25-Hydroxyvitamin D3 26,23-lactone: a new in vivo metabolite of vitamin D

Abstract

A major vitamin D metabolite was isolated in pure form from the blood plasma of chicks either maintenance levels or large doses of vitamin D3. The isolation involved methanol-chloroform extraction and five column chromatographic procedures. The metabolite purification and elution position on these columns were followed by a competitive protein binding assay. The metabolite was identified, using high- and low-resolution mass spectrometry, 270-MHz proton nuclear magnetic resonance spectrometry, ultraviolet absorption spectrophotometry, Fourier transform infrared spectrophotometry, and specific chemical reactions, as 3 beta,-25-dihydroxy-9,10-seco-5,7,10(19)-cholestatrieno-26,23-lactone. The trivial names 25-hydroxyvitamin D3 26,23-lactone or calcidiol 26,23-lactone are suggested for this compound.

Stereochemistry of 25‐hydroxyvitamin D3—26,23‐lactone and 1α,25—dihydroxyvitamin D3—26,23‐lactone in rat serum

“…The natural metabolite was directly compared to 2 diastereoisomers, 23(S)25@)-25-OH-Da-26,23-lactone and 23@)25(S)-25-OH-Ds-26,23-lactone stereospecifically synthesized by [7,8]. Both compounds were chosen for comparison because of higher similarity of NMR spectrum of either compound to that of natural metabolite than the other 2 diastereoisomers [ 1,4,6]. The 2 synthetic diastereoisomers, 23(S)25@)-25-OH-Ds-26,23-lactone and 23@)25(S)-…”

Role of kidney tissue in the production of 25-hydroxyvitamin D3-26,23-lactone and 1 alpha, 25-dihydroxyvitamin D3-26,23-lactone.

“…The isolation and characterization of 25-OH-D3-26,23-lactone (8) and the fact that this compound is a major vitamin D metabolite under conditions of high intake raise questions concerning its possible in vivo function, mode of biosynthesis, and site of production.…”

“…Some of the metabolites have been structurally identified and their physiological functions are well defined, but others either remain unidentified or their functions are unknown (1,2). The 25-hydroxylation of vitamin D3 takes place in liver; the further hydroxylation of 25-OH-D3 to la,25-dihydroxyvitamin D3 [1, Recently, a new metabolite of the vitamin has been isolated from the plasma of chickens and identified as 25-hydroxyvitamin D3-26,23-lactone (25-OH-D3-26,23-lactone) (8). This metabolite was first observed as an interfering substance in the determination of plasma levels of 24,25-(OH)2D3 by the use of the competitive rat plasma protein radioassay method (9).…”

23,25-Dihydroxyvitamin D3: a natural precursor in the biosynthesis of 25-hydroxyvitamin D3-26,23-lactone.

“…3). This compound is not produced in nephrectomized rats, but kidney homogenate prepared from vitamin D-supplemented chickens produces it from 25-hydroxyvitamin D3 (25-OH-D3; refs.…”