Meteorites as catalysts for prebiotic chemistry

Article abstract of DOI:10.1002/chem.201303690

From outer space: Twelve meteorite specimens, representative of their major classes, catalyse the synthesis of nucleobases, carboxylic acids, aminoacids and low-molecular-weight compounds from formamide (see figure). Different chemical pathways are identified, the yields are high for a prebiotic process and the products come in rich and composite panels.

Full text of DOI:10.1002/chem.201303690

DOI: 10.1002/chem.201303690
Meteorites as Catalysts for Prebiotic Chemistry
Raffaele Saladino,*[a] Giorgia Botta,[a] Michela Delfino,[a] and Ernesto Di Mauro[b]
Meteorite late heavy bombardment[1] was a major event
after the accretion of the earth. The relevance of organic
syntheses driven by impact shocks was first proposed by
Chyba and Sagan in 1992,[2] based on the scanty indications
available at the time. How would the contribution by mete-
orites to an early earth organic pool compare with the syn-
theses these meteorites might have induced after their
impact?[2]
medium,[10] in Europa[11] and Orion-KL,[12] in the dense
cloud SgrB2,[13] and in carbonaceous chondrites.[14] Recently,
NH2CHO was identified as a common constituent of star-
forming regions that foster planetary systems within the ga-
lactic habitable zone, with abundances comparable to that
found in comet Hale-Bopp and a potential influx of exoge-
nous delivery to Earth as high as 0.1 molkmÀ2 yrÀ1 or
0.18 mmolmÀ12 per single impact.[15] From a synthetic point
of view, NH2CHO could be either an alternative to hydro-
gen cyanide (HCN),[16] or a possible nonvolatile source of
HCN.[17] Unlike HCN, NH2CHO has a boiling point of
2108C without any azeotropic effect. Regardless of its initial
concentration, physical phenomena were described that con-
centrate 1000-fold organic molecules in capillary spaces.[18]
Additional concentration processes by eutectics, clays ab-
sorption and evaporation have been reviewed.[19,6]
Here, we report the catalytic effect of several types of me-
teorites,[3a,b] iron, stony-iron,[3b] chondrites,[4] and achondrites
(entreis 1–12 in Table 1[2,5]) in the syntheses of organic mole-
cules of prebiotic interest using the model reaction of the
thermal condensation of formamide (NH2CHO).[6]
NH2CHO is a ubiquitous molecule in the universe that has
been observed in the comet Hale-Bopp,[7] in the stellar ob-
ACTHNUTRGNEUNG
jects W33A,[8] NGC7538, and W3(H2O),[9] in the interstellar
Synthetic procedure: NH2CHO (2.5 mL) was treated with
a catalytic amount of the appropriate meteorites powder
(1.0% in weight; similar grain size distribution of particles
in the range of 0–125 mm) at 1408C or 608 for 24 h. After re-
moval of the catalyst and excess of NH2CHO, the products
were analyzed by GC-MS. The condensation of NH2CHO in
the absence of meteorite powder afforded purine as the
only recovered product.[20] To avoid possible contamination
problems due to the presence of terrestrial organics in the
original sample (present in Murchison at the ppb ran-
ge[21a,b]), the meteorite powders were extracted before their
use with NaOH (0.1n), CHCl3–CH3OH (2:1 v/v), and sulfu-
ric acid. In the case of chondrites, achondrites, and stony-
iron meteorites, the samples were also pyrolyzed at 6008C.
After the treatment, the powders did not release any trace
of organic substances. The synthesis of large number of com-
pounds was observed (Scheme 1): nucleobases and their an-
alogues, carboxylic acids, amino acids, and low-molecular-
weight derivatives (miscellanea). We dub these reactions
meteorite-catalyzed syntheses. Given the complexity of the
mixtures, analysis was limited to products ꢀ1 ngmLÀ1. Be-
cause of the uncertainty of the stoichiometry of the reac-
tions, the yield of products was calculated as mg (or mg) of
product per mL of starting NH2CHO. Tables 2–6 show the
50 most abundant products (the m/z value and the abun-
dance of peaks are in Supporting Information #2; selected
chromatograms and the original m/z fragmentation spectra
are in Supporting Information #3 and #4, respectively).
Table 1. Meteorites used in NH2CHO condensation processes.
