Advance Access Publication 11 June 2007 Original Article eCAM 2008;5(4)429–434 doi:10.1093/ecam/nem054 Antioxidant activity of 45 Chinese herbs and the relationship with their TCM characteristics Hui Liao1,2, Linda K. Banbury1 and David N. Leach1 1Centre for Phytochemistry and Pharmacology, Southern Cross University, Lismore, NSW 2480, Australia and 2Shanxi Provincial People’s Hospital, Taiyuan, Shanxi 030012, China Here, 45 Chinese herbs that regulate blood circulation were analyzed for antioxidant activity using the oxygen radical absorbance capacity (ORAC) assay. A recent publication by Ou et al. identified a close relationship between in vitro antioxidant activity and classification of Chinese herbs as yin or yang. The 45 Chinese herbs in this study could be assigned the traditional characteristics of natures (cold, cool, hot and warm), flavors (pungent, sweet, sour, bitter and salty) and functions (arresting bleeding, promoting blood flow to relieve stasis, nourishing blood and clearing away heat from blood). These characteristics are generalized according to the theory of yin and yang. We identified a broad range, 40–1990 mmol Trolox Equivalent/g herbs, of antioxidant activity in water extracts. There was no significant correlation between ORAC values and natures or functions of the herbs. There was a significant relationship between flavors and ORAC values. Bitter and/or sour herbs had the highest ORAC values, pungent and/or sweet herbs the lowest. Other flavors had intermediate values. Flavors also correspond with the yin/yang relationship and our results are supportive of the earlier publication. We reported for the first time antioxidant properties of many Chinese herbs. High antioxidant herbs were identified as Spatholobus suberectus vine (1990 mmol TE/g), Sanguisorba officinalis root (1940 mmol TE/g), Agrimonia pilosa herb (1440 mmol TE/g), Artemisia anomala herb (1400 mmol TE/g), Salvia miltiorrhiza root (1320 mmol TE/g) and Nelembo nucifera leaf (1300 mmol TE/g). Antioxidant capacity appears to correlate with the flavors of herbs identified within the formal TCM classification system and may be a useful guide in describing their utility and biochemical mechanism of action. Keywords: flavor – function – herbs – nature – oxygen radical absorbance capacity (orac) – traditional Chinese medicine Introduction Traditional Chinese Medicine (TCM) has relied on experiential evidence and traditional healing manuscripts. Prior to the wider use of TCM theory and medicines in other medical systems, particularly western biomedical medicine, research is required to understand the bio- chemical basis for TCM classification systems for drugs For reprints and all correspondence: Hui Liao, Associate Professor, Department of Pharmacy, Shanxi Provincial People’s Hospital, 99 Shuangtasi Street, Taiyuan, Shanxi 030012, China. Tel: þ86-351- 4960073; Fax: þ86-351-2202147; E-mail: huiliao@263.net and the mechanism of action of these drugs. A recent publication by Ou et al. (1) identified a close relationship between in vitro antioxidant activity classification of Chinese herbs as yin and yang. In TCM’s long course of development, it has absorbed the quintessence of classical Chinese philosophy, culture and science and summarized the experience of the Chinese people in fighting diseases (2). This experiential evidence as a basis of TCM has resulted in a totally different medical theory compared with western conven- tional medicine (3). TCM believes that the different characters of herbs are employed to treat diseases, rectify 2007 The Author(s). This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.