Amino Alkaloids
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One or more carbon rings with a nitrogen atom on a carbon side chain. One of the most interesting alkaloids in this group is mescaline from Lophophora williamsii. Mescaline has a molecular structure that is remarkably similar to the brain neurotransmitter dopamine. It is also structurally similar to the neurohormone norepinephrine (noradrenalin) and to the stimulant amphetamine. In the peyote cactus, mescaline is formed in a complex pathway from the amino acid tyrosine.
AMINO ALKALOIDS
One or more carbon rings with a nitrogen atom on a carbon
side chain. One of the most interesting alkaloids in this group is mescaline
from Lophophora williamsii. Mescaline
has a molecular structure that is remarkably similar to the brain
neurotransmitter dopamine. It is also structurally similar to the neurohormone
norepinephrine (noradrenalin) and to the stimulant amphetamine. In the peyote
cactus, mescaline is formed in a complex pathway from the amino acid tyrosine.
A similar pathway in humans produces epinephrine (adrenalin) and its
demethylated precursor norepinephrine from tyrosine. Dopamine and its precursor
L-dopa are also derived from a tyrosine pathway, Mescaline also occurs in
several other cactus species, including the commonly cultivated,
night-blooming, South American San Pedro cactus (Trichocereus pachanoi).
Another alkaloid called ephedrine has a molecular structure
similar to that of mescaline. Since ephedrine has a chemical structure similar
to epinephrine (adrenalin), it works like a powerful cardiac stimulant that may
cause cardiac arrest in infants and heart patients. New synthetic drugs based
on the ephedrine/epinephrine ring structure are now marketed as effective and
safer bronchodilators. Pseudoephedrine, an isomer of ephedrine, also occurs in
species of Ephedra, and may be produced synthetically. Compared to ephedrine,
it causes fewer heart symptoms, such as palpitation, but is equally effective
as a bronchodilator.
Colchicine is a 3-ring amine alkaloid derived from the corms
of Colchicum autumnale, a member of
the lily family (Liliaceae). Like the anticancer indole alkaloids, vinblastine and
vincristine, it is a spindle poison causing depolymerization of mitotic
spindles into tubulin subunits. This effectively stops the tumor cells from
dividing, thus causing remission of the cancer. It is a powerful inducer of
polyploidy because it can stop plant cells from dividing after the chromatids
have separated during anaphase of mitosis. It is used as a mutagen.
