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Hugh McGuigan.

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226



CHEMICAL PHABMACOLOOY



H



H
H



H



H



N



or quinoline



H



\/ \



the three




hydrogen atoms of N^ — H may be regarded as being replaced



'\



\



H



CH— CH



\.



by a group ^^^

= CH— CH
which may be considered a tertiary amine.
H,



Piperidine,



H,



H2



H2



H2



may be classed as a secondary



NH



amine.



Tests for Amines



1. Like ammonia, they form white clouds of finely divided
salts, when brought in contact with HCl or other volatile acid.
The amines differ from ammonia in being combustible.

2. The amines can be separated from ammonia, if in solution
together, by making strongly alkaline with NaOH or Na2C0a.
Then the addition of very fine amorphous mercuric oxide, which
will precipitate the NHj, as follows:

2HgO + NH3 = HgjN.OH + H2O
The precipitate may be separated from the amines by filtration.



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AMINES 227

3. Primary and secondary amines will condense with formalde-
hyde while tertiary amines do not. The free bases can then be
regenerated by hydrolysis, and the difference in the distillation
temperature allows separation of primary from secondary.

4. Primary amines all give Hoflfinan's carbylamine reaction;
secondary and tertiary amines do not. r

R - NHj + CHCI3 + KOH = R - N = C + 3KC1 + SHjO

The disagreeable, indescribable odor is characteristic.

Another method of distinguishing primary, secondary and
tertiary amines is to determine 'the number of alkyl groups with
which the substance can combine. For example: A substance
having the formula C3H9N. might be:

(a) CsHtNEs — propyl amine — primary

(6) C2H6V

yNH — methyl ethyl amine — secondary or
CH3^

(c) CHav

CH3-7N — trimethyl amine — tertiary
CW

If when heated with an excess of CHjI a quaternary compound
should be formed in each case, with the primary amine this

would be: C3H7V

^NIorCeHieNI

(CH3)3"^

C2H6V
With the secondary it would be: yNIor CsHhNI

, with the tertiary: (CH3)4NI or C4H12NI

The determination of the amount of iodine added will decide
the question. The titration of the iodine may be done in a
manner similar to that described under thymol iodide.

Other tests for the dififerent amines are as follows:

/R -

First. — Primary amines N^H



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228 CHEMICAL PHARMACOLOGY

When primary amines are treated with nitrous acid HNO2,
they yield alcohols and nitrogen is evolved:



R.
+H0



H2

->R.OH + H,0 + Ns
O



This reaction is analogous to the reaction of nitrous acid with
ammonia, which yields nitrogen and water:



NHa + HNOj = H.



N



RO^



.H2 = N2 + 2H2O
O



Second, — Secondary amines. When these are treated with
nitrous acid they yield nitroso amines:

R. Rk

>N.HHO - NO = >N - N = O + H2O
W R^

Third. — Tertiary amines either do not react with nitrous acid
or are oxidized by it without the formation of definite products.

QUATERNARY AMMONIUM BASES
Ammonia, NHj, will imite directly with HCl to form

H



/h



w

In a similar way, tertiary amines unite with alkyl iodide to form
quaternary ammonium iodides or quaternary ammonium bases.
The physiological action of these quaternary bases differs from the
trivalent type. The characteristic action is a paralysis of the
motor nerve ending to striated muscle. This action seems to
depend more on the physical configuration of the molecule than
upon the chemical elements, since phosphorus or arsenic may be
substituted for nitrogen. This paralytic action is also exerted
by alkaloids in which the nitrogen is quinquivalent, siich as
curare, methyl strychnine, methyl quinine, methylmorphine,
ethyl brucine, and ethyl nicotine.



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AMINES 229

Sources of Amines

Amines occur in nature as the decomposition products of
proteins, and the decarboxylation of amino acids, e,g. :

CHaNHaCOOH-^CHsNHz + CO2
CHaCHsNHaCOOH-^CHaCHzNHa + CO2

In this way amines corresponding to all the known amino
acids are thought to have arisen. This process is favored by the
presence of some peptone which serves as a source of nitrogen
for the bacteria and in this way prevents deaminization. They
may also be prepared synthetically; if a concentrated solution
of ammonia be heated in a sealed tube with an alkyl iodide, the
corresponding amine is formed:

NH3 + CHsI-^NHaCCHs) + HI

By further action of the methyl iodide, the other H atoms of
the ammonia may be substituted.

