**1. Introduction**

#### **1.1 What are flavonoids?**

Flavonoids are naturally occurring secondary metabolites in plants, possessing a polyphenolic structure. They are widely distributed in the leaves, seeds, barks, flowers, fruits, and vegetables. Over 8000 flavonoids have been identified to date and most of them have been found to be engaged in various biological activities in plants, animals, and bacteria. Apart from imparting pigmentation in plants, flavonoids afford protection against UV radiation, herbivores, and pathogens [1–3]. In addition, flavonoids have also been found to serve as detoxifying and antimicrobial defense

agents in the animal world. They appear to have played a significant part in the effectiveness of ancient medicinal therapies, and since then, their usage has continued to this day. Notably, detailed pieces of evidence from various studies have confirmed flavonoids' role in growth metabolism and gene regulation as well [4].
