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Author: Abdulkerim Eroğlu
Publisher:
ISBN:
Category :
Languages : en
Pages : 129
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Book Description
Abstract: Beta-carotene (BC) is the major dietary source of provitamin A. Central cleavage of BC catalyzed by beta-carotene oxygenase 1 yields two molecules of retinaldehyde. Subsequent oxidation produces all-trans-retinoic acid (ATRA) which functions as a ligand for a family of nuclear transcription factors, the retinoic acid receptors (RARs). Eccentric cleavage of BC at non-central double bonds is catalyzed by other enzymes and can also occur non-enzymatically. The products of these reactions are beta-apocarotenals and beta-apocarotenones, whose biological functions in mammals are unknown. We used reporter gene assays to show that none of the beta-apocarotenoids significantly activated RARs and RXR[alpha]. Beta-Apo-13-carotenone was found to antagonize the activation of RXR[alpha] by 9-cis-retinoic acid and was effective at concentrations as low as 1 nM. Molecular modeling studies revealed that beta-apo-13-carotenone makes molecular interactions like an antagonist of RXR[alpha]. The results suggest a possible function of BACs on RXR[alpha] signaling. Moreover, beta-apo-14'-carotenal, beta-apo-14'-carotenoic acid, and beta-apo-13-carotenone antagonized ATRA-induced transactivation of RARs. Competitive radioligand binding assays demonstrated that these putative RAR antagonists compete directly with retinoic acid for high affinity binding to purified receptors. Molecular modeling studies confirmed that beta-apo-13-carotenone can directly interact with the ligand binding site of the retinoid receptors. Beta-Apo-13-carotenone and the beta-apo-14'-carotenoids inhibited ATRA-induced expression of retinoid responsive genes in Hep G2 cells. Finally, we developed an LC/MS method and found 3-5 nM beta-apo-13-carotenone was present in human plasma. These findings suggest that beta-apocarotenoids function as naturally-occurring retinoid antagonists. We have also tested apo-lycopenoids that have a structural resemblance to beta-apo-13-carotenone to see if they exert a similar action as beta-apo-13-carotenone in modulating retinoid receptor activation. We found that apo-13-lycopenone was able to block ATRA induced expression of RAR[beta] and CYP26A1 like the action of beta-apo-13-carotenone. This suggests that the ionone ring may not be prerequisite for beta-apo-13-carotenone's binding to RARs. The antagonism of retinoid signaling by these metabolites may have implications for the activities of dietary beta-carotene as a provitamin A and as a modulator of risk for cardiovascular disease and cancer.
Author: Abdulkerim Eroğlu
Publisher:
ISBN:
Category :
Languages : en
Pages : 129
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Book Description
Abstract: Beta-carotene (BC) is the major dietary source of provitamin A. Central cleavage of BC catalyzed by beta-carotene oxygenase 1 yields two molecules of retinaldehyde. Subsequent oxidation produces all-trans-retinoic acid (ATRA) which functions as a ligand for a family of nuclear transcription factors, the retinoic acid receptors (RARs). Eccentric cleavage of BC at non-central double bonds is catalyzed by other enzymes and can also occur non-enzymatically. The products of these reactions are beta-apocarotenals and beta-apocarotenones, whose biological functions in mammals are unknown. We used reporter gene assays to show that none of the beta-apocarotenoids significantly activated RARs and RXR[alpha]. Beta-Apo-13-carotenone was found to antagonize the activation of RXR[alpha] by 9-cis-retinoic acid and was effective at concentrations as low as 1 nM. Molecular modeling studies revealed that beta-apo-13-carotenone makes molecular interactions like an antagonist of RXR[alpha]. The results suggest a possible function of BACs on RXR[alpha] signaling. Moreover, beta-apo-14'-carotenal, beta-apo-14'-carotenoic acid, and beta-apo-13-carotenone antagonized ATRA-induced transactivation of RARs. Competitive radioligand binding assays demonstrated that these putative RAR antagonists compete directly with retinoic acid for high affinity binding to purified receptors. Molecular modeling studies confirmed that beta-apo-13-carotenone can directly interact with the ligand binding site of the retinoid receptors. Beta-Apo-13-carotenone and the beta-apo-14'-carotenoids inhibited ATRA-induced expression of retinoid responsive genes in Hep G2 cells. Finally, we developed an LC/MS method and found 3-5 nM beta-apo-13-carotenone was present in human plasma. These findings suggest that beta-apocarotenoids function as naturally-occurring retinoid antagonists. We have also tested apo-lycopenoids that have a structural resemblance to beta-apo-13-carotenone to see if they exert a similar action as beta-apo-13-carotenone in modulating retinoid receptor activation. We found that apo-13-lycopenone was able to block ATRA induced expression of RAR[beta] and CYP26A1 like the action of beta-apo-13-carotenone. This suggests that the ionone ring may not be prerequisite for beta-apo-13-carotenone's binding to RARs. The antagonism of retinoid signaling by these metabolites may have implications for the activities of dietary beta-carotene as a provitamin A and as a modulator of risk for cardiovascular disease and cancer.