NH3 + CH3I = CH3.NH2.HI

Methylamine hydriodide.

CH3.NH2 + CH3I = (CH3)2 NH.HI

Dimethylamine hydriodide.

(CH3)2NH + CH3I = (CH3)3N.HI

Trimethylamine hydriodide

(CH3)3N + CH3I = (CH3)4N.I

Tetramethyl ammonium iodide.

Trimethyl amine can also be formed by heating ammonium chlo-
ride with formalin in an autoclave at 120-1 60°C. (cf. urotropine)

2NH3 + 9CH2O -^ 2(CH3)3N + CO2 + 3H2O

Amines may also be prepared by the reduction of nitro com-
pounds

CH3NO2 + 3H2 -^ CH3NH2 + 2H2O
Nitro methane methylamine

This is a common method of obtaining phenyl amine or aniline

C6H6NO2 + 3H2 -^ C6H5NH2 + 2H2O
Nitro-benzene Aniline



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230



CHEinCAL PHABMACOLOGY



These aromatic amines may also be primary, secondary or
tertiary as in case of the alkyls



Primary
•CcHs

phenylamine or Ani-
line

•CbHs

Aniline or phenyl-
amine



Secondary

•CeHft
N^CHs
\ H

phenyl
Methylamine

•CeHe
NfCH,

Diphenylamine



Tertiary



CeHs



N^CHs
^CHa
phenyl
Dimethylamine

N^CeHfi
\C5H5
Triphenylamine



The aromatic amines are more active pharmacologically than the
aliphatic.
Amines may also be prepared by reduction of nitrils

CH3 CN + 4H -* CfisCHjNHs
Methyl nitrile

CeHfiCN + 4H -* CeHftCHjNHj
Benzo nitrile Benzyl amine

The Physiological Action of the Amines

When anmionia is injected intravenously or when given other-
wise in rather strong solution it stimulates respiration and by
stimulation of the central nervous system may cause convulsions.
As the H atoms of ammonia are replaced by alkyl radicals, the
stimulating action is much diminished, and the extent of the
diminution increases with the molecular weight of the substi-
tuted alkyl.

Alkyl groups are cerebral depressants and the hypnotic action
of alcohol, ether, etc., is due to the alkyl groups. When quater-
nary amine bases are formed, the action becomes paralytic due
to a paralysis of the motor nerve ends in a manner similar to
that effected by curara. The nitrogen atom in the quaternary
amine has little to do with the curara action, since the corre-
sponding phosphorus and arsenic compounds have a like action.

Many amines (substituted ammonias) raise the blood pressure



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AMINES 231

after the maimer of nicotine and epinephrine. Barger and Dale
have made a rather exhaustive study of the physiological effects
of the amines on the rise in blood pressure, the action on the uterus,
pupil; etc. (Journal of Physiol., 1910, 41, p. 19) and have com-
pared the action on these locations with that of epinephrine.
Of the aliphatic amines, only the higher open chain primary
amines such as amyl amine, CsHnNHa, and hexyl amine,
CttHi8NH2, produced a marked rise in blood pressure. Isobutyl
amine, C4H9NH2, is the first to cause any significant rise. The
normal straight chained compounds were more eflfective than
the isocompounds. Cadaverine, NH2(CH2)6NH2, the only
diamine examined, caused a fall of blood pressure instead of a
rise. Trimethyl amine and tetramethyl amine were inactive,
and of little physiological importance.

A large number of aromatic compounds vrUhoiU a phenolic OH
and containing an amine aliphatic side chain were investigated,
and it was found that only when the amino group in the side
chain is attached to the second carbon from the ring is there a
marked epinephrine — ^like action. Beta-phenyl ethyl amine
produced all the actions of epinephrine.

Amines with one phenolic hydroxyl group in the orthp position,
such as ortho hydroxyphenyl ethyl amine



>CH2.CH2NH2,



HO i

are no more active than phenyl ethyl amine itself. The para
compound which is present in ergot (tyramine) and may also be
prepared by heating tyrosin



H0< >CH2CH.C00H

NH2
has a similar action.

