Odorants as Chemical Messengers - ACS Symposium Series (ACS

11 Odorants as Chemical Messengers JOHN N. LABOWS, JR.

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The relationship between chemical structure and perceived odor has been studied by electrophysiological, chemical-analytical, and psychophysical techniques. Certain odorants in addition to being detected by the olfactory system evoke specific behavioral responses. Recent studies on various mammalian species have attempted to equate specific odor sources with behavioral patterns and to profile the odorants in hopes of identifying the biologically active components (1). In addition, studies on human odor suggest similarities in odor sources and types with other mammalian species and also suggest some of these odors may be reflective of internal body processes. Our i n i t i a l research efforts have been directed at chemically characterizing the odors which normally emanate from the body and using this information to diagnose disease states, sexual receptivity, and stress. Vaginal secretions, saliva, secretion from the apocrine gland in the axillae (underarm), and sebum from the sebaceous gland a l l represent unique substrates which can be metabolized by the resident microorganisms to generate odoriferous materials. Table I summarizes the useful types of information which may be contained in these odors. Described below are some of the attempts at profiling these odors and relating them to physiological states. The present interest in the characterization of both animal and human secretions has paralleled the development in psychophysical measurement techniques and in analytical methods such as headspace concentration, gas chromatography, and the combination of gas chromatography/mass spectrometry (GC/MS) which have made it possible to routinely separate and identify submicrogram quantities of organic compounds. GC/MS profiling of the small organic compounds present in body secretions, such as blood serum, cerebrospinal fluid, and urine of diseased and healthy individuals, has provided useful diagnostic information (2). The metabolic profiles are analyzed for qualitative or quantitative changes in individual components which might correlate with the onset of disease processes or the female reproductive cycle. 0097-6156/81/0148-0195$05.00/0 © 1981 American Chemical Society

Moskowitz and Warren; Odor Quality and Chemical Structure ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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GC/olfactory a n a l y s i s i s u s e f u l f o r determining which components of these complex mixtures c o n t r i b u t e to the observed odor ( 3 ) . Table I

Diagnostic P o t e n t i a l of Human Odors

Odor Source

Information

Content

Scalp

Microorganisms A c t i n g on Sebum

Oral

Time of Ovulation P e r i o d o n t a l Disease G a s t r o i n t e s t i n a l Disorders

Saliva

Axillae

Stress L e v e l Mental Health

Apocrine Secretion

Vaginal

Time of Ovulation Metabolic I n f e r t i l i t y

Vaginal

Foot

Bacterial Infection

E c c r i n e Sweat Epidermal L i p i d

Odor and

Secretions

Disease:

Systemic disease processes such as g a s t r o i n t e s t i n a l d i s o r d e r s and d i a b e t i c k e t o - a c i d o s i s (acetone) manifest themselves i n odors a s s o c i a t e d w i t h breath and/or s a l i v a (4). The c l a s s i c uremic breath odor has been described as ' f i s h y ' or 'ammoniacal' and involves the presence of dimethylamine and trimethylamine i n the breath (5). Elevated l e v e l s of mercaptans and C2-C5 a l i p h a t i c acids are found i n the breath of p a t i e n t s with c i r r h o s i s of the l i v e r (6), Other i l l n e s s e s such as s k i n u l c e r s , gout, typhoid, d i p h t h e r i a , smallpox and scurvy have been reported to have d i s t i n c t odors (7). In most cases no odor d e s c r i p t i o n or chemical c h a r a c t e r i z a t i o n of the odor has been attempted. The most important use of body odors i n disease diagnosis r e l a t e s to the i n f a n t diseases i n v o l v i n g e r r o r s i n amino a c i d metabolism. Strong and unusual odors are manifest i n the breath, sweat, and u r i n e of these i n d i v i d u a l s . Table II summarizes s e v e r a l known a c i d u r i a s , the amino acids that are not p r o p e r l y metabolized, and the odors a s s o c i a t e d with the compounds which accumulate and can be detected i n the u r i n e (8). In the case of the Maple Syrup Urine and Oasthouse syndrome, the keto- and hydroxy- a c i d s which have been i d e n t i f i e d may not be r e s p o n s i b l e f o r the observed maple and c e l e r y / y e a s t odors (9). A l t e r n a t i v e l y , these odors could be the r e s u l t of conversion of 2-keto-butyric a c i d to m e t h y l - e t h y l - t e t r o n i c a c i d (Slusser's lactone) which i s used as an extender i n maple and c e l e r y f l a v o r s and has a maple s y r u p - l i k e odor (R. Soukup, personal communication). With these a c i d u r i a s i t i s imperative that an immediate diagnosis i s made, since c o r r e c t i v e d i e t can prevent the b r a i n damage that r e s u l t s from these diseases. T h i s i s r e a d i l y done on an o l f a c t o r y b a s i s which can subsequently be supported by gas chromatographic



leucine, valine isoleucine

methionine

phenyl a l a n i n e

leucine

Oasthouse

PKU

Sweaty Feet

Amino A c i d ( s ) branched chain decarboxylase

Enzyme D e f e c t

(63)

i s o v a l e r y l CoA dehydrogenase

phenyl alanine hydroxylase

methionine utilization

Metabolic Disorders i n Infants

MSUD

Table I I Accumulated

isovaleric (sweaty)

