LIPOXYGENASE-MEDIATED FORMATION OF HYDROCARBONS AND UNSATURATED ALDEHYDES IN FRESH-WATER DIATOMS

Upon initiation of lipoxygenase reactions one group of freshwater diat oms synthesized unsaturated acyclic and alicyclic hydrocarbons (ectoca rpene, dictyopterenes and fucoserratene); another group synthesized po lyunsaturated aldehydes. Among others (2E),(4Z),(7Z)-decatrienal is de scribed as a new lipoxygenase cleavage product in Melosira. The patter ns of the volatile organic compounds were typical for particular speci es of diatoms, indicating different specificities of the enzymes invol ved. The formation of unsaturated hydrocarbons and aldehydes was fully inhibited by strict exclusion of dioxygen, but could be regained by s ubsequent addition of dioxygen. The application of radical scavengers or chelating agents resulted in a high percentage inhibition of hydroc arbon and aldehyde formation.