The pressor or blood pressure raising property in this case
depends on the basic property of the substance, for acetyl p.
hydroxyethyl amine



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232 CHEMICAL PHARMACOLOGY



H0< >CH2.CH2NH CO.CHs



is inactive. The tyrosin ester



COOC2H5



HOC >CH2.CH:



^NH2



is also inactive. Methylation or ethylation of the amino group



H0< >CH2.CH2NH.R



changes the action but slightly and the alkaloid hordenine, which
is the tertiary base, has a very weak action



H0< >CH2.CH.N(CH3)2



Amines with two phenolic hydroxyl compounds were tested
and their comparative effect on the blood pressure is as follows
(arranged after Percy May Synthetic Drugs) :

Amines with Two Hydroxyl Compounds. — The following
compounds in which the two hydroxyl groups are in the 3-4
position were tested:

(a) Derivatives op Aceto-catechol (Ketones)

Ratio of

(1) Amino-aceto-catechol, Activity

(HO)2C6H3— CO-CHa— NH2. 1 . 50

(2) Methylamino-aceto-catechol —

(HO)2C,H3— CO— CH2— NH— CHs.

(3) Ethylamino-aceto-catechol —

(HO)2C6H3— CO— CH2— NH— C2H6. 2.25

(4) Propylamino-aceto-catechol —

(HO)2C6H3— CO— CH2— NH— CeHy 0.25

(5) Trimethylamino-aceto-catechol chloride

(HO)2C6H3— CO— CH2— N(CH3)3C1.



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AMINES 233

(6) Derivatives of Ethyl-catechol

(6) Amino-ethyl-catechol,

(HOaCeHs— CHa— CH2— NH2. * 1 . 00

(7) Methylamino-ethyl-catechol —

(HO)sC6H3— CH2— CH2— NH— CHs. 5 . 00

(8) Ethylamino-ethyl-catechol —

(HO)2C6Hj^CH2— GHz— NH— C2H6. 1 . 50

(9) Propylamino-ethyl-catechol —

(HO)2C6H8— CH2— CH2— NH— C3H7 . 25

(10) Trimethylamino-ethyl-catechol chloride —

(HO)2C6Hr^CH2— CH2— N(CH8)3C1

(c) Derivatives of Ethanol-catechol (Secondary
Alcohols)

(11) Amino-ethanol-catechol —

(HO)2C6H3CH(OH)— CH2— NH2. 50.00

(12) Methylamino-ethynol-catechol (adrenaline) —

(HO)2C«H3CH(OH)— CH2— NH— CHs 35 . 00

The main conclusions of Barger and Dale from their Investiga-
tion of the amines are:

1. An action simulating that of the true sympathetic nervous
system is not peculiar to adrenine, but is possessed by a large
series of amines, the simplest being primary fatty amines. We
describe all such amines and their action as "sympathomiirietic. ''

2. Approximation to adrenine in structure is, on the whole,
attended with increasing intensity of sympathomimetic activity,
and with increasing specificity of the action.

3. All the substances producing this action in characteristic
manner are primary and secondary amines. The quaternary
amines corresponding to the aromatic members of the series
have an action closely similar to that of nicotine.

• 4. The optimiun carbon skeleton for sympathomimetic activity
consists of a benzene ring with a side chain of two carbon atoms,
the terminal one bearing the amino group. Another optimum
condition is the presence of two phenolic hydroxyls in the 3-4
position relative to the side chain; when these are present, an
alcoholic hydroxyl still further intensifies the activity. A phenolic
hydroxyl in the 2 position does not increase the activity.
5. Catechol has no sympathomimetic action.



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234



CHEMICAL PHARBIACOLOGY



6. Motor and inhibitor sympathomimetic activity vary to
some extent independently. Of the catechol bases those with
a methylamino group, including adrenine, reproduce inhibitor
sympathetic effects more powerfully than motor effects: the
opposite is true of the primary amines of the same series.

