Antifungal polyoxygenated fatty acids from Aellanthus parvifolius

Two polyoxygenated fatty acids with antifungal activity have been isolated from aerial parts of Aeollanthus parvifolius (Labiatae) using bioassay-guided isolation procedures. Spectroscopic analysis was used to identify the compounds as (Z)-4 xi,9 xi-diacetoxy-6 xi,7 xi-epoxy-5 xi-hydroxy-8-oxododeca-2-enoic acid and (Z)-4 xi,6 xi,7 xi,9 xi-tetraacetoxy-5 xi-hydroxy-8-oxododeca-2-enoic acid. Both of these compounds inhibited spore germination of Cladosporium cucumerinum. Minimum inhibitory doses were 1 mu g and 5 mu g, respectively, but only the former inhibited germination of Aspergillus niger at a dose of 5 mu g. Neither compound exhibited antibacterial activity. (Z)4 xi,9 xi-Diacetoxy-6 xi,7 xi-epoxy-5 xi-hydroxy-8-oxododeca-2-enoic acid reduced the hyphal growth of Pythium ultimum. The mode of action was not resolved but did not involve either the disruption of the cell wall membrane or the inhibition of extracellular enzymes. Application of (Z)-4 xi,6 xi,7 xi,9 xi-tetraacetoxy-5 xi-hydroxy-8-oxodo-deca-2-enoic acid to seedling plants did not give any protection against fungal attack, and indeed the compound appeared to be phytotoxic.