The homolytic and heterolytic fatty acid hydroperoxide lyase-like activities of hematin.

Pentenols and pentene dimers are biosynthetized in plants by homolytic fatty acid hydroperoxide lyase (HPL) or HPL-like enzymes. It has been found that these compounds can modify the flavor of olive oil. Reactions between hematin and 13-hydroperoxyoctadecatrienoic acid resulted in the formation of the same compounds via a free radical reaction in which an alkoxyl radical derived from linolenic acid hydroperoxide undergoes a beta-scission. (Z)-3-Hexenal has also been detected as a minor product of the reaction. It is bioconversed from the same substrate in plants by heterolytic HPL. Thanks to the redox cycle of its central iron, hematin has both homolytic and heterolytic HPL-like activities.

Potato tubers exhibit both homolytic and heterolytic hydroperoxide fatty acid-cleaving activities.

The action of a crude potato-tuber extract on 9- and 13-hydroperoxides of linoleic and linolenic acids was investigated. HPLC analysis revealed that 50% of the 9-hydroperoxide isomers and almost all the 13-hydroperoxide isomers were rapidly enzymically metabolized. No degradation of fatty acid hydroperoxides was observed with a thermally denatured enzymic extract. GC-MS identification of the volatiles formed by the reaction revealed that no volatiles were detected from the 9-hydroperoxide isomers, whereas 13-hydroperoxide of linolenic acid was cleaved into (Z)-3-hexenal, pentenols or dimers of pentene.