7. Instability and activity show no parallelism in the series.

The amines are very slightly toxic and their ultimate fate es-
pecially that of the lower members in the body is perhaps similar
to ammonia, urea and carbon dioxide being the ultimate products.
In some cases various intermediate products are formed. Ewins
and Laidlow f oimd that one-half the amoimt of p. hydroxy phenyl
amine given by mouth to dogs was excreted in the urine as para
hydroxy phenyl acetic acid. This same conversion of the amine
into the acid occurred when it was perfused through the rabbit's
liver, but when perfused through the isolated heart it was com-
pletely destroyed without the formation of acid. In the vast
majority of the cases, however, little is known of the fate in the
body. In view of the great activity of histamine and its probable
relation to anaphylactic shock and to the toxicity of proteins as
emphasized by Vaughan, many think that a detailed investi-
gation of the fate of the higher amines, especially those like his-
tidine and the more complex peptamine will go far to explain
symptoms now classified as ptomaine poisoning or other equally
vague terms.

ALKALOIDS DERIVED FROM ALIPHATIC AMINES
A niunber of important alkaloids are aUphatic derivatives or
combinations. The most important in pharmacology are:
1. Epinephrine



2. Arginine

3. The putrefactive alkaloids



Betaine
Choline
Muscarine



Putrescine



Cadaverine



4. Ergot alkaloids



Tryamine,
Histamine,
Ergotoxine,
Isoamylamine.

5. Sinapine

6. Hordenine

Epinephrine or the pressor principle of the adrenal glands is
a derivative of para hydroxyphenylethyl amine



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AMINES



235



H0<

and has the formula
OH— <



>CH2CH,NHa



NcH(OH)CH 2.NH.CH8



It was first isolated by Abel in 1879 and. 1899* (Zeit. f. Physiol.
Chem., 1898, 28, 318; and Am. Jour. Physiol., 1900, 3, XVII)
and by Takamine who obtained it in crystalline form and from
its decomposition thought he obtained catechol and pyrocate-
chuic acid. These products have been used in the preparation
of synthetic epinephrine. It has since been isolated and analyzed
by others. It has also been prepared synthetically. The natural
product is a slightly yellowish powder, and levo-rotatory. The
synthetic product is optically inactive and resolvable into a
dextro and levo form. Th natural product is twice as effective
as the synthetic judged by its action in raising the blood pres-
sure. The levo form is about 12 times as active as the dextro.
The action on the blood pressure is due to a stimulation of the
sympathetic nerve endings to the heart and blood vessels. Its
action in any location can be predicted if we know the result of
stimulation of the regional sympathetics. In the intestine and
bronchioles, stimulation of the sympathetics causes a relaxation
and dilation; and in these regions, epinephrine has a like effect.
Because it mimics the action of the sympathetics, Barker and
Dale suggest the terln sympath-o-mimetic, to describe its action.
The synthesis of epinephrine has been effected by Friedman
as follows:

OH OH



OH + CI.CO.CH2CI



OH



Catechol + Chloracetylchloride



CO.CH2CI
► chloracetyl catechol



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236



CHEMICAL PHABHACOLOGY
OH



+ HNH-CHs



OH



CO.CH2.NH.CH,
Methylamine Methyl amino aceto catechol or adrenalone

OH



+ Hj >



OH



HC(OH)CH2.NH.CH3
Epinephrine.

Epinephrine has been prepared by another method, starting
with pyrocatechuic aldehyde



0H<



>CHO + HCN



OH

Pyrocatechuic
aldehyde



OH



> CHOH.cn + Reduction



OH



0H<



>



COHH.CH2.NH2 which on methylation



OH



> 0H<



)CHOH.CH2.NH.CH8.



OH Epinephrine



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AMINES 237

This is the accepted formula — others suggested are:



CH2CHOH.NH.CH8 and




CH.NH.CH3

\
CH2OH

In favor of the accepted formula I is the fact that methyl-
amino aceto catechol or adrenalone from which adrenaline may
be prepared by reduction, is formed by the action of methyl
amine on chloracetyl catechol




H04 >— CH2— CH2.N(CH3)2



Hordenine.



Hordenine, an alkaloid in malt, is very closely related to epine-
phrine in structure, but its action is more like phenol than epine-
phrine. It is only slightly toxic:

1 gram per kilo per os in a dog or rabbit causes some rise in
blood pressure and acceleration of the pulse. It acts both on
sympathetic and para sympathetic endings, and also centrally.
After a fatal dose, which for a dog is 0.3 gm. per kilo intraven-
ously, death occurs from respiratory failure — similar to phenol.

