Mammalian exocrine secretions. XVII: chemical characterization of preorbital secretion of male suni, Neotragus moschatus.

Article abstract of DOI:10.1023/A:1013562818965

Gas chromatographic and gas chromatographic-mass spectrometric techniques were employed to identify 83 compounds, including alkanes, alkenes, aldehydes, 2-methylalkanes, carboxylic acids, 1-alkyl formates and alken-1-yl formates, benzoic acid, and cholest

Full text of DOI:10.1023/A:1013562818965

Journal of Chemical Ecology, Vol. 28, No. 1, January 2002 (�C 2002)
MAMMALIAN EXOCRINE SECRETIONS. XVII: CHEMICAL
CHARACTERIZATION OF PREORBITAL SECRETION
OF MALE SUNI, Neotragus moschatus
M. A. STANDER, B. V. BURGER,* and M. LE ROUX
Laboratory for Ecological Chemistry
Department of Chemistry
University of Stellenbosch
Stellenbosch 7600, South Africa
(Received April 3, 2001; accepted September 5, 2001)
Abstract—Gaschromatographic andgaschromatographic–massspectrometric
techniqueswereemployedtoidentify83compounds, includingalkanes, alkenes,
aldehydes, 2-methylalkanes, carboxylic acids, 1-alkyl formates and alken-1-yl
formates, benzoic acid, and cholesterol, in the preorbital secretion of the male
suni, Neotragus moschatus. Dimethyl disulfide derivatization and lithium alu-
minum hydride reduction were used to determine the position of double bonds
and to confirm the identity of the functional groups in some of the constituents
of the secretion.
Key Words—Suni, Neotragus moschatus, semiochemicals, pheromones.
INTRODUCTION
Extensive research has been done on the role of the secretions of the preorbital
glands of hoofed mammals or ungulates of the order Artiodactyla in their rutting
and territorial behavior (e.g., Langguth and Jackson, 1980; Mossing and Damber,
1981; Frey and Hofmann, 1997; Marmazinskaya, 1997; Roberts, 1997, 1998;
Arcese, 1999; Brashares and Arcese, 1999; Lawson et al., 2000, 2001), but in spite
of the biological importance attributed to them, little is known about the chemical
composition of preorbital secretions. Andersson (1979) has identified two ketones
inthepreorbitalpouchsecretionofthereindeer, Rangifert. tarandus. Severalheavy
constituents such as cholesterol, lanosterol, fatty acids, and triglycerides were
subsequently identified in this secretion (Sokolov et al., 1977). Cholesterol, ben-
zaldehyde, and a homologous series of saturated � -lactones have been identified
*
To whom correspondence should be addressed. E-mail: lecus@maties.sun.ac.za
8
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098-0331/02/0100-0089/0 �C 2002 Plenum Publishing Corporation

