The structure of a new indole derivative, serotobenine (1), from safflower meal (Carthamus tinctorius L.) is proposed based on 1H- and 13C-NMR spectral data and X-ray crystallography. The known compounds N-feruloyltryptamine (2) and N-(p-coumaroyl)tryptamine (3) were also isolated and identified. The occurrence of conjugate-formed amines and cinnamic acids in various plants has been reported.1~3) In a previous paper, we found that the seed of safflower (Carthamus tinctorius L.) contained some novel serotonin conjugates such as β-coumaroyl and feruloyl serotonin together with free serotonin.4?5) In a further survey of the associated substance, we have now isolated a new indole derivative designated as serotobenine (1). This paper deals with isolation and structural determination of this compound, and simultaneously its in vitro formation from N-feruloylserotonin in oxidative systems. Additionally, the identification of β-coumaroyl and feruloyl tryptamine, which were isolated from the same sample, is also described.