A New Aromatase Inhibitor, FR901537

FR901537 is a new aromatase inhibitor produced by a bacterium Bacillus sp. No. 3072. Structural studies of FR901537 suggested that it was a novel naphthol derivative having pantetheine in its structure. FR901537 showed a potent inhibitory activity against aromatase from human placenta or rat ovary, but did not inhibit the activity of 11β-hydroxylase from bovine adrenal cortex. Lineweaver-Burk plot analysis revealed that FR901537 is a competitive inhibitor.