The Sample Preparation Techniques and Their Application in the Extraction of Bioactive Compounds from Medicinal Plants

People have used plants for centuries to prevent and treat illness and to maintain good health. Different parts of the plant (root, seed, fruit, flower) are used directly, and extracts are prepared by various methods. Various applications and techniques have been developed to extract bioactive compounds from plants. Extraction aims to obtain chemical compounds from plant tissues most effectively and efficiently. The effectiveness of different extraction techniques (maceration, percolation, decoction, Soxhlet extraction, hydrodistillation, microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), supercritical fluid extraction (SFE), enzyme-assisted extraction (EAE), pressurized hot water extraction (PHWE), pressurized liquid extraction (PLE), ionic liquids extraction (ILs), deep eutectic solvents extraction (DESs), bio-based solvents extraction (BBS), and natural deep eutectic solvents extraction (NADES)), the chemical profile of the resulting bioactive compounds, and their effects on biological activities have been extensively studied. Their effectiveness in extracting various bioactive compounds (flavonoids, phenolic acids, alkaloids, terpenoids, saponins, and essential oils) has been evaluated. This review provides a detailed description of the applications of various traditional extraction methods, modern extraction methods, and green extraction methods in medicinal plants for better understanding. It provides an overview of their potential to help determine their appropriateness and financial feasibility. It also compares the effectiveness, advantages, and disadvantages of different approaches.