17β-HSD2 inhibitors for the treatment of osteoporosis: Identification of a promising scaffold.

17β-Hydroxysteroid dehydrogenase type 2 (17β-HSD2) catalyses the conversion of active 17β-hydroxysteroids into the less active 17-ketosteroids thereby controlling the availability of biologically active estrogens (E2) and androgens (T) in the tissues. The skeletal disease osteoporosis occurs mainly in post-menopausal women and in elderly men when the levels of estrogens and androgens, respectively, decrease. Since 17β-HSD2 is present in osteoblasts, inhibition of this enzyme may provide a new and promising approach to prevent the onset of osteoporosis, keeping a certain level in estrogens and androgens in bone cells of ageing people. Hydroxynaphthyl, hydroxyphenyl and hydroxymethylphenyl-substituted moieties were synthesised as mimetics of the steroidal substrate. Compound 8 has been identified as promising scaffold for 17β-HSD2 inhibitors displaying high activity and good selectivity toward 17β-HSD1, ERα and ERβ.