Name[a]
Class
Type
A
1
2
3
4
5
6
7
8
9
Canyon-Diablo
Campo-del-Cielo
Sikhote-Alin
Seymchan
NWA4482
NWA2828
Gold basin
Dhofar 959
Murchison
iron
iron
iron
stony iron
stony iron
chondrite
chondrite
chondrite
chondrite
chondrite
IA hexaoctahedrite normal
IAB hexaoctahedrite coarse
IIB hexaoctahedrite coarsest
pallasite main group
pallasite anomalous
enstatite
ordinary
L6
carbonaceoous
LV3 anomalous
B
C
10 NWA1465
11 NWA5357
D
achondrites diogenite
12 Al-Haggounia 001 achondrites aubrite
[a] References, composition, historical and terrestrial provenience, and
cosmo-origin data are available as an appendix of this table in the Sup-
porting Information (#1).
[a] Prof. R. Saladino, Dr. G. Botta, Dr. M. Delfino
Dipartimento di Scienze Ecologiche e Biologiche
Universitꢀ della Tuscia
Via San Camillo De Lellis, 01100 Viterbo (Italy)
Fax: (+39)0761357242
E-mail: saladino@unitus.it
[b] Prof. E. Di Mauro
Istituto Pasteur—Fondazione Cenci Bolognetti
c/o Dipartimento di Biologia e Biotecnologie “Charles Darwin”
University la “Sapienza” Piazzale Aldo Moro, 5, Rome 00185 (Italy)
E-mail: ernesto.dimauro@uniroma1.it
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201303690.
16916
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 16916 – 16922

COMMUNICATION
Scheme 1. Syntheses of biogenic molecules from NH2COH catalyzed by meteorites. The compounds are numbered according to their mention in the
text. Nucleobases and analogues: uracil (1), cytosine (2), isocytosine (3), dihydrouracil (4), purine (5), adenine (6), guanine (7), hypoxanthine (8), 2-ami-
nopurine (9), 4ACHTUNGTRENNUNG(3H)-pyrimidinone (10), 2ACHTUNGTRNE(NUGN 1H)-pyrimidinone (11), 3-hydroxypyrimidine (12), and hydantoine (13). Acids: oxalic (14), glycolic (15), glyox-
ylic (16), acetic (17), pyruvic (18), propanoic (19), parabanic (20), lactic (21), malonic (22), malic (23), maleic (24), succinic (25), oxalacetic (26), ketoglu-
taric (27), hexanoic (28), pimelic (29), octanoic (30), and nonanoic (31). Amino acids: glycine (32), N-formylglycine (33), N-methylglycine (34), alanine
(35), b-alanine (36), 2-methylalanine (37), valine (38), leucine (39), tert-leucine (40), b-amino isobutyric acid (b-AIBA) (41), 2-aminobutanoic acid (2-
ABA) (42), hydroxyproline (43), and phenylalanine (44). Miscellanea: diaminomalonitrile (DAMN) (45), carbodiimide (46), urea (47), guanidine (48),
guanidine acetic acid (49), and glycocyanidine (50). Yields of the reactions are in Tables 2–6. GC-MS spectra of compounds (1–50) are in Supporting In-
formation #4.
Nucleobases: The extraterrestrial origin of nucleobases de-
dant purine, pyrimidine and pyrimidinone derivatives), that
is more than 100 times greater than those recovered in the
original samples[21a,b] (Scheme 1, Table 2, Supporting Infor-
mation #3 and #4). Irons, stony-irons, and achondrites
showed a catalytic effect higher than chondrites. Mecha-
nisms for the formation of nucleobases are well reviewed.[6]
Adenine prevailed with chondrites and achondrites (with
the exception of NWA1465, Murchison, and NWA2828),
while comparable amounts of uracil, cytosine, and adenine
were detected in the presence of iron and stony-iron meteor-
ites. Guanine was synthesized only with achondrites, while
large amounts of isocytosine (a well-known bioisoster of
guanine[23]) were obtained. 2-Aminopurine (previously ob-
tected in carbonaceous chondrites[21b,22a,b] is not unequivo-
ACHTUNGTRENNUNG
cal.[22a] In the richest chondrites the highest purine yields
were <100 ppb, guanine reaching exceptionally 250 ppb,
other compounds being lower by one to two orders of mag-
nitude. In our syntheses we obtained: uracil (1), cytosine
(2), isocytosine (iC) (3), 5,6-dihydrouracil (DHuracil, 4),
purine (5), adenine (6), guanine (7), hypoxanthine (8), 2-
aminopurine [2ACHTUNGTRENNUNG(NH2)purine, (9)], 4ACHTUGNTREN(NUGN 3H)-pyrimidinone (10),
2ACHTUNGTRENNUNG(1H)-pyrimidinone (11), 3-hydroxypyrimidine (12), and hy-
dantoine (13). Compounds (1–13) were synthesized in the
range of 0.009 (NWA2828) and 2.33 mgmLÀ1 (Seymchan)
(total amount of nucleobases disregarding the more abun-
Chem. Eur. J. 2013, 19, 16916 – 16922
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16917