Perfumer and Flavorist

acid

phenyl pyruvate phenyl a c e t i c a c i d (mousy, h o r s e y )

2-keto-butyric acid 2-hydroxy-butyric acid (celery, yeast)

2-hydroxy a c i d s 2-keto a c i d s (maple-syrup)

Compound(s)

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ODOR QUALITY AND

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a n a l y s i s of the u r i n e . I t i s accepted procedure f o r the p e d i a t r i c i a n to 'smell h i s p a t i e n t and at l e a s t one medical school uses odors as a part of i t s l e c t u r e m a t e r i a l (10). As we understand what odors are a s s o c i a t e d with v a r i o u s disease processes, i t would be appropriate f o r the p h y s i c i a n to use o l f a c t i o n f o r a diagnosis. There appears to be a r e l a t i o n s h i p between v a r i o u s o r a l pathologies and the chemicals found i n human s a l i v a (11). Various v o l a t i l e compounds such as s k a t o l e , i n d o l e , s u l f i d e s , and long chain a l c o h o l s have been i d e n t i f i e d i n the headspace of s a l i v a samples. These m a t e r i a l s i n c r e a s e i n both a q u a n t i t a t i v e and q u a l i t a t i v e fashion with v a r y i n g degrees of p e r i o d o n t i t i s . S p e c i f i c a l l y , a l k y l p y r i d i n e s appear to be present i n the s a l i v a only i n i n d i v i d u a l s with p e r i o d o n t a l disease. The monitoring of these compounds may allow the d e t e c t i o n of the e a r l y stages of t h i s disease process which e f f e c t s 60-70% of the p o p u l a t i o n . 1

Odor and Communication:

Mammalian

Studies which have been undertaken to i m p l i c a t e s p e c i f i c chemicals i n mammalian o l f a c t o r y s i g n a l s must f i r s t be considered i n order to a p p r e c i a t e the p o s s i b i l i t y of human odor communication. Chemical odorants, present i n animal s k i n glands, u r i n e , s a l i v a , and v a g i n a l f l u i d s have pronounced p h y s i o l o g i c a l and b e h a v i o r a l e f f e c t s (1,12). The scent-marking s k i n glands are e i t h e r a p o c r i n e - l i k e and analogous to the human apocrine gland or are a combination of apocrine-sebaceous glands. A v a r i e t y of these glands present i n the r a b b i t and deer convey alarm and f r i g h t messages as w e l l as information on i n d i v i d u a l i d e n t i t y (13). The i s o l a t e d boar ketones, 5a-androst-16-en-3a-ol (androstenol) and androst-16-en-3-one (androstenone) secreted by the subm a x i l l a r y gland, have a d i r e c t e f f e c t on the sexual r e c e p t i v i t y of the sow and are used commercially to a s s i s t i n a r t i f i c i a l insemination (14). The f a c t that e s t r u s can be determined i n the sow by her response to these compounds suggests that there i s a heightened a c u i t y f o r these compounds at the time of o v u l a t i o n . T h i s i s s i m i l a r to the i n c r e a s e i n o l f a c t o r y a c u i t y f o r c e r t a i n compounds noted i n human females p r i o r to o v u l a t i o n (15)• A somewhat unique but analogous s i t u a t i o n i s the elephant temporal gland which i s an apocrine gland that i s a c t i v e under s t r e s s and possesses an 'elephanty odor (16). Table I I I summarizes some of the mammalian communication systems that have been studied and the chemicals which have been found to have b e h a v i o r a l e f f e c t s . In some cases there are unique odors, such as V a b b i t o d o r , 'monkey odor', 'deer odor', which are a s s o c i a t e d with s p e c i a l i z e d s k i n glands and s p e c i f i c chemical s t r u c t u r e s (13). 1

1

The c h a r a c t e r i z a t i o n of a b e h a v i o r a l l y a c t i v e chemical i s a tedious task and i n v o l v e s i s o l a t i o n and s t r u c t u r a l i d e n t i f i c a t i o n of numerous c o n s t i t u e n t s from a s e c r e t i o n . A s u i t a b l e bioassay, which i n v o l v e s p r e s e n t i n g the chemical(s) to the animal i n a


Moskowitz and Warren; Odor Quality and Chemical Structure ACS Symposium Series; American Chemical Society: Washington, DC, 1981. sexual activity 'rabbity odor' heart rate

short-chain (vagina)

methyl-p-hydroxybenzoate (vagina)

cis-undec-4-enal (anal gland)

short-chain acids; ketones (interdigital)

isovaleric acid (subauricular)

aldehyde, alcohols

Dog

Rabbit

Reindeer

Pronghorn

Reindeer

(tarsal)

aliphatic

sniffing

sexual a c t i v i t y not r e p r o d u c i b l e

attraction

Rhesus monkey

elicits

dimethyl (vagina)

