Principal phenolic phytochemicals and antioxidant activities of three Chinese medicinal plants Hung-Der Jang a , Ku-Shang Chang a,b , Yung-Sheng Huang a,b , Chuan-Liang Hsu a , Sheng-Hsien Lee b , Min-Sheng Su a, * a Department of Food Science, Yuanpei University, 360 Yuanpei Street, Hsinchu 300, Taiwan b Institute of Biotechnology, Yuanpei University, Hsinchu 300, Taiwan Received 13 April 2006; received in revised form 24 June 2006; accepted 4 September 2006 Abstract The principal antioxidant components and content of cinnamon (Cinnamomum cassia), turmeric (Curcuma longa) and golden thread (Coptidis rhizoma) extracts were determined using high performance liquid chromatography (HPLC) with UV detection. In general, C. cassia, C. longa and C. rhizoma extracts from domestic Taiwan were rich in cinnamaldehyde, curcumin, and berberin, respectively. The contents of cinnamaldehyde, curcumin, and berberin in the acetone extracts were 1911, 2029, and 840 mg l À1 , respectively. The Folin–Ciocalteu method was used to measure the total phenolic concentrations of extracts, which had the content of 9.6 (C. cassia), 2.6 (C. longa), and 4.3 (C. rhizoma) mM l À1 . In addition, DPPH radical-scavenging, ferric-reducing antioxidant power (FRAP), and ferric thiocyanate (FTC) assays were employed to measure antioxidant activities. The C. cassia fresh extracts had higher antioxidant activities which were 84–90% (DPPH), 17–33 lmol l À1 (FRAP), and 53–82% (FTC). The activities of C. longa fresh extracts were 22–44% (DPPH), 7–11 lmol l À1 (FRAP), and 53–81% (FTC) while C. rhizoma were 53–64% (DPPH), 18–26 lmol l À1 (FRAP), and 59–82% (FTC). Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Cinnamaldehyde; Berberin; Curcumin; HPLC; Total phenols; Antioxidant activity 1. Introduction The active oxygen and nitrogen species may induce some damage to the human body. Over production of var- ious forms of activated oxygen species, such as oxygen rad- icals and non-free radical species are considered to be the main contributor to oxidative stress (Ellnain-Wojtaszek, Kruczynski, & Kasprzak, 2003; Gulcin, Oktay, Kufrayvio- glu, & Aslan, 2002; Yildirim et al., 2000). These oxygen radicals may induce some oxidative damage to biomole- cules such as carbohydrates, proteins, lipids and DNA (Lai & Piette, 1977; Wiseman & Halliwell, 1996), thus accelerating aging, cancer, cardiovascular diseases, neuro- degenerative diseases and inflammation (Ames, 1983; Stadtman, 1992). The protective action of medicinal plants has been attributed to the presence of antioxidants, espe- cially polyphenolic compounds and antioxidant vitamins, including ascorbic acid, tocopherol, b-carotene, flavonoids, tannins, anthocyanins, and other phenolic constituents (Salah et al., 1995; Saskia et al., 1996; Soong & Barlow, 2004). Food rich in antioxidants plays an essential role in the prevention of cardiovascular diseases and cancers (Ger- ber et al., 2002; Kris-Etherton et al., 2002) and neurodegen- erative diseases, including Parkinson’s and Alzheimer’s diseases (Di Matteo & Esposito, 2003). Thus, it is impor- tant to increase the antioxidant intake in the diet and search for natural antioxidant sources among plants used as food additives. In the past decade, the essential oils and various extracts of plants have provoked interest as sources of natural products. They have been screened for their potential uses as alternative remedies for the treatment of many infectious diseases and the preservation of foods from the toxic effects 0308-8146/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2006.09.026 * Corresponding author. Tel.: +886 3 6108764; fax: +886 3 5385353. E-mail address: mssu@mail.ypu.edu.tw (M.-S. Su). www.elsevier.com/locate/foodchem Food Chemistry 103 (2007) 749–756 Food Chemistry