Antifungal activity of three spermidine conjugates

Three tri-substituted spermidines, di-p-coumaroyl-caffeoylspermidine, tri-c affeoylspermidine and tri-p-coumaroylspermidine, isolated from pollen of Qu ercus alba, were examined for antifungal activity. Both di-p-coumaroyl-caff eoylspermidine and tri-p-coumaroylspermidine reduced mycelial growth of the oat leaf stripe pathogen, Pyrenophora avenae and reduced powdery mildew (B lumeria graminis f. sp. hordei) infection of barley seedlings when applied as a post-inoculation treatment. When used as a pre-inoculation treatment, only di-p-coumaroyl-caffeoylspermidine reduced powdery mildew infection sig nificantly. Growth of P. avenae in the presence of 100 muM di-p-coumaroyl-c affeoylspermidine reduced activity of S-adenosylmethionine decarboxylase (A doMetDC), and led to a reduction in the incorporation of labelled ornithine into spermidine. The other two spermidine conjugates increased AdoMetDC ac tivity and the flux label from ornithine into spermine in P. avenae signifi cantly. (C) 2001 Federation of European Microbiological Societies. Publishe d by Elsevier Science B.V. All rights reserved.