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STANDER, BURGER, AND LE ROUX
in the preorbital secretion of the muskox, Ovibos moschatus (Flood et al., 1989).
The preorbital secretions of the bontebok, Damaliscus dorcas dorcas, and blesbok,
D. d. phillipsi, contain, among other compounds, some unbranched primary alco-
hols, a few short-chain saturated and several long-chain saturated and unsaturated
unbranched carboxylic acids and aldehydes, three long-chain �-lactones, benzoic
acid, 4-hydroxybenzoic acid, 4-hydroxybenzaldehyde, 2-heptanone, piperitone,
dimethylsulfone, isopropyl tetradecanoate, isopropyl hexadecanoate, hexadecyl
acetate, cholesterol, �-tocopherol, and squalene (Burger et al., 1999a).
With the exception of the female oribi, Ourebia ourebi, which does not pro-
duce a preorbital secretion (Mo et al., 1995), and the preorbital secretion of fe-
male klipspringer, Oreotragus oreotragus, which has not yet been investigated,
the males and females of the other members of the subfamily Antilopinae pro-
duce qualitatively identical preorbital secretions. In sharp contrast, exploratory
gas chromatographic–mass spectrometric (GC-MS) analyses of the preorbital se-
cretions of suni, Neotragus moschatus, a dwarf antelope of the tribe Neotragini,
revealed prominent qualitative and quantitative differences in the secretions of
male and female animals. The suni was, therefore, selected for further study of its
preorbital secretions in a continuing investigation of the role of preorbital secre-
tions in the territorial behavior of South African antelope species.
METHODS AND MATERIALS
General. All Pyrex glassware was thoroughly cleaned with water and organic
�
solvents and then heated at 500 C in an annealing oven to remove any trace of
organic contaminants. Syringes and other apparatus that could not be heated to
�
5
00 C were cleaned with dichloromethane (Merck, Residue Analysis Grade). Pre-
orbital secretions were extracted and the extracts diluted, where necessary, with
this solvent.
Collection and Sample Preparation. Preorbital gland secretions were col-
lected with a tubular PTFE scoop from male suni kept in pens (10 � 10 m) at the
Tygerberg Zoo, Cape Town, South Africa. The scoop, with an inside diameter of
5
mm, was furnished with a PTFE plunger with which the collected material could
be ejected into a 1-ml Reacti-Vial. Samples were taken at different times of the
year as needed from six males bred from two unrelated lineages. To avoid the risk
of losing animals, males were not trapped in the presence of pregnant females.
The organic constituents were extracted from the mucoid secretion by stirring
the collected material with an appropriate quantity of dichloromethane, using a
thin (ca.1 mm diam.) glass rod, centrifuging the resulting suspension at 3500 rpm
for 15 min, and removing the organic fraction from underneath the supernatant
mucoid layer with a 100-�l syringe. In a typical sample preparation, 108 mg of
secretion was collected from the glands of a male and extracted with 120 �l of

MAMMALIAN EXOCRINE SECRETIONS XVII
91
dichloromethane to give 97 �l of extract. This extract was used without further
concentration for quantitative determination of the volatile organic constituents.
However, to avoid having to concentrate extracts for GC-MS analysis with the
concomitant loss of volatiles, the organic material was mostly extracted with the
smallestpossiblevolumeofsolventthatstillgaveaseparablesolventlayer. Extracts
�
were transferred to clean Reacti-Vials and stored at � 30 C until used for analysis.
Analytical Methods. Instrumentation for the identification of the volatiles has
beendescribedindetailbyBurgeretal. (1996). GCandGC-MSanalysesweredone
with the following capillary columns: (1) 40-m � 0.3-mm glass column coated
with PS-089 (polarity equivalent to that of SE-52) at a film thickness of 0.25 �m,
and (2) 30-m � 0.25-mm glass column coated with OV-240 at a film thickness of
0
.25 �m. Helium was employed as carrier gas at a linear velocity of 28.6 cm/sec
�
�
at 40 C. Samples were injected at an injector temperature of 220 C, thermally
focused on the column at 30 C and analyzed using a temperature program of
2
The flame ionization detector was operated at 280 C. Quantitative GC analyses
were done with the same instrument and the PS-089 column, and data acquisition
with Borwin Intuitive Chromatography Software (JMBS Developments, 38600
Fontaine, France) using hexadecanoic acid as external standard.
�
�
�
�
�
C/min from 40 C to 270 C and holding the temperature at 270 C for 80 min.
�
Low-resolution electron impact mass spectra (EI-MS) were obtained at 70 eV
on a Carlo Erba QMD 1000 GC-MS instrument by using the columns and
�
temperature program specified above. An ion source temperature of 100 C was
used. Chemical ionization mass spectra, with methane as reactant gas [CI(CH4)-
MS], were obtained on an AMD 604 double-focusing mass spectrometer at a
resolution of 1000 and a mass range of 100–500 atomic mass units.
Dimethyl Disulfide Derivatization. DMDS derivatization was carried out ac-
cording to the method of Vincenti et al. (1987). A dichloromethane extract (18 �l)
of the secretion was concentrated in a 1-ml Reacti-Vial with a slow stream of
purified (activated charcoal) nitrogen. Residual dichloromethane was removed by
the addition and slow evaporation of carbon disulfide 50 �l. This process was
repeated three times. The residual material was dissolved in 50 �l carbon disul-
fide, and 5 �l of an iodine solution (60 mg iodine in 1 ml diethylether) as well as
5
0 �l dimethyl disulfide were added. The screw-capped vial was sealed using a
�
PTFE-lined septum and left in the oven of a gas chromatograph at 60 C for 40 hr.
The reaction was quenched with an aqueous solution of sodium thiosulfate (5%),
and the DMDS derivatives were isolated by centrifuging the reaction mixture for a
few minutes at 2000 rpm. The organic layer was transferred to a clean Reacti-Vial
with a 100-�l syringe and concentrated to 5 �l for GC-MS analysis.
Lithium Aluminium Hydride Reduction. The organic constituents of the se-
cretion were subjected to lithium aluminum hydride reduction to confirm the
presence of reducible functional groups. A 7-�l aliquot of the extract was evap-
orated to dryness in a stream of nitrogen. The residual material was redissolved

