Methylspinazarin is a naphthoquinone bacterial metabolite that has been found in Streptomyces and is an inhibitor of catechol O-methyltransferase (COMT; IC50 = 0.8 μg ml).1 It is selective for COMT over tyrosine hydroxylase, DOPA decarboxylase, and dopamine-β-hydroxylase at 100 μg ml. Methylspinazarin decreases blood pressure in spontaneously hypertensive rats when administered at a dose of 50 mg kg. |1. Chimura, H., Sawa, T., Takita, T., et al. Methylspinazarin and dihydromethylspinazarin, gatechol-O-methyl transerfase inhibitors produced by Streptomyces. J. Antibiot. 26(2), 112-114 (1973).