Chemistry Reference
In-Depth Information
Figure 1.14
Coumarins, stilbenes, flavonoids, anthocyanidins, and isoflavonoids of plant
origin.
the most important of which include terpenoid and steroidal alkaloids. A limited
number of alkaloids that contain a purine ring (e.g., caffeine) also occur in plants.
Of the large number and variety of plant alkaloids, only a few are considered
here for the purpose of illustration of their chemical diversity.
1.6.1 Alkaloids Derived from Aliphatic Amino Acids and Nicotinic Acid
Alkaloids that contain pyrrolidine and pyrrolizidine ring systems are derived from
the nonprotein amino acid, L-ornithine. Cocaine (
N1
)and(
−
)-hyoscyamine, the
two important pyrrolidine alkaloids that contain a tropane ring system, have been
found to occur in coca (
Erythroxylon coca
, Erythroxylaceae) leaves and the whole
plant of the deadly nightshade (
Atropa belladonna
, Solanaceae). The hepatotoxic
alkaloid senecionine (
N2
) contains a bicyclic pyrrolizidine skeleton derived from
two molecules of L-ornithine.
Piperidine alkaloids, for example, piperine (
N3
), and pseudopelletierine, are
known to be derived from the amino acid, L-lysine. Piperine is responsible for the
pungency of black pepper (
Piper nigrum
, Piperaceae), whereas pseudopelletier-
ine is a constituent of the bark of pomegranate (
Punica granatum
, Punicaceae).
