Chemical model for phosphine‐induced lipid peroxidation

Phosphine (PH₃) from hydrolysis of metal phosphides is highly toxic and is important for control of stored‐product insect pests (AlP, Mg₃P₂) and rodents (Zn₃P₂). This fumigant inhibits respiration and induces lipid peroxidation in insects and mammals. PH₃ (from Mg₃P₂) and H₂O₂, acting for 15 min in phosphate buffer (pH 7.4), oxidized cod liver oil (high in unsaturated lipids) to malondialdehyde. Both Mg₃P₂ and H₂O₂ 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 H₂O₂ but no PH₃. 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 PH₃/H₂O₂ were trapped with salicylic acid. Reactive oxygen species for lipid peroxidation may therefore be derived from direct reaction of PH₃ with H₂O₂ as an alternative hypothesis to their respiration‐linked formation. © 2000 Society of Chemical Industry