NEW STEROIDAL DIAZO KETONES AS POTENTIAL PHOTOAFFINITY-LABELING REAGENTS FOR THE MINERALOCORTICOID RECEPTOR - SYNTHESIS AND BIOLOGICAL-ACTIVITIES

Three diazo ketones in the progesterone series were synthesized as pot ential photoaffinity reagents. The diazo ketone group was introduced a t the C17 (21-diazopregn-4-ene-3,20-dione, 1) or C13 18-(diazomethyl)- 20-hydroxypregn-4-ene-3,18-dione, 2, 18-(diazomethyl)pregn-4-ene-3,18, 20-trione, 3) position of the pregnene skeleton. Whereas compound 1 co uld be easily obtained from the corresponding acid chloride, preparati on of 2 and 3 required a less straightforward route involving reaction of tosyl azide on the formyl derivative of methyl ketone 5. The affin ity of the diazo ketones for the human mineralocorticoid receptor (hMR ), expressed in Sf9 insect cells using the Baculovirus system, was est imated by competition experiments using [H-3]aldosterone as specific l igand. The affinity of 1 for hMR was almost identical with that of ald osterone. The affinities of 2 and 3 were 1 order of magnitude lower th an that of aldosterone. The mineralocorticoid activity of the diazo ke tones was measured in cis-trans cotransfection assays in CV-1 cells wi th the mouse mammary tumor virus as DNA target sequence. Compound 1 ex hibits an agonist activity (ED(50) = 6 x 10(-9) M) With no antagonist activity. In contrast 2 and 3 behave as antagonists, displaying an IC5 0 of similar to 10(-6) M whether the substituent at the C20 position i s a hydroxy (2) or an oxo (3) group.