432 Antioxidant and TCM characteristics Table 3. Comparison of mean ORAC values for the different characters with which the herb may be classified based on TCM; errors are presented as SD Medicinal characteristics Flavory Nature Function bitter and/or sour bitter with sweet and pungent sour with sweet and pungent pungent and/or sweet cold and cool hot and warm neutral yin yin within yang and yang within yin yang yin yang stop internal and external bleeding promote blood circulation and disperse blood stasis nourishing the blood dispelling pathogenic heat from the blood systems 15 17 12 18 19 8 15 19 5 6 yThe flavor of Arnebia euchroma is sweet and salty; it is not included in the list. *The mean ORAC value for bitter, sour flavor is significantly different from sweet, pungent flavor. (P50.01), Student’s t-test. Number of herbs in group max mmol TE/g 1940 1990 min mmol TE/g 96 43 640 1940 1990 1440 1940 1990 790 680 40 54 40 43 75 43 40 65 mean mmol TE/g 856 550* 528 558 213 198* 559 504 558 567 443 540 722 568 537 584 267 284 313 215 ORAC value that was similar or higher than that of vitamin E. Figure 1 shows a breakdown of these 10 herbs into their particular flavor classifications. Discussion The ORAC assay has become a valuable and popular method for measuring the antioxidant or radical scaven- ging capacity of biological samples. A trend has been to investigate a variety of plants as new potential sources of antioxidants. Many phytochemicals have antioxidant activity and may help protect cells against the oxidative damage caused by free radicals, such as quercetin that belongs to a group of polyphenolic substances known as flavonoids and has strong antioxidant activity (18). Research into the antioxidant properties of herbs may provide information on the mechanism of action of the plant extracts, the utility of the medicines in mitigating against oxidative damage and help to identify the presence of specific antioxidant constituents. In this assay, 45 Chinese herbs that regulate blood circulation were analyzed for antioxidant activity. The results showed that they had a wide range of antioxidant activity. There was a 50-fold difference in antioxidant capacity between Spatholobus suberectus vine (1990 mmol TE/g) and Ziziphus jujuba fruit (40 mmol TE/g). One difference between our protocol and that of Ou et al. (13) is that we used extracts prepared by the traditional method of water extraction while the earlier study employed 70% acetone extraction. We focused on the herb’s clinical usage form, which is generally prepared by water and still most widely used at present. Another difference is that in choosing the 45 herbs we also considered their ancient pharmacologic Figure 1. Comparison of the flavors of 10 herbs that had ORAC value similar to or higher than that of Vitamin E (1162 mmol TE/g). Bitter, bitter and sour belong to yin. Bitter and pungent, bitter and sweet, sour and sweet belong to yin within yang and yang within yin. properties—natures, flavors and functions and the relationship of these properties with antioxidant activity. If a combination of ORAC values, natures, flavors, functions and yin/yang theory were all taken into consideration, it would assist in the selection of the best herbs to achieve optimal therapeutic activity. Chinese herbs have their characterization based on natures and flavors. In the earliest extant medical canon