Although human beings have been using different parts of plants from the ancient
age as drinks like tea, or as medicines like antimalarial, narcotic analgesics, but these
alkaloidal substances were not separated and identified from the plant sources up to
the beginning of the nineteenth century due to unavailability of modern analytical
instruments (Seigler 1995). Alkaloids are not present in the lower plants. Lysergic
acid derivatives (LSD) and gliotoxins (alkaloids having sulphur atom) are available
in fungi. Other kinds of alkaloids such as ephedra, taxol, and lycopodium present in
pteridophytes and gymnosperms are reported for their medicinal values. Based on
the taxonomic characteristics, the alkaloids are classified as (a) Centrospermae
belonging to the family Chenopodiaceae, (b) Magnoliales belonging to the families
Lauraceae, Magnoliaceae, (c) Ranunculales belonging to the families
Berberidaceae, Menispermaceae, Ranunculaceae, (d) Papaverales belonging to the
families Papaveraceae, Fumariaceae, (e) Rosales belonging to the families
Leguminosae, subfamily Papilionaceae, (f) Rutales belonging to the family
Rutaceae, (g) Gentiales belonging to the families Apocynaceae, Loganiaceae,
Rubiaceae, (h) Tubiflorae belonging to the families Boraginaceae, Convolvulaceae,
Solanaceae (i) Campanulales belonging to the family Campanulaceae having
subfamily Lobelioideae, and another family Compositae having subfamily
Senecioneae. But yet, no such scientific proofs are available to show the availability
of alkaloids in the plants of various dicot orders such as Salicales, Cucurbitales,
Fagales, and Oleales (Evans 2009).
Chemicals found in fruits inhibit spoilage of fruits and provide signals in the
form of color, aroma, and flavor to prove the presence of significant materials such
as sugars, vitamins, and flavoring agents. Alkaloidal substances exhibit a lot of
biological properties such as a) analgesic or painkiller, i.e.,morphine, colchicine; b)
local anesthesia, i.e., cocaine; c) respiratory stimulation and relaxation, i.e.,
arecoline, lobeline; d) vasoconstriction, muscle relaxation, i.e., d-tubocurarine; e)
anti-neoplastic, i.e., vincristine, vinblastine; f) hypotensive properties, i.e., reserpine, protoveratrine, and g) cardiac stimulation, i.e., ephedrine. The alkaloids also
show another type of biological properties mentioned in the various journals like
protection of plants from the herbivorous animals, arrest the growth or killing the
bacteria, anticancer property, action against fungi and viruses, causing cancer.
Some of the alkaloids are so toxic that they can even cause the death of animals.
Several alkaloids like as nicotine and anabasine are useful as insecticides (Seigler
1995; Hoffmann 2003).
Various categories of alkaloids having different taxonomic distribution and
pharmacological activities can be brought under the same category. This classification provides the significance of the precursor from which the alkaloids are
biosynthesized in the plant. The alkaloids are biosynthetically classified on the basis
of their amino acid precursor like lysine, tyrosine, phenylalanine, ornithine, tryptophan, etc. (Kokate et al. 2005).
The chemical structures of some major amino acid precursor are represented
below (Fig. 10.2).
The chemical structures of some well-known alkaloids (Fig. 10.3), are as follows
(Kokate et al. 2005; Tyler et al. 1988).
10 Secondary Metabolites from Plant Sources
335
age as drinks like tea, or as medicines like antimalarial, narcotic analgesics, but these
alkaloidal substances were not separated and identified from the plant sources up to
the beginning of the nineteenth century due to unavailability of modern analytical
instruments (Seigler 1995). Alkaloids are not present in the lower plants. Lysergic
acid derivatives (LSD) and gliotoxins (alkaloids having sulphur atom) are available
in fungi. Other kinds of alkaloids such as ephedra, taxol, and lycopodium present in
pteridophytes and gymnosperms are reported for their medicinal values. Based on
the taxonomic characteristics, the alkaloids are classified as (a) Centrospermae
belonging to the family Chenopodiaceae, (b) Magnoliales belonging to the families
Lauraceae, Magnoliaceae, (c) Ranunculales belonging to the families
Berberidaceae, Menispermaceae, Ranunculaceae, (d) Papaverales belonging to the
families Papaveraceae, Fumariaceae, (e) Rosales belonging to the families
Leguminosae, subfamily Papilionaceae, (f) Rutales belonging to the family
Rutaceae, (g) Gentiales belonging to the families Apocynaceae, Loganiaceae,
Rubiaceae, (h) Tubiflorae belonging to the families Boraginaceae, Convolvulaceae,
Solanaceae (i) Campanulales belonging to the family Campanulaceae having
subfamily Lobelioideae, and another family Compositae having subfamily
Senecioneae. But yet, no such scientific proofs are available to show the availability
of alkaloids in the plants of various dicot orders such as Salicales, Cucurbitales,
Fagales, and Oleales (Evans 2009).
Chemicals found in fruits inhibit spoilage of fruits and provide signals in the
form of color, aroma, and flavor to prove the presence of significant materials such
as sugars, vitamins, and flavoring agents. Alkaloidal substances exhibit a lot of
biological properties such as a) analgesic or painkiller, i.e.,morphine, colchicine; b)
local anesthesia, i.e., cocaine; c) respiratory stimulation and relaxation, i.e.,
arecoline, lobeline; d) vasoconstriction, muscle relaxation, i.e., d-tubocurarine; e)
anti-neoplastic, i.e., vincristine, vinblastine; f) hypotensive properties, i.e., reserpine, protoveratrine, and g) cardiac stimulation, i.e., ephedrine. The alkaloids also
show another type of biological properties mentioned in the various journals like
protection of plants from the herbivorous animals, arrest the growth or killing the
bacteria, anticancer property, action against fungi and viruses, causing cancer.
Some of the alkaloids are so toxic that they can even cause the death of animals.
Several alkaloids like as nicotine and anabasine are useful as insecticides (Seigler
1995; Hoffmann 2003).
Various categories of alkaloids having different taxonomic distribution and
pharmacological activities can be brought under the same category. This classification provides the significance of the precursor from which the alkaloids are
biosynthesized in the plant. The alkaloids are biosynthetically classified on the basis
of their amino acid precursor like lysine, tyrosine, phenylalanine, ornithine, tryptophan, etc. (Kokate et al. 2005).
The chemical structures of some major amino acid precursor are represented
below (Fig. 10.2).
The chemical structures of some well-known alkaloids (Fig. 10.3), are as follows
(Kokate et al. 2005; Tyler et al. 1988).
10 Secondary Metabolites from Plant Sources
335