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The absorption and malabsorption of folic acid and its polyglutamates

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      Abstract

      Folic polyglutamate, the principal dietary form of folate, consists of folic acid bound to one to six glutamic acid residues in a gamma peptide linkage. Small intestinal conjugase is necessary for the hydrolysis and absorption of these polyglutamates. Folic acid absorption is an active process that occurs primarily in the duodenum and jejunum. Following absorption, folic acid present in human and canine portal blood is not methylated, although methylation may occur later in the liver following reduction.
      Because of its essential role in folate absorption, intestinal conjugase has been the subject of considerable experimental study recently. The enzyme can be inhibited by sulfobromophthalein sodium, and in vitro by unconjugated dihydroxy bile salts, as well as by conjugated lithocholate. The low serum folate level present in some women taking oral contraceptives may also be due to conjugase inhibition. Enzyme inhibition has been suggested as the cause of megaloblastic anemia occasionally seen in patients receiving diphenylhydantoin, but this has not been consistently confirmed.
      Both conjugase and unmethylated folic acid monoglutamate are present in human bile. The role of biliary conjugase, if any, is unclear at present.
      The recent synthesis of radioactive folic polyglutamate has provided a significant new tool for the study of normal absorption and malabsorption of folate as well as for the assay of conjugases.
      Although folic acid deficiency is almost always present in tropical sprue, deficiency of this substance alone is insufficient to explain the many abnormalities in small intestinal structure and function. An additional factor(s) has therefore been suggested to explain the pathogenesis of this malabsorptive disorder. The response of patients with this disease to certain antibiotics, the occasional epidemic nature of sprue and the finding of increased small intestinal colony counts suggest that bacteria or a bacterial metabolite(s) may be responsible for the disorder. Recent evidence indicates that folic polyglutamate is malabsorbed to a greater degree than free folic acid, suggesting that intestinal conjugase deficiency or inhibition may play an important role in pathogenesis.
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      References

        • Angier R.B.
        • Boothe J.M.
        • Hutchings B.L.
        • et al.
        The structure and synthesis of the liver L. casei factor.
        Science. 1946; 103: 667
        • Bird O.D.
        • Binkley S.B.
        • Bloom E.S.
        • Emmett A.D.
        • Pfiffner J.J.
        On the enzymatic formation of vitamin Bc from its conjugate.
        J Biol Chem. 1945; 157: 413
        • Laskowski M
        • Mims V
        • Day P
        Studies on the enzyme which produces the Streptococcus lactis-R stimulating factor from inactive precursor substance in yeast.
        J Biol Chem. 1945; 157: 731
        • Pfiffner J.J.
        • Binkley S.B.
        • Bloom E.S.
        • O'Dell B.L.
        Isolation and characterization of vitamin Bc from liver and yeast. Occurrence of an acid-labile chick antianemic factor in liver.
        J Amer Chem Soc. 1947; 69: 1476
        • Gallup P.M.
        • Seifter S
        • Luken M
        • Meilman E
        Application of the Lossen rearrangement of dinitrophenylhydroxamates to analysis of carboxyl groups in model compounds and gelatin.
        J Biol Chem. 1960; 235: 2619
        • Fruton J.S.
        Chemical aspects of protein synthesis.
        in: The Proteins. ed 2. Academic Press, New York1963: 212
        • Bruckner V
        • Kajtar M
        • Kovacs J
        • Nagy H
        • Wein J
        Synthese des immunspezifischen polypeptidartigen Haptens der Anthraxsubtilis Bacillengruppe. Ein synthetetischer Beweis der Konstitution der naturlichen Polyglutaminsäuren.
        Tetrahedron. 1958; 2: 211
        • Butterworth Jr, C.E.
        • Santini Jr, R
        • Frommyer Jr, W.B.
        The pteroyl-glutamate components of American diets as determined by Chromatographic fractionation.
        J Clin Invest. 1963; 42: 1929
        • Santini Jr, R
        • Berger F.M.
        • Berdasco G
        • Sheehy T.W.
