Plant cyclopeptides

This review systematically describes the progress in the chemistry and biology of cyclopeptides discovered from higher plants during the past 120 years, especially the recent half century. Since Clinch noted the presence of alkaloids in Ceanothus americanus (Rhamnaceae) in 1884 and Kaufmann et al. isolated cyclolinopeptide A from Linum usitassimum (linseed oil, Linaceae) and determined its structure in 1959, exploration of plant cyclopeptides by human beings has not stopped. It is noteworthy that some important discoveries and breakthroughs on plant cyclopeptides have been acquired during the past decade. On the basis of the recent known understanding of plant cyclopeptides, it is preliminarily inferred that cyclotides (type VIII) with 28-37 amino acids are gene products and other cyclopeptides (types I, II, III, IV, V, VI, and VII) may not be gene products.