epimer


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epimer

[′ep·ə·mər]
(organic chemistry)
A type of isomer in which the difference between the two compounds is the relative position of the H (hydrogen) group and OH (hydroxyl) group on the last asymmetric C (carbon) atom of the chain, as in the sugarsD-glucose andD-mannose.
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References in periodicals archive ?
One of those confounders is the C-3 epimer of (3-epi) 25(OH)[D.
One form of vitamin D that deserves mention is an epimer of 25(OH) D at the hydroxyl group on carbon-3 of vitamin D.
N-octyl-[beta]-valienamine, an epimer of NOEV, was found as a new chaperone compound for this disease.
Finally, the C-3 epimer, 3-epi-25(OH)D, will also give overestimated 25(OH)D concentrations if not properly resolved by chromatography (vide infra) (7, 15, 16).
As it seems unlikely that the vitamin D sufficiency/insufficiency status of an individual would be altered by the presence of the epimer, it is not necessary to quantify the epimer in these subjects.
Saikosaponin a and its epimer saikosaponin d exhibit anti-inflammatory activity by suppressing activation of NF-kappaB signaling pathway.
2]D, which may have a regulatory role in intestinal calcium transport (9);a metabolite hydroxylated at carbon C4 by CYP3A4, which may explain certain drug-induced disorders of bone, (10); and an epimer at carbon C3 in the A ring, a form that appears to have a relatively constant concentration throughout the human lifespan but has an unclear biological function after 1[alpha]-hydroxylation (11-13).
A limitation of the LC-MS/MS methods used in this study is that they did not separate the epimer forms.
50] > 100 [micro]M), which is an epimer of compound 6, differing in the stereochemistry at C-3.
Of particular interest is the C3 epimer of 25(OH)D, 3-epi-25(OH)D, which can be present at relatively high concentrations in sera from infants, but can also be found in sera from adults, albeit at lower concentrations (1,2).