Introduction : General Biosynthesis Pathways of Secondary Metabolites

Babylon University Third Class Pharmacy College 1st. Semester

Pharmacognosy ( II ) 2016 / 2017
Lecture ( 1 )

Introduction : General Biosynthesis Pathways of Secondary Metabolites


The study of the Plant Biochemical pathways reaching to the formation of secondary constituents used as drugs is commonly referred to as ( Drug Biosynthesis ) or ( Biogenesis ) .

A knowledge of the biochemical synthesis of drugs of natural origin has high importance to the student of Pharmacognosy .

The biosynthetic pathways leading to the formation of secondary constituents used as drugs have been a subject of scientific investigation throughout most of the twentieth century .

In 1912 , the Swiss chemist ( G. Trier ) supposed that Amino acids ( A.A. ) and their simple derivatives served as precursors of structurally complex alkaloids .

However , it was not until isotopically labeled organic compounds became readily available in the second half of the twentieth century , that positive confirmation of this and other " Paper Chemistry " hypotheses could be achieved .
To facilitate a general understanding of the pathway involved and their interrelationships , ( Interrelationships of Biosynthetic Pathways Leading to Secondary Constiuents ) , they are summarized in (Fig. 1) as follow :







































Pharmacological effects of some well known alkaloids.
Pharmacological activity
Source
Alkaloid name

Competitive antagonist of Muscarinic acetylcholine receptors,anti cholinergic, anti myopia effects. Atropa belladonna
Darura stramonium
Mandragora officinarum
1- Atropine


Anti inflammatory, anti bacterial/viral, recently experiments showed anti diabetic and beneficial effects on cardiovascular system and anti cancer and others disorders such as intestinal . Berberis species
Hydrastis, Canadensis
Xanthorhiza simplicissima
Phellodendron amurense
Coptis chinensis
Tinospora cordifolia
Argemone Mexicana
Eschscholzia californica


2- Berberine
Analgesic, antitussive, anti diarrheal, antidepressant, sedative and hypnotic properties.
Papaver somniferum
3-Codeine

Poisonous Poisonous Cytisine (baptitoxine, sophorine) Labum and cytisus of Fabaceae family, most extracted from seeds of Cytisus laborinum Acetylcholine agonist, smoking cessation drug

Conium macularum
Sarracenia flave Neurotoxin

4-Coniine

Act on CNS (central nervous system), on myenteric plexus, acute pulmonary edema and reduce the shortness of breath.

Papaver somniferum and poppy derivatives


5-Morphine

Stimulant, antiherbivore, insectide, anti inflammatory.
Solanaceae plants family

6-Nicotine

Antimalarial, antpyretic, analgesic, anti-inflammatory, antiarrhythmic, bacteriostatic.

Cinchona succirubra, C. calisya, c. ledgeriana, plants of Rubiaceae family.

7-Quinine

Antifungal, antipesticide, sedative, anticonvulsant, anticarcinogenic, anti inflammatory.

Solanum tuberosum, s. lycopersiam, s. igrum, plants of Solanaceae family

8-Solanine

Persticide, strong poisonous, Convulsant.
Strychnos nux-vomica, loganiaceae plants family
9-Strychnine

Analgesic, not therapeutically used.
Papaver bracteatum
10-Thebaine: (paramorphine)

Immune effects, anticancer, antifungal, poisonous.

Green parts of tomato plants
11-Tomatine





























Professor Dr. Saad Ali Ihsan
Ph.D. in Pharmacognosy & Medicinal Plants