9
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STANDER, BURGER, AND LE ROUX
twice in diethyl ether, evaporated to eliminate traces of dichloromethane, and then
dissolved in diethyl ether (30 �l) and treated with a saturated solution of LiAlH4 in
ether (20 �l). The Reacti-Vial was closed using a PTFE-lined septum and heated
�
for 5 min at 40 C, after which the reaction mixture was cooled and treated with
cold water (30 �l), centrifuged, the organic layer transferred to a clean Reacti-Vial,
and the resulting solution concentrated for GC-MS analysis.
Reference Compounds. Some of the compounds identified in the preorbital
secretion of the male suni were available from previous research projects in this
series, while others were obtained commercially. Unsaturated alcohols were pur-
chased from Pherobank (Wageningen, The Netherlands). The following com-
pounds were synthesized.
2-Methylicosane. A mixture of 1-bromohexadecane (2.78 g, 0.01 mol),
1-bromo-3-methylbutane (1.51 g, 0.01 mol), and sodium (0.92 g, 0.04 mol) was re-
fluxed under argon until the Wurtz condensation started. The reaction went to com-
pletion within 3 hr. The unreacted sodium was destroyed with ethanol, where-
after water (5 ml) was added to the reaction mixture and the organic material
extracted with hexane. According to GC-MS analysis, the extract contained 2,7-
dimethyloctane(26%), 1-hexadecene(49%), 1-hexadecanol(6%), 2-methylicosane
(18%), and dotriacontane (1%). EI-MS of 2-methylicosane: m/z 43 (85), 57 (100),
71 (66), 85 (45), 99 (18), 113 (8), 127 (6), 141 (5), 155 (4), and 253 (4%).
1-Alkyl Formates. A mixture of the primary alcohols, 1-butanol, 1-pentanol,
1
1
-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol,1-undecanol, 1-dodecanol,
-tetradecanol, 1-hexadecanol, 1-octadecanol, 1-icosanol, 1-docosanol (15 mg
�
each), and formic acid (420 �l) was heated overnight at 80 C and the products
extracted with hexane for comparison with the constituents of the secretion.
Alken-1-yl Formates. A mixture of (Z)- and (E)-6-tridecen-1-yl formate, (Z)-
and (E)-8-tetradecen-1-yl formate, and (Z)- and (E)-8-hexadecen-1-yl formate was
prepared by heating the corresponding alkenols with formic acid and extracting
the products from the reaction mixture as described above for the preparation of
the saturated formates.
RESULTS AND DISCUSSION
The preorbital secretions of male and female suni differ both qualitatively
and quantitatively, although they do contain a few constituents that are common
to both. Male glands appear to be more productive than those of females, and
the male secretion is also more complex. A series of related compounds forming
the bulk of the female secretion could not be identified despite the availability of
extensive 600-MHz NMR, HR-MS, and other physical data. Therefore, only the
male secretion will be discussed here.

