Page 1
Institute of Lifelong Learning, University of Delhi
Botany
Paper: Plant Metabolism
Lesson: Secondary Metabolites
Lesson Developer: Dr Girish Mishra
Department/College: Department of Botany,
University of Delhi
Page 2
Institute of Lifelong Learning, University of Delhi
Botany
Paper: Plant Metabolism
Lesson: Secondary Metabolites
Lesson Developer: Dr Girish Mishra
Department/College: Department of Botany,
University of Delhi
Institute of Lifelong Learning, University of Delhi
Table of Contents
Secondary Metabolites
? Learning outcomes
? Introduction
? Terpenes
? Structure
? Types
? Biosynthesis
? Biological Functions
? Plant Phenolic Compounds
? Classification
? Biosynthesis
? Simple phenolic compounds
? Lignin
? Flavonoids
? Biosynthesis
? Anthocyanins
? Flavones and flavonols
? Tannins
? Nitrogen-containing compounds
? Alkaloids
? Cyanogenic glycosides
? Summary
? Exercise
? Further reading
? Weblinks
Page 3
Institute of Lifelong Learning, University of Delhi
Botany
Paper: Plant Metabolism
Lesson: Secondary Metabolites
Lesson Developer: Dr Girish Mishra
Department/College: Department of Botany,
University of Delhi
Institute of Lifelong Learning, University of Delhi
Table of Contents
Secondary Metabolites
? Learning outcomes
? Introduction
? Terpenes
? Structure
? Types
? Biosynthesis
? Biological Functions
? Plant Phenolic Compounds
? Classification
? Biosynthesis
? Simple phenolic compounds
? Lignin
? Flavonoids
? Biosynthesis
? Anthocyanins
? Flavones and flavonols
? Tannins
? Nitrogen-containing compounds
? Alkaloids
? Cyanogenic glycosides
? Summary
? Exercise
? Further reading
? Weblinks
Institute of Lifelong Learning, University of Delhi
Learning Outcomes
In this chapter you will be able to learn:
? Different types of secondary metabolites in the plants
? Terpenes and their biosynthesis, structure and significance
? Plant phenolic compounds and its biosynthesis
? Nitrogen containing secondary metabolites
Page 4
Institute of Lifelong Learning, University of Delhi
Botany
Paper: Plant Metabolism
Lesson: Secondary Metabolites
Lesson Developer: Dr Girish Mishra
Department/College: Department of Botany,
University of Delhi
Institute of Lifelong Learning, University of Delhi
Table of Contents
Secondary Metabolites
? Learning outcomes
? Introduction
? Terpenes
? Structure
? Types
? Biosynthesis
? Biological Functions
? Plant Phenolic Compounds
? Classification
? Biosynthesis
? Simple phenolic compounds
? Lignin
? Flavonoids
? Biosynthesis
? Anthocyanins
? Flavones and flavonols
? Tannins
? Nitrogen-containing compounds
? Alkaloids
? Cyanogenic glycosides
? Summary
? Exercise
? Further reading
? Weblinks
Institute of Lifelong Learning, University of Delhi
Learning Outcomes
In this chapter you will be able to learn:
? Different types of secondary metabolites in the plants
? Terpenes and their biosynthesis, structure and significance
? Plant phenolic compounds and its biosynthesis
? Nitrogen containing secondary metabolites
Institute of Lifelong Learning, University of Delhi
Introduction
Plants produce a large diverse range of organic compounds that are not directly
involved in the growth, reproduction, development, or the other ?primary? functions,
and are called ?secondary metabolites? or secondary products. Unlike primary
metabolites (sugars, amino acids, nucleotides, acyl lipids) which are essential for
plant’s survival, the absence of secondary metabolites does not result in immediate
death, but rather leads to long-term impairment of various important roles. Where
primary metabolites are found throughout the plant kingdom, secondary metabolites
are more or less widespread in plants. Due to the restricted distribution of secondary
metabolites, they can potentially be used as taxonomic markers for classification of
plants. Secondary metabolites were earlier considered to be waste products with
having no important role. Alternatively it was argued by E. Stahl in late 19
th
century
that secondary metabolites serve as defence components against herbivores. In
recent past this claim was confirmed and it was observed that secondary metabolites
have important functions in plants. These roles include defence against predators,
pathogens, and herbivory, serving as attractants (odour, colour, taste) for pollinators
thus helping in pollination and seed dispersal and also as agents of plant-plant
competition and plant-microbe symbiosis(in root nodules).
Page 5
Institute of Lifelong Learning, University of Delhi
Botany
Paper: Plant Metabolism
Lesson: Secondary Metabolites
Lesson Developer: Dr Girish Mishra
Department/College: Department of Botany,
University of Delhi
Institute of Lifelong Learning, University of Delhi
Table of Contents
Secondary Metabolites
? Learning outcomes
? Introduction
? Terpenes
? Structure
? Types
? Biosynthesis
? Biological Functions
? Plant Phenolic Compounds
? Classification
? Biosynthesis
? Simple phenolic compounds
? Lignin
? Flavonoids
? Biosynthesis
? Anthocyanins
? Flavones and flavonols
? Tannins
? Nitrogen-containing compounds
? Alkaloids
? Cyanogenic glycosides
? Summary
? Exercise
? Further reading
? Weblinks
Institute of Lifelong Learning, University of Delhi
Learning Outcomes
In this chapter you will be able to learn:
? Different types of secondary metabolites in the plants
? Terpenes and their biosynthesis, structure and significance
? Plant phenolic compounds and its biosynthesis
? Nitrogen containing secondary metabolites
Institute of Lifelong Learning, University of Delhi
Introduction
Plants produce a large diverse range of organic compounds that are not directly
involved in the growth, reproduction, development, or the other ?primary? functions,
and are called ?secondary metabolites? or secondary products. Unlike primary
metabolites (sugars, amino acids, nucleotides, acyl lipids) which are essential for
plant’s survival, the absence of secondary metabolites does not result in immediate
death, but rather leads to long-term impairment of various important roles. Where
primary metabolites are found throughout the plant kingdom, secondary metabolites
are more or less widespread in plants. Due to the restricted distribution of secondary
metabolites, they can potentially be used as taxonomic markers for classification of
plants. Secondary metabolites were earlier considered to be waste products with
having no important role. Alternatively it was argued by E. Stahl in late 19
th
century
that secondary metabolites serve as defence components against herbivores. In
recent past this claim was confirmed and it was observed that secondary metabolites
have important functions in plants. These roles include defence against predators,
pathogens, and herbivory, serving as attractants (odour, colour, taste) for pollinators
thus helping in pollination and seed dispersal and also as agents of plant-plant
competition and plant-microbe symbiosis(in root nodules).
Institute of Lifelong Learning, University of Delhi
Figure: Interrelation between primary and secondary metabolites
Source: http://www.intechopen.com/books/oxidative-stress-and-chronic-
degenerative-diseases-a-role-for-antioxidants/food-phenolic-compounds-main-
classes-sources-and-their-antioxidant-power#F2 (CC)
Secondary metabolites are classified on the basis of composition (whether containing
nitrogen or not), stereo chemical structure (whether contains a sugar moiety or a ring), or
the biosynthetic pathway. Secondary metabolites mainly are composed of three groups.
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