Synthesis and plant growth inhibitory activity of N-trans-cinnamoyltyramine: Its possible inhibition mechanisms and biosynthesis pathway

The search for potent, selective bioherbicides has been the focus of numerous studies for several decades. Developing an economically viable total chemical synthesis procedure has been the challenge for commercial-scale application of these nature-derived chemicals. An efficient and lowcost total synthesis of an allelopathic and antitumor N-trans-cinnamoyltyramine (NTCT) first reported in rice (Oryza sativa L.) was successfully achieved by one-step amidation from transcinnamic acid and tyramine. The synthesized NTCT inhibited root and hypocotyl growth of cress (Lepidium sativum L.) and barnyardgrass (Echinochloa crus-galli L.) at concentrations as low as 0.24 µM. The means of ED₅₀ (the effective dose required for 50% plant growth inhibition) levels of the compound on cress and barnyardgrass hypocotyl and root elongations were 0.96 and 0.73 µM, respectively. Potential mechanisms underlying NTCT growth inhibition and its biosynthesis pathway were also suggested. The developed synthesis strategy could permit production of this synthesized allelochemical at a commercial scale as a bioherbicide.