MAMMALIAN EXOCRINE SECRETIONS XVII
93

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STANDER, BURGER, AND LE ROUX
A typical total ion chromatogram of the male secretion is shown in Figure 1.
At the level of sensitivity at which the qualitative analyses were done, secretions
from individual males were identical. Constituents from the male were tentatively
identified by comparison of their mass spectra with mass spectral data in the
NBS and Wiley mass spectral libraries. The identification of many compounds
could be confirmed by coinjection of commercially available reference compounds
or synthesized material. The molecular mass of some of the compounds and,
therefore, their chain lengths were confirmed by CI(CH4)-MS data.
There are two homologous series of alkanes present in the secretion. The first
consists of long-chain, unbranched alkanes, the structures of which could easily
be confirmed by GC coelution with reference compounds, and the second series
contains saturated hydrocarbons with the typical EI mass spectra of isoalkanes.
2-Methylicosane was synthesized as a model compound to confirm interpretation
of the mass spectral data. A series of unbranched, long-chain fatty acids, com-
pounds that appear to be almost ubiquitous in the exocrine secretions of various
antelope species, were also found in this secretion. These and the other compounds
identified in the secretion are listed in Table 1.
Dimethyl disulfide derivatization and GC-MS analysis of the DMDS deriva-
tives were used to determine the presence and position of double bonds in the
unsaturated constituents of the secretion (Vincenti et al., 1987). The interpretation
of the mass spectra of the DMDS derivatives was discussed in detail previously
(Burger et al., 1996). Due to the complexity of the male secretion and extensive
coelution of its constituents, almost none of the peaks in the chromatogram in
Figure 1 represent pure compounds. With the exception of a few alkenyl formates
identified using the PS-089 column, it was impossible to correlate the unsaturated
constituents with their DMDS derivatives using the apolar PS-089 column. How-
ever, an OV-240 capillary column gave better separation of the large number of
alkenes, saturated and unsaturated formic acid esters, and DMDS derivatives of
the unsaturated compounds than the PS-089 column. The unsaturated compounds
are listed in Table 1 in the order in which they eluted from the OV-240 column.
Although these compounds do not necessarily elute in the same order from the less
polar PS-089 column, the numbers are used in Figure 1 to indicate approximately
where the different homologous groups of unsaturated compounds elute in the
total ion chromatogram. In a few cases, DMDS derivatization showed both the E
and Z isomers of the unsaturated alkenes and formates present in the secretion. It
was, therefore, possible to assign E or Z configuration to the double-bond isomers
based on the GC elution order of these compounds and their DMDS derivatives.
The double-bond configuration of a few of the unsaturated constituents was also
determined by GC retention time comparison with authentic samples. The elu-
cidation of the stereochemistry of all unsaturated and chiral constituents of the
secretion was not attempted. The stereochemistry of some of the unsaturated and

MAMMALIAN EXOCRINE SECRETIONS XVII
95
TABLE 1. COMPOUNDS IDENTIFIED IN PREORBITAL SECRETION OF MALE SUNI
No. in Fig.1
PS-089 column)
Compound (arranged
according to compound type)
Analytical
method
Quantity
(�g/animal)
a
(
1
2
4
6
7
1
2
3
4
6
7
7
8
8
3
5
5
5
9
2
0
0
0
3
1
6
2
7
9
7
8
9
1
2
3
4
5
6
7
8
9
1
2
3
4
8
9
0
8
9
0
1
2
4
8
9
4
7
8
Pentadecane
Heptadecane
Nonadecane
Henicosane
a,b,d
a,b,d
a,b
a,b,d
a,b,d
a,d
a
a,d
a,d
a,b,d
a,d
46
137
45
23
23
1
76
5
169
208
59
300
48
Tricosane
2-Methyltetradecane
2-Methylhexadecane
2-Methylheptadecane
2-Methyloctadecane
2-Methylicosane
2-Methylhenicosane
2-Methyldocosane
2-Methyltricosane
2-Methyltetracosane
Impurity
(Z)-6-Heptadecene
5-Heptadecene
(Z)-4-Heptadecene
7-Heptadecene
(E)-6-Heptadecene
(E)-4-Heptadecene
Unidentified heptadecene
(Z)-7-Nonadecene
6-Nonadecene
a,d
a
a,d
a
46
1
1
1
2
2
2
2
3
3
3
3
3
4
4
4
4
4
4
5
5
5
6
6
6
6
6
6
7
7
7
a,e,g
a,e,g
a,e,g
a,e,g
a,e,g
a,e,g
a,h
a,e,g
a,e,g
a,e,g
a,e,g
a,e,g
a,e,g
a,h
a,h
a,h
a,e,g
a,h
a,h
a,e,g
a,e,g
a,e,g
a,e,g
a,e,g
a,e,g
a,e,g
a,e,g
a,e,g
a,e,g
a,e,g
7
6
15
9
16
13
21
16
133
31
81
11
9
5-Nonadecene
9-Nonadecene
(E)-7-Nonadecene
4-Nonadecene
Unidentified nonadecene
Unidentified nonadecene
Unidentified nonadecene
5-Icosene
Unidentified icosene
Unidentified icosene
8-Henicosene
(Z)-9-Henicosene
10-Henicosene
7-Henicosene
6-Henicosene
(E)-9-Henicosene
9-Docosene
10-Docosene
5
11
14
3
3
4
117
103
31
68
141
23
17
14
3
9-Tricosene
10-Tricosene
11-Tricosene
5
5

