Journal of Lipid Research, Vol 27, 1328-1332, Copyright © 1986 by Lipid Research, Inc.
Configuration at C-25 in 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25,26-pentol excreted by patients with cerebrotendinous xanthomatosis: circular dichroism and 13C-NMR studies
B Dayal, G Salen, V Toome and GS Tint
The configuration at C-25 in 5 beta-cholestane-3 alpha, 7 alpha, 12
alpha,25,26-pentol isolated from the bile and feces of patients with
cerebrotendinous xanthomtosis (CTX) was determined from the lanthanide-
induced circular dichroism (CD) Cotton effects and 13C-NMR measurements.
Under anhydrous conditions, CD spectra of 5 beta- cholestane-3 alpha, 7
alpha, 12 alpha,25,26-pentol in the presence of Eu(fod)3 exhibited a large
induced negative Cotton effect at 320 nm. On the basis of the empirical
rule (primary-tertiary-alpha-diols) in which R compounds have positive
Cotton effects and S compounds have negative Cotton effects at 320 nm, it
was concluded that 25,26-pentol has the 1,2,glycol structure with C-25
having the S-configuration. This assignment was based upon comparison with
model compounds, 25(R and S),26-dihydroxy cholesterols and 25(R and
S),26-dihydroxy cholecalciferols whose single-crystal X-ray structure and
13C-NMR studies have been performed. It is suggested that these data may be
helpful to clarify the stereospecificity of the hydroxylation of the
terminal methyl group of the cholesterol side chain in CTX.