R. Saladino, E. Di Mauro et al.
Table 2. Synthesis of nucleobases and their analogues: products [mg] grouped by meteorite type.
Product[a]
Iron meteorites
Stony iron
meteorites
Chondrites
Achondrite
Canyon
Diablo
Campo del
Cielo
Sikhote Seymchan NWA
NWA
2828
Gold
Basin
Dhofar NWA
959 1465
Murchison NWA
5357
Al
Alin
4482
Haggounia
1
2
3
4
5
6
7
8
9
10
11
12
13
250.2
122.3
395.7
0.0
238.5
51.4
790.6
0.0
19.06
211.3
0.0
489.2
0.0
4221.5
0.0
N
278.0
345.2
30.6
1836.3
0.0
5.26
107.5
0.0
300.6
5.5
2.3
1.1
0.0
N
34.2
23.2
270.3
0.0
2.37
499.5
0.0
0.0
0.0
344.5
50.6
23.9
0.0
61.2 33.4
50.6
29.8
249.6
0.0
2.66
41.4
0.0
0.0
0.0
362.8
481.5
30.3
700.8
62.3
470.9
44.4
613.6
70.1
0.77
810.5
60.6
0.0
120.6
811.1
0.0
1.4
400.1
0.0
500.2
0.0
2470.8
0.0
32.3
689.2
0.0
1.86 0.03
103.5
0.0
0.0
128.6
2546.8
16.7
32.5
323.5
0.0
13.4
337.9
0.0
41.32[b]
250.5
0.0
1.38
0.7
0.89
0.0
0.0
0.0
0.0
39.4
0.0
510.3
0.0
50.3
0.0
800.5
50.3
0.0
380.6
0.0
1296.1
0.0
0.0
0.0
0.0
10.8
5545.4
20.1
15.4
0.0
0.0
0.0
0.0
0.0
350.9
41.8
25.6
0.0
6053.2
1687.6 1400.6
31.6
264.6
821.6
649.2
12.6
0.0
297.1
668.3
10.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
12.3
0.0
0.0
0.0
26.2
100.2
[a] The data are the mean values of three experiments. Products are given in mgmLÀ1. See Text. [b] Data expressed in mgmLÀ1. [c] Reaction performed
with untreated meteorite.
served in iron-sulfur/NH2COH syntheses),[24] and hypoxan-
thine, are prebiotically interesting.[25] The effect of the min-
eral on the selectivity of the reaction was previously report-
ed for the condensation of NH2COH in the presence of
cosmic dust analogues (CDAs), in which case the yield of
pyrimidine nuocleobases increased by increasing the amount
(24), succinic (25), oxalacetic (26), ketoglutaric (27), hexa-
noic (28), pimelic (29), octanoic (30), and nonanoic (31)
acids. These compounds are part of numerous extant meta-
bolic cycles: the components of direct and reversed citric
acid, glycolysis, and gluconeogenesis cycles are immediately
recognized.[27a,b] Iron and stony-iron meteorites performed
as the best catalysts, followed by achondrites and chondrites.
In terms of structural complexity (defined as the number of
carbon atoms in the molecule, Cn), C3 and C4 acids pre-
vailed with iron and stony-iron meteorites, while C2 and C5
acids (followed by C4) prevailed with chondrites. C2 and C3
acids were the major products of achondrites. The formation
of acids 14–18 and 21 may be explained by the generation
“in situ” of HCN followed by oligomerization to monoami-
no malonitrile (AMN) and diamino malonitrile (DAMN)
of iron in the catalyst[26]
.
