TAN-931

A novel nonsteroidal aromatase inhibitor, TAN-931, was isolated from the culture filtrate of a soil isolate fungus, No. 8974. The strain was identified as Penicillium funiculosum No. 8974. TAN-931 inhibited human placental and rat ovarian aromatase activity, and the IC50 value was 17.2 and 162 microM, respectively. The inhibition of human placental aromatase was uncompetitive with respect to androstenedione conversion with a Ki value of 40 microM. When TAN-931 was subcutaneously administered at doses of 25, 50 and 100 mg/kg (once/day, x4) to 20-day-old female Sprague-Dawley rats treated with gonadotropin, the plasma estradiol-17 beta level and the weight of ovaries and uterus were markedly reduced in a dose-dependent manner. The in vivo inhibitory activity of TAN-931 was more potent than that of 4-hydroxyandrostenedione. Consecutive administration of TAN-931 (100 mg/kg, sc, twice/day, x 7) to 9-week-old male Sprague-Dawley rats did not induce any adrenal hypertrophy even though administration of aminoglutethimide caused 2-fold enlargement of the adrenal under the same conditions. Specific binding of TAN-931 to the estrogen receptor from a human breast cancer cell line, MCF-7, was not detected.

Fractionation of the ethyl acetate extract of an acid-tolerant fungus, Penicillium purpurogenum JS03-21, resulted in the isolation of six new compounds, purpurquinones A-C (1-3), purpuresters A and B (4 and 5), and 2,6,7-trihydroxy-3-methylnaphthalene-1,4-dione (6), together with three known compounds, TAN-931 (7), (-)-mitorubrin (8), and orsellinic acid. The structures of 1-6 were elucidated primarily by NMR experiments. The absolute configurations of 1-4 were assigned on the basis of CD and NOESY data. Compounds 2-4 and 7 exhibited significant antiviral activity against H1N1, with IC50 values of 61.3, 64.0, 85.3, and 58.6 μM, respectively.

The structure of TAN-931, a novel nonsteroidal aromatase inhibitor, was determined by chemical reactions and spectral analyses including 2D NMR experiments to be 4-(2,6-dihydroxybenzoyl)-3-formyl-5-hydroxybenzoic acid. Several derivatives of TAN-931 were prepared, and it was found that the 3-formyl and 2'- and/or 6'-hydroxyl groups play an important role in its inhibitory activity. Among the compounds synthesized, 4-(2,6-dihydroxybenzoyl)-3-formyl-5-methoxy-N,N-dimethyl-benzamide was found to be more effective than TAN-931 when administered orally.