Ubiquinone and tocopherylquinone

Studies on vitamin E. 4. The simultaneous determinations of tocopherols, ubiquinones and ubichromenols (substance SC) in animal tissues: a reconsideration of the Keilin–Hartree heart preparation

“…The present work explains adequately the earlier results of Slater (1957) andBouman et al (1958). It is clear that single-dimensional chromatography on zinc carbonate-treated paper is inadequate for the analysis of animal tissues and, owing to the co-chromatography phenomena we have described, R values can be grossly misleading.…”

“…Several factors combined to urge a reinvestigation of these fildings. Our own studies indicated that the chromatographic data given by Bouman et al (1958) could hardly be correct. Work by has shown that animal tissues contain a reducing substance that simulates oc-tocopherol (from which it can, however, be separated by two-dimensional paper chromatography) and that this substance runs near ubiquinone on chromatograms.…”

“…They found further that by treating the lipid extract with a mixture of ascorbic acid and ethanolic hydrochloric acid, a naturally occurring quinone, thought to be tocopherylquinone, was reduced and cyclized to a new substance apparently identical with rmtocopherol (criteria being ultraviolet spectrum and chromatography on zinc carbonate-treated paper). More recently, Bouman, Slater, Rudney & Links (1958) have reconsidered the interpretation of their original observations, in view of their findings that ubiquinone 50, a naturally occurring quinone [in particularly high concentration in normal heart, see ] could be reduced and cyclized to give a product with the same ultraviolet maximum and apparently the same chromatographic behaviour as m-tocopherol. The nature of this product has not been confirmed, but it may have the structure of the chromanol (I).…”

“…We have therefore preferred for the present to call the product RC-ubiquinone. Bouman et at. (1958) concluded that the formation of this product accounted quantitatively for the earlier results of Bouman & Slater (1957) and were of the opinion that the presence of a-tocopherylquinone in heart remained to be established.…”

Substance SC (ubichromenol): a naturally-occurring cyclic isomeride of ubiquinone-50

“…So far substance SC appears to contain an aromatic ring with para-oxygen substitution, two methoxyl groups and a large unsaturated side chain, and these are also present in ubiquinol (Morton et al 1957). Ubiquinol can be converted into a chroman-type of molecule by a cyclization involving the double bond of the first isoprene unit of the side chain and the hydroxyl group in the ortho position to this (Bouman, Slater, Rudney & Links, 1958). A structure of this type (II) is more in accord with the desiderata for the structure of substance SC, with the exception that there is no double bond conjugated to the ring, whereas there is evidence for this in substance SC.…”