Importance of the stereochemical position of the 24-hydroxyl to biological activity of 24-hydroxyvitamin D3.
Both stereoisomers of 24-hydroxyvitamin D3, i.e. 24(S)-hydroxyvitamin D3 and 24(R)-hydroxyvitamin D3, stimulate intestinal calcium transport almost equally well in the rat. The duration of effect is somewhat shorter for the 24(S)-hydroxyvitamin D3 than for the 24(R)-hydroxyvitamin D3. However, the 24(S)-hydroxyvitamin D3 has little or no activity in the mobilization of calcium from bone, in the growth of rats on a low calcium diet, in the elevation of serum phosphorus of rachitic rats, or in the calcification of bone. On the other hand, the 24(R)-hydroxyvitamin D3 is almost as active as 25-hydroxyvitamin D3 in all of these systems, although its activity is not always of equal duration to that of 25-hydroxyvitamin D3. The selectivity of these systems for only one of the 24-hydroxy stereoisomers supports the idea that in vivo 24-hydroxylation of vitamin D compounds is of functional importance.
D000818:Animals; D001693:Biological Transport, Active; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000097:blood / Q000378:metabolism; D004386:Duodenum / Q000187:drug effects / Q000378:metabolism; D006887:Hydroxycholecalciferols / Q000494:pharmacology / Q000627:therapeutic use; D007408:Intestinal Absorption / Q000187:drug effects; D008297:Male; D010710:Phosphates / Q000097:blood; D051381:Rats; D012279:Rickets / Q000188:drug therapy / Q000378:metabolism; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013997:Time Factors
D006887:Hydroxycholecalciferols; D010710:Phosphates; D002118:Calcium