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STANDER, BURGER, AND LE ROUX
TABLE 1. CONTINUED
No. in Fig.1
PS-089 column)
Compound (arranged
according to compound type)
Analytical
method
Quantity
(�g/animal)
a
(
1
3
5
7
2
4
6
8
Hexanal
Heptanal
Octanal
Nonanal
Pentanoic acid
Hexanoic acid
Heptanoic acid
Benzoic acid
a,b,f
a,b,f
a,b,f
a,b,f
a,b,f
a,b,f
a,b,f
a,b,f
2
2
0.5
1
1
3
1
23
1
10
51
70
11
14
16
28
34
47
57
67
75
81
86
89
93
95
15
26
27
32
53
54
72
73
80
83
84
85
88
90
91
92
94
96
97
98
Octanoic acid
a,b,f
Hexadecanoic acid
Octadecanoic acid
1-Undecyl formate
1-Dodecyl formate
a,b,f
a,b,f
7
26
5
34
107
103
73
3
a,b,c,d,f
a,b,c,d,f
a,b,c,d,f
a,b,c,d,f
a,f
a,b,c,f
a,d,f
a,b,c,f
a,d,f
a,b,c,d,f
a,d,f
a,b,c,d,f
a,d,f
1-Tridecyl formate
1-Tetradecyl formate
1-Pentadecyl formate
1-Hexadecyl formate
1-Heptadecyl formate
1-Octadecyl formate
1-Nonadecyl formate
1-Icosyl formate
1-Henicosyl formate
1-Docosyl formate
1-Tricosyl formate
1-Tetracosyl formate
(Z)-6-Tridecen-1-yl formate
7-Tetradecen-1-yl formate
(Z)-8-Tetradecen-1-yl formate
8-Pentadecen-1-yl formate
8-Heptadecen-1-yl formate
10-Heptadecen-1-yl formate
10-Nonadecen-1-yl formate
12-Nonadecen-1-yl formate
13-Icosen-1-yl formate
12-Henicosen-1-yl formate
16-Henicosen-1-yl formate
14-Henicosen-1-yl formate
15-Docosen-1-yl formate
14-Tricosen-1-yl formate
18-Tricosen-1-yl formate
16-Tricosen-1-yl formate
17-Tetracosen-1-yl formate
16-Pentacosen-1-yl formate
18-Pentacosen-1-yl formate
Unidentified steroid
25
14
195
273
762
162
130
30
57
42
19
782
14
4
60
171
107
72
206
2319
142
53
137
761
27
36
106
2
a,f
a,c,e,f,g
a,e,f,g
a,c,e,f,g
a,d,e,f
a,e,f,g
a,d,e,f
a,e,f,g
a,d,e,f
a,e,f,g
a,e,f,g
a,e,f,g
a,d,e,f
a,e,f,g
a,e,f,g
a,e,f,g
a,d,e,f
a,e,f,g
a,e,f,g
a,e,f,g
a,b,f