Carboxylic acids: Carboxylic acids, including citric and pyr-
uvic acids, were reported in carbonaceous chondrites in the
ppb range.[21a] Meteorite-catalyzed syntheses afforded
orders-of-magnitude higher yields (Scheme 1, Table 3). The
18 more abundant acids were: oxalic (14), glycolic (15),
glyoxylic (16), acetic (17), pyruvic (18), propanoic (19), par-
abanic (20), lactic (21), malonic (22), malic (23), maleic
Table 3. Synthesis of carboxylic acids: products [mg] grouped by meteorite type.
Product[a]
Iron meteorites
Stony iron
meteorites
Chondrites
Achondrite
Canyon Campo del
Sikhote Seymchan NWA
NWA Gold
Dhofar NWA Murchison NWA Al
Diablo
Cielo
Alin
4482
2828
Basin
105.4 140.6
0.0 0.0
1044.7 988.3
167.5 150.3
959
1465
5357
Haggounia
C2
C3
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
528.0
48.9
98.2
572.9
103.0
145.6
0.0
700.0
514.6
218.2
1200.3
33.4
900.9
62.4
125.9
3269.1
31.1
G
419.9
35.2
69.1
126.3
0.0
69.3
0.0
20.6
0.0
31.5
2048.3
0.0
0.0
377.1
0.0
260.2
894.4
0.0
27.5
0.0
112.3
N
5.7
0.0
4.5
0.0
0.0
0.0
0.0
16.3
0.0
0.0
0.0
0.0
0.0
4.9
0.0
0.0
0.0
3.58
60.7
0.0
0.0
0.0
0.0
127.6
0.0
0.0
0.0
0.0
0.0
4.2
9.0
35.6
0.0
11.6
45.2
89.8
165.1
0.0
0.0
0.0
0.0
762.2
0.0
99.1
0.0
412.3
0.0
0.0
452.2
0.0
7.9
0.0
0.0
75.5
250.3
0.0
0.0
10.1
0.0
251.8
0.0
112.6
0.0
530.6
0.0
0.0
398.3
0.0
15.1
0.0
E
0.0
58.6
0.0
16.9
0.0
29.8
1407.4
0.0
0.0
46.2
0.0
278.5
870.4
0.0
N
0.0
E
0.0
734.1
700.1
151.3
1792.2
32.5
360.3
132.2
146.5
2017.1
30.4
T
600.2
350.3
487.3
1665.2
40.1
354.7
45.3
267.3
1100.0
93.5
48.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
25.7
0.0
0.0
0.0
0.0
0.0
0.0
0.0
G
0.0
7.1
G
R
10.5
30.1
0.0
12.3
39.3
110.2
200.2
0.0
R
C4
N
G
G
0.0
G
115.4 106.5
388.6 215.5
90.3
229.8
0.0
0.0
7.9
C5
C6
C7
C8
C9
N
157.9
0.0
0.0
153.4
0.0
0.0
G
419.3
0.0
0.0
20.3
0.0
27.6
0.0
N
3.1
0.0
19.0
0.0
0.0
0.0
T
28.7
0.0
30.3
0.0
0.0
0.0
A
0.0
2.4
0.0
[a] The data are the mean values of three experiments. [b] Reaction performed with untreated meteorite.
16918
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ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 16916 – 16922

Prebiotic Chemistry
COMMUNICATION
Table 4. Synthesis of amino acids: products [mg] grouped by meteorite type.