Hamster

disulfide

butyrate esters of long-chain alcohols ( c i r c u m g e n i t a l gland)

acids

sniffing licking

Cis-4-hydroxydodec-6-enoic acid lactone (urine) subspecies identity

induces lordosis

a n d r o s t e n o l and a n d r o s t e n o n e (submaxillary gland)

Behavior

Communication

Marmoset monkey

Deer

Boar

Chemical

Animal

(source)

Mammalian C h e m i c a l

Table I I I

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ODOR QUALITY AND

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1

n a t u r a l context and 'measuring a b e h a v i o r a l response, i s then necessary to determine i f the chemical(s) are of i n t e r e s t to the animal (1,17,28) . Though many mammalian s e c r e t i o n s have been found which give b e h a v i o r a l responses, few chemicals with d e f i n i t i v e e f f e c t s have been c h a r a c t e r i z e d (Table I I I ) , The best example i s the two androgen s t e r o i d s used by the boar. Recently, methyl-p-hydroxybenzoate has been i s o l a t e d from the v a g i n a l s e c r e t i o n s of female dogs and shown to be a h i g h l y e f f e c t i v e sexual e x c i t a n t to males (22). An understanding of the chemical language that c o n t r o l s the s o c i a l and feeding behavior of an i n d i v i d u a l species would be u s e f u l i n the care and breeding of that s p e c i e s . However, research on the assignment of s t r u c t u r e - a c t i v i t y r e l a t i o n s h i p s i n mammalian behavior i s only i n i t s i n f a n c y . Odor and Communication:

Human

Anecdotal s t o r i e s i n the l i t e r a t u r e r e f e r to the a b i l i t y of human odors to e f f e c t sexual and s o c i a l behavior (29). P s y c h o l o g i s t s have r e c e n t l y attempted to decipher the information content of these v a r i o u s odors (30). The c o n t r o l of endocrine s t a t e s by odor i s suggested by the work on the synchronization of c y c l e s of females l i v i n g together (31). R u s s e l l demonstrated that subjects can detect sexual d i f f e r e n c e s and i n d i v i d u a l i d e n t i t y using a x i l l a r y odors (32). In a s i m i l a r experiment using a d i f f e r e n t p r o t o c o l , Doty determined that i n d i v i d u a l s equated the more intense odors with male subjects (20). No e f f e c t s were found f o r a l i p h a t i c acids on sexual behavior (33), while n e i t h e r the acids nor androstenol had any s i g n i f i c a n t e f f e c t s on i n d i v i dual judgments (34). In the presence of the androstenol, photographs of women were judged as more a t t r a c t i v e although no c o n t r o l odors or other ' s y n t h e t i c musks' were evaluated i n t h i s study (35). The chemical and p s y c h o l o g i c a l changes a s s o c i a t e d with the menstrual c y c l e include changes i n o l f a c t o r y a c u i t y as w e l l as c y c l i c changes i n numerous biochemical processes. The l a t t e r may be r e f l e c t e d i n c y c l i c a l v a r i a t i o n s i n body odors, as i s the case i n many mammalian species where information on female r e c e p t i v i t y i s transmitted to the male through odors from body s e c r e t i o n s . Odors from the mouth and vagina have been examined as p o s s i b l e sources of chemicals which undergo c y c l i c a l changes. P r e l i m i n a r y work with female breath samples has centered on three v o l a t i l e s u l f u r compounds (hydrogen s u l f i d e , methyl mercaptan and dimethyl s u l f i d e ) which are p r i m a r i l y r e s p o n s i b l e f o r endogenous bad breath ( " h a l i t o s i s " ) . These three compounds were found to change i n c y c l i c a l fashion i n c r e a s i n g at the time of o v u l a t i o n and again during menstruation (36). With a gas chromatograph adapted f o r the d e t e c t i o n of s u l f u r compounds, these m a t e r i a l s can be quantitated at the low nanogram l e v e l s . T h e i r increase corresponds to increases i n both b a c t e r i a l counts and i n e x f o l i a t i o n o f c e l l s i n the o r a l c a v i t y .


11.

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Odorants as Chemical Messengers

