13(S)-HpOTrE(γ) is a monohydroxy PUFA produced by the action of soybean lipoxygenase-1 (LO-1) on γ-linolenic acid. Further action of soybean LO-1 converts 13(S)-HpOTrE(γ) to all four isomers of 6,13-DiHOTrE. At concentrations greater than 100 μM, 13(S)-HpOTrE(γ) inhibits the activity of soybean LO-1.