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One-Step, Low-Cost, Operator-Friendly, and Scalable Procedure to Synthetize Highly Pure N-(4-ethoxyphenyl)-retinamide in Quantitative Yield without Purification Work-Up. Molecules 2022; 27:molecules27113632. [PMID: 35684568 PMCID: PMC9182364 DOI: 10.3390/molecules27113632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/01/2022] [Accepted: 06/04/2022] [Indexed: 12/10/2022] Open
Abstract
It is widely reported that N-(4-hydroxyphenyl)-retinamide or fenretinide (4-HPR), which is a synthetic amide of all-trans-retinoic acid (ATRA), inhibits in vitro several types of tumors, including cancer cell lines resistant to ATRA, at 1–10 µM concentrations. Additionally, studies in rats and mice have confirmed the potent anticancer effects of 4-HPR, without evidencing hemolytic toxicity, thus demonstrating its suitability for the development of a new chemo-preventive agent. To this end, the accurate determination of 4-HPR levels in tissues is essential for its pre-clinical training, and for the correct determination of 4-HPR and its metabolites by chromatography, N-(4-ethoxyphenyl)-retinamide (4-EPR) has been suggested as an indispensable internal standard. Unfortunately, only a consultable old patent reports the synthesis of 4-EPR, starting from dangerous and high-cost reagents and using long and tedious purification procedures. To the best of our knowledge, no article existed so far describing the specific synthesis of 4-EPR. Only two vendors worldwide supply 4-ERP, and its characterization was incomplete. Here, a scalable, operator-friendly, and one-step procedure to synthetize highly pure 4-EPR without purification work-up and in quantitative yield is reported. Additionally, a complete characterization of 4-EPR using all possible analytical techniques has been provided.
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Napoli JL. Physiological insights into all-trans-retinoic acid biosynthesis. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:152-67. [PMID: 21621639 DOI: 10.1016/j.bbalip.2011.05.004] [Citation(s) in RCA: 246] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 05/05/2011] [Accepted: 05/12/2011] [Indexed: 01/25/2023]
Abstract
All-trans-retinoic acid (atRA) provides essential support to diverse biological systems and physiological processes. Epithelial differentiation and its relationship to cancer, and embryogenesis have typified intense areas of interest into atRA function. Recently, however, interest in atRA action in the nervous system, the immune system, energy balance and obesity has increased considerably, especially concerning postnatal function. atRA action depends on atRA biosynthesis: defects in retinoid-dependent processes increasingly relate to defects in atRA biogenesis. Considerable evidence indicates that physiological atRA biosynthesis occurs via a regulated process, consisting of a complex interaction of retinoid binding-proteins and retinoid recognizing enzymes. An accrual of biochemical, physiological and genetic data have identified specific functional outcomes for the retinol dehydrogenases, RDH1, RDH10, and DHRS9, as physiological catalysts of the first step in atRA biosynthesis, and for the retinal dehydrogenases RALDH1, RALDH2, and RALDH3, as catalysts of the second and irreversible step. Each of these enzymes associates with explicit biological processes mediated by atRA. Redundancy occurs, but seems limited. Cumulative data support a model of interactions among these enzymes with retinoid binding-proteins, with feedback regulation and/or control by atRA via modulating gene expression of multiple participants. The ratio apo-CRBP1/holo-CRBP1 participates by influencing retinol flux into and out of storage as retinyl esters, thereby modulating substrate to support atRA biosynthesis. atRA biosynthesis requires the presence of both an RDH and an RALDH: conversely, absence of one isozyme of either step does not indicate lack of atRA biosynthesis at the site. This article is part of a Special Issue entitled: Retinoid and Lipid Metabolism.
