Sugars and its related compounds in space and on the early Earth
Yoshihiro Furukawa1, Yoshito Chikaraishi2, Chiaki Abe1, Naohiko Ohkouchi3, and Tomoki Nakamura1
1
Department of Earth Science, Tohoku University
2
Institute of Low Temperature Science, Hokkaido University
3
Japan Agency for Marine-Earth Science and Technology
Sugars are essential components of life, employing as substrates in nucleic acid formation and working as energy resourcein numerous biological reactions. The distribution of sugars, particularly bio-important pentoses and hexose, in space including
the Earth would be important for the origin of life.
Carbonaceous chondrites contain many bio-important molecules suchABC
as amino acids and nucleobases [e.g., 1,2]. Thus, they were a source ofbuilding blocks of life on the prebiotic Earth. The detection of glucose,mannose, arabinose, and xylose by paper chromatography incarbonaceous and enstatite chondrites was originally reported in 1960’s[3,4]. However, the paper chromatography has not sufficient resolution toidentify any sugar isomers, and these reports were not clear proof on their
extraterrestrial origin. Thus, a review concluded that the origin of thesereported sugars were terrestrial contamination [5]. More recently,Fig. 1: Structures of sugar, sugar acids and sugar
Cooper’s group have intensively investigated sugars and their related
alcohols detected in meteorites. A) dihydroxyacetone,B) ribonic acid, and C) 2-Deoxypentantonic
compounds in Murchison and Mary carbonaceous chondrites. They foundacid. Cooper et al., 2001.
3-carbon sugar, dihydroxyacetone, several sugar acids, and several sugar
alcohols by gas chromatography/mass spectrometry (GC/MS) (Fig. 1)[6,7]. Some of the detected compounds were confirmed on those extraterrestrial origins by compound-specific carbon isotope
analysis. However, the presence of meteoritic bio-important sugars remained unclear.
The formose-like reaction is a plausible process to form sugars in meteorite parent bodies, on interstellar dusts, and on theprebiotic Earth. In the Formose reaction, the condensation of formaldehyde forms numerous sugars, simultaneously. Ribose isan intermediate product of this reaction. However, characterization of the product “formose” remained insufficient so far,which causes ambiguity in the potential availability of sugars in space.
We developed a protocol to effectively extract sugars from mineral assemblages. Then, we found multiple sugars incarbonaceous chondrites with GC/MS. The carbon isotopic composition of individual sugars in meteorite extracts wasdetermined by gas chromatography/isotope ratio mass spectrometry (GC/IRMS). For comparison, we analyzed the products oftypical Formose reaction simulating meteorite parent bodies. Insoluble organic matter (IOM) was extracted from the samechondrites by demineralization with inorganic acids, and the carbon and nitrogen isotopic compositions of bulk chondrite andIOM were determined. These carbonaceous chondrites were also investigated by scanning electron microscopy (SEM) toevaluate the aqueous alteration levels. In this talk, we will present our preliminary results of these analyses for sugars incarbonaceous chondrites as well as in several experimental Formose reaction products, and will discuss the availability ofsugars in space including Earth.

References[1] Glavine. D. et al. 2011. Meteoritics & Planetary Science 45: 1948-1972. [2] Callahan M. et al. 2011. Proceedings of theNational Academy of Sciences USA 108: 13995-13998. [3] Degens E.T., Bajor M. 1962. Naturwiss. 49: 605-606. [4] KaplanI.R., Degens E.T., Reuter J.H., Geochim. Cosmochim. Acta 27: 805-834. [5] Hayes J.M., 1967. Geochimica et Cosmochimica
Acta 31: 1395-1440. [6] Cooper G. et al. 2001. Nature 414: 879–883. [7] Cooper G. and Rioss A.C. 2016. Proceedings of theNational Academy of Sciences USA. 113: E3322-31.