title: A retro-biosynthetic approach to the prediction of biosynthetic pathways from position-specific isotope analysis as shown for tramadol.
abstract: Tramadol, previously only known as a synthetic analgesic, has now been found in the bark and wood of roots of the African medicinal tree Nauclea latifolia. At present, no direct evidence is available as to the biosynthetic pathway of its unusual skeleton. To provide guidance as to possible biosynthetic precursors, we have adopted a novel approach of retro-biosynthesis based on the position-specific distribution of isotopes in the extracted compound. Relatively recent developments in isotope ratio monitoring by (13)C NMR spectrometry make possible the measurement of the nonstatistical position-specific natural abundance distribution of (13)C (δ(13)Ci) within the molecule with better than 1‰ precision. Very substantial variation in the (13)C positional distribution is found: between δ(13)Ci = -11 and -53‰. Distribution is not random and it is argued that the pattern observed can substantially be interpreted in relation to known causes of isotope fractionation in natural products. Thus, a plausible biosynthetic scheme based on sound biosynthetic principals of precursor-substrate relationships can be proposed. In addition, data obtained from the (18)O/(16)O ratios in the oxygen atoms of the compound add support to the deductions made from the carbon isotope analysis. This paper shows how the use of (13)C NMR at natural abundance can help with proposing a biosynthetic route to compounds newly found in nature or those difficult to tackle by conventional means.
authors.affiliation: Elucidation of Biosynthesis by Isotopic Spectrometry Group, Interdisciplinary Chemistry: Synthesis, Analysis, Modeling, CNRS-University of Nantes Unité Mixte de Recherche 6230, F-44322 Nantes, France; Laboratory for Isotope Effects Studies, Department of Chemistry, Institute of Applied Radiation Chemistry, Lodz University of Technology, 90-924 Lodz, Poland;
authors.forename: Katarzyna M
authors.initials: KM
authors.lastname: Romek
authors.affiliation: Elucidation of Biosynthesis by Isotopic Spectrometry Group, Interdisciplinary Chemistry: Synthesis, Analysis, Modeling, CNRS-University of Nantes Unité Mixte de Recherche 6230, F-44322 Nantes, France;
authors.forename: Pierrick
authors.initials: P
authors.lastname: Nun
authors.affiliation: Elucidation of Biosynthesis by Isotopic Spectrometry Group, Interdisciplinary Chemistry: Synthesis, Analysis, Modeling, CNRS-University of Nantes Unité Mixte de Recherche 6230, F-44322 Nantes, France;
authors.forename: Gérald S
authors.initials: GS
authors.lastname: Remaud
authors.affiliation: Elucidation of Biosynthesis by Isotopic Spectrometry Group, Interdisciplinary Chemistry: Synthesis, Analysis, Modeling, CNRS-University of Nantes Unité Mixte de Recherche 6230, F-44322 Nantes, France;
authors.forename: Virginie
authors.initials: V
authors.lastname: Silvestre
authors.affiliation: Department of Zoology and Animal Physiology, University of Buea, Buea, Cameroon;
authors.forename: Germain Sotoing
authors.initials: GS
authors.lastname: Taïwe
authors.affiliation: Department of Medicinal Chemistry, University Grenoble Alpes-CNRS Unité Mixte de Recherche 5063, F-38041 Grenoble, France;
authors.forename: Florine
authors.initials: F
authors.lastname: Lecerf-Schmidt
authors.affiliation: Department of Medicinal Chemistry, University Grenoble Alpes-CNRS Unité Mixte de Recherche 5063, F-38041 Grenoble, France;
authors.forename: Ahcène
authors.initials: A
authors.lastname: Boumendjel
authors.affiliation: Grenoble Institute of Neuroscience, Unit Inserm U836, F-38700 La Tronche, France; University Joseph Fourier, F-38041 Grenoble, France.
authors.forename: Michel
authors.initials: M
authors.lastname: De Waard
authors.affiliation: Elucidation of Biosynthesis by Isotopic Spectrometry Group, Interdisciplinary Chemistry: Synthesis, Analysis, Modeling, CNRS-University of Nantes Unité Mixte de Recherche 6230, F-44322 Nantes, France; Richard.ROBINS@univ-nantes.fr.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Robins
mesh_terms: D053898:Biosynthetic Pathways; D002244:Carbon / Q000378:metabolism; D002247:Carbon Isotopes / Q000378:metabolism; D007553:Isotope Labeling / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D013058:Mass Spectrometry; D015394:Molecular Structure; D010100:Oxygen / Q000378:metabolism; D010103:Oxygen Isotopes / Q000378:metabolism; D024301:Plant Bark / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D019666:Rubiaceae / Q000737:chemistry; D014147:Tramadol / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D014934:Wood / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D010103:Oxygen Isotopes; D014147:Tramadol; D002244:Carbon; D010100:Oxygen
keywords: NMR spectrometry; Nauclea latifolia; position-specific isotope analysis; retro-biosynthesis; tramadol