TABLE OF CONTENTS

Title Page    –         –         –         –         –         –         –         –         –         i

Certification –         –         –         –         –         –         –         –         –         ii

Dedication   –         –         –         –         –         –         –         –         –         iii

Acknowledgements         –         –         –         –         –         –         –         iv

Table of Contents  –         –         –         –         –         –         –         –         v-vi

CHAPTER ONE: INTRODUCTION          –         –         –         –         1-3

CHAPTER TWO : FLAVONOID AND SAPONINS

2.1     Classification of flavonoids       –         –         –         –         –         4

2.1.1  Flavones      –         –         –         –         –         –         –         –         4

2.1.2  Flavonols     –         –         –         –         –         –         –         –         4-5

2.1.3  Flavonones  –         –         –         –         –         –         –         –         5

2.1.4  Isoflavonoids         –         –         –         –         –         –         –         5

2.1.5  Anthocyanins        –         –         –         –         –         –         –         6

2.2     Sources of Saponins        –         –         –         –         –         –         6-7

2.3     Flavonoid Biosynthesis    –         –         –         –         –         –         7-11

CHAPTER THREE: PROPERTIES AND DISTRIBUTION OF FLAVONOID AND SAPONINS

3.1     Distribution and Properties of flavonoids in plants  –         –         12

3.1.1  Distribution of flavonoid –         –         –         –         –         –         12-14

3.1.2  Properties of flavonoid    –         –         –         –         –         –         14-16

3.2     Biological properties of flavonoids in plant   –         –         –         16

3.2.1  Roles in Nodulation         –         –         –         –         –         –         16-17

3.2.2  Roles in Plant defense     –         –         –         –         –         –         17-19

3.2.3  Roles in Plant Production and Fertility –         –         –         –         19-20

3.3     Distribution and Properties of Saponin in Plant       –         –         20

3.3.1  Distribution of Saponin in Plant –         –         –         –         –         20-21

3.3.2  Physicochemical Properties of Saponin         –         –         –         21-25

3.3.3  Biological Properties       –         –         –         –         –         –         25-28

CHAPTER FOUR: SUMMARY AND CONCLUSION

4.1     Summary     –         –         –         –         –         –         –         –         29-30

4.2     Conclusion  –         –         –         –         –         –         –         –         30-31

References

CHAPTER ONE: INTRODUCTION

Saponins, glycosides widely distributed in the plant kingdom, include a diverse group of compounds characterized by their structure containing a steroidal or triterpenoid aglycone and one or more sugar chains. Their structural diversity is reflected in their physicochemical and biological properties, which are exploited in a number of traditional (as soaps, fish poison, and molluscicides) and industrial applications (Price et al., 1987). While plant extracts containing saponins have been widely used in food and other industrial applications mainly as surface active and foaming agents (San Martin and Briones, 1999); saponins in foods have traditionally been considered as “antinutritional factors” and in some cases have limited their use due to their bitter taste. Therefore, most of the earlier research on processing of saponins targeted their removal to facilitate human consumption. However, food and non-food sources of saponins have come into renewed focus in recent years due to increasing evidence of their health benefits such as cholesterol lowering and anticancer properties. Recent research has established saponins as the active components in many herbal medicines and highlighted their contributions to the health benefits of foods such as soybeans (Kerwin, 2004).

The commercial potential of saponins has resulted in the development of new processes/processing strategies and reevaluation of existing technologies  for their extraction/concentration. The objective of this review is to provide a timely update on the sources, properties and applications of saponins with special focus on their extraction and purification (Muir et al., 2002).

The pigments that color most flowers, fruits and seed are flavonoids. These secondary metabolites, widely distributed in plants are classified in six major subgroups, chalcones flavones, flavonols, flavandiols, anthocyanins, and proanthocyanidins or condensed tannins and a seventh group is found in some species, the aurones. Legumes and a small number of nonlegume plants also synthesize specialized flavonoids such as isoflavonoids. While few species either produce 3-deoxyanthoeyanins and phlobaphenes. Groups of unrelated species, including grape and peanut, synthesize stilbenes, compounds closely related to chalcones (Chong et al., 2009).

More than 6000 different flavonoids have been identified, and surely this number will increase. The different flavonoids have diverse biological functions including protection against ultraviolet (Uv) radiation and phytopathogens, signaling during nodulation, male fertility, auxin transport, as well as the coloration of lowers as a visual signal that attracts pollinators (Mol et al., 1998). Flavonoids are also responsible for the display of fall color in many plants, which may protect leaf cells from photoxidative damage, enhancing the efficiency of nutrient retrieval during senescence. Flavonols are probably the most important flavonoids participating in stress responses, they are the most ancient and widespread flavonoids, having a wide range of potent physiological activities (Stafford, 1991).