Binding and Peroxidative Action of Oxyfluorfen in Sensitive and Tolerant Algal Species

Peroxidative activity of oxyfluorfen and binding of this nitrodiphenyl ether to cell fractions was investigated with the susceptible alga Scenedesmus acutus and the resistant alga Bumilleriopsis filiform is. Although a 10-fold higher concentration of oxyfluorfen was applied to Bumilleriopsis, the lag phase for initiation of peroxidative evolution of short-chain hydrocarbons from fatty acids was much longer than found with Scenedesmus. Oxyfluorfen was predominantly recovered after hom ogenization from the pellet which was separated into a lipid and a chloroform/methanol insoluble fraction. Parts of the oxyfluorfen which is present in the insoluble pellet fraction during the lag phase before the onset of peroxidation can be found in the lipid fraction when measurable peroxidative activities have started. This was observed with Scenedesmus as well as with Bum il­ leriopsis. During peroxidation initiated by oxyfluorfen acyl lipids are degradated as monitored by the disappearance of the plastidic sulfolipid. Analysis of bound fatty acids showed that they are targets for peroxidative reactions in acyl lipids. Destruction of polyunsaturated fatty acids was higher than for saturated ones.