Spermine and spermidine hydroxycinnamoyl transferases in Aphelandra tetragona

Roots of Aphelandra tetragona (Vahl) Nees contain the macrocyclic polyamine alkaloid, aphelandrine, consisting of spermine and two units of 4-hydroxycinnamic acid. Spermine hydroxycinnamoyl transferase (SpmHT) and spermidine hydroxycinnamoyl transferase (SHT) activities were detected in the cell-free extracts of stems of this plant. Maximal activities were measured in the apical stems 10 weeks after propagation. The enzyme preparation was ca. 2.5-fold more active with spermine than with spermidine as polyamine substrate. No activity was detected with putrescine. The identification of the product of the enzyme reaction as monocoumaroylspermine could be achieved. SpmHT activity was also detected in callus cultures from the same plant. To the best of our knowledge, this is the first report of a Spermine hydroxycinnamoyl transferase in plants.