Fourier transform infrared spectroscopy of retinoids

Biodegradable Elastomers with Antioxidant and Retinoid-like Properties

Intimal hyperplasia (IH) is a type of scarring that involves complex pathophysiological responses of the vasculature to injury, including overproliferation and migration of vascular smooth muscle cells (VSMCs), adventitial fibroblasts, and the activation of macrophages. The objective of this research was to develop a biodegradable polymer with intrinsic properties that would combat the cellular processes that contribute to IH. Citric acid, 1,8-octanediol, and all-trans retinoic acid (atRA) were incorporated into a polyester network via a condensation reaction to form the thermoset poly(1,8-octamethylene-citrate-co-retinate) (POCR). POCR was chemically characterized and assessed for the presence of antioxidant and retinoidlike properties. ^HNMR and ATR-FTIR confirmed the incorporation of atRA into the backbone of the polymer network. POCR was able to scavenge radicals and inhibit lipid peroxidation. The proliferation and migration of vascular smooth muscle cells cultured on POCR were inhibited, whereas endothelial cell proliferation and migration were not. These results are consistent with the biological effects of atRA. These results are the first to demonstrate the synthesis of a polymer with intrinsic antirestenotic properties for potential use in the fabrication of vascular devices such as stents and vascular grafts.

Analysis of retinoids and carotenoids: problems resolved and unsolved

Progress in nutritional biochemistry has always depended on progress in analysis of nutrients. Animal growth assays were fundamentally important in the discovery and initial isolation of the fat-soluble vitamins. Chromatography, initially introduced by Tswett for separation of plant pigments (including carotenoids), quickly became indispensable for separation of carotenoids and vitamin A compounds; the early open-column methods were eventually superseded by more efficient HPLC techniques, and reversed-phase HPLC has become the current method of choice for analysis of retinoids and carotenoids in biological tissues. Detection and quantitation of retinoids and carotenoids most often has depended on their unparalleled spectral properties; the conjugated polyene structures of these compounds give them unique light absorption spectra and high molar absorptivities, and hence outstanding lower limits of detection. Other techniques, such as gas chromatography (GC) and mass spectroscopy (coupled with GC and HPLC), immunoassays, supercritical fluid chromatography, and capillary electrophoresis, have proven useful in certain applications. Analysis of retinoid-binding proteins has been mostly by conventional protein methods, although the fluorescence of the retinol ligand has been useful in some instances to provide a highly specific assay. Current challenges in retinoid and carotenoid analysis include the resolution of stereoisomers, and quantitation of these compounds at ultratrace levels in biological tissues. Possible new approaches include accelerator mass spectroscopy, and use of gene expression assays to assess vitamin A status.

Properties of retinoids. Structure, handling, and preparation

Retinoids are unstable compounds being readily oxidized and/or isomerized to altered compounds, especially in the presence of oxidants including air, light, and excessive heat. They are labile toward strong acids and solvents that have dissolved oxygen or peroxides. In this review, procedures for handling and storage of retinoids and biological samples containing them have been described. The physical and chemical properties of retinoids have been reported. Simplified procedures for derivatizations and purification, and methods for quantitation of retinoids have been presented.