PT  - JOURNAL ARTICLE
AU  - STERN, PAULA H.
AU  - TANAKA, YOKO
AU  - DELUCA, HECTOR F.
AU  - IKEKAWA, NOBUO
AU  - KOBAYASHI, YOSHIRO
TI  - Bone Resorptive Activity of Side-Chain Fluoro Derivatives of 25-Hydroxy- and 1α,25-Dihydroxyvitamin D<sub>3</sub> in Culture
DP  - 1981 Nov 01
TA  - Molecular Pharmacology
PG  - 460--462
VI  - 20
IP  - 3
4099  - http://molpharm.aspetjournals.org/content/20/3/460.short
4100  - http://molpharm.aspetjournals.org/content/20/3/460.full
SO  - Mol Pharmacol1981 Nov 01; 20
AB  - Three side-chain fluorinated analogues of vitamin D3 were tested for their bone-resorbing activity on fetal rat forelimb bones in vitro. Two fluoro derivatives of 25-hydroxyvitamin D3 (25-OH-D3), 24,24-difluoro-25-hydroxyvitamin D3 and 25-hydroxy-26,26,26,27,27,27-hexafluorovitamin D3, were compared with 25-OH-D3. The difluoro compound was approximately 7 times more potent than 25-OH-D3, and the hexafluoro analogue was approximately 40 times more potent than 25-OH-D3 in this system. In contrast, the 24,24-difluoro analogue of lα,25-dihydroxyvitamin D3 (lα,25-(OH)2D3) was slightly less potent than lα,25-(OH)2D3. The results indicate that the presence of fluoride groups on carbon atoms immediately adjacent to the 25-hydroxyl group enhances the in vitro bone-resorbing effects of 25-hydroxyvitamin D3. On the other hand, fluorination of the lα-hydroxylated compound on position 24 actually diminished rather than increased bone-resorptive activity. ACKNOWLEDGMENT We thank Thalia Mavreas for her excellent technical assistance.