Author: Siva Ramamoorthy
Publisher: CRC Press
ISBN: 1000224694
Category : Medical
Languages : en
Pages : 216
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Book Description
Carotenoids are a large class of isoprenoid pigments produced by plants and certain microbes. More than 700 naturally occurring carotenoids have been identified. Apocarotenoids are tailored from carotenoids by oxidative enzymes. Apocarotenoids act as visual or volatile signals to attract pollinating and seed dispersal agents. They are also the key players in allelopathic interactions and plant defense. Biology, Chemistry and Applications of Apocarotenoids provides detailed account of the fundamental chemistry of apocarotenoids and the basic methods used in carotenoid research, and critical discussions of the biochemistry, functions, and applications of these important compounds. Topics covered in the proposed book include various aspects of the roles of apocarotenoids in colour and colouration, photosynthesis and other photofunctions and protection. The formation and roles of carotenoid metabolites and breakdown products as perfume/aroma compounds are also be outlined. Features: Provides an organized overview of apocarotenoids and their chemistry and biological functions Focuses on recent discoveries on apocarotenoids, their nature and functions. Details potential uses of apocarotenoids in agriculture, pharmacy, food industry, and apocarotenoid production at industrial level This book has been written by leading experts in apocarotenoid research and gives a comprehensive overview on the diversity of apocarotenoid compounds and would serve as a reference book for researches in Plant Physiology, Molecular Biology, Biochemistry, Biophysics and Medicine.
Author:
Publisher: Academic Press
ISBN: 0323913520
Category : Science
Languages : en
Pages : 566
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Book Description
Carotenoids: Biological Functions of Carotenoids and Apocarotenoids in Natural and Artificial Systems, Volume 674 in the Methods in Enzymology series, highlights new advances in the field, with this new volume presenting interesting chapters on topics such as Ultrafast laser spectroscopic studies on carotenoids in solution and on those bound to photosynthetic pigment-protein complexes, Assessing photoprotective functions of carotenoids in photosynthetic systems of plants and green algae, Fluorescence of carotenoids: probing binding site interactions and conformational motion in carotenoproteins, Resonance Raman: A powerful tool to interrogate carotenoids in biological matrices, and much more. Other chapters in the book cover Engineering the carotenoid biosynthetic pathway to study the function of carotenoids in light-harvesting complexes, Carotenoids as proxies for variations in photosynthesis and phenology in response to environmental and climatic change, Apocarotenoid pigment biosynthesis in non-model plants, Apocarotenoid transport in plants, Screening for apocarotenoid plant growth regulators in Arabidopsis, Effects of herbivory on carotenoid biosynthesis and breakdown, Biosynthesis and action of apocarotenoid plant hormones, and much more. - Provides the authority and expertise of leading contributors from an international board of authors - Presents the latest release in Methods in Enzymology series - Updated release includes the latest information on Carotenoids: Biological functions of carotenoids and apocarotenoids in natural and artificial systems
Author: H. DeLuca
Publisher: Springer Science & Business Media
ISBN: 1461588707
Category : Science
Languages : en
Pages : 297
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Book Description
The first demonstration of the existence of a vitamin and the full recognition of this fact are often attributed to the work of McCollum, who found that a sub stance in butterfat and cod-liver oil was necessary for growth and health of ani mals fed purified diets. It became obvious that an organic substance present in microconcentrations was vital to growth and reproduction of animals. Following the coining of the word vitamine by Funk, McCollum named this fat-soluble sub stance vitamin A. We can, therefore, state that vitamin A was certainly one of the first known vitamins, yet its function and the function of the other fat-soluble vitamins had remained largely unknown until recent years. However, there has been an explosion of investigation and new information in this field, which had remained quiescent for at least two or three decades. It is now obvious that the fat-soluble vitamins function quite differently from their water-soluble counter parts. We have learned that vitamin D functions by virtue of its being converted in the kidney to a hormone that functions to regulate calcium and phosphorus metabolism. This new endocrine system is in the process of being elucidated in detail, and in addition, the medical use of these hormonal forms of vitamin D in the treatment of a variety of metabolic bone diseases has excited the medical com munity.
