Techniques for the Isolation of Plant-Based Bioactive Compounds

Introduction

Natural bioactive compounds are the class of compounds that originates from the natural plant-based sources and possess great promise to develop effective small molecule and drug therapies. Attributed to the chemical diversity that is present in the bioactive compounds from plant sources provides immense opportunity for the development of new drug leads targeted towards several different conditions in humans (Sasidharan et at., 2011; Altemimi et al., 2017). These compounds include alkaloids, phenolics, terpenoids, organosulfur compounds and nitrogen containing compounds (Singh A., & Navneet, 2016; Altemimi et al., 2017). These compounds have gained enormous recognition in recent years as they are generally considered safe, eco-friendly, and majorly due to their significant medicinal properties like anti-inflammatory, anticancer, immunostimulatory, immunomodulatory, anti-microbial and antioxidant etc. (Sasidharan et at., 2011; Christaki et al., 2012; Tsiaka et al., 2017; Singh S., et al., 2018; Ortega et al., 2019). Owing to their better advantages they have been used in food, chemical and pharmaceutical, nutraceutical and cosmeceutical industries in form of food supplements, as substitutes for drugs and as additives to increase the functionality of the desired product (Azmir et al., 2013; Tsiaka et al., 2017). Firstly, these bio-active compounds are present in limited quantities within the plant and secondly, most of the times they are either implanted in plant matrix or present in the form of complexes with other compounds, these two factors make the extraction a crucial step for obtaining these compounds from the plant-based sources (Azmir et al., 2013).

There are several conventional methods for extraction of bio-active compounds which includes methods like Soxhlet extraction, percolation, infusion, steam, decoction, maceration, digestion, and hydro distillation (Azmir et al., 2013). But there are several disadvantages associated with the conventional methods which includes excessive usage of organic solvents, longer processing hours, higher temperature which altogether leads to higher costs for the extracted products. Taking these parameters into consideration, several nonconventional methods have been developed for extraction of natural bioactive compounds but none of them can be regarded as a standard extraction procedure. The choice of extraction procedure depends on several critical factors which includes parameters like chemical properties and structural information of the phytochemical compounds, nature of plant-matrix followed by a good scientific knowledge and skillset. These nonconventional methods include microwave assisted extraction, ultrasound assisted extraction, pressurized liquid extraction, supercritical fluid extraction, enzyme assisted extraction etc. These methods utilize lower consumption of organic solvents and are eco-friendly when compared to the conventional methods due to which they are also referred to as green technology (Ghasemi et al., 2011; Kate et al., 2016; Chemat et al., 2017; Zhang et al., 2018; Uwineza et al., 2020).