MAMMALIAN EXOCRINE SECRETIONS XVII
TABLE 1. CONTINUED
97
No. in Fig.1
PS-089 column)
Compound (arranged
according to compound type)
Analytical
method
Quantity
(�g/animal)
a
(
9
2
3
3
4
5
5
5
6
9
9
1
3
6
2
5
6
6
Cholesterol
Unidentified
Unidentified
Unidentified
Unidentified
Unidentified
Unidentified
Unidentified
Unidentified
a,b,f
1848
149
96
197
69
124
3
862
46
aa: Low-resolution GC-MS; b: retention-time comparison using PS-089 column; c:
retention-time comparison using OV-240 column; d: CI(CH4)-MS; e: DMDS derivati-
zation; f: reduction with LiAlH4; g: unsaturated compounds listed in the order in which
they are eluted from the OV-240 column, elution order interchangeable on the PS-089
column within each group of homologs; h: not observed with OV-240 column.
chiral constituents of the exocrine secretions of various South African antelope
species will be dealt with in a future publication.
It is often difficult to differentiate between saturated and unsaturated long-
chain alcohols, formates, and alkenes, especially if they are present in such small
quantities that it is difficult to obtain pure spectra from a GC-MS analysis. These
spectra often also lack diagnostic ions in the higher mass ranges. Furthermore,
the preparative GC isolation of constituents is not feasible if they are present in
low concentrations and only a limited quantity of secretion is available. Valuable
diagnostic information was, however, obtained by lithium aluminum hydride
reduction of the whole extract of the secretion of the male, which left some con-
stituents intact, whereas carbonyl compounds, esters, etc., were reduced to com-
pounds that coeluted with the reduction products of other reducible constituents.
Information on the contribution of this experiment to the identification of some of
the constituents of the secretion is included in Table 1.
Quantitative extraction of the volatile organic material from the secretion
was not possible with small quantities of solvent. The widely varying quantities
of secretion collected from individual males furthermore contained considerable
proportions of water, as well as heavy material that does not pass through the GC
column. It is, therefore, impossible to determine the average quantitative compo-
sition of the preorbital secretions of males with even reasonable accuracy. The
quantitative results in Table 1 are nevertheless included to give at least an approx-
imate indication of the quantities of most of the compounds present in a relatively
large sample of secretion collected from a single male.
The suni is the fifth of several small South African antelope species belonging
tothetribeNeotraginiofwhichthechemicalcompositionofthepreorbitalsecretion

9
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STANDER, BURGER, AND LE ROUX

MAMMALIAN EXOCRINE SECRETIONS XVII
99

1
00
STANDER, BURGER, AND LE ROUX
has been investigated. Of these antelope, the male klipspringer, Oreotragus oreo-
tragus, (Burger et al., 1997) is unique in that the male preorbital secretion contains
only eight short-chain, volatile organic compounds: four ketones and four esters.
The female preorbital secretion of the klipspringer has so far not been investi-
gated. As mentioned in the introduction, female oribi, Ourebia orebi (Mo et al.,
1995), do not produce any preorbital secretion, although they possess an external
structure that resembles that of the preorbital gland of the male. The preorbital se-
cretions of male and female grysbok, Raphicerus melanotis, (Burger et al., 1996)
and steenbok, R. campestris, (Burger et al., 1999b) have also been reasonably well
characterized. Male and female secretions of the two Raphicerus species are qual-
itatively identical. Perhaps the most remarkable feature of members of this tribe is
the large number of long-chain saturated and unsaturated formic acid esters present
in all secretions investigated so far, with the exception of the klipspringer’s preor-
bital secretion. The results from members of the tribe Neotragini are summarized
in Table 2. Due to the large number of double-bond positional and configurational
isomerspresentinsomemembersofthistribe, itisimpossibletoincludeallrelevant
information in Table 2. However, there does not seem to be any indication that the
position of double bonds in the unsaturated constituents and their stereochemistry
could play a part in the territorial behavior of these animals.
One aspect that merits consideration in future research is the possibility that
some constituents of the secretions are not secreted by the preorbital glands but are
produced by different strains of the same bacterium or by different bacteria present
in the glandular structures of the animals. This is supported by the observation that
the secretions are more complex in the members of the tribe that produce secretion
only very slowly, whereas the secretion of the male klipspringer, produced at a rate
of about 5 mg/min, contains only eight simple compounds. In this case, microbial
action probably cannot add to the secretion’s complexity before it is deposited as
a territorial mark and dries out.
Acknowledgments—Support by the University of Stellenbosch and the National Research Foun-
dation, Pretoria, of research reported in this paper is gratefully acknowledged. The authors are indebted
to Mr. John Spence, Director of the Tygerberg Zoo, Cape Town, for permission to collect secretions
from suni in the zoo.
REFERENCES
ANDERSSON, G. 1979. Volatile ketones from the preorbital gland of reindeer (Rangifer t. tarandus L.).
J. Chem. Ecol. 5:629–634.
ARCESE, P. 1999. Effect of auxiliary males on territory ownership in the oribi and the attributes of
multimale groups. Anim. Behav. 57:61–71.
BRASHARES, J. S. and ARCESE, P. 1999. Scent marking in a territorial African antelope: I. The main-
tenance of borders between male oribi. Anim. Behav. 57:1–10.