Author:
Publisher: Academic Press
ISBN: 0128201479
Category : Science
Languages : en
Pages : 612
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Book Description
Retinoid Signaling Pathways, Volume 637, the latest release in the Methods in Enzymology series, continues the legacy of this premier serial with quality chapters authored by leaders in the field. Sections in this release include The chemistry and biochemistry of Vitamin A and its natural derivative, Biosynthesis of retinoic acids, Biodegration of retinoic acids mediated by retinoid binding proteins, Retinoic acid homeostasis, Cryo Electron Microscopy to study retinol update via the STRA6 receptor, Immuno-detection of retinoic acid synthesis enzymes in the brain, classical pathway of gene regulation by retinoids, Protein-protein interactions in the regulation of retinoid acid receptors activity, and much more. - Provides the authority and expertise of leading contributors from an international board of authors - Presents the latest release in the Methods in Enzymology series - Includes the latest information on retinoid signaling pathways
Author: Mary Ann Asson-Batres
Publisher: Springer Nature
ISBN: 3030422828
Category : Medical
Languages : en
Pages : 232
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Book Description
This book covers subjects that have major impacts on society, such as the mechanism of maternal-fetal transfer of vitamin A, and the effects of alcohol on retinoic acid signaling and mammalian embryonic development. There has been an awareness of the importance of consuming vitamins throughout human history, but empirical studies of their physiological role and mode of action only began about 150 years ago. Since then, the biochemical nature of vitamin A and its active derivative, retinoic acid, have been identified and researchers around the globe have investigated retinoic acid’s physiological function in growth processes and in maintaining life Written by leading experts, this book discusses the latest findings and advances in retinoic acid research. It addresses topics such as the role of retinoic acid signaling in a multitude of processes, including limb, heart and respiratory system development, as well as its role in maintaining postnatal organ systems. This book is a valuable resource for scientists involved in vitamin A/retinoic acid research and readers interested in developmental biology.
Author: Zoe Diana Draelos
Publisher: John Wiley & Sons
ISBN: 111865546X
Category : Medical
Languages : en
Pages : 34
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Book Description
Back for a new edition, Zoe Draelos' outstanding resource to cosmetic dermatology again provides a highly-illustrated, clinical guide to the full range of cosmetic skin treatments. Bringing together experts from research, industry, surgery and practice, it is structured in four distinct parts for easy navigation by the busy clinician: Basic Concepts - giving an overview of the physiology pertinent to cosmetic dermatology and the delivery systems by which treatments can take effect; Hygiene Products - evaluating cleansing and moisturising products; Adornment - looking at aesthetic techniques such as cosmetics, nail protheses and hair treatment; Antiaging - ie, injectables, resurfacing and skin contouring techniques, and the rapidly growing area of Cosmeceuticals. With over 300 high-quality images and key summary boxes throughout, this new edition incorporates the newest procedural innovations in this rapidly developing field. Perfect for all dermatologists, especially those specialising in cosmetic dermatology and whether hospital-based or in private practice, it provides the complete cosmetic regimen for your patients and will be an indispensable tool to consult over and over again.
Author: Muhammad Zia-Ul-Haq
Publisher: Springer Nature
ISBN: 3030464598
Category : Technology & Engineering
Languages : en
Pages : 862
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Book Description
Plants produce chemicals as part of their normal metabolic activities. These include primary metabolites found in all plants, such as sugars and fats, as well as secondary metabolites, which can have therapeutic effects in humans and be refined to produce drugs. Plants synthesize a bewildering variety of phytochemicals, but most are derivatives of a few biochemical motifs. Numerous herbal-derived substances have been evaluated for their therapeutic potential. These include alkaloids, coumarins, saponins, plant pigments and flavonoids. Flavonoids, carotenoids and anthocyanins are probably the best known of these substances due to their antioxidant properties. Carotenoids: Structure and Function in the Human Body presents comprehensive coverage of carotenoids. The text covers the scientific literature and clinical significance of this organic pigment, with an emphasis on its therapeutic potential. The authors approach carotenoids from a range of perspectives, from their structural and physicochemical properties to their distribution in nature, interaction with the human metabolism, and use as a coloring agent in various products. The intake, metabolism and secretion of anthocyanins in the human body are covered in-depth, as are the biosynthetic pathways through which these compounds are synthesized in the natural system. Factors affecting stability and extraction are listed, and health-related uses and biological activities are covered in great detail. Present and future trends in carotenoid research are also presented. This book provides a solid background in carotenoids for researchers and professionals in food science, food technology, nutrition, biology, chemistry and medical sciences.
Author: Norman I. Krinsky
Publisher: CRC Press
ISBN: 0203026640
Category : Health & Fitness
Languages : en
Pages : 589
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Book Description
The first source to collect the latest evidence linking carotenoids to human health and disease, this stimulating reference studies the role of carotenoids in the prevention of chronic disease and reviews breakthrough studies from more than 40 field authorities on the latest research. The book reveals the most recent findings regarding the use of c
Author: P.J.J. Hooykaas
Publisher: Elsevier
ISBN: 008086094X
Category : Science
Languages : en
Pages : 565
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Book Description
This book provides up-to-date coverage at an advanced level of a range of topics in the biochemistry and molecular biology of plant hormones, with particular emphasis on biosynthesis, metabolism and mechanisms of action. Each contribution is written by acknowledged experts in the field, providing definitive coverage of the field. No other modern book covers this subject matter at such an advanced level so comprehensively. It will be invaluable to university libraries and scientists in the plant biotechnology industries.