        • Aviles J
        • Davila I
        Folic acid activity in Puerto Rican foods.
        J Amer Diet Ass. 1962; 41: 562
        • Herbert V
        Minimal daily adult folate requirement.
        Arch Intern Med. 1962; 110: 649
        • Herbert V
        • Bertini J
        Folic acid.
        in: 3rd ed. The Vitamins. vol 7. Academic Press, New York1967: 243
        • Mims V
        • Totter J.R.
        • Day P.L.
        A method for the determination of substances enzymatically convertible to the factor stimulating Streptococcus lactis-R.
        J Biol Chem. 1944; 155: 401
        • Bernstein L.H.
        • Gutstein S
        Folate conjugase in bile.
        New Eng J Med. 1969; 281: 565
        • Kazenko A
        • Laskowski M
        On the specificity of chicken pancreas conjugase (glutamic acid carboxypeptidase).
        J Biol Chem. 1948; 173: 217
        • Bird O.D.
        • Robbins M
        • Vandenbelt J.M
        • Pfiffner J.J
        Observations on vitamin Bc conjugase from hog kidney.
        J Biol Chem. 1945; 163: 649
        • Baugh C.M
        • Krumdieck C.L
        Effects of phenytoin on folic acid conjugases in man.
        Lancet. 1969; 2: 519
        • Streiff R.R.
        • Rosenberg I.H.
        Absorption of polyglutamic folic acid.
        J Clin Invest. 1967; 46: 1121
        • Wolff R.
        • Drouet L.
        • Karlin R.
        Occurrence of vitamin Bc conjugase in human plasma.
        Science. 1949; 109: 612
        • Naronha J.M.
        • Silverman M.
        Distribution of folic acid in natural material. V. Chicken liver folates.
        J Biol Chem. 1962; 237: 3299
        • Burgen A.S.V.
        • Goldberg N.J.
        Absorption of folic acid from the small intestine of the rat.
        Brit J Pharmacol. 1962; 19: 313
        • Booth C.C.
        Effect of location along the small intestine on absorption of nutrients.
        in: 3rd ed. Handbook of Physiology, Alimentary Canal. vol 3. American Physiological Society, Washington, DC1968: 1513
        • Cohen N
        Differential microbiological assay in study of folic acid absorption in vitro by everted intestinal sacs.
        Clin Res. 1965; 13: 252
        • Hepner G.W.
        The absorption of pteroyglutamic (folic) acid in rats.
        Brit J Haemat. 1969; 16: 241
        • Schedl M.B
        • Clifton J.A.
        Kinetics of intestinal absorption in man: normal subjects and patients with sprue.
        J Clin Invest. 1961; 40: 1079
        • Hepner G.W.
        • Booth C.C.
        • Cowan J
        • Hoffbrand A.V.
        • Mollin D.L
        Absorption of crystalline folic acid in man.
        Lancet. 1968; 2: 302
        • Girdwood R.N.
        A folic acid excretion test in the investigation of intestinal malabsorption.
        Lancet. 1953; 2: 53
        • Anderson B
        • Belcher E.M.
        • Chanarin I
        • Mollin D.L.
        The urinary and fecal excretion of radioactivity after oral doses of H3 folic acid.
        Brit J Haemat. 1960; 6: 439
        • Cox E.V.
        • Meznell M.J.
        • Cooke W.T.
        • Goddie R
        Folic acid excretion test in the steatorrhea syndrome.
        Gastroenterology. 1958; 35: 390
        • Chanarin I
        • Bennett M.C.
        Absorption of folic acid and D-xylose as tests of small intestinal function.
        Brit M J. 1962; 1: 985
        • Girdwood R.H.
        The megaloblastic anemias.
        Quart J Med. 1956; 25: 87
        • Klipstein F.A.
        Folate deficiency secondary to disease of the intestinal tract.
        Bull NY Acad Med. 1966; 42: 638
        • Baker H
        • Thomson A
        • Feingold S
        • Frank O
        Role of the jejunum in the absorption of folic acid and its polyglutamates.
