(4E)-6-(1,3-Dihydro-4-hydroxy-6-methoxy-7-methyl-3-oxo-5-isobenzofuranyl)-4-methyl-4-hexenoic Acid

An antibiotic produced by Penicillium brevi-compactum, P. Stoloniferum and related spp. A selective inhibitor of lymphocyte proliferation by blocking inosine monophosphate dehydrogenase, an enzyme involved in the de novo synthesis of purine nucleotides.