The accumulation of trans-4-hydroxy-N-methylproline and N-methylproline by some plant species

Trans-4-hydroxy-N-methylproline and N-methylproline have been isolated from several Angiosperm species, but the striking feature is the high content of these two proline derivatives, being in excess of 1% of the dry weight of Berchemia zeyheri, Critoniella vargasiana, Hovenia dulcis and Serjania communis and in excess of 0.8% of Berberis aggregata and Annona chirimola. These high contents suggest the possibility that these compounds have a function in abiotic stress resistance of these species.