        Amer J Clin Nutr. 1969; 22: 124
        • Booth C.C.
        Metabolic effects of intestinal resection in man.
        Postgrad Med J. 1961; 372: 725
        • Doig H
        • Girdwood R.H.
        The absorption of folic acid and labeled cyanocobalamin in intestinal malabsorption.
        Quart J Med. 1960; 29: 333
        • Chanarin I
        • Anderson B.B.
        • Mollin D.L.
        Absorption of folic acid.
        Brit J Haemat. 1958; 4: 156
        • Kinnear D.G.
        • Johns D.G.
        • MacIntosh P.C.
        • Burgen A.S.V.
        • Cameron D.G.
        Intestinal absorption of tritium labeled folic acid in steatorrhea: effect of a gluten free diet.
        Canad Med Ass J. 1963; 89: 975
        • Waters D.H.
        • Mollin D.L.
        Studies on the folic acid activity of human serum.
        J Clin Path. 1961; 14: 335
        • Klipstein F.A.
        Urinary excretion of orally administered tritium labeled folic acid as a test of folic acid absorption.
        Blood. 1963; 21: 626
        • Klipstein F.A.
        Tropical sprue in New York City.
        Gastroenterology. 1964; 47: 454
        • Butterworth C.E.
        • Nadel H
        • Perez Santiago E
        • Santini Jr, R
        • Gardner F.H.
        Folic acid absorption, excretion and leukocyte concentration in tropical sprue.
        J Lab Clin Med. 1957; 50: 673
        • Klipstein F.A.
        • Samloff I.M.
        • Schenk E.A.
        Tropical sprue in Haiti.
        Ann Intern Med. 1966; 64: 575
        • Klipstein F.A.
        • Falaiye J.M.
        Tropical sprue in expatriates from the tropics living in the continental United States.
        Medicine. 1969; 48: 475
        • Whitehead V.M.
        • Cooper B.A.
        Absorption of unaltered folic acid from the gastrointestinal tract in man.
        Brit J Haemat. 1967; 13: 679
        • Baker H
        • Frank O
        • Feingold S
        • Ziffer H
        • Gillene R.A.
        • Leevy C.M.
        • Sobotka H
        The fate of orally and parenterally administered folate.
        Amer J Clin Nutr. 1965; 17: 83
        • Chanarin I
        • Perry J
        Evidence for reduction and methylation of folate in the intestine during normal absorption.
        Lancet. 1969; 2: 776
        • Butterworth C.E.
        • Baugh C.M.
        • Krumdieck C
        A study of folate absorption and metabolism in man utilizing carbon-14 labeled polyglutamates synthesized by the solid phase method.
        J Clin Invest. 1969; 48: 1131
        • Lanzkowsky P
        • Erlandson M.E.
        • Bezan A.I.
        Isolated defect of folic acid absorption associated with mental retardation and cerebral calcification.
        Blood. 1969; 34: 452
        • Cooperman J.M.
        • Luhby A.L.
        The physiological fate in man of some naturally occurring polyglutamates of folic acid.
        Israel J Med Sci. 1965; 1: 704
        • Banerjee D.K.
        • Chatterjee J.B.
        Observations on the presence of pteroyl polyglutamates in human serum.
        Blood. 1966; 28: 913
        • Herbert V
        • Larrabee A.R.
        • Buchanan J.M.
        Studies on the identification of a folate compound of human serum.
        J Clin Invest. 1962; 41: 1134
        • Schertel M.E.
        • Boehne J.W.
        • Libby D
        Folic acid derivatives in yeast.
        J Biol Chem. 1965; 240: 3154
      1. Baugh CM, Krumdieck C: Personal communication.

        • Rosenberg I.H.
        • Streiff R.R.
        • Godwin M.D.
        • Castle W.B.
        Absorption of polyglutamic folate: participation of deconjugating enzymes of the intestinal mucosa.
        New Eng J Med. 1969; 280: 985
        • Hoffbrand A.V.
        • Necheles T.F.
