Lagunamycin is a 5-lipoxygenase inhibitor isolated from the culture medium of Streptomyces sp. AA0310. Lagunamycin has a significant inhibitory activity against rat 5-lipoxygenase with an IC50 value of 6.08 μM. Lagunamycin can effectively inhibit 5-lipoxygenase without causing lipid peroxidation, indicating that it has an effective inhibitory effect without causing side effects.