Search results for "Retinoids"
showing 10 items of 32 documents
Heterocycle-containing retinoids. Discovery of a novel isoxazole arotinoid possessing potent apoptotic activity in multidrug and drug-induced apoptos…
2001
In a search for retinoic acid (RA) receptor ligands endowed with potent apoptotic activity, a series of novel arotinoids were prepared. Because the stereochemistry of the C9-alkenyl portion of natural 9-cis-RA and the olefinic moiety of the previously synthesized isoxazole retinoid 4 seems to have particular importance for their apoptotic activity, novel retinoid analogues with a restricted or, vice versa, a larger flexibility in this region were designed and prepared. The new compounds were evaluated in vitro for their ability to activate natural retinoid receptors and for their differentiation-inducing activity. Cytotoxic and apoptotic activities were, in addition, evaluated. In general, …
Synthetic retinoids dissociate coactivator binding from corepressor release.
2002
The ligand-activated retinoid receptors RXR and RAR control development, homeostasis and disease by regulating transcription of retinoic acid (RA) responsive target genes or crosstalk with other signalling pathways. According to the current model ligand-binding triggers an exchange between corepressor- and coactivator-complexes that inhibit or potentiate transcription by deacetylating and acetylating nucleosomal histones, respectively. Additional cofactors may modify the transcriptional regulatory process by linking liganded retinoid receptors to structural components of chromatin or protein degradation. The desire to specifically influence defined events in RA-signalling, while others are …
Effects of vitamin A deficiency on mitochondrial function in rat liver and heart.
2000
The aim of this study was to investigate comparative effects of vitamin A deficiency on respiratory activity and structural integrity in liver and heart mitochondria. Male rats were fed a liquid control diet (control rats) or a liquid vitamin A-deficient diet (vitamin A-deficient rats) for 50 days. One group of vitamin-A deficient rats was refed a control diet for 15 days (vitamin A-recovered rats). To assess the respiratory function of mitochondria the contents of coenzyme Q (ubiquinone, CoQ), cytochrome c and the activities of the whole electron transport chain and of each of its respiratory complexes were evaluated. Chronic vitamin A deficiency promoted a significant increase in the endo…
Comparative assessment of the toxicology of vitamin A and retinoids in man.
1989
As the title implies, any assessment of the toxic effects of vitamin A derivatives must distinguish between vitamin A in the truest sense, i.e. retinol, and retinoic acid and its synthetic derivatives. Just as no single description is universally applicable to the mode of action of vitamin A derivatives, so too do their toxic effects defy generalization. The recommendation made in 1982 by IUPAC [Eur. J. Biochem., 129 (1989) 1] to designate all derivatives with the typical structure of the vitamin as being retinoids may be chemically logical and correct but, when it comes to describing the effects and side-effects of vitamin A derivatives, it leads to misunderstandings. Retinol, which is fre…
Xanthine oxidase catalyzes the oxidation of retinol.
2007
In mammals, xanthine oxidase (E.C. 1.17.3.2) catalyzes the hydroxylation of a wide variety of heterocyclic substrates such as purines, pyrimidines, and pterins, in addition to aldehydes [1] as all-trans-retinaldehyde [2-5]. Here, we show that buttermilk xanthine oxidase was capable to oxidizing all-trans-retinol (t-ROL) to all-trans-retinaldehyde (t-RAL) that was successively oxidized to all-trans-retinoic acid (t-RA). A rise in the enzyme activity, when t-ROL-CRBP complex was assayed, with respect to the free t-ROL, was observed. Furthermore, treatment of the enzyme with Na2S and glutathione resulted in a significant increment in catalytic activity toward t-ROL and t-RAL, due to the recons…
Retinoid dynamics in chicken eye during pre- and postnatal development.
1994
Changes in the steady state level of retinols, retinaldehydes and retinyl esters in the trans and 11-cis forms and trans retinoic acid were measured in whole chicken eye during development from day 6 in ovo to day 3 post-hatch. These retinoids, quantified by different HPLC systems, were detected in this time sequence: trans-retinol and trans-retinyl esters in the first week in ovo, 11-cis-retinol in the second week. The highest level of 11-cis-retinaldehyde and 11-cis-retinyl esters was reached at the end of development in ovo; however, their levels increased further after hatching. The retinoic acid level decreased at the end of the first week, rising again at the end of the second week. T…
Retinoids as a Perspective in Treatment of Alzheimer’s Disease
2010
<i>Background:</i> In the past, we demonstrated that the disintegrin metalloproteinase ADAM10 has α-secretase activity in vitro and in cultured cells. We also found out that moderate overexpression of this proteinase inhibits Aβ peptide production and prevents the formation of amyloid plaques in an Alzheimer’s disease (AD) mouse model. Moreover, it corrects early hippocampal defects like LTP impairment and increases cortical synaptogenesis. <i>Objective:</i> Upregulation of ADAM10 might be an alternative approach concerning AD therapy. Our current research therefore focuses on substances and/or pathways which regulate ADAM10 gene expression. <i>Methods:</i&g…
Acanthosis nigricans: A review.
2020
Background Acanthosis nigricans (AN) is a cutaneous disorder characterized by symmetric velvety hyperpigmented plaques on intertriginous areas like axilla, neck, inframammary, and groin. Aims To summarize the pathophysiology and classification of AN, provide an update of diagnostic testing strategies, and describe the current therapeutic options described so far in the literature for this disease. Methods A comprehensive english language literature search across multiple databases (PubMed, EMBASE, MEDLINE, and Cochrane) for keywords (alone and in combination) was performed. MeSH as well as non-MeSH terms such as "acanthosis nigricans," "classification," "pathophysiology," "diagnosis," "trea…
Topical therapies for oral lichen planus management and their efficacy: a narrative review.
2012
Oral Lichen Planus (OLP) is a chronic inflammatory condition implicating T cell-mediated cytotoxicity, and involving oral mucosal surfaces. Several therapeutic regimens have been evaluated to treat OLP and pain related, but often without high level of evidence. Topical formulations are the favourite for the majority of cases; bioadhesive formulations have been considered very useful and practical for local drug delivery in oral mucosa, due to the increased residence time on the oral mucosa of the dosage forms and better therapeutic efficacy. In this narrative review, authors try to illustrate the current topical managements for OLP from the accessible literature on this topic. Steroids are …
Retinoids induce MMP-9 expression through RARalpha during mammary gland remodeling.
2007
Retinoic acid (RA) is a signaling molecule in the morphogenesis of the mammary gland, modulating the expression of matrix metalloproteinases (MMPs). The aim of this paper was to study the role of RA during weaning, which consists of three events: apoptosis of the secretory cells, degradation of the extracellular matrix, and adipogenesis. CRABP II and CRBP-1 carrier proteins increased significantly during weaning compared with lactating glands but reverted to control values after the litter resuckled. The effects of RA are mediated by the nuclear receptors RARalpha, RARbeta, RARgamma, and RXRalpha, which underwent an increase in protein levels during weaning. In an attempt to elucidate the R…