        • Maldonado N
        • Horta E
        • Santini R
        Malabsorption of folate polyglutamates in tropical sprue.
        Brit Med J. 1969; 2: 543
        • Butterworth Jr, C.E.
        • Baugh C.M.
        • Krumdieck C
        A study of folate absorption in man utilizing carbon-14-labeled polyglutamates synthesized by the solid phase method.
        Clin Res. 1969; 17: 29
        • Perry J
        • Chanarin I
        Absorption and utilization of polyglutamyl forms of folate in man.
        Brit Med J. 1968; 4: 546
        • Bernstein L.H.
        • Gutstein S
        • Weiner S
        Folic acid conjugase: inhibition by unconjugated dihydroxy bile acids.
        in: 3rd ed. Proc Soc Exp Biol Med. 132. 1969: 1167
        • Sheehy T.W.
        • Rubini M.E.
        • Perez-Santiago E
        • Santini Jr, R
        • Nadock J
        The effect of “minute” and “titrated” amounts of folic acid on the megaloblastic anemia of tropical sprue.
        Blood. 1961; 18: 623
        • Klipstein FA
        Absorption of physiologic doses of folic acid in subjects with tropical sprue responding to tetracycline therapy.
        Blood. 1969; 34: 191
        • Klipstein F.A.
        Subnormal serum folate and macrocytosis associated with anticonvulsant drug therapy.
        Blood. 1964; 23: 68
        • Reynolds E.H.
        • Milner G
        • Mathews D.M.
        • Chanarin I
        Anticonvulsant therapy, megaloblastic haemopoiesis and folic acid metabolism.
        Quart J Med. 1966; 35: 521
        • Horwitz S.J.
        • Klipstein F.A.
        • Lovelace R.E.
        Relation of abnormal folate metabolism to neuropathy developing during anticonvulsant drug therapy.
        Lancet. 1968; 1: 563
        • Hoffbrand A.V.
        • Necheles T.F.
        Mechanism of folate deficiency in patients receiving phenytoin.
        Lancet. 1968; 2: 528
        • Rosenberg I.M.
        • Streiff R.R.
        • Godwin M.A.
        • Castle W.B.
        Impairment of intestinal deconjugation of dietary folate.
        Lancet. 1968; 2: 530
        • Yoshino T.
        The clinical and experimental studies on the metabolism of folic acid using tritiated folic acid. II. The experimental studies on the absorption site and mechanism of tritiated folic acid in rats.
        J Vitamin. 1968; 14: 35
        • Meynell M.J.
        Megaloblastic anemia in anticonvulsant therapy.
        Lancet. 1966; 1: 487
        • Dahlke M.B.
        • Mortens-Roesler E
        Malabsorption of folic acid due to diphenylhydantoin.
        Blood. 1967; 30: 341
        • Streiff R.R.
        Malabsorption of polyglutamic folic acid secondary to oral contraceptives.
        Clin Res. 1969; 17: 345
        • Shojania O.M.
        • Hornady G
        • Banes P.H.
        Oral contraceptives and serum folate level.
        Lancet. 1968; 1: 1376
        • Snyder L.M.
        • Necheles T.F.
        Malabsorption of folate polyglutamates associated with oral contraceptive therapy.
        Clin Res. 1969; 17: 602
        • Binkley F
        • Olson C.K.
        Metabolism of glutathione. IV. Activators and inhibitors of the hydrolysis of glutathione.
        J Biol Chem. 1951; 188: 451
        • Hill M.J.
        • Drasar B.S.
        Degradation of bile salts by human intestinal bacteria.
        Gut. 1968; 9: 22
        • Baker S.J.
        • Kumar S
        • Swaminathan S.P.
        Excretion of folic acid in bile.
        Lancet. 1965; 1: 685
        • Herbert V
        Excretion of folic acid in bile.
        Lancet. 1965; 1: 913
        • Klipstein F.A
        Intestinal folate conjugase activity in tropical sprue.
        Amer J Clin Nutr. 1967; 20: 1004
        • Bernstein L.H
        • Gutstein S
        Folate conjugase in bile.