201

O l f a c t o r y a n a l y s i s of v a g i n a l odors has shown that human observers rate the odor l e a s t unpleasant and l e s s intense at the time of o v u l a t i o n . However, the l a r g e v a r i a t i o n s i n response on i n d i v i d u a l subjects suggests that t h i s i s not a u s e f u l pred i c t i v e approach (37). D e t a i l e d chemical p r o f i l i n g of v a g i n a l s e c r e t i o n s has l e d to the i d e n t i f i c a t i o n of a v a r i e t y of low molecular weight organic compounds (38). Long chain acids and a l c o h o l s , 3-hydroxy-2-butanone, dimethysulfone, f u r f u r a l , c r e s o l , phenol, f u r f u r y l a l c o h o l , p y r i d i n e , propylene g l y c o l , g l y c e r o l , benzoic a c i d , and c h o l e s t e r o l were c o n s i s t e n t l y present i n a l l s u b j e c t s . L a c t i c a c i d concentrations d i d r i s e at midcycle and t h i s information may be u s e f u l i n p r e d i c t i n g the time of o v u l a t i o n . Short-chain a l i p h a t i c a c i d s were present i n only s i x of fourteen women and d i d not vary i n c o n c e n t r a t i o n i n a c y c l i c a l manner. These a l i p h a t i c a c i d s , r e f e r r e d to as c o p u l i n s , were found o r i g i n a l l y i n rhesus monkey v a g i n a l s e c r e t i o n s ; but t h e i r pheromonal e f f e c t s have been questioned (20,21). The odorants that may be of importance f o r human o l f a c t o r y communication are those f o r which man possesses s p e c i f i c o l f a c t o r y receptors as shown by the s t u d i e s on s p e c i f i c anosmias, i . e . the i n a b i l i t y to detect the odor of s p e c i f i c chemicals. These odors i n c l u d e spermous, musky, f i s h y , urinous, malty and sweaty, and can be r e l a t e d to some observed human odors (39). Thus, Amoore suggests that, i f we have a s p e c i f i c o l f a c t o r y receptor f o r a given odorant then that odorant might be n a t u r a l l y given o f f by the body. The sweaty odor of i s o v a l e r i c a c i d i s probably part of the foot odor and i s produced by the a c t i o n of skin b a c t e r i a on apocrine s e c r e t i o n (see below). P y r o l l i n e , the spermous odor, has been shown to be produced by enzymatic breakdown of the polyamines i n semen (40). Androst-16-en-3-one, the urinous primary odor, has a x i l l a r y - l i k e odor; the r e l a t e d androstenol, which i s found i n urine, i s perceived as a musky odor to some i n d i v i d u a l s (41). Both s t e r o i d s are found i n a x i l l a r y sweat and may be formed as metabolites of apocrine s e c r e t i o n . Chemicals which f i t the malty anosmia have not as yet been reported from human odor sources. The n a t u r a l musks, such as cycloheptadecenone ( c i v e t ) , were f i r s t obtained from animal scent glands. I t i s of i n t e r e s t to note that observed odorants are i n most cases metabolic by-products of human s e c r e t i o n s , r a t h e r than odorants which were d i r e c t l y s e c r e t e d . The same s i t u a t i o n may be true i n a number of mammalian species where b a c t e r i a may be involved i n the eventual formation of chemicals used i n odor communication (42). Odor A n a l y s i s : There has been an i n t e r e s t i n developing techniques f o r sampling t o t a l body odors. Dravnieks group has sampled the v o l a t i l e s emitted by i n d i v i d u a l s by p l a c i n g them i n a glass c y l i n d e r and sweeping the tube with a i r to concentrate the 1


