Structure-Activity Study of Vitamin D Analogues

To clarify the structure-function relationship of vitamin D analogues我们联合novel vitamin D analogues and evaluated their biological activities.(1) A系列singly dehydroxylated 19-no -1α，25-dihydroxyvitamin D - 23 D2 A-ring analogues were synthesized. The analogues could be clearlydivided into two categoriesone group, bearing 1α-hydroxy or 3β-hydroxy group in the A-ringwere potent differentiators and the second group, bearing 1β-hydroxy or 3α-hydroxy group，apoptosis potent stimulators of apoptosis.这些findings will provide useful information only fordevelopment of therapeutic agents for treatment of leukemia and其他cancers.(2) Biologicalactivities of a series of 2β-substituted analogues of 1α，25(OH) y D22 y D2)D y D23 y D2 were evaluated. Binding affinity for VDR，transactivation potency on the target gene and VDR-mediated gene regulation of the hydroxyalkyl andhydroxyalkoxy 2β-substituted analogues almost comparable to those of 1α，25(OH) D22 (OH) d2…2, while the alkyl and alkenyl analogues were much less active than 1α，25(OH) i D22 i D2 i D23 i D2. Furthermore，我们发现了一个promising candidate for preventive and therapeutic medicine of osteoporosis among thesecompounds.(3) The biological activity of two sets of ring A stereo isomers of 2-methyl-1α，25-dihydroxyvitamin D - 23 D2 and 2-methyl-20-epi-1α，25-dihydroxyvitamin D - 23 D -2 were evaluated. We found that 2β-methyl-20-epi-3-epi-1β，25(OH) - D22 - D2 - D23 - D2 is transcriptionally more active than 1α，25(OH) - D22 - D2 - D23 - D2 despite lacking the 1α-hydroxyl group，关于VDR-mediated gene transcription.自C-20natural counterpart, 2β-methyl-3-epi-1β, 25(OH) - D22 - D2D - D23 - D2，was almost completely biologically inactive20 . epimerization是很可能的反应，为基因表达式的活动。(4)我们发现了绑定affinity 1α, 25(OH) i - D22 i - D22 i - D2 and 1α，25(OH) i - D22 i - D2D i - D24 i - D2 were almost comparable to the effects of 1α, 25(OH) i - D22 i - D2D i - D23 i - D2while 24-epi-1α, 25(OH) - D22 - D22 - D2 and 1α，25(OH) i D22 i D2D i D27 i D2 were much less active than 1α，25(OH) - D22 - D2 - D23 - D2 in these respects. This is the first finding concerning biologicalassessment of 1α, 25(OH) i - D22 i - D22 i - D2, 1α, 25(OH) i - D22 i - D2D i - D23 i - D2, 1α，25(OH) - D22 - D2 - D24 -epi-1α, 25(OH) - D22 - D2 - D22 - D2 and 1α，25(OH) - D22 - D2 - D27 - D2 at the molecular level，especially with regards to the structural differences at the 24r - or 24s -methyl group and a doublebond between carbons 22 and 23 in the side chain of 1α，2 .(5) The effects of 1α，25(OH) - D22 - D2D - D23 - D2 and its analogues on transmembrane Ca - D12+ - D1 influx were examined inthe growth phase of rat osteosarcoma ROS17/2.8 cells.The results suggest that 1α，25(OH) - D22 - D2D - D23 - D2 and its analogues modulate transmembrane Ca - D12+ - D1 influx inosteoblast-like cells by opening L-type Ca D12+ D1 channels which can recognize 1α-hydroxy(6)我们demonstrated that 1α， 1β-hydroxy analogues as antagonists.25(OH) - D22 - D2-mediated suppressive effects on the inducible expression of cytokine genesin human T cells may, in part，be due to diminished activity of the transcription factor NFAT. the vitamin D - 23 - D2 receptor（VDR） specifically bound to the distal NFAT site in the human IL-2 promoter. Less