        New Eng J Med. 1969; 281: 565
        • Slater T.F
        • Griffiths D.B
        Studies on enzymic composition of rat bile following administration of toxic substances.
        in: Taylor N The Biliary System. Blackwell Scientific Publications, Oxford1965: 431
        • Bradford W.D.
        • Elchlepp J.G.
        • Arstila A.U
        • Trump B.F
        • Kinney T.D
        Iron metabolism and cell membranes.
        Amer J Clin Path. 1969; 56: 201
        • Jeejeebhoy K.N
        Intestinal folate conjugases.
        New Eng J Med. 1969; 281: 50
        • Bird OD
        • McGlohon VM
        • Vailkus JW
        Naturally occurring folates in the blood and liver of the rat.
        Anal Biochem. 1965; 12: 18
        • Novikoff AB
        • Heus M
        A microsomal nucleoside diphosphatase.
        J Biol Chem. 1963; 238: 710
        • Krumdieck CL
        • Baugh CM
        Observations in human pteroyl poly gamma glutamyl glutamic acid conjugases.
        in: 3rd ed. Fed Proc. 28. 1969: 869
        • Krumdieck CL
        • Baugh CM
        The solid phase synthesis of polyglutamates of folic acid.
        Biochemistry. 1969; 8: 1568
      2. Baugh CM, Stevens JC, Krumdieck CL: Studies on conjugase. I. The solid phase synthesis of analogs of polyglutamates of folic acid and their effects on human liver conjugase. Biochemistry (In press).

        • Merrifield RB
        Solid phase peptide synthesis. I. The synthesis of a tetrapeptide.
        J Amer Chem Soc. 1963; 85: 2149
        • Merrifield RB
        • Stewart JM
        • Jernberg N
        Instrument for automated synthesis of peptides.
        Anal Chem. 1966; 38: 1905
        • Levy CC
        • Goldman P
        The enzymatic hydrolysis of methotrexate and folic acid.
        J Biol Chem. 1967; 242: 2933
      3. Krumdieck CL, Baugh CM: A radioactive assay of folic acid polyglutamate conjugase(s). Anal Biochem (in press).

        • Klipstein FA
        • Samloff IM
        Folate synthesis by intestinal bacteria.
        Amer J Clin Nutr. 1969; 19: 237
        • Teply LJ
        • Krehl WD
        • Elvehjem CA
        The intestinal synthesis of niacin and folic acid in the rat.
        Amer J Physiol. 1947; 148: 91
        • Miller HT
        • Luckey TD
        Intestinal synthesis of folic acid in monoflora chicks.
        J Nutr. 1963; 80: 236
        • Daft FS
        • McDaniel EG
        • Herman LG
        • Romine MK
        • Hegner JR
        Role of coprophagy in utilization of B vitamins synthesized by intestinal bacteria.
        in: 3rd ed. Fed Proc. 22. 1963: 129
        • Hoffbrand AV
        • Tabaqchali S
        • Mollin DL
        High serum folate levels in intestinal blind loop syndrome.
        Lancet. 1966; 1: 1339
        • Donaldson Jr, RM
        Studies on the pathogenesis of steatorrhea in the blind loop syndome.
        J Clin Invest. 1965; 44: 1815
        • Kim YS
        • Spritz N
        • Blum M
        • Terz J
        • Sherlock P
        The role of altered bile acid metabolism in the steatorrhea of experimental blind loop.
        J Clin Invest. 1966; 45: 956
        • Tabaqchali S
        • Booth CC
        Jejunal bacteriology and bile-salt metabolism in patients with intestinal malabsorption.
        Lancet. 1966; 2: 12
        • Rosenberg IH
        • Hardison WG
        • Bull DM
        Abnormal bile-salt patterns and intestinal bacterial overgrowth associated with malabsorption.
        New Eng J Med. 1967; 276: 1391
        • Klipstein FA
        • Schenk EA
        • Samloff IM
        Folate repletion associated with oral tetracycline therapy in tropical sprue.