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Moise AR, Noy N, Palczewski K, Blaner WS. Delivery of retinoid-based therapies to target tissues. Biochemistry 2007; 46:4449-58. [PMID: 17378589 PMCID: PMC2562735 DOI: 10.1021/bi7003069] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Through its various metabolites, vitamin A controls essential physiological functions. Both naturally occurring metabolites and novel retinoid analogues have shown effectiveness in many clinical settings that include skin diseases and cancer, and in animal models of human conditions affecting vision. In this review, we analyze several potential retinoid-based therapies from the point of view of drug metabolism and transport to target tissues. We focus on the endogenous factors that affect the absorption, transport, and metabolism of retinoids by taking into account data obtained from the analysis of animal models that lack the enzymes or proteins involved in the storage and absorption of retinoids. We also discuss findings of toxicity associated with retinoids in an effort to improve the outcome of retinoid-based therapies. In this context, we review evidence that esterification of retinol and retinol-based drugs within target tissues provides one of the most efficient means to improve the absorption and to reduce the toxicity associated with pharmacological doses of retinoids. Future retinoid-based therapeutic strategies could involve targeted delivery mechanisms leading to lower toxicity and improved effectiveness of retinoids.
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Affiliation(s)
- Alexander R Moise
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965, USA.
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Schmidt CK, Volland J, Hamscher G, Nau H. Characterization of a new endogenous vitamin A metabolite. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1583:237-51. [PMID: 12117568 DOI: 10.1016/s1388-1981(02)00212-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Here, we describe the discovery of a new major endogenous vitamin A metabolite with particularly high hepatic concentrations. This metabolite was isolated from mouse livers and was characterized as 9-cis-4-oxo-13,14-dihydro-retinoic acid (RA) based on mass spectral, ultraviolet, and nuclear magnetic resonance analyses. It was also detected in one human liver. To gain further insight into endogenous retinoid metabolism, mice were fed over a period of 14 days ad libitum with diets enriched with different amounts of retinyl palmitate [15,000, 45,000 or 150,000 international units (IU)/kg diet]. Higher retinyl palmitate amounts in the diet resulted surprisingly in a dose-dependent decrease in all-trans-RA levels in serum, kidney, and brain, whereas levels of 9-cis-4-oxo-13,14-dihydro-RA, retinol, and retinyl esters were dose-dependently elevated in serum, kidney, and liver. 13-cis-RA levels could be detected in serum, liver, and kidney, but were unaffected by the dietary vitamin A status. 9-cis-RA levels were below the detection limit of 0.2 ng/ml serum or 0.4 ng/g tissue. This study indicates that the oxidation at C4 of the cyclohexenyl ring, isomerization of the C9/C10 double bond, and reduction of the C13/C14 double bond are major endogenous metabolic pathways of vitamin A.
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Affiliation(s)
- Carsten K Schmidt
- Department of Food Toxicology, School of Veterinary Medicine Hannover, Bischofsholer Damm 15, D-30173 Hannover, Germany
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Napoli JL. Interactions of retinoid binding proteins and enzymes in retinoid metabolism. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1440:139-62. [PMID: 10521699 DOI: 10.1016/s1388-1981(99)00117-1] [Citation(s) in RCA: 313] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Naturally occurring retinoids (vitamin A or retinol and its active metabolites) are vital for vision, controlling the differentiation program of epithelial cells in the digestive tract and respiratory system, skin, bone, the nervous system, the immune system, and for hematopoiesis. Retinoids are essential for growth, reproduction (conception and embryonic development), and resistance to and recovery from infection. The functions of retinoids in the embryo begin soon after conception and continue throughout the lifespan of all vertebrates. Both naturally occurring and synthetic retinoids are used in the therapy of various skin diseases, especially acne, for augmenting the treatment of diabetes, and as cancer chemopreventive agents. Retinol metabolites serve as ligands that activate specific transcription factors in the superfamily of steroid/retinoid/thyroid/vitamin D/orphan receptors and thereby control gene expression. Additionally, retinoids may also function through non-genomic actions. Various retinoid binding proteins serve as partners in retinoid function. These binding proteins show high specificity and affinity for specific retinoids and seem to control retinoid metabolism in vivo qualitatively and quantitatively by reducing 'free' retinoid concentrations, protecting retinoids from non-specific interactions, and chaperoning access of metabolic enzymes to retinoids. Implementation of the physiological effects of retinoids depends on the spatial-temporal expressions of binding proteins, receptors and metabolic enzymes. This review will discuss current understanding of the enzymes that catalyze retinol and retinoic acid metabolism and their unique and integral relationship to retinoid binding proteins.