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ODOR QUALITY AND

CHEMICAL STRUCTURE

v o l a t i l e s (3). He h a s a l s o d e v e l o p e d s y s t e m s f o r s a m p l i n g s k i n and a x i l l a r y o d o r s . E l l i n u s e d a t e l e p h o n e b o o t h - l i k e chamber i n w h i c h human v o l a t i l e s w e r e s a m p l e d ( 4 3 ) . Here approximately 3 0 0 - 4 0 0 i n d i v i d u a l c h e m i c a l s w e r e d e t e c t e d and 135 identified. The o b j e c t o f t h e s e t r i a l s was t o e x p l o r e t h e p o s s i b i l i t y t h a t body o d o r s m i g h t be u n i q u e t o a g i v e n i n d i v i d u a l o r a g i v e n r a c e and s e r v e as a p e r s o n a l s i g n a t u r e . Room a i r a l s o h a s b e e n s a m p l e d i n t h e p r e s e n c e and a b s e n c e o f i n d i v i d u a l s i n an a t t e m p t t o d e t e r m i n e what c o n t a m i n a n t s were a d d e d t o t h e e n v i r o n m e n t b y body v o l a t i l e s ( 4 4 ) . This i s p a r t i c u l a r l y relevant to r e s t r i c t e d e n v i r o n m e n t s s u c h as s u b m a r i n e s and s p a c e c a b i n s w e r e a i r r e circulation i s a necessity. The t h e r m a l l y i n d u c e d t o t a l b o d y sweat o f s c h i z o p h r e n i c p a t i e n t s was c o l l e c t e d f o r a n a l y s i s o f u n i q u e o d o r s by t h e use o f l a r g e p l a s t i c b a g s ( 4 5 ) . In a l l of t h e s e c o l l e c t i o n s , i n c l u d i n g one on a x i l l a r y odor u s i n g c o t t o n pads ( 4 6 ) , no v o l a t i l e c h e m i c a l s w h i c h r e p r e s e n t s p e c i f i c 'human o d o r s ' were i d e n t i f i e d . The s a m p l i n g and i d e n t i f i c a t i o n o f 'body o d o r s ' and t h e i r r o l e i n d i a g n o s i n g and m o n i t o r i n g d i s e a s e s t a t e s has r e c e n t l y been r e v i e w e d (47). A major c o n t r i b u t o r to whole body o d o r a r e the s k i n o d o r s which r e s u l t from the i n t e r a c t i o n of microorganisms w i t h s e c r e t i o n s f r o m t h e e c c r i n e , s e b a c e o u s and a p o c r i n e g l a n d s . T h e s e s e c r e t i o n s d i f f e r i n t h e i r c h e m i c a l c o m p o s i t i o n and t h u s provide unique s u b s t r a t e s f o r the organisms (48). The e c c r i n e g l a n d s w h i c h a r e p r e s e n t o v e r most o f t h e b o d y a r e t h e t h e r m o r e g u l a t o r y sweat g l a n d s w h i c h r e s p o n d t o p h y s i c a l a c t i v i t y . The e c c r i n e s e c r e t i o n h a s b e e n w e l l c h a r a c t e r i z e d and c o n s i s t s o f an aqueous s o l u t i o n o f i n o r g a n i c s a l t s and amino a c i d s w h i c h h a s no s i g n i f i c a n t odor. The s e b a c e o u s g l a n d s w h i c h a r e l o c a t e d p r i m a r i l y on t h e f o r e h e a d , f a c e and s c a l p a r e u n d e r h o r m o n a l c o n t r o l and s e c r e t e l i p i d m a t e r i a l s s u c h as t r i g l y c e r i d e s , c h o l e s t e r o l and wax e s t e r s . T h i s s e c r e t i o n has a s l i g h t p l e a s a n t o d o r b u t c a n be r e a d i l y m e t a b o l i z e d by s k i n m i c r o o r g a n i s m s . The t h i r d g l a n d u l a r system i s t h a t of the a p o c r i n e glands which are l o c a t e d p r i m a r i l y i n t h e g e n i t a l and a x i l l a r y a r e a s . T h e y become a c t i v e at puberty because of the presence of androgen s t e r o i d s f r o m t h e a d r e n a l g l a n d s , t e s t e s and o v a r i e s , and s e c r e t e i n r e s p o n s e to e m o t i o n a l s i t u a t i o n s (49). A n a l y s i s h a s shown t h a t t h e s e c r e t i o n c o n t a i n s p r o t e i n ( 1 0 % ) , c h o l e s t e r o l (1%), and s t e r o i d s (~0.02%). The most p r o d u c t i v e a p p r o a c h t o t h e s t u d y o f s k i n o d o r s has b e e n t h e d u p l i c a t i o n o f t h e n a t u r a l o d o r s i n v i t r o by i n cubating the normal s k i n microorganisms w i t h these s e c r e t i o n s . F o r example, t h e y e a s t P i t y r o s p o r u m o v a l e , the major s c a l p r e s i d e n t , i s able to metabolize l i p i d s u b s t r a t e s to 4-hydroxya c i d s w h i c h r e a d i l y u n d e r g o r i n g c l o s u r e t o t h e v o l a t i l e and odorous Y ~ l c t o n e s . The t e c h n i q u e o f h e a d s p a c e c o n c e n t r a t i o n on T e n a x f o l l o w e d by gas c h r o m a t o g r a p h i c / m a s s s p e c t r o m e t r i c analysis has b e e n u s e d t o p r o f i l e a l l t h e v o l a t i l e s p r o d u c e d by P i t y r o sporum ( F i g u r e 1 ) . T h e s e compounds i n c l u d e i s o p e n t a n o l , benzyl a


11.

203


LABOWS

hexanol

Y-deca lactone Y-octa-

18

16

TA—'—IT Fatty

i s —

Acid Ethyl Estar (FAIE)

r

T

Retention

I

I 6

Indices

Applied and Environmental Microbiology

Figure 1.

Odor profile of Pityrosporum ovale (50)


204

ODOR QUALITY AND CHEMICAL STRUCTURE

x=6

DMTS C H

3

( C H

2>xC-CH

3

to 1-und« x=8

xx 2 .

p«ntanol II

LU1DM i—*—i—

1

~i—"~l—'—I— —r 16

14

12

10

8

1

6

r 4

FAEE Journal of Clinical Microbiology Figure 2.

T" 12

"i

Odor profile of Pseudomonas aeruginosa (51 a)

1 10

r

i

r

FAEE Perfumer and Flavorist

Figure 3.

Micrococci on apocrine secretion (63)


11.

