The Contribution of cocoa additive to cigarette smoking addiction

Page 198 of 207 RIVM report 650270002
unlikely that cocoa will affect the addiction to cigarette smoking through the psychoactive
compound phenylethylamine. Because phenylethylamine exposure through smoking is
relatively high compared with the exposure level through food, it is interesting to investigate
the contribution of phenylethylamine to the addiction to cigarette smoking.
Derivatives of phenylethylamine are stimulant and hallucinogenic substances such as
amphetamine, mescaline and some neurotransmitters such as dopamine, adrenaline and
noradrenaline. Phenylethylamine is classified as a neuromodulator of dopaminergic and
possibly serotinergic and noradrenergic synapses. Phenylethylamine has biphasic effect on
guinea pig isolated lung. After an initial relaxation at low concentration (10 -7 – 10 -5 M) it
induces contraction at higher concentration (10 -4 – 10 -3 M). When phenylethylamine was
perfused in guinea-pig lung, the pulmonary MAO inactivated 95 % of phenylethylamine,
indicating a rapid metabolisation by MAO. It is unclear how these results can be extrapolated
to the effect of phenylethylamine in cigarette smoke on the bioavailability of nicotine in the
pulmonary system. Phenylethylamine has reinforcing properties comparable to amphetamine.
Whether phenylethylamine in cigarettes plays a role to the reinforcing effect of cigarette
smoking is unknown. Phenylethylamine, like tryptophan, contains reactive groups and forms
reaction products during combustion, which have MAO-I properties. Therefore,
phenylethylamine may play a role in the cigarette smoking addiction through the MAO-I
effects of its reaction products.
It can be concluded that phenylethylamine level from added cocoa to cigarette is insufficient
to exert any physical effect. However, the phenylethylamine level originating from tobacco
may increase the addiction to cigarette smoking by its reinforcing properties or by the MAO-I
properties of its reaction products.
4.2.7 Tryptamine
Tryptamine occurs naturally in tobacco plant and in cocoa. The estimated tryptamine level in
cigarettes originating from tobacco is at least 5000 times higher than from added cocoa.
Therefore, it is unlikely that cocoa will affect the addiction to cigarette smoking through its
psychoactive compound tryptamine. Because the tryptamine level is relatively high compared
with the exposure level through food, it is interesting to investigate the contribution of
tryptamine to the addiction to cigarette smoking. There are not enough data on the pulmonary
effects of tryptamine through smoking. Although tryptamine does affect the serotonin activity
in the brain, it is unknown whether tryptamine plays a role in the tobacco dependency
process. Furthermore, tryptamine is a substrate for MAO and will be metabolised rapidly by
absorption through the pulmonary system. Tryptamine, like tryptophan and
phenylethylamine, contains reactive groups and forms reaction products during combustion,
such as beta-carbolines, which has MAO-I properties. Therefore, tryptamine may play a role
in the cigarette smoking addiction through the MAO-I effects of its reaction products.
4.2.8 Tyramine
Tyramine is a natural compound of tobacco plant and cocoa. The estimated tyramine level in
cigarettes originating from tobacco is at least 2700 times higher than from added cocoa.
Therefore, it is unlikely that cocoa will affect the addiction to cigarette smoking through the
psychoactive compound tyramine. Because tyramine level in cigarettes (10 mg/25 cigarette)
is relatively high compared with the exposure level through food (< 10 mg/day), it is
interesting to investigate the contribution of tyramine to cigarette smoking addiction.
Tyramine is an indirectly acting sympathomimetic substance. Tyramine releases
noradrenaline from the sympathetic nervous system and leads to physiological reactions, such
as increased blood pressure. Any direct effect of tyramine on the addiction to cigarette