Investigation of lipoxygenase-like activity in strawberry homogenates

Abstract

Unsaturated fatty acids are oxidized by lipoxygenase enzymes. The resulting products can easily be detected e.g., in strawberries, by comparing fruit homogenates obtained in water and in a chloroformmethanol mixture, since lipoxygenases are active only in aqueous solutions. A comparison can be made by applying gas chromatography to the methylated fatty acid fractions of the two homogenates. Moreover, the differences between ripe and unripe fruits can be detected using this method. 10-Hydroxy-octadeca-8,12-dienoic acid and 10-hydroxyoctadec-8-enoic acid were detected in large quantities in the aqueous homogenates. These compounds possess fungi-toxic activity and may be involved in the self-defence mechanism of the plant. Additionally, 8-(2-furyl)octanoic acid is detectable in aqueous homogenates. This compound has previously been shown to arise from the thermal decomposition of 9-hydroperoxy-10,12-epidioxyoctadecanoic acid.