{{Chembox <!-- Images --> | ImageFile = Galactoflavin.svg | ImageSize = 200px <!-- Names --> | IUPACName = 7,8-Dimethyl-10-[(2''S'',3''R'',4''S'',5''R'')-2,3,4,5,6-pentahydroxyhexyl]benzo[g]pteridine-2,4-dione | OtherNames = <!-- Sections --> | Section1 = {{Chembox Identifiers | CASNo = 5735-19-3 | ChEBI = | ChEMBL = | ChemSpiderID = 16736134 | UNII = Y30ZN232IC | DrugBank = | EINECS = | EC_number = | InChI = 1S/C18H22N4O7/c1-7-3-9-10(4-8(7)2)22(5-11(24)14(26)15(27)12(25)6-23)16-13(19-9)17(28)21-18(29)20-16/h3-4,11-12,14-15,23-27H,5-6H2,1-2H3,(H,21,28,29)/t11-,12+,14+,15-/m0/s1 | InChIKey = RPADDAUXKBBASM-MXYBEHONSA-N | KEGG = | MeSHName = | PubChem = 12310019 | SMILES = CC1=CC2=C(C=C1C)N(C3=NC(=O)NC(=O)C3=N2)C[C@@H]([C@H]([C@H]([C@@H](CO)O)O)O)O }} | Section2 = {{Chembox Properties | C=18 | H=22 | N=4 | O=7 | Appearance = Yellow solid | Density = | MeltingPtC = 260 | MeltingPt_notes = (dec) | BoilingPt = | Solubility = }} | Section3 = {{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }} }}
'''Galactoflavin''' is a synthetic compound and riboflavin (vitamin B<sub>2</sub>) antagonist and antimetabolite. It is a biochemical tool used primarily in research to induce riboflavin deficiency in animal models and humans. It is structurally similar to riboflavin, where the ribose-derived side chain is replaced by a galactose-derived group.
== Chemical properties ==
Galactoflavin's chemical formula is C<sub>18</sub>H<sub>22</sub>N<sub>4</sub>O<sub>7</sub> and has a molecular weight of 406.40 g/mol. Galactoflavin appears as yellow crystals that decompose at 260 °C and exhibit absorption maxima at 223, 267, 370, and 445 nm.<ref name=Merck>{{citation | title = Merck Index | id = '''4239'''. Galactoflavin | edition = 11th | page = 678 }}</ref> It displays yellow-green fluorescence in water.<ref name=Merck/>
== Biological activity ==
As a riboflavin analog, galactoflavin competes with riboflavin in metabolic pathways, leading to depletion of riboflavin-containing coenzymes such as flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) in tissues such as liver and kidney.<ref>{{cite journal | author1 = PROSKY L | author2 = BURCH HB | author3 = BEJRABLAYA D | author4 = LOWRY OH | author5 = COMBS AM | title = The Effects of Galactoflavin on Riboflavin Enzymes and Coenzymes | journal = The Journal of Biological Chemistry | date = 1964 | volume = 239 | issue = 8 | pages = 2691–2695 | doi = 10.1016/S0021-9258(18)93906-2 | doi-access = free | pmid = 14235554 }}</ref> This antagonism results in riboflavin deficiency symptoms that are reversible with excess riboflavin supplementation. In rats, galactoflavin feeding reduces flavin content in mitochondria and affects oxidative phosphorylation.<ref>{{cite journal | last1 = Beyer | first1 = Robert E. | last2 = Lamberg | first2 = Stanley L. | last3 = Neyman | first3 = M. Arthur | title = The Effect of Riboflavin Deficiency and Galactoflavin Feeding on Oxidative Phosphorylation and Related Reactions in Rat Liver Mitochondria | journal = Canadian Journal of Biochemistry and Physiology | date = 1961 | volume = 39 | pages = 73–88 | doi = 10.1139/o61-009 }}</ref>
The antiriboflavin effect of galactoflavin was first demonstrated in 1945 and was found to produce riboflavin deficiency in rats reversible by excess riboflavin.<ref>{{cite journal | journal = Journal of Biological Chemistry | volume = 160 | issue = 1 | pages = 165–167 | date = 1945 | title = The Antiriboflavin Effect of Galactoflavin | author = Gladys A. Emerson, Elizabeth Wurtz, and Oscar H. Johnson | doi = 10.1016/S0021-9258(18)43108-0 | doi-access = free }}</ref>