Product[a]
Iron meteorites
Stony iron
meteorites
Chondrites
Achondrites
Canyon Campo del
Sikhote Seymchan NWA NWA
Gold
Dhofar NWA Murchison NWA Al
Diablo
Cielo
Alin
4482
2828
Basin 959
1465
5357
Haggounia
32
33
34
35
36
37
38
39
40
41
42
43
44
321.5
767.5
11.3
42.6
47.3
72.6
0.0
47.7
0.0
218.6
0.0
300.6
800.3
34.8
50.5
46.6
85.3
0.0
60.8
0.0
236.5
0.0
N
90.1
56.2
0.0
15.3
18.5
0.0
0.0
72.3
0.0
3.2
0.0
24.4
0.0
88.4
79.5
0.0
45.5
7.9
0.0
0.0
19.7
0.0
4.1
73.05
5.8
0.0
3.9
4.7
0.0
0.0
0.0
0.0
6.1
5.4
0.0
0.0
N
271.1
129.2
0.0
1.1
130.6
0.0
42.2
0.0
0.0
9.1
0.0
198.8
98.5
0.0
1.6
123.6
0.0
36.7
0.0
0.0
5.8
0.0
550.6
300.1
0.0
20.3
32.2
0.0
0.0
0.0
32.7
100.1
801.5
0.0
600.1
270.6
0.0
25.3
34.8
0.0
0.0
0.0
40.2
94.8
760.6
0.0
700.5
9.8
78.5
84.3
123.3
0.0
112.2
0.0
300.4
0.0
160.5
0.0
43.3
298.4
0.0
30.2
0.0
0.0
175.6
0.0
53.1
270.2
0.0
37.3
0.0
0.0
39.6
0.0
0.0
50.1
0.0
0.0
0.0
30.3
0.0
0.0
110.3
0.0
127.6
0.0
108.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
[a] The data are the mean values of three experiments. [b] Reaction performed with untreated meteorite.
(actually detected in the reaction mixture), hydrolysis, and
successive redox processes[28]
acids derivatives.[32] In fact, carbodiimide, urea, guanidine
and guanidine acetic acid are all involved in the catalytic
cycle for the formation of N-formyl glycine 33 (the detailed
description of formation of 33 is in Supporting Information
#5). This hypothesis is partly demonstrated through the syn-
thesis of 33 in high yield by treatment of commercially avail-
able 49 with NH2CHO.
Note that this process is a well-recognized synthetic and
theoretical probe for the formation of the peptide bond.[33]
Since the chemical (alkaline and acidic) and thermal treat-
ment (6008C) of the meteorite samples may have signifi-
cantly affected their catalytic properties, the reactions with
Canyon-Diablo and NWA2828 were repeated with untreat-
ed samples. As reported in Tables 2–5, we observed a reactiv-
ity similar to that previously obtained.
.
Amino acids: Amino acids are present in carbonaceous
chondrites.[29a,b,30] As abundant products, we observed gly-
cine (32), N-formylglycine (33), N-methylglycine (34), ala-
nine (35), b-alanine (36), 2-methylalanine (37), valine (38),
leucine (39), tert-leucine (40), b-amino isobutyric acid (b-
AIBA) (41), 2-amino butanoic acid (2-ABA) (42), hydroxy-
proline (43), and phenylalanine (44) (Table 4). With the
only exception of b-AIBA and 2-ABA, glycine and alanine
(and their derivatives) prevailed. Achondrites and iron me-
teorites were the most reactive, followed by chondrites and
stony-iron meteorites. Amino acids were probably produced
by a thermal induced Strecker-like condensation.[6]
Miscellanea: Low-molecular-weight reactive intermediates
were also detected (Table 5) including: diamino malonitrile
(DAMN) (45), carbodiimide (46), urea (47), guanidine (48),
guanidine acetic acid (49), and glycocyanidine (50) (that is
the cyclic form of 49). DAMN (HCN tetramer) is a key in-
termediate in the synthesis of purines and pyrimidines from
HCN.[31] Carbodiimide is a well-known condensing agent.
Excess of NH2CHO and the presence of carbodiimide were
probably responsible for the formation of N-formyl amino
Syntheses at different temperatures: As representative ex-
amples, the reactivity of Canyon Diablo, Campo-del-Cielo,
Sikhote-Alin, and Al-Haggounia was evaluated also at
608C. All the meteorites proved to be efficient in the syn-
thesis of prebiotically relevant molecules even at this rela-
tively low temperature, the carboxylic acids generally pre-
vailing on nucleobases and amino acids, respectively. In ac-
cordance with data at 1408C, the C3 and C4 acids were the
most abundant products in the presence of iron meteorites,
Table 5. Synthesis of low-molecular-weight compounds (miscellanea): products [mg] grouped by meteorite type.
