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Chemistry Stinks! And How Nature Uses These Noxious Chemicals

Download slides after webinar: http://acswebinars.org/wood

Contact ACS Webinars™at acswebinars@acs.org

ACS WEBINARS™January 26, 2012

Darren Griffin, University of Kent

William Wood, Humboldt State

University

Chemistry Stinks!And How Nature Uses These

Noxious Chemicals.

William Wood

Department of Chemistry

Humboldt State University

Arcata, California

Jan. 26, 20126

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Chemical Ecology

• Pheromones

• Allomones

• Kairomones

Study of how living organism use chemicals to convey messages.

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AllomonesChemical messages between members of different species

that benefit the sender. (Attraction or Defense)

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Skunk Species in North America

1. Striped Skunk (Mephitis mephitis)

2. Hooded Skunk (Mephitis macroura)

3. Western Spotted Skunk (Spilogale gracilis)

4. Eastern Spotted Skunk (Spilogale putorius)

5. Hog-nosed Skunk (Conepatus mesoleucus)

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Striped Skunk (Mephitis mephitis)

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Hooded Skunk (Mephitis macroura)

Photograph - J. Dragoo 11

Sample of Skunk Spray

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Thomas Aldrich, 1896, 1897

• Investigated skunk defensive secretion as a possible anesthetic.

• Odor threshold of skunk spray determined at 10 ppb.

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Thomas Aldrich, 1896, 1897

1. An Isomer of 1-Butanethiol

CH3CH2CH2CH2SH

2. Other Mercaptans (Thiols)

3.N CH3

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Andersen & Bernstein 1975

1-Butanethiol (butyl mercaptan) was mistakenly incorporated into the chemical literature by the 1930s as the odoriferous compound in skunk spray.

In 1975 this was shown to be incorrect.

CH3CH2CH2CH2SH

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Andersen & Bernstein 1975

C CH

H

CH2SH

CH3

C CH

H

CH2SSCH3

CH3

CH3CHCH2CH2SH

CH3

(structure incorrectly assigned)16

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Striped & Hooded SkunkThiols and Thioacetates

C CH

H

CH2SH

CH3C C

H

H

SCCH3

CH3 O

CH3CHCH2CH2SH

CH3

CH3CHCH2CH2SCCH3

CH3 O

Wood 1990Wood, Sollers, Dragoo & Dragoo 2002

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Striped & Hooded SkunkAlkaloids

N CH2SH N CH2SCCH3

O

N CH3

Wood 1990

Wood, Sollers, Dragoo & Dragoo 2002 18

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Spotted Skunk (Spilogale gracilis)

Photograph - J. Dragoo 19

Spotted Skunk (Spilogale gracilis)

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Spotted Skunk Thiols(No Thioacetates!)

C CH

H

CH2SH

CH3

CH3CHCH2CH2SH

CH3

CH2CH2SH

Wood, Morgan and Miller 199121

Spotted Skunk Alkaloids

N CH2SH N CH3

Wood, Morgan and Miller 1991

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Hog-nosed Skunk (Conepatus mesolucas)

Photograph - J. Dragoo23

Hog-nosed Skunk(A Single Thiol and Thioacetate)

C CH

H

CH2SH

CH3C C

H

H

SCCH3

CH3 O

not in secretion

Wood, Fisher and Graham 1993

CH3

CH3CHCH2CH2SH

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Hog-nosed Skunk Alkaloids

N CH2SH N CH3

Wood, Fisher and Graham 1993

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How do the components work?

1. Thiols - They stink, are lachrymators

and cause nausea.

2. Thioacetates - Decompose to thiols

and make the spray long-lasting.

3. Alkaloids - Do they taste bitter?

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Deodorizing Skunk SprayThe Tomato Juice Myth

Experiment

1. Add skunk spray to tomato juice.

2. Smell mixture - result “skunk odor.”

3. Smell again - result no “skunk odor” only

“tomato juice odor.” DID IT WORK?

4. Smell mixture after 1 hour - result “skunk odor.”

Conclusion: Olfactory fatigue responsible for myth.27

Deodorizing Skunk Spray Pets(Paul Krebaum’s Recipe)

1. 1 Quart of 3% Hydrogen Peroxide

2. 1/4 Cup of Baking Soda

3. 1 Tsp. of Liquid Detergent

--Use Immediately--

--No Closed Container!--

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Skunks Are AggressiveSpray Used Only In Defense

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Phylogenetic Implications

Ancestral Skunk

MephitisSpilogale

Conepatus

Thiols andThioacetates Thiols but no

Thioacetates

Only one Thioland Thioacetate

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Garter Snake Defensive Secretion

CH3CHCH2CO2H

CH3

CH3CH2CH2CO2H

CH3CHCO2H

CH3

CH3CH2CO2H

CH3CO2H

Short-Chain Carboxylic Acids

CH3

N

CH3

CH3

Trimethylamine

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Garter Snake Defensive Secretion

RCO

O

HN

CH3

H3C

CH3

acid

base

R C O

O

H

salt (pH =7)

N

CH3

H3C

CH3

Wood, Parker & Weldon 1995

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Wolverine Defensive Secretion

CH3CHCH2COH

CH3 O

CH3CH2CHCOH

CH3

OCH2COH

O

Wood, Terwilliger and Copeland 200536

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CH3(CH2)6CH3

CH3(CH2)5CHO

CH3(CH2)6CHO

CH3(CH2)7CHO

OH

CH3

Alkane

Aldehydes

Aromatics

N

H

N

H

CH3

Fatty Acids

OH

O

OH

O

Wood and Weldon 2002 38

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Chemical in the Devil’s Tongue

NH

Indole (Feces)

CH2CH2OH

Phenethyl Alcohol (Roses)

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Pheromones

Chemical messages between members of the same species.

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Long-tailed Weasel

Scent markswith anal gland secretion.

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Thiatanes in Anal Secretion

SCH3CH3

S

CH3

CH3

SCH2CH2CH3

SCH3

CH3

Wood and Joest 200844

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Dithiolanes in Anal Secretion

SS

CH3

CH3 SS

CH2CH3

Wood and Joest 2008

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Indole and 2-Aminoacetophenone

N

H

C

O

CH3

NH2

Wood and Joest 200846

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Chemical Ecology Review

Pheromones - Chemical messages between members of the same species.

Allomone - Chemical messages between members of different species that benefits the sender.

Kairomone - Chemical messages between members of different species that benefit the

receiver. 47

The End You Don’t Want To See

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