Properties and Roles of Secondary Metabolites in Botanical Extracts

Secondary metabolites are organic compounds found in plants that are not directly involved in the normal growth, development, or reproduction of plants but play pivotal roles in plant defense and ecological interactions. This chapter provides a critical overview of the classification, extraction, and defense mechanism of secondary metabolites in botanical extracts. This chapter provides a critical overview of the three major classes of plant metabolites, such as phenolic compounds, terpenes, and nitrogen-containing compounds. Secondary metabolites are classified into three principal categories, including phenolic compounds, terpenes and nitrogen-containing compounds. The extraction of secondary metabolites from botanical sources is a crucial step in natural product research and phytopharmaceutical development. High-performance liquid chromatography (HPLC) is a widely used technique for separating and quantifying, gas chromatography–mass spectrometry (GC–MS) is ideal for analyzing volatile compounds, and nuclear magnetic resonance (NMR) spectroscopy is indispensable for structural determination and purity assessment of secondary metabolites. Secondary metabolites have evolved over millions of years to serve as essential tools for survival in changing and competitive environments. Plants have evolved a wide range of mechanisms to synthesize secondary metabolites for defense against various biotic and abiotic stresses. Furthermore, the chapter discusses the role of allelochemicals, the ecological interaction of secondary metabolites, and the therapeutic and industrial applications of these compounds, emphasizing their potential in pharmaceuticals.