Natural Inhibitor for Volatile C6-Aldehyde Formation from C18-Unsaturated Fatty Acids

Abstract

The homogenate of tea seed cotyledons contained an inhibitor for C6-aldehyde formation from linoleic acid and linolenic acid by isolated tea chloroplasts. Seed homogenates of other plants, such as soybean, kidney bean, cucumber, Japanese radish and rice, also contained the inhibitor for C6-aldehyde formation. The inhibitor from tea seed and cucumber seed inhibited C6-aldehyde formation by the homogenate of cucumber hypocotyl. Hydroperoxides of linoleic acid detected were reduced when the tea seed inhibitor was added to the reaction mixture, but the enzyme activities of lipoxygenase and hydroperoxide lyase were not inhibited. This means that the inhibitor is a decomposer of fatty acid hydroperoxides as an intermediate of C6-aldehyde formation. The tea seed inhibitor was formed during the seed ripening and it was stable during the seed germination. These findings obtained here suggest that the inhibitor is widely present in plant seeds and inhibits C6-aldehyde formation by a variety of plant tissues.