In Vitro and In Vivo Demonstration of Ultraefficient and Broad-Spectrum Antibacterial Agents for Photodynamic Antibacterial Chemotherapy.

Increasing threats from both pathogenic infections and antibiotic resistance highlight the pressing demand for nonantibiotic agents and alternative therapies. Herein, we report several new phenothiazinium-based derivatives, which could be readily synthesized via fragment-based assembly, which exhibited remarkable bactericidal activities both in vitro and in vivo. Importantly, in contrast to numerous clinically and preclinically used antibacterial photosensitizers, these compounds were able to eliminate various types of microorganisms, including Gram-(+) Staphylococcus aureus (S. aureus), Gram-(-) Escherichia coli, multidrug-resistant S. aureus, and their associated biofilms, at low drug and light dosages (e.g., 0.21 ng/mL in vitro and 1.63 ng/cm2 in vivo to eradicate S. aureus at 30 J/cm2). This study thus unveils the potential of these novel phenothiaziniums as potent antimicrobial agents for highly efficient photodynamic antibacterial chemotherapy.

Palmatine hydrochloride mediated photodynamic inactivation of breast cancer MCF-7 cells: Effectiveness and mechanism of action.

Breast cancer is one of the commonest malignant tumors threatening to women. The present study aims to investigate the effect of photodynamic action of palmatine hydrochloride (PaH), a naturally occurring photosensitizer isolated from traditional Chinese medicine (TCM), on apoptosis of breast cancer cells. Firstly, cellular uptake of PaH in MCF-7 cells was measured and the cytotoxicity of PaH itself on breast cancer MCF-7 cells was estimated using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Subcellular localization of PaH in MCF-7 cells was observed using confocal laser scanning microscopy (CLSM). For photodynamic treatment, MCF-7 cells were incubated with PaH and then irradiated by visible light (470nm) from a LED light source. Photocytotoxicity was investigated 24h after photodynamic treatment using MTT assay. Cell apoptosis was analyzed 18h after photodynamic treatment using flow cytometry with Annexin V/PI staining. Nuclear was stained using Hoechst 33342 and observed under a fluorescence microscope. Intracellular production of reactive oxygen species (ROS) was studied by measuring the fluorescence of 2, 7-dichlorofluorescein (DCF) using a flow cytometry. Results showed that PaH treatment alone had no or minimum cytotoxicity to MCF-7 cells after incubation for 24h in the dark. After incubation for 40min, the cellular uptake of PaH reached to the maximum, and PaH mainly located in mitochondria and endoplasmic reticulum of MCF-7 cells. Photodynamic treatment of PaH demonstrated a significant photocytotoxicity on MCF-7 cells, induced remarkable cell apoptosis and significantly increased intracellular ROS level. Our findings demonstrated that PaH as a naturally occurring photosensitizer induced cell apoptosis and significantly killed MCF-7 cells.

Photodynamic action of palmatine hydrochloride on colon adenocarcinoma HT-29 cells.

Palmatine hydrochloride (PaH) is a natural active compound from a traditional Chinese medicine (TCM). The present study aims to evaluate the effect of PaH as a new photosensitizer on colon adenocarcinoma HT-29 cells upon light irradiation. Firstly, the absorption and fluorescence spectra of PaH were measured using a UV-vis spectrophotometer and RF-1500PC spectrophotometer, respectively. Singlet oxygen ((1)O2) production of PaH was determined using 1, 3-diphenylisobenzofuran (DPBF). Dark toxicity of PaH was estimated using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Cellular uptake of PaH in HT-29 cells was detected at different time intervals. Subellular localization of PaH in HT-29 cells was observed using confocal laser fluorescence microscopy. For photodynamic treatment, HT-29 cells were incubated with PaH and then irradiated by visible light (470nm) from a LED light source. Photocytotoxicity was investigated 24h after photodynamic treatment using MTT assay. Cell apoptosis was observed 18h after photodynamic treatment using a flow cytometry with Annexin V/PI staining. Results showed that PaH has an absorption peak in the visible region from 400nm to 500nm and a fluorescence emission peak at 406nm with an excitation wavelength of 365nm. PaH was activated by the 470nm visible light from a LED light source to produce (1)O2. Dark toxicity showed that PaH alone treatment had no cytotoxicity to HT-29 cancer cells and NIH-3T3 normal cells after incubation for 24h. After incubation for 40min, the cellular uptake of PaH reached to the maximum and PaH was located in mitochondria. Photodynamic treatment of PaH demonstrated a significant photocytotoxicity on HT-29 cells. The rate of cell death increased significantly in a PaH concentration-dependent and light dose-dependent manner. Further evaluation revealed that the early and late apoptotic rate of HT-29 cells increased remarkably up to 21.54% and 5.39% after photodynamic treatment of PaH at the concentration of 5µM and energy density of 10.8J/cm(2). Our findings demonstrated that PaH as a naturally occurring photosensitizer has potential in photodynamic therapy on colon adenocarcinoma.