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Evidence-Based Complementary and Alternative Medicine
Volume 2011, Article ID 492148, 6 pages
http://dx.doi.org/10.1093/ecam/nep220
Original Article

Antiproliferative Activity of Cinnamomum cassia Constituents and Effects of Pifithrin-Alpha on Their Apoptotic Signaling Pathways in Hep G2 Cells

1Department of Agricultural Chemistry, National Taiwan University, No.1, Roosevelt Road Section 4, Taipei 106, Taiwan
2Department of Nutritional Health, Chia-Nan University of Pharmacy and Science, 60, Erh-Jen Road, Section 1, Jen-Te, Tainan 717, Taiwan

Received 25 August 2009; Accepted 25 November 2009

Copyright © 2011 Lean-Teik Ng and Shu-Jing Wu. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Cinnamaldehyde (Cin), cinnamic acid (Ca) and cinnamyl alcohol (Cal), major constituents of Cinnamomum cassia, have been shown to possess antioxidant, anti-inflammatory, anticancer and other activities. In this study, our aim was to evaluate the antiproliferative activity of these compounds in human hepatoma Hep G2 cells and examine the effects of pifithrin-alpha (PFTα; a specific p53 inhibitor) on their apoptotic signaling transduction mechanism. The antiproliferative activity was measured by XTT assay. Expression of apoptosis-related proteins was detected by western blotting. Results showed that at a concentration of 30 μM, the order of antiproliferative activity in Hep G2 cells was Cin > Ca > Cal. Cin (IC50 9.76 ± 0.67 μM) demonstrated an antiproliferative potency as good as 5-fluorouracil (an anti-cancer drug; IC50 9.57 ± 0.61 μM). Further studies on apoptotic mechanisms of Cin showed that it downregulated the expression of Bcl-XL, upregulated CD95 (APO-1), p53 and Bax proteins, as well as cleaving the poly (ADP-ribose) polymerase (PARP) in a time-dependent pattern. PFTα pre-incubation significantly diminished the effect of Cin-induced apoptosis. It markedly upregulated the anti-apoptotic (Bcl-XL) expression and downregulated the pro-apoptotic (Bax) expression, as well as effectively blocking the CD95 (APO-1) and p53 expression, and PARP cleavage in Cin-treated cells. This study indicates that Cin was the most potent antiproliferative constituent of C. cassia, and its apoptotic mechanism in Hep G2 cells could be mediated through the p53 induction and CD95 (APO-1) signaling pathways.