Lead N-naphthylaminobenzoates display competitive enzyme inhibition for the oxidation of S-tetralol and reduction of 4-Androstene-3,17-dione catalyzed by AKR1C3. Panels (A-C) competitive inhibition of S-tetralol oxidation by compounds 1, 3 and 4, respectively. Panels (D-F) competitive inhibition of 4-androstene-3,17-dione reduction by compounds 1, 3 and 4, respectively.