title: Synthesis and biological activities of 2 beta-chloro-, 2 beta-fluoro-, and 2 beta-methoxy-1 alpha,25-dihydroxyvitamin D3.
abstract: Using 1 alpha,2 alpha-oxido-cholesta-5,7-diene-3 beta,25-diol (2) as a starting material, the provitamins of calcitriol with an additional 2 beta-chloro-, 2 beta-fluoro-, and 2 beta-methoxy-substituent (3,4,5) are obtained by transdiaxial opening of the oxirane ring with nucleophiles. An efficient irradiation process is described and used for the synthesis of the 2 beta-substituted calcitriols NS2 (2 beta-Cl), NS6 (2 beta-F), and NS7 (2 beta-OCH3). The affinity of these three vitamin D3 derivatives to the vitamin D receptor (VDR) and was determined. These three A-ring derivatives of 1,25(OH)2D3 were further tested for their proliferation-inhibitory and anti-adipogenic activity and gene regulatoric activity in the vitamin D3-sensitive, murine, mesenchymal cell line C3H10T1/2. The VDR-affinity of the 2 beta-chloro derivative, NS2 (2 beta-Cl), was identical to 1,25(OH)2D3 and its vitamin D binding protein (DBP)-affinity was in the range of 1,25(OH)2D3. NS2 inhibited the proliferation of C3H10T1/2(BMP-4)-cells in the presence of fetal calf serum (FCS) 9 times, and, in the absence of FCS, 111 times lower, as compared with 1,25(OH)2D3. The ID50 dose of adipogenesis-inhibition of NS2 was 13 times higher than the ID50 dose of 1,25(OH)2D3. NS6 (2 beta-F) displayed a slightly higher affinity than 1,25(OH)2D3 to the VDR and DBP-affinity. The proliferation-inhibitory activity in the presence of FCS was 90 times higher, as compared with 1,25(OH)2D3. In the FCS-free proliferation assay NS6 displayed an inhibitory activity in the range of 1,25(OH)2D3. NS6 showed an 5 times higher potency to inhibit (pre)adipocyte-differentiation in C3H10T1/2(BMP-4)-cells than 1,25(OH)2D3. NS7 (2 beta-OCH3) showed the lowest VDR-affinity and the highest DBP-affinity of the tested substances, as compared with 1,25(OH)2D3 (11 times lower and 35 times higher respectively). Its proliferation-inhibitory activity in the FCS-free medium was 9 times and in the FCS-containing assay 67 times lower in comparison with 1,25(OH)2D3. A 1250 times higher NS7-dose was needed to reach the anti-adipogenic potency of 1,25(OH)2D3. All tested substances displayed a similar ability to activate a vitamin D responsive element-regulated reporter gene compared to 1,25(OH)2D3 (NS2 and NS6: 1.3 times higher activity; NS7: 1,4 times lower activity).
authors.affiliation: Department of Gene Regulation and Differentiation, Association for Biotechnological Research, Braunschweig, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Scheddin
authors.forename: H
authors.initials: H
authors.lastname: Mayer
authors.forename: B
authors.initials: B
authors.lastname: Schönecker
authors.forename: S
authors.initials: S
authors.lastname: Gliesing
authors.forename: M
authors.initials: M
authors.lastname: Reichenbächer
mesh_terms: D017667:Adipocytes / Q000166:cytology / Q000187:drug effects; D000818:Animals; D002117:Calcitriol / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D005786:Gene Expression Regulation / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D051379:Mice; D008809:Mice, Inbred C3H; D015394:Molecular Structure; D018167:Receptors, Calcitriol / Q000187:drug effects; D013056:Spectrophotometry, Ultraviolet
chemical_list: D018167:Receptors, Calcitriol; D002117:Calcitriol