Niacin
Judy A. Driskell, Ira Wolinsky in Sports Nutrition, 2005
Niacin is a generic term for the water-soluble vitamin in the B complex that occurs as an acid (nicotinic acid) or as an amide (nicotinamide) (Figure 5.1). Both nicotinic acid and nicotinamide are stable in the dry state and soluble in water, although nicotinamide has a much higher solubility. Nicotinamide is the main component of the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which have a major role in the catabolic reactions of metabolism.3,5The acid (nicotinic acid) and the amide (nicotinamide) forms of niacin. (From Berdanier, C.D., Advanced Nutrition: Micronutrients, CRC Press, Boca Raton, FL, 1998.)
The Biochemistry of the 17-Hydroxysteroid Dehydrogenases
Ronald Hobkirk in Steroid Biochemistry, 1979
Studies on the subcellular distribution of the 17-hydroxysteroid dehydrogenases of mammalian systems have shown that these enzymes are located in the particulate fractions of some tissues and are soluble enzymes in other tissues. Some tissues have both soluble and particulate activities. Such is the case in rabbit liver, where 17β-hydroxysteroid dehydrogenase activity toward androgens and estrogens is present in both the microsomal and soluble fractions (Table 2). The microsomal enzyme activity is essentially specific for NAD; however, the soluble enzyme can utilize either NAD or NADP. It is interesting to note that soluble 17β enzyme activity toward 17β-estradiol is higher with NAD while activity toward testosterone is higher with NADP. The 17α-hydroxysteroid dehydrogenase activity of rabbit liver is found essentially only in the soluble fraction of the cell and has a marked preference for NADP.
Mitochondrial Function in Diabetes: Pathophysiology and Nutritional Therapeutics
Jeffrey I. Mechanick, Elise M. Brett in Nutritional Strategies for the Diabetic & Prediabetic Patient, 2006
Niacin refers to nicotinic acid (NA; pyridine-3-carboxylic acid) and its derivatives, which produce biologic effects qualitatively similar to nicotinamide (nicotinic acid amide). Niacin is synthesized from the essential amino acid tryptophan via the kynurenine pathway and quinolinate phosphori-bosyltransferase. This biosynthetic pathway is inhibited by deficiencies in vitamin B6, Rf, or iron, and enhanced with restricted protein intake [281]. Nicotinamide is the essential moiety in the coenzymes nicotinamide adenine dinucleotide (NAD) and NAD phosphate (NADP), which serve as electron acceptors or hydrogen donors in many biologic redox reactions.
Cytotoxicity and antigenotoxicity evaluation of acetylshikonin and shikonin
Published in Drug and Chemical Toxicology, 2021
Ramona Figat, Anna Zgadzaj, Sylwia Geschke, Patrycja Sieczka, Agnieszka Pietrosiuk, Sylwester Sommer, Agata Skrzypczak
Shikonin (SH) (CAS no. 54952–43-1) was purchased from Sigma Aldrich and dissolved in methanol. Cyclophosphamide (CPA) (CAS no. 6055–19-2), clinafloxacin (CLFX) (CAS no. 105956–97-6) and ethyl methanesulfonate (EMS) (CAS no. 62–50-0) were also purchased from Sigma Aldrich and dissolved in phosphate-buffered saline (PBS). Methanol (CAS no. 67–56-1), acetic acid (CAS no. 64–19-7), ethanol (CAS no. 64–17-5), KCl (CAS no. 7447–40-7) and neutral red (NR) (CAS no. 553–24-3) were purchased from POCh S.A. (Gliwice, Poland). Dimethyl sulphoxide (DMSO) (CAS no. 67–68-5), D-glucose 6-phosphate disodium salt hydrate (G-6-P) (CAS no. 3671–99-6), cytochalasin-B and 3–(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) were purchased from Sigma Aldrich. Nicotinamide adenine dinucleotide phosphate (NADP) (CAS no. 24292–60-2) was purchased from MP Biomedicals. Vectashield mounting medium with 4′,6-Diamidino-2-phenylindole (DAPI) was purchased from Vector Laboratories.
A metabolomic study on the anti-depressive effects of two active components from Chrysanthemum morifolium
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2020
Tong Liu, Ning Zhou, Ruihao Xu, Yangang Cao, Yanli Zhang, Zhen Liu, Xiaoke Zheng, Weisheng Feng
Niacin is one of the 13 essential vitamins, and it can be converted to nicotinamide in the human body [38]. Niacin deficit symptoms include several nervous system pathologies, such as dementia and depression, as well as other symptoms resembling those observed in other neurodegenerative diseases [39]. In our study, a low level of niacin in depressed mice was detected. After the administration of Chr and its two active components, the level of nicotinuric acid increased significantly. In terms of energy metabolism, nicotinamide and phosphoribosyl- pyrophosphate combine to generate nicotinamide mononucleotide, which can continue to react with adenosine triphosphate (ATP) to generate coenzyme I. The generation of coenzyme II (NADP) is the result of the combination of coenzyme I and ATP. Coenzyme I and coenzyme II are coenzymes of dehydrogenase and indispensable substance transfer carriers in the human body that participate in the process of lipid metabolism and saccharide anaerobic decomposition. The symptoms of energy deficiency or fatigue in patients with major depression have been described above [36]. Chr and its two active components could increase the level of nicotinuric acid. Furthermore, as a direct metabolite of niacin, the level of nicotinuric acid increased after Chr/Nar/Api treatment, indicating that more niacin exerts its biological activity in the body. Thus, Chr/Nar/Api improved the energy supply by accelerating the niacin and niacinamide metabolism in depressed mice.
The nuclear receptor REV-ERBα regulates CYP2E1 expression and acetaminophen hepatotoxicity
Published in Xenobiotica, 2022
Li Zhang, Fugui Zhang, Yifei Xiao, Jianhao Du, Xingwang Zhang, Min Chen, Baojian Wu
APAP and alamethicin were purchased from Aladdin Chemicals (Shanghai, China). Nicotinamide adenine dinucleotide phosphate (NADPH) was obtained from Sigma-Aldrich (St. Louis, MO). p-Nitrophenol was purchased from Macklin Biochemical (Shanghai, China). The assay kits for ALT (alanine aminotransferase) and AST (aspartate aminotransferase) were obtained from Jiancheng Bioengineering Institute (Nanjing, China). Anti-CYP2E1 (ab28146), anti-CYP3A11 (ab3572), and anti-CYP1A2 (ab22717) antibodies were purchased from Abcam (Cambridge, MA). Anti-REV-ERBα (14506-1-AP) and anti-GAPDH (10494-1-AP) antibodies were obtained from Proteintech (Chicago, IL). All primary antibodies were diluted with 5% bovine serum albumin at a ratio of 1:1000. siRev-erbα (siRNA targeting Rev-erbα) and siNC (a negative control for siRev-erbα) were obtained from Tsingke Biotechnology (Beijing China). Short hairpin RNA (shRNA) targeting human REV-ERBα (named shREV-ERBα) and a control shRNA were purchased from Biowit Technologies (Shenzhen, China).