Antifungal polyoxygenated fatty acids fromAeollanthus parvifolius.

Two polyoxygenated fatty acids with antifungal activity have been isolated from aerial parts ofAeollanthus parvifolius (Labiatae) using bioassay-guided isolation procedures. Spectroscopic analysis was used to identify the compounds as (Z)-4ξ,9ξ-diacetoxy-6ξ,7ξ-epoxy-5ξ-hydroxy-8-oxododeca-2-enoic acid and (Z)-4ξ,6ξ,7ξ,9ξ-tetraacetoxy-5ξ-hydroxy-8-oxododeca-2-enoic acid. Both of these compounds inhibited spore germination ofCladosporium cucumerinum. Minimum inhibitory doses were 1 µg and 5 µg, respectively, but only the former inhibited germination ofAspergillus niger at a dose of 5 µg. Neither compound exhibited antibacterial activity. (Z)-4ξ,9ξ-Diacetoxy-6ξ,7ξ-epoxy-5ξ-hydroxy-8-oxododeca-2-enoic acid reduced the hyphal growth ofPythium 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)-4ξ,6ξ,7ξ,9ξ-tetraacetoxy-5ξ-hydroxy-8-oxododeca-2-enoic acid to seedling plants did not give any protection against fungal attack, and indeed the compound appeared to be phytotoxic.