Novel oxygenated fossil nor-diterpenoids from Cretaceous amber (South-Western France) as potential markers from Cupressaceae and/or Cheirolepidiaceae. (May 2022)

• Record Type: Journal Article
• Authors: De Lama Valderrama, Noelia; Schaeffer, Philippe; Leprince, Agathe; Schmitt, Swann; Adam, Pierre
• Is Part Of: Organic geochemistry. Volume 167(2022)
• Publication Date: 2022-05
• Subjects: Amber -- Cretaceous -- Diterpenes -- NMR -- Identification; Organic geochemistry -- Periodicals; Biogeochemistry -- Periodicals; Géochimie organique -- Périodiques; 553.205
• DOI: 10.1016/j.orggeochem.2022.104372
• Languages: English
• ISSNs: 0146-6380

Abstract

Graphical abstract: Highlights: Four isolated oxygenated labdanoid diterpenoids from a Cretaceous amber were identified by NMR. Identified labdanoids are potential markers for Cupressaceae or Cheirolepidiaceae. A diagenetic formation pathway from bound oxygenated labdanoids is proposed. Abstract: In the frame of palaeobotanical studies aimed at identifying reliable molecular markers for the determination of the botanical origins of Cretaceous ambers, four diterpenoids from the amber from Archingeay (Charente-Maritime, South western France) were identified, after chromatographic isolation and detailed nuclear magnetic resonance studies, as 13-hydroxy- and 8, 13-epoxy-nor-labdanoids. These compounds are structurally related to cupressic acid and torulosol, which are C-13 oxygenated labdanoids sometimes occurring as predominant constituents in resins from Cupressaceae s.l. and Araucariaceae. A diagenetic pathway leading from cupressic acid and torulosol to the fossil terpenoids is proposed. This involves incorporation of the parent diterpenoids into macromolecular constituents of amber during burial, followed by the progressive release of the identified nor-labdanoids during maturation. The newly identified nor-labdanoids might thus be considered as potential biomarkers for amber originating from Cupressaceae s.l and/or Araucariaceae. Nevertheless, detailed investigation of the other terpenoid assemblages from the Archingeay amber points to an origin from Cupressaceae s.l. However, since biomarkers exclusive to this botanical family have not been identified, the possibility that the amber originates from Cheirolepidiaceae is also considered.