To clarify the structure-function relationship of vitamin D analogues, we synthesized novel vitamin D analogues and evaluated their biological activities.(1) A series of singly dehydroxylated 19-nor-1α, 25-dihydroxyvitamin DィイD23ィエD2 A-ring analogues were synthesized. The analogues could be clearly divided into two categories ; one group, bearing 1α-hydroxy or 3β-hydroxy groups in the A-ring, were potent differentiators and the second group, bearing 1β-hydroxy or 3α-hydroxy groups, were potent stimulators of apoptosis. These findings will provide useful information not only for development of therapeutic agents for treatment of leukemia and other cancers.(2) Biological activities of a series of 2β-substituted analogues of 1α, 25(OH)ィイD22ィエD2)DィイD23ィエD2 were evaluated. Binding affinity for VDR, transactivation potency on the target gene and VDR-mediated gene regulation of the hydroxyalkyl and hydroxyalkoxy 2β-substituted analogues were almost comparable to those of 1α, 25(OH)ィイD22ィエD2Dィ … More イD23ィエD2, while the alkyl and alkenyl analogues were much less active than 1α, 25(OH)ィイD22ィエD2DィイD23ィエD2. Furthermore, we found a promising candidate for preventive and therapeutic medicine of osteoporosis among these compounds.(3) The biological activity of two sets of ring A stereo isomers of 2-methyl-1α, 25-dihydroxyvitamin DィイD23ィエD2 and 2-methyl-20-epi-1α, 25-dihydroxyvitamin DィイD23ィエD2 were evaluated. We found that 2β-methyl-20-epi-3-epi-1β, 25(OH)ィイD22ィエD2DィイD23ィエD2 is transcriptionally more active than 1α, 25(OH)ィイD22ィエD2DィイD23ィエD2 despite lacking the 1α-hydroxyl group, which was believed to be essential for expressing VDR-mediated gene transcription. Since the C-20 natural counterpart, 2β-methyl-3-epi-1β, 25(OH)ィイD22ィエD2DィイD23ィエD2, was almost completely biologically inactive, 20-epimerization is probably responsible for activation of gene expression.(4) We found that binding affinity 1α, 25(OH)ィイD22ィエD2DィイD22ィエD2 and 1α, 25(OH)ィイD22ィエD2DィイD24ィエD2 were almost comparable to the effects of 1α, 25(OH)ィイD22ィエD2DィイD23ィエD2, while 24-epi-1α, 25(OH)ィイD22ィエD2DィイD22ィエD2 and 1α, 25(OH)ィイD22ィエD2DィイD27ィエD2 were much less active than 1α, 25(OH)ィイD22ィエD2DィイD23ィエD2 in these respects. This is the first finding concerning biological assessment of 1α, 25(OH)ィイD22ィエD2DィイD22ィエD2, 1α, 25(OH)ィイD22ィエD2DィイD23ィエD2, 1α, 25(OH)ィイD22ィエD2DィイD24ィエD2, 24-epi-1α, 25(OH)ィイD22ィエD2DィイD22ィエD2 and 1α, 25(OH)ィイD22ィエD2DィイD27ィエD2 at the molecular level, especially with regards to the structural differences at the 24R- or 24S-methyl group and a double bond between carbons 22 and 23 in the side chain of 1α, 25(OH)ィイD22ィエD2D derivatives.(5) The effects of 1α, 25(OH)ィイD22ィエD2DィイD23ィエD2 and its analogues on transmembrane CaィイD12+ィエD1 influx were examined in the growth phase of rat osteosarcoma ROS17/2.8 cells.The results suggest that 1α, 25(OH)ィイD22ィエD2DィイD23ィエD2 and its analogues modulate transmembrane CaィイD12+ィエD1 influx in osteoblast-like cells by opening L-type CaィイD12+ィエD1 channels which can recognize 1α-hydroxy analogues as agonists and 1β-hydroxy analogues as antagonists.(6) We demonstrated that 1α, 25(OH)ィイD22ィエD2DィイD23ィエD2-mediated suppressive effects on the inducible expression of cytokine genes in human T cells may, in part, be due to diminished activity of the transcription factor NFAT. The vitamin DィイD23ィエD2 receptor (VDR) specifically bound to the distal NFAT site in the human IL-2 promoter. Less