Nitrogen-Containing Compounds - Natural Products Chemistry: Sources, Separations, and Structures - page 76

N

H

N

H

O

O

H

FIGURE 7.13 Chemical structure of the naturally occurring alkaloid strychnine.

used as a pesticide, causing muscular convulsions leading to death through asphyxia.
The compound is isolated from the seeds of the plant Strychnos nux- vomica .
It should be noted that many other alkaloids are produced in nature by a large
variety of organisms, including bacteria, fungi, plants, and animals. Due to the basic
nature of the nitrogen in their alkaloid skeleton, they can be isolated and purified
from crude extracts using a combination of acid-base extraction against immiscible
solvents such as dichloromethane (DCM). Alkaloids are often divided into the fol-
lowing major groups:

1. Alkaloids containing nitrogen in the heterocyclic and originating from
amino acids, for example, atropine, nicotine (see Chapter 1, Figure 1.4),
and morphine (see Figure 8.1).

2. “Protoalkaloids” that originate from amino acids, for example, mescaline,
adrenaline, and ephedrine (Figure 7.14). Ephedrine is commonly used as a
decongestant in over-the-counter preparations and also used as an appetite
suppressant. Ephedrine is similar in molecular structure to the well-known
drug methamphetamine, as well as to the important neurotransmitter epi-
nephrine (adrenalin). Chemically, ephedrine is an alkaloid with a phenethyl-
amine skeleton found in various plants in the genus Ephedra . In Traditional
Chinese Medicine (TCM), the herb, known in Chinese as má huáng from
the plant Ephedra sinica , contains ephedrine and pseudoephedrine as the
principal active constituents.

3. Polyamine alkaloids, for example, spermidine (Figure 7.15). Spermidine
was originally isolated from semen, as its name suggests. It is a simple lin-
ear chain polyamine compound and found in ribosomes and living tissues.
Polyamines are polycationic aliphatic amines and serve important roles in
cell survival. Their main function in the body is to synchronize several bio-
logical processes (such as Ca 2+ , Na + , K + -ATPase) affecting the membrane
potential and controlling intracellular pH and volume.

OH

CH 3

HN

CH 3

FIGURE 7.14 Example of a protoalkaloid ephedrine.