retinyl-stearate and retinol-acetate

A nonaqueous packed capillary electrochromatographic reversed-phase method for separation of retinyl esters has been developed. The retinyl esters all-trans-retinyl acetate, palmitate, heptadecanoate, stearate, oleoate, and linoleoate were separated on a 180 microm ID column packed with 5 microm C30 particles with a mobile phase consisting of 2.5 mM lithium acetate in N,N-dimethylformamide-methanol (99:1, v/v). With this mobile phase, the electroosmotic flow was 0.8 mm/s at 650 V/cm and 40 degrees C, and the separation was completed in less than 30 min on 30 cm columns. To obtain electrostable frits of the hydrophobic C30 material both the preparation of the frits and the conditioning of the column prior to electroconditioning were of importance. Selectivity changes were introduced by replacing up to 70% v/v of the N,N-dimethylformamide by acetonitrile. The increase in the amount of acetonitrile was, however, accompanied by a significant increase in analysis time. Liver extracts obtained from arctic seal were analyzed.

Topics: Animals; Chromatography, High Pressure Liquid; Diterpenes; Electric Conductivity; Electrophoresis, Capillary; Liver; Retinyl Esters; Seals, Earless; Temperature; Vitamin A

Many tissues which require vitamin A store the vitamin as long-chain fatty acyl esters of retinol. As part of a study designed to characterize vitamin A metabolism in the lacrimal gland, which transports retinol from blood to lacrimal gland fluid, extracts from lacrimal glands of rabbits and rats were analyzed by non-aqueous high performance liquid chromatography. Retinyl linoleate, retinyl palmitate, and retinyl stearate were identified in these extracts by their co-elution with standards, their retention time relative to retinyl palmitate, and their susceptibility to hydrolysis by saponification. Retinyl palmitate was present in rabbit lacrimal gland at 51.0 +/- 10.1 ng/g tissue. After treatment of vitamin A-deficient rabbits with orally administered [11,12-3H] retinyl acetate, the radiolabeled esters retinyl linoleate, palmitate, and stearate were extracted from the lacrimal glands. These data show that the lacrimal gland stores vitamin A as fatty acyl esters of retinol.

Topics: Animals; Chromatography, High Pressure Liquid; Diterpenes; Lacrimal Apparatus; Rabbits; Retinoids; Retinyl Esters; Vitamin A; Vitamin A Deficiency

All-trans-[11-3H]retinyl acetate was injected directly into the testes of young rats and testicular and liver metabolites were analyzed by HPLC at 6, 24 and 72 h post injection. All-trans-retinyl acetate was hydrolyzed to retinol and further metabolized to polar compounds and a trace of retinoic acid, or reesterified to various retinyl esters including retinyl palmitate and retinyl stearate. Thus, retinyl ester hydrolyzing and esterifying enzymes are present in the testes of young rats. Eleven, twelve and ten radioactive peaks were observed at 6, 24 and 72 h, respectively. The amount of radioactivity in retinyl palmitate and retinyl stearate increased with time and reached 24 and 4%, respectively, by 72 h. Although retinol predominated, retinyl palmitate was the major esterified form in testis. The amount of radioactivity in retinol and retinyl acetate decreased with time and increased in unidentified metabolites and retinyl esters. An insignificant amount of radioactivity was found in liver. We conclude from these results that some vitamin A is stored/accumulated in the testes as retinyl esters in order to support the process of spermatogenesis and other physiological functions and that the retinol esterifying enzyme is quite active in the testes of young rats.

Topics: Animals; Chromatography, High Pressure Liquid; Diterpenes; Injections; Liver; Male; Rats; Rats, Inbred Strains; Retinyl Esters; Testis; Time Factors; Tretinoin; Vitamin A