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101
BURGER, B. V., TIEN, F.-C., LE ROUX, M., and MO, W.-P. 1996. Mammalian exocrine secretions. X:
Constituents of preorbital secretion of grysbok, Raphicerus melanotis. J. Chem. Ecol. 22:739–764.
BURGER, B. V., YANG, T.-P., LE ROUX, M., BRAND, W. F., COX, A. J., and HART, P.-F. 1997. Mam-
malian exocrine secretions. XI: Constituents of preorbital secretion of klipspringer, Oreotragus
oreotragus. J. Chem. Ecol. 23:2383–2400.
BURGER, B. V., NELL, A. E., SPIES, H. S. C., LE ROUX, M., and BIGALKE, R. C. 1999a. Mammalian
exocrine secretions. XIII: Constituents of preorbital secretions of bontebok, Damaliscus dorcas
dorcas, and blesbok, D. d. phillipsi. J. Chem. Ecol. 25:2085–2097.
BURGER, B. V., GREYLING, J., and SPIES, H. S. C. 1999b. Mammalian exocrine secretions. XIV:
Constituents of preorbital secretion of steenbok, Raphicerus campestris. J. Chem. Ecol. 25:2099–
2
108.
FLOOD, P. F., ABRAMS, S. R., MUIR, G. D., and ROWELL, J. E. 1989. Odor of the muskox. J. Chem.
Ecol. 15:2207–2217.
FREY, R. and HOFMANN, R. R. 1997. Skull, proboscis musculature and preorbital gland in the saiga
antelope and Guenther’s dik-dik (Mammalia, Artiodactyla, Bovidae). Zool. Anz. 235:183–199.
LANGGUTH, A. and JACKSON, J. 1980. Cutaneous scent glands in pampas deer, Blastoceros bezoarticus.
Z. Saeugetierkd. 45:82–90.
LAWSON, R. E., PUTMAN, R. J., andFIELDING, A. H. 2000. Individualsignaturesinscentglandsecretions
of Eurasian deer. J. Zool. (London) 251:399–410.
LAWSON, R. E., PUTMAN, R. J., and FIELDING, A. H. 2001. Chemical communication in Eurasian deer
(Cervidae): Do individual odours also code for attributes? J. Zool. (London) 253:91–99.
MARMAZINSKAYA, N. V. 1997. Territorial and marking behaviour of Persian gazelle, Gazella subgut-
turosa (Artyodactyla, Bovidae) at the Bukhara Ecological Center. Zool. Zh. 75:1737–1751.
MO, W.-P., BURGER, B. V., LE ROUX, M., and SPIES, H. S. C. 1995. Mammalian exocrine secretions.
IX: Constituents of preorbital secretion of oribi, Ourebia ourebi. J. Chem. Ecol. 22:739–764.
MOSSING, T. and DAMBER, J.-E. 1981. Rutting behavior and androgen variation in reindeer (Rangifer
tarandus L.). J. Chem. Ecol. 7:377–389.
ROBERTS, S. C. 1997. Selection of scent-marking sites by klipspringers (Oreotragus oreotragus).
J. Zool. (London) 234:555–564.
ROBERTS, S. C. 1998. Behavioural responses to scent marks of increasing age in klipspringer, Oreo-
tragus oreotragus. Ethology 104:585–592.
SOKOLOV, V. E., BRUNDIN, A., and ZINKEVICH, E. P. 1977. Differences in the chemical composition of
skin gland secretions of reindeer (Rangifer tarandus). Dokl. Akad. Nauk S.S.S.R. 237:1529–1532.
VINCENTI, M., GUGLIELMETTI, G., CASSANI, G., and TONINI, C. 1987. Determination of double bond
position in diunsaturated compounds by mass spectrometry of dimethyl disulfide derivatives. Anal.
Chem. 59:694–699.