LABOWS


205

a l c o h o l , phenyl ethanol, and s e v e r a l l a c t o n e s , i n c l u d i n g y-octalactone (coconut f l a v o r ) ; y-nonalactone (cream, f r u i t y ) ; y-decalactone (peach, p e a r ) . The odor of the c u l t u r e i s s i m i l a r to that of unwashed h a i r and c l o s e l y matches that of y-decalactone, the major lactone component. Because of the compounds i t produces, t h i s scalp microorganism has the p o t e n t i a l to be used for the n a t u r a l formation o f f l a v o r a d d i t i v e s (50). I n t e r e s t i n g l y , a s i m i l a r l a c t o n e - p r o f i l e i s observed f o r another yeast., Sporobolomyces odorus i s o l a t e d from orange leaves (51). T h i s o d o r - p r o f i l e may a l s o be used f o r the d e t e c t i o n o f the Pityrosporum genus, since other yeasts that may be found as t r a n s i e n t s on the s k i n grown on the same media f a i l e d t o y i e l d any l a c t o n e s . In a d d i t i o n , when sebum i s the major s u b s t r a t e and longer i n c u b a t i o n times are used a 'scalp odor' i s generated. Our p r e l i m i n a r y headspace a n a l y s i s suggestes that t h i s odor contains s h o r t - c h a i n a l i p h a t i c acids i n a d d i t i o n to the l a c t o n e s . The formation o f odors on the scalp may be a cooperative e f f o r t of Propionibacterium acnes, which r e a d i l y hydrolyzes t r i g l y c e r i d e s , and Pityrosporum ovale, which can metabolize the r e s u l t a n t f a t t y acids and/or g l y c e r o l t o v a r i o u s odorants. The odor p r o f i l e of a s k i n pathogen, Pseudomonas aeruginosa has a l s o been i n v e s t i g a t e d . T h i s organism, though present normally i n some i n d i v i d u a l s , i s r e s p o n s i b l e f o r s e r i o u s i n f e c t i o n s i n burn v i c t i m s and i n lung i n f e c t i o n s i n c y s t i c f i b r o s i s p a t i e n t s . The v o l a t i l e p r o f i l e i s shown i n Figure 2 where 2-aminoacetophenone (2-AA), methyl ketones and s u l f i d e are the major unique odorants (51a). The 2-AA, which imparts a g r a p e - l i k e odor t o the c u l t u r e , i s formed from tryptophan and i s c h a r a c t e r i s t i c o f t h i s species (52). The methyl ketones a l s o appear t o be species s p e c i f i c and may be o f value i n the d e t e c t i o n of lung i n f e c t i o n s through breath a n a l y s i s . The unique human a x i l l a r y odor i s the r e s u l t of m i c r o b i a l a c t i o n on an odorless s e c r e t i o n . The two major r e s i d e n t s o f the a x i l l a e are diphtheroids ( l i p o p h i l i c and large colony) and the micrococci bacteria. S p e c i f i c odorants can be produced by incubating these b a c t e r i a with apocrine s e c r e t i o n e i t h e r on a cleansed forearm or i n a t e s t tube. The m i c r o c o c c i produce a sweaty, a c i d odor which by headspace a n a l y s i s has been shown to be i s o v a l e r i c a c i d (Figure 3). The d i p t h e r o i d s a l s o produce t h i s a c i d , but i t s odor i s masked by other odor components which impart a h e a v i e r 'apocrine odor' to the incubated sample (63)« B a c t e r i a l sampling along with o l f a c t o r y a n a l y s i s o f i n d i v i d u a l subjects f u r t h e r demonstrates that the 'apocrine odor' i s associated with the d i p h t h e r o i d b a c t e r i a . These odorants, which represent unique human odors i n analogy t o the animal scents, are p r e s e n t l y being i n v e s t i g a t e d . However, the f o l l o w i n g experimental observations r e l a t e to the p o s s i b l e i d e n t i f i c a t i o n of these odorants. The boar pheromone, androst-16-en-3-one and i t s precursor, androsta-di-4,16-en-3-one, both have intense odors which c l o s e l y resemble the 'apocrine odor' (53). Both of


206


Table I V

0

S t e r o i d s Found i n Human A x i l l a e (63) Reference

Steroid

Sample

Androst-4-ene-3, 17-dione Androsterone (sulphate) DHA (sulphate) Cholesterol

A x i l l a r y Hairs and sweat

55

Androst-4-ene-3, 17-dione P re gn-5-en-3 &-o1-2 0-one

A x i l l a r y Sweat

56

5a-Androst-16-en-3a-ol


57

5a-Androst-16-en-3-one


58,58a,59

Androsterone (sulphate) DHA (sulphate) Cholesterol

Apocrine

60

Secretion

Perfumer and Flavorist


11.

LABOWS


207

these 16-androstene s t e r o i d s i n a d d i t i o n to 5a-16-androsten-3a-ol c i r c u l a t e i n human blood (54). Trace amounts of androstenone and androstenol as w e l l as other s t e r o i d s have been reported to be present i n human a x i l l a r y sweat (Table I V ) . More r e c e n t l y we have found that heated apocrine s e c r e t i o n (>150°) gives an a p o c r i n e - l i k e odor. The major c o n t r i b u t o r s to t h i s odor are isomeric androstadien-17-ones and androst-2-en-17-one which a r i s e from the thermal breakdown of dehydroepiandrosterone and androsterone s u l f a t e s r e s p e c t i v e l y (60). Thus the apocrine s e c r e t i o n contains s p e c i f i c s t e r o i d m a t e r i a l s , i n a d d i t i o n to c h o l e s t e r o l , which may be metabolized to the odorous A ^-androgens by the d i p h t h e r o i d b a c t e r i a . Whether t h i s i n f a c t occurs remains to be demonstrated. However, i f i t i s the case, the f a c t that about 50% of the p o p u l a t i o n i s anosmic to these odorants (61) suggests that a x i l l a r y odor would be perceived as a sweaty odor by anosmic i n d i v i d u a l s , whereas others would p e r c e i v e an 'apocrine o d o r . F i n a l l y , the f a c t that these s t e r o i d s have demonstrated sexual e f f e c t s i n one animal suggests that they might a l s o be p h y s i o l o g i c a l l y a c t i v e i n other s p e c i e s . 1