Epinephrine Tests

1. To a dilute solution of adrenaline chloride or an extract of
the gland, add a few drops of ferric chloride. An emerald green .
color develops but this is quite transient (phenolic reaction).

2. To a solution add some sodium carbonate. A reddish color
is formed. Alkalies destroy the physiologic effect of the substance
rapidly.

3. Physiological test: 1 cc. 1-10,000 solution injected into the
vein of a mammal will cause a great rise in blood presure.



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238 CHEMICAL PHARMACOLOGY

ARGININE

Arginine is physiologically inactive in animals, consequently is
of little interest from a purely pharmacodynamic point of view.
Chemically it is alpha amino guanidine valerianic acid.

NH2

.1

C = NH

I
N— H

I
H— C^H

I
H — C— H

H— C— H

I
H— (>-NH2

I
O =O-0H

All proteins contain arginine, and the head of salmon sperm
yields nearly 90 per cent. Arginine, lysine and histidine have
been called hexone bases, by Kossel, because they contain 6
carbon atoms, and he thought proteins were built up of such
amino acids in a manner similar to the formation of complex
carbohydrates from hexoses. The relationship of proteins to
alkaloids is again apparent here.

The Fate of Arginine in the Body

By the action of so-called carboxylase bacteria, which decar-
boxylate arginine, agmatine is formed :

NH2— C(NH)— NH.CH2(CH2)2CHNH2.COOH =

Arginine.

CO2 + NH2.C(NH).NH.CH2(CH2)2.CH2NH2
Agmatine.

Agmatine has also been obtained from ergot and has been
synthesized by Kossel. It is regarded as amino butylene guanid-
ine. According to Dale and Laidlow agmatine contributes but



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AMINES 239

little to the activity of ergot. It acts like histamine but is only
1/50 as active. Arginine may also be split in the body by an
enzyme into urea and ornithine, i.e. alpha d-diaminovaleric acid.

/NH2 NH2

NH = C^ I

HO^^ "^NH— CH2— (CH2)2— CH— COOH
H

NH2 NH2

CO + NH2— CH2— (CH2)2— CH— COOH

I
NH2

This change may also be accomplished by boiling with alkali.
A further decomposition of the ornithin to ammonia and carbon
dioxide may occur.

PTOMAINES OR PUTREFACTIVE ALKALOIDS

Ptomaines or putrefactive alkaloids are products of the putre-
faction of meat. They are basic bodies, usually amines of simple
constitution, such* as methyl alxiine CH8NH2 — dimethyl amine
(CH8)2NH or trimethyl amine (CH3)8N.

Many ptomaines are toxic, others non-toxic. The toxicity
may be due in part to ptomaines directly and in part to associ-
ated unknown toxins.

In their reactions ptomaines may resemble some alkaloid.
This pharmacologic and chemical resemblance may make the
identification of the alkaloids difficult. The similarity, however,
is usually confined to one of the reactions of the alkaloid, and
never extends to all the reactions characteristic of any particular
alkaloid. Ptomaines have been found that show certain re-
semblances to coniine, nicotine, codeine, strychnine, veratrine,
atropine, hyoscyamine and morphine; but as stated above these
resemblances are frequently confined to one reaction and never
in any case agree with all the characteristic reactions of the
alkaloid.

Ptomaines are of limited importance as medicines, having a
toxicologic interest only. Their great toxicity is probably due



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240 CHEMICAL PHABHACOLOOY

to the inability of the body to oxidize them, even in minute
amoimt.
The most important ptomaines are:

Putrescine NH2(CH2)4NH2

Cadaverine NH2(NH2)8NH2

Choline N(CH,),OH

I
CHjCHjOH

Muscarine N(CH3)30H

I
CH2CHO

Betaine N(CH,)8v

I >o

Neurine N(CH3)80H

CH = OH

Choline, muscarine, betaine, and neurine are sometimes called
the betaines.

