Identification and characterization of chlorin e(4) ethyl ester in sera ofindividuals participating in the chlorophyllin chemoprevention trial

Chlorophyllin (CHL), a mixture of water soluble derivatives of chlorophyll, has been shown to be an effective inhibitor of aflatoxin B-1 (AFB(1)) carc inogenesis and AFB(1)-DNA adduct formation in rainbow trout and rats [Brein holt, V., Hendricks, J., Pereira, C., Arbogast, D., and Bailey, G. (1995) C ancer Res. 55, 57-62; Kensler, T. W., Groopman, J. D., and Roebuck, B. D. ( 1998) Mutat. Res. 402, 165-172]. The chemopreventive action of CHL has been previously attributed to molecular complexing. In 1997, a randomized, doub le-blind clinical trial of CHL Was conducted in Qidong, Jiangsu Province, P eople's Republic of China. At the completion of the study, when serum sampl es were regrouped by subject identification number, it was noted that many of the participant samples were green in color. Using HPLC, ESI/MS, and MS/ MS techniques, serum samples from individuals receiving CHL were found to c ontain previously unreported copper chlorin e(4) ethyl ester (CuCle(4) ethy l eater) as well as copper chlorin e(4) (CuCl(e)4). Both chlorins originate d in the study tablet, were absorbed into the bloodstream, and conferred a green color to the sera. This initial finding of in vivo absorption and bio availability of two chlorin derivatives suggests that the mechanism of CHL chemoprevention may lie in the actions of these two components in vivo in a ddition to preventing carcinogen absorption from the gut.