The apocrine s e c r e t i o n and the r e s u l t a n t odor i s a normal response to emotional s t i m u l i . Dehydroepiandrosterone, which i s present i n the apocrine s e c r e t i o n , a l s o has been reported to increase i n u r i n e i n i n d i v i d u a l s under s t r e s s (62). Thus, a s e n s i t i v e method f o r monitoring of the a c t i v i t y o f the apocrine gland could provide information r e l a t i v e t o the emotional s t a t e o f an i n d i v i d u a l . Since man possess odor sources s i m i l a r to mammalian s p e c i e s , i t i s of value to determine both the nature and the biochemical o r i g i n of these odorants. P r o f i l i n g o f human odors represents a non-invasive technique which might prove u s e f u l i n the d e t e c t i o n of many metabolic and i n f e c t i o u s d i s o r d e r s and f o r monitoring normal body processes. A l t e r n a t i v e l y , we may be unknowingly e m i t t i n g and p e r c e i v i n g odorants which could e f f e c t our i n t e r p e r s o n a l r e l a t i o n s h i p s . Only f u r t h e r research i n t h i s area w i l l determine to what extent t h i s occurs. Ackn owledgemen t s The work described on s k i n odors i s i n cooperation with the Department of Dermatology, U n i v e r s i t y o f Pennsylvania and i s supported by a grant from the N a t i o n a l I n s t i t u t e of A r t h r i t i s , Metabolic, and D i g e s t i v e Diseases.


208


Literature Cited 1a. Müller-Schwarze, D., Mozell, M.M., Eds. Chemical Signals in Vertebrates; Plenum Press, N.Y., 1977. 1b. Müller-Schwarze,D., Silverstein, R.M., eds. Chemical Signals Vertebrates and Aquatic Invertebrates; Plenum Press, N.Y., 1980. 2. Jellum, E . , J . of Chromatogr., 1977 143: 427. 3. Dravnieks, A., J. Soc. Cosmet. Chem., 1975 26: 551. 4. Krotoszynski, B., Gabriel, G. O'Neill, H., J. Chrom. Sci., 1977, 15: 239. 5. Simenhoff, M.L., Burke, J.F., Saukkonen, J.J., Ordinario, A.T., Doty, R., New Engl. J. Med. 1977, 297: 132-135 6. Chen, S., Mahadevan, V., Zieve, L . , J. Lab. Clin. Med., 1970, 75: 622-628. 7. Lidell, K., Postgrad. Med. J., 1976, 52: 136. 8. Mace, J.W., Goodman, S.I., Centerwall, W.R., Chinnock, R.F., Clin. Ped., 1976, 15: 57. 9. Sulser, H., Depizzol, J., Buchi, W., J. of Food Sci., 1967, 32: 611-615. 10. Lukas, T., Berner, E . , Kanakis, C., J. Med. Educ., 1977, 52: 349. 11. Kostelc, J.G., Preti, G., Zelson, P.R., Stoller, N.H., Tonzetich, J., J. Periodont. Res., 1980 15: 185-192. 12. Freeman, S.K., J . Soc. Cosmet. Chem., 1978, 29: 47. 13. Mykytowycz, R., Goodrich, B.S., J. of Inv. Derm., 1974, 62: 124. 14. Reed, H., Melrose, D., Patterson, R.L.S., Brit. Vet. J., 1974, 130: 61-67. 15. Doty, R.L., Ed., Mammalian Olfaction, Reproductive Processes, and Behavior, Academic Press, 1976. 16. Adams, J., Garcia, A., Foote, C.S., J. Chem. Ecol., 1978, 4: 17. 17. Müller-Schwarze, D., Ref. 1, p. 413. 18. Epple, G., Golob, N.F., Smith, A.B., in Chemical Ecology: Odour Communication in Animals, ed. F.J. Ritter, Elsevier/ North Holland Biomedical Press, 1979 p. 117-130. 19. Singer, A.G., Agosta, W.C., O'Connell, R.J., Pfaffmann, C., Bowen, D.V., Field, F.H., Science, 1975, 191: 948-950. 20. Goldfoot, D.A., Kravetz, M.A., Goy, R.W., Freeman, S.K., Hormones and Behavior, 1976, 7: 1-7. 21. Michael, R.P., Bonsall, R.W., Zumpe, D., Evidence for Chemical Communication in Primates, in Vitamins and Hormones, Academic Press, 1976, 137-183. 22. Goodwin, M., Gooding, K.M., Regnier, F., Science, 1979, 203: 559. 23. Goodrich, B.S., Hesterman, E.R., Murray, K.E., Mykytowycz, R. Stanley, G., Sugowdz, G., J. Chem. Ecol., 1978, 4(5), 581-594. 24. Anderson, G., Brundin, A., Anderson, K., J. of Chem. Ecol. 1978, 5(3): 321-333.


11.

25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50.

