Photosensitizing effectiveness of a novel chlorin-based photosensitizer for photodynamic therapy in vitro and in vivo

Effects of excitation power density on the Stern-Volmer constant measurement

The Stern-Volmer constant (KSV) is an important parameter to describe the capability of energy transfer to oxygen for porphyrin and its derivatives. By fitting Stern-Volmer equation, IP0/IP = 1 + KSV[O2], the KSV is generally determined through phosphorescence intensities (IP) under aerobic and oxygen-free conditions. In this work, the effect of excitation power density on the KSV measurement is theoretically analyzed and experimentally studied, using palladium octaethylporphyrin (PdOEP) as an example. The IP of PdOEP increased nonlinearly with excitation power density, and the power dependent slope of IP0/IP could be obtained. By way of the functional relationship between the slope of IP0/IP and power density, the real KSV of PdOEP was fitted to be 58 ± 2 kPa-1. The oxygen-dependent phosphorescence lifetimes (τP) and IP under a weak excitation power are also measured to calculate the real KSV, which verifies our analysis.

Accurate Determination of the Photosensitizer Stern-Volmer Constant by the Oxygen-Dependent Consumption of 1,3-Diphenylisobenzofuran

Because of the absence of phosphorescence, the Stern-Volmer constant (KSV) of the photosensitizer is hard to determine accurately. Although the delayed fluorescence and correlated fluorescence methods have been proposed to determine KSV, the weak signal detection and non-uniform excitation enlarged the measurement error. In this work, a method was proposed to accurately determine KSV by oxygen-dependent consumption of 1,3-diphenylisobenzofuran. The consumption time (δ), as a measurable quantity, is introduced and could be obtained by the absorption spectrum with a high signal-to-noise ratio. Analytically, δ is linearly related to the inverse of oxygen content, and the ratio of the intercept to the slope equals KSV. Experimentally, rose Bengal was selected to perform this determination; the KSV is measured to be 43(1) kPa-1, and the error is reduced by 1 order of magnitude. In addition, metalloporphyrin was used to verify this method.

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.

Synthesis and evaluation of novel fluorinated hematoporphyrin ether derivatives for photodynamic therapy

A photosensitizer with high phototoxicity, suitable amphipathy and low dark toxicity could play a pivotal role in photodynamic therapy (PDT). In this study, a facile and versatile approach was adopted to synthesize a series of novel fluorinated hematoporphyrin ether derivatives (I1-I5 and II1-II4), and the photodynamic activities of these compounds were studied. Compared to hematoporphyrin monomethyl ether (HMME), all PSs showed preferable photodynamic activity against A549 lung tumor cells. The longest visible absorption wavelength of these compounds was approximately 622 nm. Among them, II3 revealed the highest singlet oxygen yield (0.0957 min-1), the strongest phototoxicity (IC50 = 1.24 μM), the lowest dark toxicity in vitro, and exhibited excellent anti-tumor effects in vivo. So compound II3 could act as new drug candidate for photodynamic therapy.

Method for monitoring singlet oxygen quantum yield in real time by time resolved spectroscopy measurement

The singlet oxygen quantum yield (Φ_Δ) was monitored in real time through time resolved spectroscopy measurement, using gadolinium labeled hematoporphyrin monomethyl ether (Gd-HMME) as photosensitizer. According to the kinetics equations of singlet oxygen generation and reaction, Φ_Δ was related to phosphorescence lifetime (τ_p). Through measuring τ_p of Gd-HMME in different oxygen conditions, the radiation transition property of first exited triplet state (T₁) was monitored; combined with the triplet state quantum yield (Φ_T) determined by linear fitting the Φ_Δ, which was measured in different oxygen content using a relative measurement, Φ_Δ can be determined in real time. The identification of anoxia during the treatment of photodynamic therapy (PDT) by this method is also presented.

