(E)-2-alkenals (C10-C16), isolated from coriander (Coriandrum sativum L.) leaves, were found to be a chemopreventive agent for deformation of Raji cells carrying the genome of Epstein-Barr virus (EBV) early antigen, induced by 12-O-teradecanoylphorbol 13-acetate (TPA). Intensities of chemopreventive activity of (E)-2-alkenals (C6-C14) were positively correlated with the carbon chain length of the unsaturated aldehydes. The α,β-unsaturated double bond was found to be the most essential molecular requirement for the activity in its chemical structure and activity relationship. Furthermore, it was established that the behavior of administered (E)-2-dodecenal in rat blood was successfully monitored by the dynamic amount of (E)-2-dodecenal through a plastic cannular. In consequence, administered (E)-2-dodecenal in blood disappeared at 30 min after the administration. Additionally, ca 1% of administered (E)-2-dodecenal was observed in the environmental air emitted from rat breath or rat skin at 90 min after the administration by Tenax TA adsorbent. The chemopreventive agent, (E)-2-dodecenal mostly stayed in the rat body. These kinds of monitoring systems are helpful in understanding the metabolism of useful food components for nutraceutical science.