title: Photodynamic action of palmatine hydrochloride on colon adenocarcinoma HT-29 cells.
abstract: 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.
authors.affiliation: School of Chinese Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China; Laboratory of Food Science and Human Health, College of Food Science and Engineering, Ocean University of China, Qingdao, PR China.
authors.forename: Juan
authors.initials: J
authors.lastname: Wu
authors.affiliation: School of Chinese Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
authors.forename: Qicai
authors.initials: Q
authors.lastname: Xiao
authors.affiliation: Laboratory of Food Science and Human Health, College of Food Science and Engineering, Ocean University of China, Qingdao, PR China.
authors.forename: Na
authors.initials: N
authors.lastname: Zhang
authors.affiliation: Laboratory of Food Science and Human Health, College of Food Science and Engineering, Ocean University of China, Qingdao, PR China.
authors.forename: Changhu
authors.initials: C
authors.lastname: Xue
authors.affiliation: School of Chinese Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
authors.forename: Albert Wingnang
authors.initials: AW
authors.lastname: Leung
authors.affiliation: School of Chinese Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Chinese Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China. Electronic address: xcshan@163.com.
authors.forename: Chuanshan
authors.initials: C
authors.lastname: Xu
authors.affiliation: Laboratory of Food Science and Human Health, College of Food Science and Engineering, Ocean University of China, Qingdao, PR China. Electronic address: tangqingjuan@ouc.edu.cn.
authors.forename: Qing-Juan
authors.initials: QJ
authors.lastname: Tang
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D001600:Berberine Alkaloids / Q000008:administration & dosage*; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D019073:HT29 Cells; D006801:Humans; D008027:Light; D009374:Neoplasms, Experimental / Q000188:drug therapy* / Q000473:pathology*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage
chemical_list: D001600:Berberine Alkaloids; D017319:Photosensitizing Agents; C005413:palmatine
keywords: Cell apoptosis; Colon adenocarcinoma; Palmatine hydrochloride; Photodynamic therapy; Singlet oxygen