Synthesis and biological activities of the two C(23) epimers of 1α,23,25-trihydroxy-24-oxo-19-nor-vitamin D3: novel analogs of 1α,23(S),25-trihydroxy-24-oxo-vitamin D3, a natural metabolite of 1α,25-dihydroxyvitamin D3
作者:Nancy E Lee、Paul G Williard、Alex J Brown、Moray J Campbell、H.Phillip Koeffler、Sara Peleg、D.Sunita Rao、G.Satyanarayana Reddy
DOI:10.1016/s0039-128x(99)00110-5
日期:2000.5
In a previous report. we indicated that 1 alpha,23(S).25-trihydroxy-23-oxovitamin D-3 [1 alpha,23(S).25(OH)(3)-24-oxo-D-3], a natural metabolite of 1 alpha,25-dihydroxyvitamin D-3 [1 alpha,25(OH)(2)D-3] is almost equipotent to 1 alpha,25(OH)(2)D-3 in suppressing parathyroid hormone (PTH) secretion (Lee et al., 1997. Biochemistry 36, 9429-9437). Also, 1 alpha,23(S),25(OH)(3)-24-oxo-D-3 has been shown to possess only weak in vivo calcemic actions. Thus. vitamin D-3 analogs structurally related to 1 alpha,23(S),25(OH)(3)-24-oxo-D-3 may have therapeutic value. Furthermore. biologic activity studies of various synthetic analogs of 1 alpha,25(OH)(2)D-3 showed that the removal of carbon-19 (C-19) reduces the calcemic activity of 1 alpha,25(OH)(2)D-3. Therefore, in an attempt to produce vitamin D-3 analogs with a better therapeutic index, we synthesized C(23) epimers of 1 alpha,23,25(OH)(3)-24-oxo-19-nor-vitamin D-3 1 alpha,23,25(OH)(3)-24-oxo-19-nor-D-3]. The two epimers were compared to 1 alpha,25(OH)(2)-19-nor-D-3 and 1 alpha.25(OH)(2)D-3 in their ability to generate biologic activities in several in vitro assay systems. In the assay measuring the suppression of parathyroid hormone (PTH) secretion in bovine parathyroid cells, 1 alpha,23(S),25(OH)(3)-24-oxo-19-nor-D-3 was as potent as 1 alpha,25(OH)(2)-19-nor-D-3 but was less potent than 1 alpha,25(OH)(2)D-3. In the same assay 1 alpha,23(R)25(OH)(3)-24-oxo-19-nor-D-3 exhibited greater potency than 1 alpha,23(S),25(OH)(3)-24-oxo-19-nor-D-3. In the assays measuring the ability of vitamin D compounds to inhibit clonal growth and to induce differentiation of human promyelocytic leukemia (HL60) cells, 1 alpha,23(S),25(OH)(3)-24-oxo-19-nor-D-3 was less potent than 1 alpha,25(OH)(2)-19-nor-D-3 but was equipotent to 1 alpha,25(OH)(2)D-3. More importantly, in the same assays, 1 alpha,23(R),25(OH)(3)-24-oxo-19-nor-D-3 was more potent than 1 alpha,23(S),25(OH)(3)-24-oxo-19-nor-D-3 and was equipotent to 1 alpha,25(OH)(2)-19-nor-D-3. Also, the vitamin D receptor-mediated transcriptional activity or 1 alpha,23(R),25(OH)(3)-24-oxo-19-nor-D-3 was almost equal to that of 1 alpha,25(OH)(2)-19-nor-D-3, but higher than that of 1 alpha,23(S),25(OH)(3)-24-oxo-19-nor-D-3. This finding explains in part the greater in vitro biologic activities of 1 alpha,23(R),25(OH)(3)-24-oxo-19-nor-D-3. In summary, our results indicate that 1 alpha,23(R),25(OH)(3)-24-oxo-19-nor-D-3 and to a lesser extent 1 alpha,23(S),25(OH)(3)-24-oxo-19-nor-D-3 are potent 19-nor vitamin D-3 analogs, which suppress PTH secretion in bovine parathyroid cells and strongly inhibit clonal growth and induce differentiation of HL-60 cells in vitro. (C) 2000 Elsevier Science Inc. All rights reserved.