Putrescine: (from putresco, to rot or putrefy), or tetramethy-
lene diamine —

NH2.CH2.CH2.CH2.CH,.NH2

occurs associated with cadaverine. It was first obtained from
putrefying human internal organs. It has also been found
in the excreta of cholera patients, and in the urine in cases of
cystinuria. Carbohydrate diet lessens the amount excreted in
these cases, while meat diet increases it. This points to protein
as the source of putrescine. Normal feces do not contain it.
The use of salol, sulphur, and other intestinal antiseptics does
not appreciably influence the amount excreted. Garcia, how-
ever, has shown that when cane sugar is added to putrefying
meat and pancreas in vitro, less diamine is formed. The bacteria
forming the diamines apparently live on the sugar in preference
to the protein. Sugar or carbohydrate for this reason has been



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AMINES 241

advocated as the preferable diet in many cases of gastro-intes-
tinal putrefactions.

The relation of putrescine to cystinuria is but little under-
stood. It was suggested that putrescine and other diamines
united with cystin to prevent its oxidation. When diamines
are fed to dogs no cystinuria occurs, and the formula of cystine

H H

I I

H — C— S S C— H

I I

NH^C— H H— C NH2

I I

O = C— OH O = C— OH

does not suggest an origin from the diamines.

The source of putrescine is most probably directly from orni-
thine or a, €, diamino valeric acid.

Nfl2.CH2.CH2.CH2,CH2.NH.COOH->
ornithine

NH2.CH2.CH2.CH2.CH2.NH2.+CO2
putrescine.

Putrescine has also been prepared synthetically. Addition
or substitution products can be readily formed. The tetramethyl
derivative N(CH8)2(CH2)4N(CH3)2, is much more poisonous
than putrescine, and resembles muscarine in action. The symp-
toms are: nausea, vomiting, salivation, increase then decrease of
respiration, contracted pupils, diarrhoea and collapse. Atropine
will counteract many but not all of these symptoms.

Cadaverine or penta-methylene diamine is found associated
with putrescine and is formed similarly. It is probably formed
from lysine or a, €, diamino caproic acid by decarboxylation:

NH2.CH2.CH2.CH2.CH2.CHNH2COOH—
lysine

NH2.CH2.CH2.CH2.CH2.CH2.NH2. + CO2

and is probably identical with so-called animal coniine which
has been isolated from cadavers, it may produce marked in-
flammation and necrosis, and like turpentine and some other

16



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242 CHEMICAL PHARMACOLOGY

drugs, can cause suppuration in the absence of bacteria. With
putrescine it probably causes the cystitis of cystinuria. It is
not very poisonous however, — ^large doses will kill mice, but it is
relatively non-poisonous to dogs.

By heating pentamethylene hydrochloride piperidine may be
formed which has a definite toxic action:



/CHj.CHjNH


H


+ HC1


NHs


CHj


/\


CH, CH,


+ NH4CI


CH2 CH,


\y


NH


Piperidine.





By oxidation of piperidine to pyridine the toxicity is again
markedly reduced.

Choline (chole-bile). — Choline is partly amine and partly
alcohol. It is found as a constituent of lecithin, which occurs
especially in nervous tissue, egg-yolk, seeds, and elsewhere. It
is also found in ergot, and io many-plants. Its composition is
shown by its synthesis from trimethylamine and ethylene oxide
in aqueous solution

(CH3),N -I- CHj. CH2 /CH2.CH2OH

\y +n,o = (ch.),n(

O ^OH Choline

It is related to muscarine and to neurine:

/CH2.COH /CH:CH2

(CH,)aN< (CH,),N^

Muscarine Neurine

While choline is but slightly toxic, its dehydrated product neurine
is extremely toxic. In the formation of neurine from choline, by
the elimination of a iholecule of water, a double-bonded carbon



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CHOLINE



243



combination is formed. If this double-bond is changed to a
triple bond by the fonnation of



(CH,)3N;



\



C:CH



OH



the product is still more toxic. See p. 148 for influence of triple
bond.

The formation of choline from lecithin can be seen from the
formula of lecithin, R and R' being similar to dissimilar acid
radicals :

CH2OR

I
CHOR'



/OH
CH.O— PC = O



^0— CH2.CH2.N(CH3)3.0.H

Lecithin, however, cannot be regarded as the only soiu*ce of



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