Antifungal activity of natural volatile compounds in relation to their vapour pressure.
Caccioni, D. R. L.; Gardini, F.; Lanciotti, R.; Guerzoni, M. E.;
Sciences des Aliments Year: 1997 Vol: 17 Issue: 1 Pages: 21-34 Ref: 34 ref.
1997
บทคัดย่อ
The antifungal effects of 9 volatile compounds on Penicillium expansum and Botrytis cinerea (fungal pathogens associated with postharvest decay of pome fruits) were evaluated. Compounds used were characteristic of the flavour of apples, namely: estragole, hexanal, hexanol, ethyl acetate, methyl acetate, hexyl acetate, butanol, butyl acetate, and benzyl acetate. Preliminary studies involved diluting these compounds in 9 micro l methanol to a final concentration of 2500, 250, 125, or 62 mg/litre and applying them directly to inoculated broth. Microbial growth was monitored through gas chromatographic analysis of metabolically-produced CO2 in the headspace of the vials. Of the compounds added to the liquid medium, benzyl acetate, hexanal, and estragole were the strongest inhibitors of the growth of both fungi; all 3 being effective at the lowest dose (62 mg/litre). Some fundamental chemical, physical, and biological characteristics of these compounds are tabulated. More detailed investigations invo
lved soaking these selected compounds onto filter paper and suspending them above superficially-inoculated solid agar in sealed vials. Doses used were 0.1, 0.25, 0.5, 1.0, 2.5, 5 and 10 micro l. At the higher doses (5 and 10 micro l), the activity of the pathogens was completely inhibited by the volatile compounds in the headspace of the vial. The amounts of these compounds in the headspace were determined by gas chromatography, and these readings were converted into measurements of vapour pressure. Hexanal was found to be actively fungicidal at lower concentrations than estragole and benzyl acetate, and also possessed a higher vapour pressure than the others. In fact, the fungistatic properties of these compounds were found to be dependent on their vapour pressure in the system.