Tetrahedron Letters
Identification and synthesis of the male produced volatiles of the
carrion beetle, Oxelytrum erythrurum (Coleoptera: Silphidae)
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Douglas H. Fockink, Camila B. C. Martins, Paulo H. G. Zarbin
Laboratório de Semioquímicos, Chemistry Department, Federal University of Paraná, CP 19081, CEP 81531-990 Curitiba, PR, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
Necrophagous beetles belonging to the family Silphidae are recognized as potentially useful in forensic
investigations (to estimate post mortem interval). Gas chromatography analyses of extracts of aerations
of adult Oxelytrum erythrurum revealed the presence of two male-specific compounds. These compounds
were identified as (Z)-1,10-nonadecadiene (major) and 1-nonadecene (minor) using microderivatizations
of the natural male extract, such as hydrogenation, partial reduction and methylthiolation, mass spec-
trum comparisons, and co-injections with authentic standards. Both compounds might be components
of a pheromone responsible for sexual communication in this species.
Received 10 July 2015
Revised 4 August 2015
Accepted 5 August 2015
Available online 8 August 2015
Keywords:
Coleoptera
Silphidae
Ó 2015 Published by Elsevier Ltd.
Forensic entomology
Micro-derivatization
GC/FTIR
Through decomposition, the nutrients, and organic matter that
are present in carcasses are recycled, and decomposing carcasses
support a large and dynamic arthropod community.1 Among mem-
bers of this community, ‘carrion beetles’ (Coleoptera: Silphidae)
are usually associated with vertebrate carcasses.2,3 Due to this
association, silphid beetles might be important tools to estimate
the post mortem interval of corpses in criminal investigations.
Species in the genus Oxelytrum are particularly useful because lar-
vae are strictly necrophagous.4
In the current study, volatiles emitted by males and females of
O. erythrurum were analyzed through gas chromatography9,10 and
two male-specific compounds were detected (Fig. 1), presenting
the following Kovats Indexes (KI) on a RTX-5, RTX-WAX and EC-1
columns, respectively: (A) 1888, 1988, and 1896; (B) 1897, 1938,
and 1932. The emission of the compounds started on the 15th
day after the emergence of males, during the photophase and the
scotophase. The ratio between the major (A) and the minor (B)
compounds was of 92:8, respectively.
Oxelytrum discicolle (Brullé) is the most commonly collected
species of Silphidae in South America,3 co-occurring with
Oxelytrum erythrurum (Blanchard) in the southern regions of the
continent. Not only is their distribution similar, but based on mor-
phology it has been hypothesized that these species are closely
related (evolutionary speaking).3 Despite a few existing papers
addressing their occurrence5,6 and feeding habits,7 only recently
has the chemical ecology of O. discicolle been studied, revealing
the existence of a male produced sex pheromone composed by a
major and a minor component, (Z)-1,8-heptadecadiene and 1-hep-
tadecene, respectively.8 Because of the taxonomic proximity and
the similarities concerning the feeding habits and the habitat of
O. discicolle and O. erythrurum, the objective of this study was to
identify and synthetize the chemical compounds produced by O.
erythrurum using the same methodology applied by Fockink et al.8
for O. discicolle.
The GC/FTIR and the GC/MS spectra of O. erythrurum
male-specific components are shown in Figure 2. For the major
compound (A), the infrared spectrum (Fig. 2a) showed characteris-
tic bands in the region of hydrocarbons between 2800 cmÀ1 and
3000 cmÀ1
,
beyond of bands at 3089 cmÀ1
,
3002 cmÀ1
,
1640 cmÀ1, 995 cmÀ1, and 911 cmÀ1 indicating a terminal and
Z-configuration double bond.11–16 The mass spectra (Fig. 2b)
exhibited molecular ion at m/z 264 and through these data, the
compound A may have the molecular formula C19H36.
The infrared spectrum of the minor compound (B) also revealed
bands characteristic of hydrocarbons (Fig. 2c). However, it is possi-
ble to observe only one characteristic band of the double bond at
3084 cmÀ1, and along the bands at 1645 cmÀ1, 992 cmÀ1, and
916 cmÀ1 indicating a single terminal double bond. The mass spec-
tra of the compound B (Fig. 2d) revealed a molecular ion (m/z 266)
with two mass units more than compound A, confirming the exis-
tence of only one double bond. The empiric formula proposed was
C19H38.
⇑
Corresponding author. Tel.: +55 41 3361 3174; fax: +55 41 3361 3186.
0040-4039/Ó 2015 Published by Elsevier Ltd.