4-(4-Phenoxybenzoyl)benzoic acid derivatives (PBADs) were found to inhibit rat and human alpha-reductase isozymes 1 and 2 in vitro. Chemiluminescence (CL), electron spin resonance, spin trapping techniques, and spectrophotometry were used to examine the effect of PBADs on reactive oxygen species (superoxide radical, O(2)(.-); hydroxyl radical, HO(*); singlet oxygen, (1)O(2)) generating systems. All test compounds at a concentration of 0.5 mM enhanced the CL from O(2)(.-) up to fivefold, which was recorded as the light sums during 1 min. At 0.38 mM PBAD enhanced production of HO(*) from H(2)O(2) in the presence of Co(II) up to 90%, as measured by a deoxyribose assay. Using the spin trap agent 5,5-dimethyl-1-pyrroline-N-oxide, it was found that the amplitude of the signal arising from the Fenton-like reaction [Co(II)/H(2)O(2)] was significantly diminished by the test compounds. The compounds also inhibited the (1)O(2) dependent 2,2,6,6-tetramethylpiperidine-N-oxide radical, which is generated in the acetonitrile/H(2)O(2) system. The measured rate constants of (1)O(2)-dimol quenching by PBAD were in the range of (0.8-2.6) x 10(8) M(-1) s(-1). The interaction between PBAD and (1)O(2) was also checked using a spectrophotometry method based on bleaching of p-nitrosodimethylaniline. These results indicate that PBAD may directly scavenge HO(*) and (1)O(2), but not O(2)(.-). However, the compounds that were examined had prooxidant ability under some reaction conditions.

In search of novel nonsteroidal mimics of steroidal inhibitors of 5 alpha reductase, 4-(2-phenylethyl)cyclohex-1-ene carboxylic acids 1-5 were synthesized with different substituents in para position of the phenyl ring (1: N, N-diisopropylcarbamoyl, 2: phenyl, 3: phenoxy, 4: benzoyl, and 5: benzyl). The principal synthetic approach for the desired compounds consisted of a Wittig olefination between 1, 4-dioxaspiro [4.5]-decane-8-carbaldehyde (4g and the appropriate phosphonium salts. The compounds were tested for inhibition of human 5 alpha reductase isozymes 1 and 2 using DU 145 cells and preparations from prostatic tissue, respectively. They turned out to be good inhibitors of the prostatic isozyme 2 with compound 1 being the most potent one (IC(50) = 760 nM). Isozyme 1 was only slightly inhibited. It is concluded that the novel structures are appropriate for being further optimized, aiming at the development of a novel drug for the treatment of benign prostatic hyperplasia.

Novel 3,4-dihydro-naphthalene-2-carboxylic acids were synthesized and evaluated for 5alpha reductase inhibitory activity. This enzyme exists in two isoforms and is a pharmacological target for the treatment of benign prostatic hyperplasia, male pattern baldness and acne. In the present study non-steroidal compounds capable of mimicking the transition state of the steroidal substrates were prepared. The synthetic strategy for the preparation of compounds 1-6 consisted of triflation followed by subsequent Heck-type carboxylation or methoxy carbonylation for 6-phenyl-3,4-dihydronaphthalen-2(1H)-one 1c. A Negishi-type coupling reaction between 6-(trifluoro-methanesulfonyloxy)-3,4-dihydro-naphthalene-2-carboxylic acid methyl ester 7b and various aryl bromides led, after further transformations, to 6-substituted 3,4-dihydro-naphthalene-2-carboxylic acids 7-15. In a similar way the corresponding naphthalene-2-carboxylic acids 16 and 17 were obtained. The DU 145 cell line and prostate homogenates served as enzyme sources for the human type 1 and type 2 isozymes, whereas ventral prostate was employed to evaluate rat isozyme inhibitory potency. The most active inhibitors identified in this study were 6-[4-(N,N-dicyclohexylaminocarbonyl)phenyl]-3,4-dihydro-naphthalene-2-carboxylic acid (3) (IC50 = 0.09 microM, rat type 1), 6-[3-(N,N-dicyclohexylaminocarbonyl)phenyl]-3,4-dihydro-naphthalene-2-carboxylic acid (13) (IC50 = 0.75 microM, human type 2; IC50 = 0.81 microM, human type 1) and 6-[4-(N,N-diisopropylamino-carbonyl)phenyl]naphthalene-2-carboxylic acid (16) (IC50 = 0.2 microM, human type 2). The latter compound was shown to deactivate the enzyme in an uncompetitive manner (Ki = 90 nM; Km, Testosterone = 0.8-1.0 microM) similar to the steroidal inhibitor Epristeride. Select inhibitors (13 and 16) were tested in vivo using testosterone propionate-treated, juvenile, orchiectomized SD-rats. None of the compounds was active at a dose of 25 mg/kg. This result might in part be ascribed to the relatively poor in vitro rat isozyme inhibitory potency.

The synthesis and biological evaluation of 4-(4-(alkyl- and phenylaminocarbonyl)benzoyl)benzoic acids (4a-4d) as non-steroidal inhibitors of steroid 5 alpha-reductase are described. The compounds were tested in vitro for inhibitory activity toward rat and human 5 alpha-reductase isozymes 1 and 2 at a concentration of 10 microM. The most active inhibitor for the human type 2 isozyme was 4-(4-(phenylaminocarbonyl)benzoyl)benzoic acid, compound 4c (IC50 = 0.82 microM).