Mephitis Skunk

In contrast to the relatively limited number of organosulfur compounds in these species, the anal sac secretions of skunks contain large numbers of malodorous compounds, which are very effectively utilized in the defensive behavior of these species. During the early years of capillary gas chromatography, Andersen et al. [108] found that 150 of the 160 components detected in the anal gland secretion of the striped skunk, Mephitis mephitis, contained sulfur. The results of recent chemical studies on North American skunks by Wood et al. [109] are summarized in Table 4. Only three of the compounds reported in this table are common to the secretions of all four skunk species and, in two of these three secretions, the common compound is present in concentrations of about 1% or less. Although it is clear that skunks use their anal gland secretions primarily for defensive purposes, it does not rule out the possibility that the difference in the composition of these secretions could also be utilized for... 

The secretion of the anal glands of skunks epitomizes mammalian defense secretions. Sulfur compovmds in the scent of striped skunk Mephitis mephitis) include rra 5-2-butene-l-thiol, 3-methyl-l-butanethiol (Andersen and Bernstein, 1975), rra 5-2-butenyl thioacetate, 3-methylbutanyl thioacetate, and 2-quinolinemethane thiol (Wood, 1990 Fig. 10.9). The thiols, once called mercaptans (because they captured mercury atoms), are like alcohols with a sulfur atom in place of the oxygen. In the striped skvmk, the thioacetates break down in water. They yield thiols, which have the more potent, characteristic skunk odor and linger for up to 2 weeks. In the spotted skunk, by contrast, the... 

FIGURE 10.9 Major sulfur compounds in the anal sac of the striped skunk Mephitis mephitis. (After Andersen and Bernstein [1975], Wood [1990], and Wood etal. [1991].)... 

Andersen, K. K. and Bernstein, D. T. (1975). Some chemical constituents of the scent of the striped skunk (Mephitis mephitis). Journal of Chemical Ecology 1,493-499. 

Skunks are small animals that wage powerful defensive warfare in the form of spray that has a sickening offensive odor. The compounds that are responsible for skunk spray odor are organosulfur compounds. Although seven or more such compounds have been isolated from the spray of the striped skunk, Mephitis mephitis, it is now believed that there are only three major ones trans-2-butene-l-thiol, t ra .v - 2 - b u t e n y I -1 - thioacetate, and 3-methyl-1-butanethiol5 ... 

The major (50%-75%) components of the malodorants in the skunk (Mephitis mephitis, Spilopgale gracilis, and Conepatus mesoleucus) defensive secretions are (E)-2-buten-1-thiol and 3-methyl-1-butanethiol. Other disulfides, thioacetates, and thiols are present in lesser amounts, and vary with species. In addition to the S-containing compounds, the alkaloid 2-methylquinoline has been identified in skunk secretions (Wood, 1990 Wood et al., 1991, 1993). Brief notes on examples of representative malodorants are given below. 

Wood, W.F., New compounds in the defensive secretions of the striped skunk. Mephitis mephitis, J. Chem. EcoL, 16, 2057-2065, 1990. 

LARIVIERE S., MESSIER, F., Aposematic behaviour in the striped skunk. Mephitis mephitis, Ethol, 1996, 102, 986-992. 

Skunk Mephitis mephitis) Sloth, three-toed Bradypus tridactylus) 0.28 2.69 1.59 0.004... 

Skunk Mephitis). When threatened, skunks spray an evil-smelling secretion from their anal glands at their enemies. This consists mainly of ( )-2-butene-l-thiol, 3-methyl-1-butanethiol, and other thiols as well as their acetates. These acetates are apparently responsible for the persisting effect of the secretion since they are cleaved by water to the thiols. 

The striped skunk Mephitis mephitis) sprays a foul mixture of thiols at Its enemies. 

Alarm pheromones (and defense substances) of the skunk Mephitis mephitis... 

Sulfur-containing substances Isopentylmercaptane (CH3)2CH—CH2—CH2SH, crotylmercaptane CHg—CH=CH—CH2SH, methylcrotyldisulfide CH3—CH=CH—CH2—S—S—CHg Synthesized in and released from the anal glands of the skunk Mephitis mephitis, if frightened, feeding deterrent... 

Wood W.F., SoUers B.G., Dragoo G.A., Dragoo J.W. Volatile components in defensive spray of the hooded skunk. Mephitis macroura. Journal of Chemical Ecology, 28 1865-1870 (2002). 

Some alcohols have rather sweet odors, but one of the distinguishing properties of thiols is then-strong, disagreeable odor. The odor of the striped skunk Memphitis mephitis) is due to 3-methyl-1-butanethiol. The human nose can detect thiols at a few parts per billion in air. There is a positive side to the obnoxious odors of thiols Small amounts of thiols are added to natural gas to aid in easy detection of leaks. 

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