Lecture 15 - Secondary metabolites and plant defense Botany Notes | EduRev

 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.