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Affiliation(s)
- J L Napoli
- Department of Nutritional Sciences, 119 Morgan Hall, University of California, Berkeley, USA.
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Van heusden J, Wouters W, Ramaekers FC, Krekels MD, Dillen L, Borgers M, Smets G. All-trans-retinoic acid metabolites significantly inhibit the proliferation of MCF-7 human breast cancer cells in vitro. Br J Cancer 1998; 77:26-32. [PMID: 9459142 PMCID: PMC2151274 DOI: 10.1038/bjc.1998.5] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
All-trans-retinoic acid (ATRA) is well known to inhibit the proliferation of human breast cancer cells. Much less is known about the antiproliferative activity of the naturally occurring metabolites and isomers of ATRA. In the present study, we investigated the antiproliferative activity of ATRA, its physiological catabolites 4-oxo-ATRA and 5,6-epoxy-ATRA and isomers 9-cis-RA and 13-cis-RA in MCF-7 human breast cancer cells by bromodeoxyuridine incorporation. MCF-7 cells were grown in steroid- and retinoid-free medium supplemented with growth factors. Under these culture conditions, ATRA and its naturally occurring catabolites and isomers showed significant antiproliferative activity in MCF-7 cells in a concentration-dependent manner (10[-11] M to 10[-6] M). The antiproliferative activity of ATRA catabolites and isomers was equal to that of the parent compound ATRA at concentrations of 10(-8) M and 10(-7) M. Only at 10(-6) M were the catabolites and the stereoisomer 13-cis-RA less potent. The stereoisomer 9-cis-RA was as potent as ATRA at all concentrations tested (10[-11] M to 10[-6] M). In addition, we show that the catabolites and isomers were formed from ATRA to only a limited extent. Together, our findings suggest that in spite of their high antiproliferative activity the catabolites and isomers of ATRA cannot be responsible for the observed growth inhibition induced by ATRA.
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Affiliation(s)
- J Van heusden
- Department of Molecular Cell Biology & Genetics, University of Maastricht, The Netherlands
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Nonnecke BJ, Horst RL, Dubeski PL, Reinhardt TA. Reactivity and phenotype of mononuclear leukocytes from nongravid heifers after in vitro exposure to 9,13-di-cis-retinoic acid. J Dairy Sci 1997; 80:2833-41. [PMID: 9406076 DOI: 10.3168/jds.s0022-0302(97)76248-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The predominant isomer of retinoic acid in the plasma of dairy cows during the periparturient period is 9,13-di-cis-retinoic acid. Because retinoic acids influence the activity of cells in a variety of tissues, including the immune system, the potential for this isomer to modulate the bovine immune system during the periparturient period must be considered. The present study examined the in vitro effects of 9,13-di-cis-retinoic acid on the reactivity and phenotype of blood mononuclear leukocytes from nongravid Holstein heifers that were sensitized to antigens and that had naturally low plasma concentrations of 9,13-di-cis-retinoic acid. In this system, 9,13-di-cis-retinoic acid, approximating the highest plasma concentrations occurring in vivo during the periparturient period, had no effect on DNA synthesis, secretion of interleukin-2 or interferon-gamma, or secretion of immunoglobulin by unstimulated cultures or cultures stimulated by mitogen (pokeweed mitogen) or antigen (ovalbumin). The composition of unstimulated and stimulated mononuclear leukocyte populations, based on percentages of specific cell types, was unaffected by 9,13-di-cis-retinoic acid at the physiologic concentration of 10(-8) M. 9,13-di-cis-Retinoic acid did not affect the actual number of cells in unstimulated cultures and cultures stimulated by antigen but did cause a moderate reduction in the number of cells, primarily CD4+ lymphocytes, in cultures stimulated by mitogen. Overall, these results suggest that the elevated concentration of 9,13-di-cis-retinoic acid in maternal plasma may have a negligible effect on the reactivity and phenotype of cells constituting the circulating mononuclear leukocyte population.