In humans, galactoflavin rapidly induces riboflavin deficiency, with clinical signs including anemia, glossitis, angular stomatitis, and dermatitis appearing within weeks.<ref>{{cite journal | last1 = Lane | first1 = Montague | last2 = Alfrey | first2 = Clarence P. | last3 = Mengel | first3 = Charles E. | last4 = Doherty | first4 = Maureen A. | last5 = Doherty | first5 = Jean | title = The Rapid Induction of Human Riboflavin Deficiency with Galactoflavin | journal = Journal of Clinical Investigation | date = 1964 | volume = 43 | issue = 3 | pages = 357–373 | doi = 10.1172/JCI104921 | pmid = 14135487 | pmc = 441929 }}</ref>
== Research uses ==
Galactoflavin has been employed to study the effects of riboflavin deficiency on growth, enzyme activity, and congenital malformations.<ref>{{cite journal | last1 = Nelson | first1 = Marjorie M. | last2 = Baird | first2 = Catherine D.C. | last3 = Wright | first3 = Howard V. | last4 = Evans | first4 = Herbert M. | title = Multiple Congenital Abnormalities in the Rat Resulting from Riboflavin Deficiency Induced by the Antimetabolite Galactoflavin | journal = The Journal of Nutrition | date = 1956 | volume = 58 | pages = 125–134 | doi = 10.1093/jn/58.1.125 | pmid = 13286747 }}</ref><ref>{{cite journal | last1 = Aksu | first1 = Oguz | last2 = MacKler | first2 = Bruce | last3 = Shepard | first3 = Thomas H. | last4 = Lemire | first4 = Ronald J. | title = Studies of the development of congenital anomalies in embryos of riboflavin-deficient, galactoflavin fed rats. II. Role of the terminal electron transport systems | journal = Teratology | date = 1968 | volume = 1 | issue = 1 | pages = 93–102 | doi = 10.1002/tera.1420010110 | pmid = 4302703 }}</ref><ref>{{cite journal | last1 = Lane | first1 = M. | last2 = Brindley | first2 = C. O. | title = Laboratory and Clinical Studies with the Riboflavin Antagonist, Galactoflavin | journal = Experimental Biology and Medicine | date = 1964 | volume = 116 | pages = 57–61 | doi = 10.3181/00379727-116-29158 | pmid = 14200132 }}</ref> In pregnant rats, it induces multiple congenital abnormalities in embryos, including cardiovascular defects and hydrocephalus, by disrupting terminal electron transport systems. It has also been investigated for potential antitumor effects due to its ability to cause regression of tumors in rodents through riboflavin deficiency.
In mice, dietary galactoflavin affects hepatocyte ultrastructure.<ref>{{cite journal | last1 = Tandler | first1 = Bernard | last2 = Hoppel | first2 = Charles L. | title = Ultrastructural effects of dietary galactoflavin on mouse hepatocytes | journal = Experimental and Molecular Pathology | date = 1974 | volume = 21 | issue = 1 | pages = 88–101 | doi = 10.1016/0014-4800(74)90081-1 | pmid = 4370691 }}</ref> It impairs adrenal ascorbic acid response to stress in rats.<ref>{{cite journal | last1 = Slater | first1 = Grant G. | title = INFLUENCE OF GALACTOFLAVIN AND INANITION ON THE ADRENAL ASCORBIC ACID RESPONSE TO STRESS IN RATS<sup>1</sup> | journal = Endocrinology | date = 1959 | volume = 65 | issue = 5 | pages = 731–738 | doi = 10.1210/endo-65-5-731 | pmid = 13831613 }}</ref>
== References == {{reflist}}
Category:Flavins Category:Antimetabolites Category:Galactosides