Phytochemical is a broad term meaning plant (phyto) chemical referring to a wide variety of compounds that occur naturally in plants. The term bioactive also has broad meaning. it is defined bioactive compounds as those that have the ability to interact with one or more component(s) of a living tissue presenting a wide range of probable effects. Generally, phytochemicals have been classified into six major categories based on their chemical structures and characteristics. These categories include carbohydrate, lipids, phenolics, terpenoids and alkaloids, and other nitrogen-containing compounds. Within each category, further division based on biogenesis or biosynthetic origin gives rise to different subcategories. 

Phytochemicals are precious for human nutrition. Indoles, isothiocyanates, and sulforaphane from vegetables, such as broccoli, alylic sulfides from onions and garlic and isoflavonoids from soybeans are known as plant phytochemicals. These are present in high concentration in raw foods but intensities are reduced during processing and handling . Enhanced amount of phytochemicals in foods can resolve this difficulty. Two genes IFS1/IFS2, encoding for isoflavone synthase in soybean are revealed and expressed in Arabidopsis thaliana, to activate the synthesis of isoflavonoid genistin