4-Cyclopropylmethyl-O-glucuronide Mycophenolic Acid is an analogue of Mycophenolic Acid (M831500), 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.