Pheophorbide a, a Major Antitumor Component Purified fromScutellaria barbata, Induces Apoptosis in Human Hepatocellular Carcinoma Cells

Abstract

Scutellaria barbata has long been used as a Chinese medicine for the treatment of liver diseases such as hepatitis and hepatocellular carcinoma. In the present study, a bioassay-guided method was used to isolate the most active components from Scutellaria barbata. The anti-proliferative effects on human hepatoma HepG2 and Hep3B cells of each fraction at every stage of the purification were monitored. An active component, which is 97% pure by high performance liquid chromatographic analysis, was isolated. Based on nuclear magnetic resonance (NMR) and mass spectrophotometric (MS) analysis, this active component was identified to be pheophorbide a (C35H36N4O5). Mechanistic studies showed that pheophorbide a induced apoptosis in Hep3B cells, a viral-induced hepatoma cell line. However, it was found to be non-toxic in normal human liver cells WRL-68. DNA fragmentation, sub-G1 cell cycle arrest, as well as suppression of the anti-apoptotic protein Bcl-2, release of cytochrome c to the cytosol, and activation of pro-caspase 3 and pro-caspase 9 were observed when Hep3B cells were treated with 40 microg/mL (i. e., 67.5 microM) pheophorbide a for 48 hours. In conclusion, this is the first report describing the isolation of pheophorbide a from Scutellaria barbata using a bioassay-guided isolation method. The anti-proliferative activity and possible mechanisms of action of pheophorbide a on hepatoma Hep3B cells are also discussed.

Anti-Proliferative effect of ursolic acid on multidrug resistant hepatoma cells R-HepG2 by apoptosis induction

“…Caspase enzymatic activity was performed according to the procedures described previously. 15 Cells (2 x 10 6 ) were seeded in the 150 cm tissue culture Efficacy of UA on Multidrug Resistant Cells flasks and incubated with 15, 20 and 25 mM UA for 48 h. After treatment, cells were harvested and lysed with cell lysis buffer (1% Igepal-CA-630, 150 mM NaCl, 50 mM Tris-HCl, 1 mM EDTA, pH 7.5) on ice for 10 min, and then centrifuged at 14,000 rpm for 3 min at 4˚C. The supernatant was collected and protein concentration of each sample was determined by bicinchoninic acid protein assay kit (Sigma).…”

The c-MET/PI3K Signaling Is Associated with Cancer Resistance to Doxorubicin and Photodynamic Therapy by Elevating BCRP/ABCG2 Expression

“…In a clinical setting, the use of PDT is largely limited to superficial tumors because the wavelengths of light used in PDT cannot penetrate the body. Pheophorbide a (Pba) is a chlorophyll derivative from silkworm excreta and the Chinese medicinal herb Scutellaria barbarta (Park et al, 1989;Chan et al, 2006). Unlike two Food and Drug Administration-approved photosensitizers Photofrin and Levulan (5-aminolevulinic acid), Pba can be excited by a longer K.-A.J.…”

Enhancing the efficacy of photodynamic therapy by a chinese herbal medicine for hepatocellular carcinoma

“…The source of Pa Scutellaria Barbata is a Chinese herbal medicine that is often used to treat HCC. 22 The mechanism of action of PDT is still not fully understood. 23,24 PDT requires a synergistic effect of the photosensitizer and light irradiation, as generally, neither the photosensitizer nor light alone is cytotoxic.…”