such as sugars, vitamins, and flavoring agents. Animals eat fruit and thereby
help in the dispersion of seeds.
(d) Some chemicals are involved in cellular functions which are unparalleled to
certain plants such as resistance to salt or resistance to drought.
The various classes of secondary plant metabolites include:
(1) Alkaloids
(2) Saponins
(3) Phenolics
(4) Terpenes
(5) Carbohydrates
(6) Lipids
(7) Glycosides.
10.2 Alkaloids
Alkaloids are organic heterocyclic compounds having minimum one nitrogen atom
in the ring or outside the ring. The term alkaloid is originated from “alkali-like” and
hence, they show alkaline character due to the presence of lone pair electrons on the
nitrogen atom. They become like the characteristics of some naturally derived
complex amines. They include greater than 6000 nitrogenous compounds in about
15% of vascular terrestrial plants and spread in more than 150 plant families. The
proper definition of alkaloids may not be described because they exist as a variety
of group of compounds (Giweli et al. 2013). The only similarity in these compounds is that all these compounds have nitrogen atom. All alkaloids are not
defined by a common definition. A huge number of alkaloids are isolated from
different plant sources. Since alkaloids have a vast variation with respect to
chemical structure present in these compounds, botanical sources, physiological
responses, similar biochemical origin in spite of different taxonomic distribution
and pharmacological activities, and therefore, they are classified chemically, taxonomically, pharmacologically and biosynthetic way, respectively (Tadeusz 2015;
Nicolaou et al. 2011; Aniszewski 2007).
Chemically alkaloids are subclassified into three groups (Kokate et al. 2005;
Clarke1970).
a. True alkaloids (Heterocyclic alkaloids): they are originated from amino acids
and contain a heterocyclic ring.
b. Proto alkaloids (non-heterocyclic alkaloids): They are originated from amino
acid but the nitrogen atom is not present in the ring structure
c. Pseudo alkaloids: They are not originated from amino acids but from purine or
terpenoids. They have a nitrogen-containing heterocyclic ring (Table 10.1).
They are classified as follows:
10 Secondary Metabolites from Plant Sources
333
help in the dispersion of seeds.
(d) Some chemicals are involved in cellular functions which are unparalleled to
certain plants such as resistance to salt or resistance to drought.
The various classes of secondary plant metabolites include:
(1) Alkaloids
(2) Saponins
(3) Phenolics
(4) Terpenes
(5) Carbohydrates
(6) Lipids
(7) Glycosides.
10.2 Alkaloids
Alkaloids are organic heterocyclic compounds having minimum one nitrogen atom
in the ring or outside the ring. The term alkaloid is originated from “alkali-like” and
hence, they show alkaline character due to the presence of lone pair electrons on the
nitrogen atom. They become like the characteristics of some naturally derived
complex amines. They include greater than 6000 nitrogenous compounds in about
15% of vascular terrestrial plants and spread in more than 150 plant families. The
proper definition of alkaloids may not be described because they exist as a variety
of group of compounds (Giweli et al. 2013). The only similarity in these compounds is that all these compounds have nitrogen atom. All alkaloids are not
defined by a common definition. A huge number of alkaloids are isolated from
different plant sources. Since alkaloids have a vast variation with respect to
chemical structure present in these compounds, botanical sources, physiological
responses, similar biochemical origin in spite of different taxonomic distribution
and pharmacological activities, and therefore, they are classified chemically, taxonomically, pharmacologically and biosynthetic way, respectively (Tadeusz 2015;
Nicolaou et al. 2011; Aniszewski 2007).
Chemically alkaloids are subclassified into three groups (Kokate et al. 2005;
Clarke1970).
a. True alkaloids (Heterocyclic alkaloids): they are originated from amino acids
and contain a heterocyclic ring.
b. Proto alkaloids (non-heterocyclic alkaloids): They are originated from amino
acid but the nitrogen atom is not present in the ring structure
c. Pseudo alkaloids: They are not originated from amino acids but from purine or
terpenoids. They have a nitrogen-containing heterocyclic ring (Table 10.1).
They are classified as follows:
10 Secondary Metabolites from Plant Sources
333