Early people confronted with illness and disease, discovered a wealth of useful therapeutic agents in the plant kingdoms. The term "phytochemicals" that occur naturally refers to a wide variety of compounds with biological significance produced by plants. They are found in fruits, vegetables, beans, grains, and other plants. Scientists have identified thousands of phytochemicals, although only a small fraction have been studied closely, which have the potential to affect diseases such as cancer, stroke or metabolic syndrome. This book is devoted to the publication of original articles concerning phytochemicals and their biological and pharmacological effects. The spectrum of coverage is broad, encompassing extraction, separation, purification, structure identification, bioactivity and quantification of compounds in plants, the food sciences and agriculture.