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Evidence-Based Complementary and Alternative Medicine
Volume 2013 (2013), Article ID 412851, 12 pages
http://dx.doi.org/10.1155/2013/412851
Research Article

Peroxidase as the Major Protein Constituent in Areca Nut and Identification of Its Natural Substrates

1Department of Medical Research, China Medical University Hospital, Taichung 40402, Taiwan
2Department of Veterinary Medicine, National Chung Hsing University, Taichung 40227, Taiwan
3Graduate Institute of Integrated Medicine, China Medical University, Taichung 40402, Taiwan
4Proteomics Research Core Lab, China Medical University, Taichung 40402, Taiwan
5Department of Biochemistry, China Medical University, Taichung 40402, Taiwan
6Wholesaler Enterprise Company, Taipei 23941, Taiwan
7Department of Pharmacology, China Medical University, Taichung 40402, Taiwan
8Department of Biological Science and Technology, China Medical University, Taichung 40402, Taiwan
9Department of Biotechnology, Asia University, Taichung 41354, Taiwan

Received 6 June 2013; Accepted 4 September 2013

Academic Editor: Jen-Hwey Chiu

Copyright © 2013 Yu-Ching Liu et al. 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

Numerous reports illustrate the diverse effects of chewing the areca nut, most of which are harmful and have been shown to be associated with oral cancer. Nearly all of the studies are focused on the extract and/or low molecular weight ingredients in the areca nut. The purpose of this report is to identify the major protein component in the areca nut. After ammonium sulfate fractionation, the concentrated areca nut extract is subjected to DEAE-cellulose chromatography. A colored protein is eluted at low NaCl concentration and the apparently homogeneous eluent represents the major protein component compared to the areca nut extract. The colored protein shares partial sequence identity with the royal palm tree peroxidase and its peroxidase activity is confirmed using an established assay. In the study, the natural substrates of areca nut peroxidase are identified as catechin, epicatechin, and procyanidin B1. The two former substrates are similarly oxidized to form a 576 Da product with concomitant removal of four hydrogen atoms. Interestingly, oxidation of procyanidin B1 occurs only in the presence of catechin or epicatechin and an additional product with an 864 Da molecular mass. In addition, procyanidin B1 is identified as a peroxidase substrate for the first time.