Synthesen in der Vitamin‐A₂‐Reihe. 4. Mitteilung. Physikalische Eigenschaften von isomeren Vitamin‐A‐ und Vitamin‐A₂‐Verbindungen

Abstract

acid (m.p. 176-178') has been prepared by the WITTIG reaction of (deh~~dro-~-ionylidene-ethyl)-triphenylphosphonium bromide and 12-butyl P-formylcrotonnte. Reduction of this acid with lithium-aluminium hydride gave a mixture of all-trms-and 13-cis-vitamin A,, which could be separated by chromatography. The same mixture has been obtained from vitamin A acid according to the first vitamin , U. Schwieter, L. Chopard-dit-Jean, R . Ruegg, M. Kofler und 0. Isler (12. I. G2) 4. Mitteilung') Die drei vorangehenden Mitteilungenl) hatten die Synthese von 6 Reihen isomerer Vitamin-A,-Verbindungen zum Inhalt. In dieser Arbeit werden die physikalischen Eigenschaften dieser Vitamin-A,-Verbindungen beschrieben und mit denj enigen der entsprechenden Vitamin-A-Verbindungen verglichen. .l,-Kcihe A-Reihc I< = CH,OIf, CHO, COOH, COOCH,Untersucht wurden ausser den in den Formeln dargestellten ungehinderten alltrans-Verbindungen 3 weitere ungehinderte Isomere (9-cis, 13-cis, 9,lS-di-cis) sowie 2 Isomere mit sterischer Hinderung (11-cis, 11,13-di-cis).

A novel isoenzyme of aldehyde dehydrogenase specifically involved in the biosynthesis of 9-cis and all-trans retinoic acid

“…as described previously [11]. From the known molar absorption coefficients of cis-isomers of retinoic acid [13], appropriate corrections were made on the all-trans-retinoic acid standard curve to quantify the cis-isomers of retinoic acid produced in the enzymic reaction.…”

Flavin-photosensitized reactions of retinal and stilbene

“…was used to follow sensitized isomerization reactions of retinols (1.0mm). The method was that of von Planta et al (1962). The plates were of Kieselgel G (E. Merck A.-G., Darmstadt, Germany) (25g +75ml of water) and the solvent system was light petroleum (b.p.…”

Gecko ι-crystallin: How cellular retinol-binding protein became an eye lens ultraviolet filter

“…Fluorescence was measured at 458 nm (bandpass 20 nm) with excitation at 348 nm (bandpass 3 nm) in the absence of light on a Shimadzu RF-5301PC spectrofluorophotometer. Stock retinoid solutions in ethanol were prepared in the dark, and concentrations were determined on a Perkin-Elmer lambda-15 spectrometer with the absorption coefficients: all-trans-retinol, ϭ 46,000 M Ϫ1 ⅐cm Ϫ1 at 325 nm (21); all-trans-retinoic acid, ϭ 45,000 M Ϫ1 ⅐cm Ϫ1 at 350 nm (21); and all-trans-3,4-didehydroretinol, ϭ 41,300 M Ϫ1 ⅐cm Ϫ1 at 350 nm (22). For direct binding assays, increasing amounts of all-trans-retinol were added to 1.5 ml of a 20 nM solution of -crystallin in phosphate buffer.…”