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Affiliation(s)
- B J Nonnecke
- USDA, ARS, National Animal Disease Center, Metabolic Diseases and Immunology Research Unit, Ames, IA 50010-0070, USA
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Fiorella P, Napoli J. Microsomal retinoic acid metabolism. Effects of cellular retinoic acid-binding protein (type I) and C18-hydroxylation as an initial step. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)34093-0] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Hill DL, Sani BP. Metabolic disposition and development of new chemopreventive retinoids. Drug Metab Rev 1991; 23:413-38. [PMID: 1935578 DOI: 10.3109/03602539109029766] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- D L Hill
- Southern Research Institute, Birmingham, Alabama 35205
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Abstract
This article reviews the determination of retinoic acids and their metabolites (first-generation retinoids), aromatic retinoids (second generation) and arotinoids (third generation) in biological samples. Because of the sensitivity of the retinoids to isomerization and oxidation, special care has to be taken from sample collection and storage, throughout extraction, till the final chromatographic separation. High and strong protein binding, and insolubility in aqueous solutions hamper the extraction from biological samples. Various extraction procedures are discussed, mainly involving liquid-liquid extraction of biological fluids or lyophilized tissue samples. The new technique involving direct injection of biological fluids or tissue homogenates, using high-performance liquid chromatography (HPLC) with automated column switching, provides full protection from light and simplifies sample work-up. HPLC with ultraviolet detection is the method of choice for the determination of retinoids, because it is rapid, sensitive and allows separation of geometric isomers and metabolites within a wide polarity range. Gas chromatography-mass spectrometry is not appropriate for first- and second-generation retinoids because of isomerization, but allows very sensitive determination of third-generation retinoids, although very extensive sample clean-up and derivatization are necessary. However, direct injection of large volumes of biological fluids into HPLC systems, using on-line solid-phase extraction and automated column-switching, results in very sensitive methods even with simple ultraviolet detection and may become the method of choice for routine analyses.
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Affiliation(s)
- R Wyss
- Department of Drug Metabolism, F. Hoffmann-La Roche Ltd., Basel, Switzerland
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Kochhar DM, Penner JD, Satre MA. Derivation of retinoic acid and metabolites from a teratogenic dose of retinol (vitamin A) in mice. Toxicol Appl Pharmacol 1988; 96:429-41. [PMID: 3206525 DOI: 10.1016/0041-008x(88)90003-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Megadose supplements of vitamin A are under suspicion as hazards to the developing embryo after the discovery that two vitamin A-related drugs, Accutane and Tigason, are human teratogens. Retinoic acid (all-trans-RA) is a natural metabolite of vitamin A which participates in many of the known functions of vitamin A and may be the active agent in teratogenesis. In this investigation we gave a single, high oral dose of retinol (vitamin A) to pregnant mice to assess its transplacental pharmacokinetics as well as to measure the formation and distribution of its metabolites in the embryo. Retinol was estimated to be 4-fold less active than retinoic acid in the whole animal teratogenesis and 20-fold less active in the in vitro bioassay. A fully teratogenic dose, 200 mg/kg, yielded considerable quantities of retinoic acid which were transferred to the embryo with kinetics similar to that of retinol. During the first 8 hr after administration of retinol, the metabolites (including all-trans-RA, 13-cis-RA, and 4-oxo-RA) constituted almost 50% of the quantity of all retinol derivatives found in the embryo. A comparison of combined peak concentrations of the metabolites (or their AUC values) with the extent of teratogenesis associated with them individually provided sufficient evidence to implicate the metabolites themselves as mediators of retinol-induced teratogenesis. However, since both retinol and retinoic acid were present in sufficient concentrations in the embryo to act as teratogens we cannot at present rule out the possibility that they may act independently. Further experimentation will be necessary to address whether retinoic acid detected in the embryo is the product of the embryo's own metabolic capability or is transferred from the maternal circulation.
