N-Coronafacoyl-L-isoleucine and N-coronafacoyl-L-alloisoleucine, potential biosynthetic intermediates of the phytotoxin coronatine

Abstract Two new naturally-occurring analogues of the phytotoxin coronatine have been isolated from liquid cultures of Pseudomonas syringae pv. glycinea . These have been identified as N -coronafacoyl- L -isoleucine and N -coronafacoyl- L -alloisoleucine by mass spectrometry and by studies of the products of acid hydrolysis of the two compounds. The compounds were purified as a mixture of ca 2:1 composition, but the two parent components were not preparatively separated. The possible significance of the two compounds, to the biosynthesis of coronatine, is discussed.