Product[a]
Iron meteorites
Stony iron
meteorites
Chondrites
Achondrites
Canyon Campo del
Sikhote Seymchan NWA
NWA
2828
Gold
Basin 959
Dhofar NWA Murchison NWA Al
Diablo
Cielo
165.3
205.1
14003.8
0.0
Alin
4482
1465
5357
Haggounia
45
46
47
48
49
50
230.4
260.3
2000.1
0.0
T
530.1
1046.6
110.8
253.7
4191.3
0.0
104.6
0.0
98.3
0.0
0.0
4.1
0.0
N
0.0
53.3
0.0
0.6
5.3
0.0
80.3
0.0
0.5
42.5
23.6
17.4
6.3
0.0
15.5
20.6
0.0
12.4
23.5
0.0
18.3
18.4
0.0
181.7
0.0
9.1
0.0
549.9
32.3
170.3
0.0
11.1
0.0
498.5
29.2
N
121.3
3800.1
0.0
112.5 87.3
0.0 0.0
A
G
0.0
250.3
0.0
225.4
0.0
289.7
0.0
U
N
N
25.1
[a] The data are the mean values of three experiments. [b] Reaction performed with untreated meteorite.
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R. Saladino, E. Di Mauro et al.
while C2 and C3 prevailed with Al-Haggounia (achondrite).
With the only exception of b-AIBA and 2-ABA, the sim-
plest amino acids, glycine and alanine, prevailed. As a gener-
al trend, the yields and structural complexity of products
were higher at 1408C than at 608C (especially for amino
acids) (Table 6).
Synthesis in NH2COH/H2O mixture: A novel experiment
was performed to better modeling the prebiotic scenario
using Campo del Cielo in diluted NH2COH (NH2COH/
H2O=1.0:10 v/v) at 1408C. We observed the formation of
several products largely similar to those formed from neat
NH2COH. The yields were lower compared to the reaction
carried out in the absence of H2O, probably due to hydrolyt-
ic processes (Table 6). These data are in accordance with re-
sults previously obtained in the condensation of dilute
NH2COH (NH2COH/H2O=7.0:30 v/v) with iron sulfur min-
erals.[24] Campo del Cielo performed as an efficient catalyst,
the general trend of reactivity being largely comparable to
that of neat NH2COH.
Table 6. Synthesis of carboxylic acids, nucleobases, amino acids, and low-
molecular-weight compounds (miscellanea) in reactions of NH2COH at
608C and/or diluted NH2COH at 1408C.
Product[a]
Canyon Campo
Campo
Sikhote Al
Diablo del Cielo del Cielo[b] Alin
Haggounia
carboxylic acids [mg]
C2
oxalic
Simple versus complex catalytic systems: The data in
Tables 2–6 were compared with those obtained with untreat-
ed minerals and metal oxides (usually present as compo-
nents in meteorites) studied singly[6]: for example, iron/
sulfur minerals (troilite, pyrrothite, pyrite), basalt, and oli-
vine (Table 7). Iron/sulfur minerals were the most efficient
catalysts for the synthesis of carboxylic acids and amino
acids (pyrrothite and troilite being more reactive than
pyrite), in agreement with the general order of reactivity ob-
served with meteorites: iron and stony-iron meteorites>
achondrites and chondrites. On the other hand, meteorites
were more efficient catalysts than their individual minera-
logical components, highlighting the presence of a synergistic
effect. A similar behavior was observed for nucleobases. In
this case pyrite was more reactive than pyrrothite and troi-
lite. Pyrite and pyrrothite are reciprocally transformed by
redox processes leading to the formation of acetic and thio-
acetic acids (Wachtershauserꢂs model).[34] In this transforma-
tion, carboxylic acids, amino acids and nucleobases may be
synthesized with different efficiencies depending on the
redox-state of the mineral (e.g., pyrite versus pyrrothite). Ir-
respective to catalytic system, carbodiimide was produced in
high yield potentially favoring polymerization processes.
In conclusions, meteorite-catalyzed syntheses afford
panels of organic compounds candidates that could fit sever-
al of the early earth environments and scenarios proposed
in the literature, such as: hydrothermal alkaline vents,[35]
anoxic geothermal fields[36] or “warm little ponds” (for spe-
cific references and discussion on the source of organics in
early earth see Supporting Information #6). It is plausible
that the complex molecular interactions leading to life
became possible when the relevant components were
brought into proximity. In this perspective the catalytic
properties of meteorites appears to be an important element
in making available the suitable precursors for life at the
time of their highest occurrence during the late heavy bom-
bardment. In origin-of-life perspectives, meteorites thus
become not only carriers of organic compounds formed or
gathered during their permanence in space, but acquire the
role of potential chemical reactors upon arrival on earth.
