Involved in the biosynthesis of cyclooctatin, a potent inhibitor of lysophospholipase. Catalyzes the hydroxylation of cyclooctat-9-ene-5,7-diol at C-18 to yield the final product, cyclooctatin. AH2 + cyclooctat-9-ene-5,7-diol + O2 = A + cyclooctatin + H2O Belongs to the cytochrome P450 family.