Inhibition of Laser-Induced Choroidal Neovascularization by Hematoporphyrin Dimethylether-Mediated Photodynamic Therapy in Rats.

This study aimed to investigate the effect of hematoporphyrin dimethylether (HDME)-mediated photodynamic therapy for laser-induced choroidal neovascularization (CNV) in adult Brown Norway rats. HDME was administered via tail vein at 14 d after the laser photocoagulation, and the rats received irradiance with a laser light at 570 nm at 15 min after injection. CNV was evaluated by fundus photography, fundus fluorescein angiography, optical coherence tomography, and hematoxylin and eosin staining. We found that CNV was occurred at 7 d after photocoagulation and reaching peak activity at 14 d after photocoagulation. There is a significant reduction in the total area of the fluorescein leakage and the number of strong fluorescein leakage spots on 7 d after HDME-mediated photodynamic therapy (PDT). The results suggest that HDME-mediated PDT inhibits laser-induced CNV in rats, representing a promising therapy for wet age-related macular degeneration.

Antiparasitic efficacy of Gracillin and Zingibernsis newsaponin from Costus speciosus (Koen ex. Retz) Sm. against Ichthyophthirius multifiliis.

The present study aims to evaluate the antiparasitic activity of active components from Costus speciosus against Ichthyophthirius multifiliis. Bioassay-guided fractionation was employed to identify active compounds from C. speciosus yielding 2 bioactive compounds: Gracillin and Zingibernsis newsaponin. In-vitro assays revealed that Gracillin and Zingibernsis newsaponin could be 100% effective against I. multifiliis at concentrations of 0.8 and 4.5 mg L(-1), with median effective concentration (EC50) values of 0.53 and 3.2 mg L(-1), respectively. All protomonts and encysted tomonts were killed when the concentrations of Gracillin and Zingibernsis newsaponin were 1.0 and 5.0 mg L(-1). In-vivo experiments demonstrated that fish treated with Gracillin and Zingibernsis newsaponin at concentrations of 1.0 and 5.0 mg L(-1) carried significantly fewer parasites than the control (P<0.05). Mortality of fish did not occur in the treatment group (Zingibernsis newsaponin at 5.0 mg L(-1)) during the trial, although 100% of untreated fish died. Acute toxicities (LD50) of Gracillin and Zingibernsis newsaponin for grass carp were 1.64 and 20.7 mg L(-1), respectively. These results provided evidence that the 2 compounds can be selected as lead compounds for the development of new drugs against I. multifiliis.

Studies on preparation and photodynamic mechanism of chlorin P6-13,15-N-(cyclohexyl)cycloimide (Chlorin-H) and its antitumor effect for photodynamic therapy in vitro and in vivo.

Photodynamic therapy (PDT) represents a promising method for treatment of cancerous tumors. The chemical and physical properties of used photosensitizer play key roles in the treatment efficacy. In this study, a novel photosensitizer, Chlorin-H [-13,15-N-(cyclohexyl)cycloimide] which displayed a characteristic long wavelength absorption peak at 698nm was synthesized. Following flash photolysis with 355nm laser, Chlorin-H is potent to react with O(2) and then produce (1)O(2). This finding indicates that Chlorin-H takes its effects through type II mechanism in PDT. Generally, Chlorin-H is localized in mitochondria and nucleus of cell. After light irradiation with 698nm laser, it can kill many types of cell, inhibit cell proliferation and colony formation, suppress cancer cell invasiveness and trigger apoptosis via the mitochondrial pathway in A549 cells in vitro. In addition, Chlorin-H-PDT can destroy A549 tumor in nude mice and a necrotic scab was formed eventually. The expression levels of many genes which regulated cell growth and apoptosis were determined by RT-PCR following Chlorin-H-PDT. The results showed that it either increased or decrease. Among which, the expression level of TNFSF13, a member of tumor necrosis factor superfamily, increased significantly. Silencing of TNFSF13 caused by RNA interference decreased the susceptibility of A549 cells to Chlorin-H-PDT. In general, Chlorin-H is an effective antitumor photosensitizer in vitro and in vivo and is worthy of further study as a new drug candidate. TNFSF13 will be an important molecular target for the discovery of new photosensitizers.