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Affiliation(s)
- D M Kochhar
- Department of Anatomy, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
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Williams JB, Shields CO, Brettel LM, Napoli JL. Assessment of retinoid-induced differentiation of F9 embryonal carcinoma cells with an enzyme-linked immunoadsorbent assay for laminin: statistical comparison of dose-response curves. Anal Biochem 1987; 160:267-74. [PMID: 3034091 DOI: 10.1016/0003-2697(87)90046-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A convenient procedure, using enzyme-linked immunoadsorbent assay of laminin, to measure retinoid-induced F9-cell differentiation into parietal endoderm was developed. Dose-response curves were fitted with the Allfit program, a statistical method for the analysis and simultaneous comparison of sigmoidal curves, which has been modified for use with a microcomputer. The procedure was standardized with respect to time of retinoid incubation, time-course of laminin production, effects of dibutyryl cAMP, and nature of individual dose-response curves. Retinoic acid produced a half-maximal response at 1.3 nM. Retinol was 175-fold less potent than retinoic acid and required 72 h to effect a maximum response, in contrast to 48 h for retinoic acid. Six oxidized and/or isomerized metabolites of retinoic acid, including 13-cis-retinoic acid, were less potent than retinoic acid, but were more potent than retinol. The dose-response curves had identical slopes with the exception of those obtained with 13-cis-4-oxo- and 4-oxo-16-hydroxyretinoic acids, the only metabolites tested with two structural alterations relative to retinoic acid. Multiple functional group alterations were synergistic in deactivating retinoic acid. The synthetic retinoids 13-cis-N-ethylretinamide and 4-hydroxyphenylretinamide and the steroid hormone 1,25-dihydroxycholecalciferol were inactive.
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Abstract
Retinoic acid, unlike the naturally occurring vitamin A (retinol), is a minor component of the human diet. It is formed in vivo from retinol and has many metabolites. The biological activity of the metabolites is not higher than that of retinoic acid itself, indicating that the metabolites must be products of retinoic acid catabolism. Little is known about the enzymatic systems responsible for forming retinoic acid or about how it enters the cell. Discovering the molecular mechanism(s) of retinoic acid activity in cellular metabolism is important to understanding its physiologic role. The pharmacologic effects of high doses of retinoic acid may be caused by its action on cellular membranes. Conversely, low concentrations appear to produce physiologic effects. Results of experiments with animals and with cell cultures indicate that the primary physiologic role of retinoic acid is in cellular differentiation. Retinoic acid influences genomic expression, inducing the appearance of some proteins while suppressing the expression of others. The existence of an intracellular retinoic acid-binding protein suggests that it may mediate the physiologic effects of retinoic acid on cellular differentiation.
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Williams JB, Napoli JL. Metabolism of retinoic acid and retinol during differentiation of F9 embryonal carcinoma cells. Proc Natl Acad Sci U S A 1985; 82:4658-62. [PMID: 3860815 PMCID: PMC390445 DOI: 10.1073/pnas.82.14.4658] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Retinol and retinoic acid dose-response curves were obtained for promotion of the differentiation of F9 murine embryonal carcinoma cells with an enzyme-linked immunoadsorbent assay for laminin, a product of differentiated F9 cells. Retinoic acid produced a half-maximum response at 1.3 nM and a maximum response at about 30 nM; retinol was 1/175th as potent. Maximum differentiation required 48 hr of continuous exposure to retinoic acid, whereas retinol required 72 hr of exposure. The half-time of retinoic acid conversion into polar metabolites was 3.5 hr; metabolism was accelerated by pretreating F9 cells with retinoic acid. An inhibitor of oxidative metabolism, ketoconazole, decreased the rate of retinoic acid metabolism and decreased the concentration of retinoic acid required to produce a half-maximum response. Unchanged retinoic acid was the sole compound isolated from nuclei of F9 cells incubated with retinoic acid. Retinol had a half-life approximately 5-fold longer than retinoic acid, attained greater cell concentrations, and was converted into retinoic acid by F9 cells. These data indicate that retinoic acid itself directs the differentiation of F9 cells and may mediate differentiation induced by retinol.
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Yakovleva IM, Vakulova LA, Samokhvalov GI. Metabolism of vitamin A, structure and synthesis of metabolites, and their biological activity (Review). Pharm Chem J 1984. [DOI: 10.1007/bf00760699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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