Structure-Antifungal Activity Relationships among Volatile C₆ and C₉ Aliphatic Aldehydes, Ketones, and Alcohols

Antifungal potentials of volatile oxygenated alkyl compounds were determined by bioassay of Alternaria alternata germ tube growth. Compounds were naturally occurring lipoxygenase enzyme system products or related to them chemically. Results were based on headspace concentrations of test compounds. Among six-and nine-carbon aldehydes and ketones related to hexanal, nonanal, 3-hexanone, and 2-nonanone, respectively, the presence of an α,β-unsaturated bond adjacent to the carbonyl moiety generally enhanced antifungal activity. Among six-carbon alcohols related to 1-hexanol, however, an α,β-unsaturated bond enhanced antifungal activity only slightly. Abundant, naturally occurring (E)-2-hexenal that higher plants emit as a response to wounding tested negatively for mutagenicity; a volatile compound modification of the Ames test with several strains of Salmonella typhimurium was used.