528.0
48.9
98.6
54.6
25.1
100.5
13.0
5.2
17.9
37.0
7.0
4.2
36.0
0.0
23.3
glycolic
glyoxylic
C3
pyruvic
propanoic
parabanic
lactic
malonic
C4
malic
maleic
succinic
oxaloacetic
C5
ketoglutaric
C6
734.3
700.4
151.0
1792.6
32.5
35.9
75.3
40.0
153.9
15.1
4.0
0.0
0.0
27.1
9.3
462.2
112.5
146.8
150.3
11.0
19.7
0.0
0.0
105.3
0.0
360.4
132.4
146.3
795.5
41.3
20.1
7.5
3.1
1.8
14.3
12.0
36.9
15.4
4.1
0.0
0.0
2017.1
562.1
10.5
21.3
30.2
23.5
37.3
0.5
25.5
17.2
0.0
hexanoic
157.9
10.0
135.2
nucleobases [mg]
uracil
cytosine
isocytosine
DHuracil
purine[c]
adenine
guanine
hypoxanthine
250.6
122.3
395.7
0.0
41.3
250.3
0.0
95.1
30.1
87.3
0.0
13.8
179.9
0.0
12.5
11.6
26.4
0.0
1.2
5.9
0.0
8.5
11.6
130.4
60.2
122.6
0.0
0.3
185.2
0.0
175.3
11.5
238.7
14.3
0.2
77.3
23.6
0.0
380.3
1296.1
34.5
368.5
50.5
117.5
4
N
112.2
miscellanea [mg]
carbodiimide
urea
guanidine ac.
DAMN
260.3
2000.4
225.4
27.8
230.5
46.3
0.3
14.1
1.9
850.0
154.6
143.9
234.2
0.0
5.7
234.8
59.9
230.2
88.4
3.4
amio acids [mg]
glycine
formyl glycine
methyl glycine
alanine
b-alanine
methyl alanine
leucine
321.2
767.5
11.2
42.6
47.5
72.2
47.7
0.0
20.1
70.2
34.5
33.0
23.3
39.8
43.6
0.0
2.9
4.5
0.0
9.2
0.3
1.2
5.4
0.0
3.1
0.0
0.0
41.6
29.6
3.2
31.3
27.2
36.6
22.0.0
0.0
77.9
66.8
0.0
7.6
27.4
0.0
0.0
tert-leucine
b-AIBA
2-ABA
21.5
14.6
138.0
0.0
218.4
0.0
110.6
104.3
0.0
42.5
89.1
0.0
39.1
phenylalanine
[a] The data are the mean values of three experiments with standard de-
viation less than 0.1%. [b] Reaction performed with diluted NH2COH
(NH2COH/H2O=1.0:10 v/v) at 1408C. [c] Data expressed in mgmLÀ1
.
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Chem. Eur. J. 2013, 19, 16916 – 16922

Prebiotic Chemistry
COMMUNICATION
Table 7. Synthesis of carboxylic acids, nucleobases, amino acids, and low-molecular-weight compounds (miscellanea) in reactions of NH2COH with se-
lected minerals and metal oxides at 1408C.
Product[a]
Troilite
Pyrrothite
Pyrite
Chalcopyrite
Volcanic basalt
Olivine
Hydrotalcite
carboxylic acids [mg]
oxalic
glycolic
glyoxylic
acetic
pyruvic
propanoic
parabanic
lactic.
