Chemical model for phosphine-induced lipid peroxidation

Abstract

Phosphine (PH 3 ) from hydrolysis of metal phosphides is highly toxic and is important for control of stored-product insect pests (AlP, Mg 3 P 2 ) and rodents (Zn 3 P 2 ). This fumigant inhibits respiration and induces lipid peroxidation in insects and mammals. PH 3 (from Mg 3 P 2 ) and H 2 O 2 , acting for 15 min in phosphate buffer (pH 7.4), oxidized cod liver oil (high in unsaturated lipids) to malondialdehyde. Both Mg 3 P 2 and H 2 O 2 were found to be necessary for this lipid peroxidation, which under optimal conditions produced a seven-fold increase in malondialdehyde relative to basal levels in cod liver oil with H 2 O 2 but no PH 3 . Under the same conditions, 15-, 9- and 2-fold increases in malondialdehyde were obtained from ethyl arachidonate, methyl linoleate and methyl oleate. Small amounts of hydroxyl radical from PH 3 /H 2 O 2 were trapped with salicylic acid. Reactive oxygen species for lipid peroxidation may therefore be derived from direct reaction of PH 3 with H 2 O 2 as an alternative hypothesis to their respiration-linked formation.