LABOWS


Brundin, A., Anderson, G., Anderson, K., Mossing, T., Kallquist, L . , J. Chem. Ecol., 1978, 4: 613-622. Müller-Schwarze, D., Müller-Schwarze, C., Singer, A.G., Silverstein, R.M., Science, 1974, 183: 860-862. Anderson, G., Anderson, K., Brundin, A., Rappe, C., J. Chem. Ecol, 1975, 1(2): 275-281. Beauchamp, G.K., Doty, R.L., Moulton, D.G., Mugford, R.A., in Mammalian Olfaction, Reproductive Processes, and Behavior ed. Doty, Academic Press, NY, 1976, 144-157. Bloch, I., Odoratus Sexualis, Panurge Press, New York, 1934. Doty, R.L., Ref. 1, p. 273. McClintock, M.K., Nature, 1971, 229: 244. Russell, M.J., Nature, 1976, 260: 520. Morris, N., Udry, R., J . Biosoc. Sci., 1978, 10: 147-157. Cowley, J., Johnson, A., Brooksbank, B., Psychoneuroendocrinology, 1977, 2: 159-172. Kirk-Smith, M., Booth, D., Carroll, D., Davies, P., Res. Comm. in Psychol., Psychiatry, and Behavior, 1978, 3: 379-384. Tonzetich, J., Preti, G., Huggins, G.R., J. Int. Med. Res., 1978, 6: 245. Doty, R., Ford, M., Preti, G., Huggins, G., Science, 1975 190: 1316-1318. Preti, G., Huggins, G.R., in The Human Vagina, ed. E. Hafez and T. Evans, Elsevier/North Holland Biomedical Press, 1978. Amoore, J., Chemical Senses and Flavor, 1977, 2: 267. Chvapil, M., Eskelson, C., Jacobs, S., Chvapil, T., Russell, D.H., Obstet. Gynecol., 1978, 52: 88. Kingsbury, A.E., Brooksbank, B.W.L., Hormone Res., 1978, 9: 254-270. Albone, E . , Gosden, P., Ware, G., Ref. 1a, p. 35. Ellin, R.L., Farrand, R.L., Oberst, F.W., Crouse, C.L., Billups, N.B., Koon, W.S., Musselman, N.P., Sidell, F.R., J. Chromatogr., 1974, 100: 137. Savina, V.P., Sokolov, N.L., Ivanov, E.A., Kosm Biol Aviakosm Med., 1976, 9: 76. Gordon, S.G., Smith, K., Rabinowitz, J . L . , Vagelos, P.R., J. of Lipid Res., 1973, 14: 495. Labows, J.N., Preti, G., Hoelze, E . , Leyden, J., Kligman, A. J. Chromatogr. - Biomed. Applic., 1979, 163: 294-299. Sastry, S., Buck, K., Janak, J., Dressler, M., Preti, G., in Biochemical Applications of Mass Spectrometry ed. G. Waller and O.C. Dermer, Wiley, 1980, p. 1086-1123. Montagna, W., Parakkal., P., Structure and Function of Skin Academic Press, 1974. Hurley, J., Shelley, W., The Human Apocrine Gland in Health and Disease, Thomas, Springfield, Illinois, 1960. Labows, J.N., McGinley, K.J., Leyden, J.J., Webster, G.F., Appl. and Environ. Micro., 1979, 38: 412-415.


210

51. 51a. 52. 53. 54. 55. 56. 57. 58. 58a. 59. 60. 61. 62. 63.


Tressel, R., Apetz, M., Arrieta, R., Grunewald, K., in Flavor of Foods and Beverages, ed. G. Charalamborus and G. Inglett, Academic Press, 1978, p. 145. Labows, J.N., McGinley, K.J., Webster, G.F., Leyden, J . J . , J. Clin. Microbiol., 1980, accepted for publication. Cox, C.D., Parker, J., J . of Clin. Micro., 1979, 9: 479484. Kloek, J., Psychiat. Neurol. Neurochir., 1961, 64: 309. Kingsbury, A., Brooksbank, B.W.L., Hormone Res., 1978, 9: 254-270. Julesz, M., Acta Med., Academy Science Hungar., 1968, 25: 273. Brookbank, B.W.L., Experentia, 1970, 26: 1012. Brookbank, B.W.L., Brown, R., Gustafsson, J.A., Experentia, 1974, 30: 864. Gower, D.B., J. Ster. Biochem., 1972, 3: 45. Bird, S., Gower, D.B., J. Endocrinol, 1980, 85: 8p-9p. Claus, R., Alsing, W., J. Endocr., 1976, 68: 483. Labows, J.N., Preti, G., Hoelzle, E., Leyden, J., Kligman, A. Steroids, 1979, 3: 249-258. Amoore, J . E . , Pelosi, P., Forrester, J.L., Chemical Senses and Flavor, 1977, 2: 401. Spiteller, G., Pure and Appl. Chem., 1978, 50: 205. Labows, J.N. Jr., Perfumer and Flavorist, 1979, 4: 12-17.

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October 13, 1980.


Odorants as Chemical Messengers - ACS Symposium Series (ACS

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