Plants' Bioactive Metabolites and Extraction Methods

*Achouak Madani, Nassima Mazouni and Mohammed Nedjhioui*

#### **Abstract**

Plants are an inexhaustible source of bioactive compounds that have been utilized by Men since antiquity. Plants' bioactive substances are called primary and secondary metabolites. Primary metabolites are dedicated to biological functions and survival. Secondary metabolites are luxury products synthesized mainly to defend against predators and to communicate with other plants. Medicinal plants have ever since been a growing source of interest for scientific research as well as food, chemical, and pharmaceutical for their diverse applications for their antioxidant, antibacterial, stimulant, and inhibiting properties. Obtaining secondary metabolite can be challenging as the inadequate choice of extraction methods could alter or destroy bioactive compounds such as thermolabile substances. Hence, a beforehand knowledge of secondary metabolites properties and a mastery of extraction methods are primordial for effective extraction. Extraction methods range from conventional extraction such as solvent extraction to modern techniques like enzymatic assisted extraction EAE and microwave-assisted extraction MAE, which are more efficient methods and more environmentally friendly as they require very little to no use of solvents.

**Keywords:** plants' metabolites, essential oils, lipids, alkaloids, phenolic compounds, extraction, green extraction

#### **1. Introduction**

Plants produce a wide range of bioactive molecules that serve many purposes. Those that are destined for biological functions and surviving are called primary metabolites. On the other hand, those compounds that are luxury products are called secondary metabolites. They serve as extra nutritionals and may have adverse effects on other living organisms. Secondary metabolites have been used since antiquity in traditional medicine due to their benefits on human health. They are potent antioxidants, anticancer, antidiabetic, anti-inflammatory, stimulants… Their use has witnessed a dramatic increase in pharmaceutical, chemical, and food industries for the advantages they present. However, obtaining these compounds is a challenging process as they represent a small portion of plants raw material.

Diverse extraction methods, from conventional methods such as solvent extraction to modern techniques like enzymatic assisted extraction EAE, have been used to improve extraction yield in terms of quality and quantity as well as environmental safety. This chapter discusses the main active substances categories, their role for plants and men as well as the different extraction methods used to obtain them.
