Planta Med 2006; 72(1): 28-33
DOI: 10.1055/s-2005-873149
Original Paper
Pharmacology
© Georg Thieme Verlag KG Stuttgart · New York

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

Judy Yuet-Wa Chan1 , Patrick Ming-Kuen Tang1 , Po-Ming Hon2 , Shannon Wing-Ngor Au1 , Stephen Kwok-Wing Tsui1 , Mary Mui-Yee Waye1 , Siu-Kai Kong1 , Thomas Chung-Wai Mak2 , 3 , Kwok-Pui Fung1 , 2
  • 1Department of Biochemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
  • 2Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
  • 3Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
Weitere Informationen

Publikationsverlauf

Received: December 29, 2004

Accepted: June 22, 2005

Publikationsdatum:
10. November 2005 (online)

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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 μg/mL (i. e., 67.5 μM) 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.

References

Dr. K. P. Fung

Department of Biochemistry

Faculty of Medicine

Room 603

Mong Man Wai Building

The Chinese University of Hong Kong

Shatin

Hong Kong

People’s Republic of China

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