displayed low levels or no dark toxicity and high phototoxicity to K562 cells, especially for 5, which offers potential application in photodynamic therapy.

Room temperature synthesis and antibacterial activity of new sulfonamides containing n,n-diethyl-substituted amido moieties

Sulfonamide drugs which have brought about an antibiotic revolution in medicine are associated with a wide range of biological activities. We have synthesized a series of α-tolylsulfonamide, 1–11 and their substituted N,N-diethyl-2-(phenylmethylsulfonamido) alkanamide derivatives, 12–22 in improved and excellent yields in aqueous medium at room temperature through highly economical synthetic routes. The chemical structures of the synthesized compounds 1–22 were confirmed by analytical and spectral data such as IR, ¹H- and ¹³C-NMR, and mass spectra. The in vitro antibacterial activity of these compounds along with standard clinical reference, streptomycin, was investigated on two key targeted organisms. It was observed that 1-(benzylsulfonyl)pyrrolidine-2-carboxylic acid, 2 emerged as the most active compound against Staphylococcus aureus at MIC value of 1.8 μg/mL while 4-(3-(diethylamino)-3-oxo-2-(phenylmethylsulfonamido) propyl)phenyl phenylmethanesulfonate, 22 was the most active sulfonamide scaffold on Escherichia coli at MIC value of 12.5 μg/mL.