Key factors affecting photoactivated fungicidal activity of sodium pheophorbide a against Pestalotiopsis neglecta

Recently, photodynamic therapy (PDT) and photoactivated pesticides have attracted considerable research attention. In the present study, we aimed to investigate the photodynamic activity of a chlorophyllous derivative, sodium pheophorbide a (SPA), and to evaluate its potential as a photoactivated fungicide. The singlet oxygen quantum yield, the photoreaction process, the anti-photobleaching ability in sterile water (H₂O), the effect of light conditions on its antifungal activity, and its stability were all investigated. SPA showed significant fungicidal activity and photostability, during which Type I and Type II photodynamic reactions occurred simultaneously on Pestalotiopsis neglecta, and the influence of Type I was slightly larger than that of Type II. In addition, light promoted the antifungal activity of SPA. In particular, the antifungal activity was enhanced with increasing light intensity, and was strongest under 8000 lx conditions. Under monochromatic light sources, antifungal activity was strongest under green light s; however, the effect of monochromatic light was not as good as that of white light. From 0 to 24 h, the antifungal effect of the SPA solution was enhanced; however, the activity of the solution began to weaken after 24 h. Furthermore, our study confirmed that the antifungal activity of SPA was stable under different temperatures, pH values, and UV irradiation durations.

Photophysical properties of sinoporphyrin sodium and explanation of its high photo-activity

Sinoporphyrin sodium (DVDMS) is a novel photosensitizer with high photodynamic therapy (PDT) effect. Reasons for its high photo-activity were investigated according to the study of photophysical characteristics of DVDMS. Extinction coefficients ([Formula: see text] of DVDMS at 405 nm and 630 nm are 4.36 × 105 and 1.84 × 104 M[Formula: see text].cm[Formula: see text]; fluorescence quantum yield ([Formula: see text] is 0.026; quantum yield of lowest triplet state formation is 0.94 and singlet oxygen quantum yield ([Formula: see text] is 0.92. Although [Formula: see text] of DVDMS is only 10% higher than that of Photofrin[Formula: see text] (0.83), the extinction coefficient of DVDMS at 630 nm is 10-fold greater than that of Photofrin[Formula: see text]. This leads to its higher singlet oxygen generation efficiency ([Formula: see text]. The higher [Formula: see text] of DVDMS can result in an effective reduction of dosage (1/10 of Photofrin[Formula: see text] reaching the same cytotoxic effect as Photofrin[Formula: see text]. Even though [Formula: see text] is approximately equal to that of Photofrin[Formula: see text], brightness ([Formula: see text] of DVDMS is 10-fold greater than that of Photofrin[Formula: see text] because of the 10-fold greater extinction coefficient. Thus, fluorescence diagnosis ability of 0.2 mg/kg DVDMS is comparable to that of 2 mg/kg Photofrin[Formula: see text] used in PDT. Overall, the 10-fold greater extinction coefficients are responsible for the high brightness and singlet oxygen generation efficiency of DVDMS.

Photophysical properties, singlet oxygen generation efficiency and cytotoxic effects of aloe emodin as a blue light photosensitizer for photodynamic therapy in dermatological treatment

Aloe emodin with anticancer and photosensitising capabilities, excited by blue light, is proposed as a photosensitizer to treat superficial diseases.

The anti-cancer potency of photodynamic therapy of a novel chlorin derivative Amidochlorin p6 (ACP)

Amidochlorin p6 (ACP) was uptaken by HeLa cells, showing excellent phototoxicity (the cell viability was 21% at a concentration of 8 μmol L⁻¹), resulting in cell death.