malonic
succinic
20.6
28.6
46.4
0.0
12.2
5.4
12.4
23.9
15.0
43.2
6.9
30.4
20.3
80.8
0.0
49.9
9.9
39.9
120.5
39.8
79.7
10.5
180.9
49.8
0.0
0.3
1.3
0.0
138.6
7.9
0.0
0.0
0.0
0.0
0.0
17.3
0.0
0.7
5.7
0.0
0.0
5.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
11.8
9.5
0.0
0.0
1.8
0.0
0.0
2.6
4.9
5.9
140.4
0.0
0.0
0.0
81.9
0.0
0.0
7.2
0.0
0.0
2.2
7.0
3.1
0.0
0.0
0.0
0.0
0.0
0.0
1.2
0.0
0.0
0.0
0.0
0.0
0.9
0.0
0.0
0.3
0.0
12.3
oxaloacetic
ketoglutaric
pentanoic
eptanoic
45.9
0.0
0.0
2.2
0.0
0.0
nucleobases [mg]
uracil
cytosine
isocytosine
purine
adenine
0.0
0.0
9.3
122.2
4.8
0.0
0.0
0.0
10.1
250.2
10.8
0.1
0.0
0.0
480.2
>1000.0
180.3
0.0
6.93
909.1
560.3
>1000.0
200.3
0.0
0.0
0.0
5.7
437.5
2.1
1.0
0.8
4.7
27.6
0.0
0.0
0.0
0.0
0.0
83.7
3289.7
0.0
hypoxanthine
2-NH2 purine
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
4
(3H)pyrimidone
39.2
0.0
0.7
0.2
250.2
0.0
91.2
1.2
8.3
0.0
5.2
20.5
184.1
0.0
3(OH)pyrimidine
miscellanea [mg]
carbodiimide
urea
0.0
44.9
0.0
29.8
10.8
0.3
110.5
99.9
0.0
>1000.0
6.7
0.0
0.0
10.2
0.0
0.2
0.0
0.0
0.0
43.9
guanidine
524.4
amino acids [mg]
glycine
formyl glycine
methylglycine
b-alanine
methyl alanine
formyl alanine
b-AIBA
22.2
12.5
0.0
7.3
0.0
87.6
63.1
0.0
10.6
0.0
0.0
1.3
0.0
0.0
0.0
0.0
0.0
29.1
0.0
1.8
0.0
0.6
0.0
0.0
2.9
33.9
0.0
0.0
0.0
26.8
11.3
0.0
55.4
2.6
0.0
1.2
0.0
1.4
0.0
0.0
98.8
33.9
0.0
11.3
23.3
20.5
50.2
0.9
0.0
[a] The data are the mean values of three experiments. Minerals are not treated.
a panel of selected minerals and metal oxides (detailed materials and
methods and the procedure for preparation of meteorite powder are in
Supporting Information #7).
Experimental Section
The reactions were performed by heating NH2COH (2.5 mL) at 1408C or
608C for 24 h in the presence of meteorite powder (1.0% by weight rela-
tive to NH2COH, grain size distribution of particles in the range of 0–
125 mm). At the end of the reaction the mineral was recovered by centri-
fugation (6000 rpm, 10 min, Haereus Biofuge), and the excess NH2COH
removed by distillation (408C, 4ꢃ10À4 barr). The crude product was ana-
Acknowledgements
lyzed by GC-MS after treatment with N,N-bistrimethylsilyl trifluoro
ACHTUNGTRENNUNGamide in pyridine (620 mL) at 608C for 4 h in the presence of betulinic
ACHTUNGTNERaNUNG cet-
This work is supported by the Italian Space Agency “MoMa project” and
by ASI-INAF n. I/015/07/0 “Esplorazione del Sistema Solare”. Thanks to
Silvia Lopizzo for helpful contributions.
acid as internal standard (3.0 mg). Mass spectrometry was performed by
the following program: injection temperature 2808C, detector tempera-
ture 2808C, gradient 1008Cꢃ2 min, 108CminÀ1 for 60 min. To identify
the structure of the products, two strategies were followed. First, the
spectra were compared with commercially available electron mass spec-
trum libraries such as NIST (Fison, Manchester, UK). Secondly, GC-MS
analysis was repeated with standard compounds. All products have been
recognized with a similarity index (S.I.) greater than 98% compared to
the reference standards. In order to evaluate the possible role of inorgan-
ic constituents of the meteorite powder in the condensation of NH2COH,
the reaction was repeated under similar experimental conditions with
Keywords: amino acids
· carboxylic acids · molecular
evolution · nucleobases · prebiotic chemistry
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Received: September 20, 2013
Published online: November 7, 2013
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Chem. Eur. J. 2013, 19, 16916 – 16922