Chem. Pharm. Bull., 53(7),796-799, July 2005

Regular Articles

Presence of Peroxyradicals in Cigarette Smoke and the Scavenging Effect of Shikonin, a Naphthoquinone Pigment

Masahiro NISHIZAWA,^a Masahiro KOHNO,^a Minemitsu NISHIMURA,^b Akio KITAGAWA,^b and Yoshimi NIWANO^*,a,b

^a New Industry Creation Hatchery Center, Tohoku University; Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan: and ^b Business Development Division, Sunny Health Co., Ltd.; Yaesu Center Bldg., 1-6-6 Yaesu, Chuo-ku, Tokyo 103-0028, Japan. * To whom correspondence should be addressed. e-mail: y.niwano@sunnyhealth.co.jp

Using a new method having been developed for the purpose of quantitative determination for peroxyradicals, the presence of peroxyradicals was proved in cigarette smoke. In brief, peroxyradicals in cigarette smoke were measured by ESR spectrometry coupled to non-reductive scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH). As a result, peroxyradicals were found to be major reactive oxygen species (ROS) since the concentration of peroxyradicals recovered from cigarette smoke was much higher than that of any of other ROS (superoxide and hydroxyl radical) and nitric oxide. Furthermore, several antioxidants (ascorbic acid, reduced glutathione, epigallocatechin gallate, shikonin) were examined for scavenging activity against peroxyradicals in the cigarette smoke. Among them shikonin alone exerted the scavenging activity, suggesting that shikonin is promising antioxidant for cigarette filters because of its effectiveness against broad range of ROS including peroxyradicals, heat resistance, nonvolatility and high affinity to the filter.

Key words peroxyradical; cigarette smoke; ESR; scavenging activity; shikonin