Structure characteristics of natural and synthetic retinoids

Reverse-phase high-performance liquid chromatography (HPLC) analysis of retinol and retinyl esters in mouse serum and tissues

The ability to measure endogenous metabolites of retinoids (vitamin A and its derivatives) in biological samples is key to understanding the crucial physiological actions of vitamin A. Over the years, many assays and methods have been developed to analyze different retinoids in biological samples. Liquid chromatography is the best analytical technique for routine analysis of these compounds. However, due to their different chemical properties, different retinoid metabolites cannot be accurately separated and quantified in a single chromatographic run. Here, we will describe a reverse-phase HPLC isocratic method that enables extraction, separation, identification, and quantification of all-trans-retinol and different molecular species of retinyl ester with high accuracy, sensitivity, and reliability.

Analysis of cyclic and acyclic analogs of retinol, retinoic acid, and retinal by laser desorption ionization-, matrix-assisted laser desorption ionization-mass spectrometry, and UV/Vis spectroscopy

Laser desorption ionization (LDI)- and matrix-assisted laser desorption ionization (MALDI)-mass spectrometry (LDI-MS, MALDI-MS) at 337-nm laser wavelength were used to analyze retinol (vitamin A), retinoic acid, and retinal and their analogs 3-hydroxyretinol, 3-hydroxyretinoic acid, 3-hydroxyretinal, 4-oxoretinol, 4-oxoretinoic acid, 4-oxoretinal, 3,4-didehydroretinol (vitamin A(2)), 3,4-didehydroretinoic acid, 3,4-didehydroretinal, acycloretinol, acycloretinoic acid, and acycloretinal. The compounds exhibit sufficient ionizability which allows to obtain mass spectra by LDI which are similar in quality to those obtained by MALDI. Mass spectra were recorded with a linear time-of-flight (TOF) instrument or a reflectron-type (RETOF) instrument in positive-ion mode. Under the conditions of LDI-MS the compounds form abundant radical molecular ions (M+*), whereas in the MALDI mass spectra abundant protonated molecular ions ([M + H]+) are observed. Characteristic fragment ions provide additional structural information. High-performance liquid chromatography (HPLC) coupled with UV/Vis photodiode detection was used to assist in retinoid characterization. Synthesis of 3-hydroxyretinal, 4-oxoretinal, and acycloretinal was performed by oxidative cleavage of the all-trans-carotenoids of zeaxanthin, canthaxanthin, and lycopene.

Retinoids--"differentiation agents" for cancer treatment and prevention

The ability of vitamin A and its derivatives to induce differentiation in certain target tissues has been appreciated for nearly a century. Recently, oral all-trans retinoic acid (ATRA), a vitamin A metabolite, has been shown to induce terminal differentiation of leukemic cells in patients with acute promyelocytic leukemia (APL). Complete remissions are obtained and normal hematopoiesis is established in an outpatient setting with minimal side effects in the majority of cases. Although remissions are not durable, disseminated intravascular coagulation, a frequent complication of remission induction in APL, is avoided by oral ATRA prior to definitive chemotherapy. The molecular basis for the efficacy of ATRA in APL appears to be the involvement of the retinoic acid receptor alpha locus in the t(15;17) translocation breakpoint characteristic of APL.