Antitumor activity evaluation of meso-tetra (pyrrolidine substituted) pentylporphin-mediated photodynamic therapy in vitro and in vivo

Photodynamic therapy is a minimally invasive and promising new method in cancer treatment and has attracted considerable attention in recent years. An ideal photosensitizer is a crucial element to photodynamic therapy. In the present paper, a novel porphyrin derivative, 5, 10, 15, 20-tetrakis (5-(pyrrolidin-1-yl) pentyl) porphin (TPPP) was synthesized. Its spectroscopic and physicochemical properties, therapeutic efficacy as a photosensitizer in photodynamic therapy for human bladder cancer in vitro and in vivo were investigated. TPPP had strong absorption at 648nm (ε=1.75×10(4)M(-1)cm(-1)), and two fluorescence emission peaks at 652nm and 718nm. PDT with TPPP showed low dark toxicity and high phototoxicity to human bladder cancer T24 cells in vitro. In bearing T24 tumor nude mice, the growth of tumor was significantly inhibited by combining use of 5mg/kg TPPP with 100J/cm(2) (650nm, 180mW/cm(2)) laser irradiation at 3h following injection of TPPP. The antitumor effect was also confirmed with histopathological assay. The histopathological study results revealed that PDT using TPPP and 100J/cm(2) (650nm, 180mW/cm(2)) laser irradiation induced tumor cells shrunken and necrotic. These results indicate that TPPP is useful as a new photosensitizer in PDT for cancer, and deserves further investigation.

Synthesis, characterization and biological evaluation of a novel biscarboxymethyl-modified tetraphenylchlorin compound for photodynamic therapy

Compound BCTC is an effective and a highly promising antitumor agent for photodynamic therapy.

Photodynamic therapy of drug-resistant human colon adenocarcinoma using verteporfin-loaded TPGS nanoparticles with tumor homing and penetrating peptide functionalization

tLyp-1-modified nanoparticles loaded with VP (t-NP) as a dual-targeting drug delivery systemviaNRP-1-mediated endocytosis and penetration.

Structure-activity relationship study of anticancer thymidine-quinoxaline conjugates under the low radiance of long wavelength ultraviolet light for photodynamic therapy

Thymidine quinoxaline conjugate (dT-QX) is a thymidine analog with selective cytotoxicity against different cancer cells. In this study, the structure activity relationship study of dT-QX analogs was carried out under the low radiance of black fluorescent (UVA-1) light. Significantly enhanced cytotoxicity was observed under UVA-1 activation among analogs containing both thymidine and quinoxaline moieties with different length of the linker, stereochemical configuration and halogenated substituents. Among these analogs, the thymidine dichloroquinoxaline conjugate exhibited potent activity under UVA-1 activation as the best candidate with EC50 at 0.67 μM and 1.3 μM against liver and pancreatic cancer cells, respectively. In contrast, the replacement of thymidine moiety with a galactosyl residue or the replacement of quinoxaline moiety with a fluorescent pyrenyl residue or a simplified diketone structure resulted in the full loss of activity. Furthermore, it was revealed that the low radiance of UVA-1 at 3 mW/cm(2) for 20 min was sufficient enough to induce the full cytotoxicity of thymidine dichloroquinoxaline conjugate and that the cytotoxic mechanism was achieved through a rapid and steady production of reactive oxygen species.

Antitumor effects evaluation of a novel porphyrin derivative in photodynamic therapy

In this paper, the antitumor activity of a novel porphyrin-based photosensitizer 5,10,15,20-tetrakis[(5-diethylamino)pentyl] porphyrin (TDPP) was reported in vitro and in vivo. The photophysical and cellular properties of TDPP were investigated. The singlet oxygen generation quantum yield of TDPP was detected; it showed a high singlet oxygen quantum yield of 0.52. The intracellular distribution of photosensitizer was detected with laser scanning confocal microscopy. The efficiency of TDPP-photodynamic therapy (PDT) in vitro was analyzed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and in situ trypan blue exclusion test. Treated with a 630-nm laser, TDPP can kill cultured human esophageal cancer cell line (Eca-109) cells and reduce the growth of Eca-109 xenograft tumors significantly in BABL/c nude mice. And histopathological study was also used to confirm the antitumor effect. It has the perspective to be developed as a new antitumor drug in photodynamic therapy and deserves further investigation.