        Gastroenterology. 1966; 51: 317
        • Cooke WT
        • Fone DJ
        • Meynell MJ
        • Brewer DB
        • Harris EL
        • Cox EV
        Jejunal biopsy in adult coeliac disease and allied diseases.
        Lancet. 1960; 1: 933
        • Menendez-Corrada R
        Current views on tropical sprue and a comparison to nontropical sprue.
        Med Clin N Amer. 1968; 52: 1367
        • Gardner FH
        A malabsorption syndrome in military personnel in Puerto Rico.
        Arch Intern Med. 1956; 98: 44
        • O'Brien WO
        • England MW
        Military tropical sprue from South-east Asia.
        Brit Med J. 1966; 2: 1157
        • Perez-Santiago E
        • Butterworth Jr, CE
        Definitions and diagnosis of sprue.
        Amer J Digest Dis. 1957; 2: 225
        • Suarez RM
        • Spies TD
        • Suarez Jr, RM
        Use of folic acid in sprue.
        Ann Intern Med. 1947; 26: 643
        • Mollin D
        Absorption and malabsorption of dietary folate.
        Amer J Clin Nutr. 1968; 21 (Discussion following Butterworth, CE, Jr): 1121
        • Winawer SJ
        • Sullivan LW
        • Herbert V
        • Zamcheck N
        The Jejunal mucosa in patients with nutritional folate deficiency and megaloblastic anemia.
        New Eng J Med. 1965; 272: 892
        • Sheehy TW
        • Cohen WM
        • Brodsky JP
        Intestinal lesion in initial phase of tropical (military) sprue.
        Amer J Digest Dis. 1963; 8: 826
        • Scott RB
        • Kanisner RB
        • Burger WF
        • Middleton FG
        Reduced absorption of vitamin B12 in two patients with folic acid deficiency.
        Ann Intern Med. 1968; 69: 111
        • Bianchi A
        • Chipman DW
        • Dreskin A
        • Rosensweig NS
        Nutritional folic acid deficiency with megaloblastic changes in the small bowel.
        in: Abstracts of American Gastroenterology Association. May 1969: A 133
        • Rosensweig NS
        • Herman RH
        • Stifel FB
        • Herman YF
        • Dreskin A
        • Chipman DW
        Effect of folic acid on Jejunal glycolytic enzyme activity in tropical sprue.
        in: Abstracts of American Gastroenterology Association. May 1969: A 133
        • Rosensweig NS
        • Herman RH
        • Stifel FB
        • Herman YF
        Regulation of human Jejunal glycolytic enzymes by oral folic acid. A new principle of enzyme regulation.
        Clin Res. 1969; 17: 310
        • Butterworth Jr, CE
        Absorption and malabsorption of dietary folate.
        Amer J Clin Nutr. 1968; 21: 1121
        • Frazer AC
        Malabsorption Syndromes.
        William Heinemann Medical Books, Ltd, London1968
        • Klipstein FA
        Tropical sprue.
        Gastroenterology. 1968; 54: 275
        • Banwell JG
        • Gorbach SL
        Tropical sprue.
        Gut. 1969; 10: 328
        • Guerra R
        • Wheby MS
        • Bayless TM
        Long term antibiotic therapy in tropical sprue.
        Ann Intern Med. 1965; 63: 619
        • Maldonado N
        • Horta E
        • Guerra R
        • Perez-Santiago E
        Poorly absorbed sulfonamides in the treatment of tropical sprue.
        Gastroenterology. 1969; 57: 559
        • Baker SJ
        • Mathan VI
        • Joseph I
        Epidemic tropical sprue.
        Amer J Digest Dis. 1962; 7: 959
        • Baker SJ
        • Mathan VI
        A sprue house.
        Amer J Digest Dis. 1964; 9: 771
        • Gorbach SL
        • Banwell JG
        • Mitra R
        • Chatterjee BD
        • Jacobs B
        • Mazumder DNG
        Bacterial contamination of the upper small bowel in tropical sprue.
        Lancet. 1969; 1: 74