Jean-Michel Trendel

Identification of a novel series of tetracyclic terpene hydrocarbons (C24–C27) in sediments and petroleums

A novel series of tetracyclic terpene hydrocarbons, the 17,21-secohopanes (C24–C27) has been conclusively identified as a widespread constituent of sediments and petroleums; these compounds could be formed by thermal or microbial degradation of pentacyclic hopanoid precursors which commonly occur in micro-organisms, but they could also represent a novel class of bacterial lipids.

Diagenesis of higher plant triterpenes in evaporitic sediments

Abstract Several samples from a Tertiary carbonated evaporitic series (Sainte-Cecile, Camargue, France) were investigated. Their analysis revealed a high abundance of new or uncommon hydrocarbons and organic S compounds related to higher plant triterpenes. Several of them, in particular, 12,29-cyclolupa-12,18,20(29)-triene 1, could be positively identified. These triterpenoids are generally absent from non-evaporitic sediments which contain essentially aromatic triterpenoids resulting from microbially mediated aromatization processes starting in ring A (or in ring B when preceded by the loss of ring A). The uncommon transformations undergone by higher plant triterpenes in the highly anoxic sediments from Sainte-Cecile are specific for each series of triterpenes (i.e., oleanane, ursane, lupane) and are probably linked with the rapid disappearance of the functionality located in ring A by reduction or by the incorporation of the triterpenes in S-rich macromolecules by reaction with inorganic S species. These biological markers represent new source parameters which may be quite useful as indicators of terrestrial inputs in evaporitic deposits.

Identification of two C-10 demethylated C28 hopanes in biodegraded petroleum

Two C-10 demethylated C28 hopanes have been isolated from a biodegraded asphalt and characterised by mass spectrometry and single-crystal X-ray diffraction; their structures reveal a major microbiological pathway of degradation of the widespread hopane triterpene skeleton.

3β-Carboxysteranes, a novel family of fossil steroids

Two 3β-carboxy-24-ethylcholestanes (24R and 24S) have been isolated as a mixture from a carbonated sediment and characterised by comparison of their mass spectrometric and 1H NMR spectroscopic data with those of synthetic standards; their origin is still unknown, since their carbon skeleton has not yet been reported in living organisms.

Novel Polycyclic Sulfides Derived from Regular Polyprenoids in Sediments: Characterization, Distribution, and Geochemical Significance

Abstract A novel series of di- to pentacyclic polyprenoid sulfides ( 6, 7, 15, 16 ) which are structurally related to the recently identified highly cyclised regular polyprenoid aromatic ( 1, 2, 3 ) and saturated hydrocarbons (5) and to the widely distributed tricyclopolyprenanes (e.g., 10 ) have been characterized in a wide range of sediments. Their distributions, extending from C 13 to C 30 , are clearly dominated by the C 15 , C 20 , C 25 and C 30 homologues, each being represented by several isomers. Two C 30 isomers ( 6a and 6b ), which are generally predominant, were isolated from a sample from Semecourt (Paris basin, France) and their structure established by NMR studies. Interestingly, these two isomers are the sole sulfides present in several samples. The structure of two C 20 isomers ( 7a, 7b ) was confirmed by synthesis of standards. These new sulfides clearly derive from precursors resulting from the incomplete cyclization of regular polyprenoids (e.g., 4 ). The presence of functionalities both on the side chain and, probably in the last ring, allowed intramolecular sulfur incorporation by a process similar to that leading to the formation of low molecular weight sulfides in sediments. Detection of these new polyprenoid sulfides in recent sediments indicates that the sulfurization step occurs at an early stage of diagenesis. The hydrocarbon skeletons of the lower di-, tri- and tetracyclic sulfides may derive from widespread terpenoids present in various organisms. The predominant pentacyclic homologues, however, have a rare and specific carbon skeleton which can not be related to any known biological precursor. The fact that these lower homologues always co-occur with the pentacyclic sulfides points to a common and specific origin for the whole series. Their origin seems, however, distinct from that of the related monoaromatic and saturated regular polycyclic polyprenoid hydrocarbons ( 1-3, 5 ) which are absent from the samples where sulfides occur. The carbon isotopic composition of two C 30 pentacyclic homologues ( 6a, 6b ) could be determined in two samples and suggests that their polyprenoid precursors originate either from primary producers or from heterotrophic organisms living in the oxic part of the water column.

C(14a)-homo-26-nor-17α-hopanes, a novel and unexpected series of molecular fossils in biodegraded petroleum

A series (C27–C35) of pentacyclic triterpene hydrocarbons, the C(14a)-homo-26-nor-17α-hopanes, has been characterized in a biodegraded petroleum by gas chromatography–mass spectrometry and NMR structural determination of the C29 and C30 members; these biological markers reveal an as yet unknown transposition of the hopane skeleton.

Allosteric effects in norbadione A. A clue for the accumulation process of 137Cs in mushrooms

A fruitful combination of potentiometry, absorption spectrophotometry, ESMS and 1H NMR enabled the characterisation of two caesium complexes with norbadione A and the determination of the respective stability constants of a mononuclear and a dinuclear caesium complex at pH approximately 6; a preliminary study allowed the assignment of five protonation sites of this pigment; a positively cooperative binding of the second Cs+ cation was observed.

Mono- and diglycosides of (E)-6,9-dihydroxymegastigma-4,7-dien-3-one in Vitis vinifera wine.

Two beta-D-glucopyranosides and two 6-O-beta-D-apiofuranosyl-beta-D-glucopyranosides of (E)-6,9-dihydroxymegastigma-4,7-dien-3-one were isolated from Vitis vinifera cv. Gewürztraminer wine and their structures were established by NMR spectroscopy.