## 1 Introduction  
For thousands of years people have used natural products for food, prophylactics, cosmetic purposes, and to treat diseases. Almost half of drugs originate from or are inspired by natural molecules. Natural medicines and ethnocosmetics are common in primary health care systems and are everyday choices in developing countries. On the other hand, growing interest in phytotherapy and natural products can be observed in developed countries. Therefore, in addition to the therapeutic, care, and pro-health facets, acquisition of natural metabolites has an economic aspect [1; 2; 3]. This is related to their widespread use in the food, cosmetic, and pharmaceutical industries. In each industry, great importance is attached to the effective extraction of active metabolites from natural material. Moreover, the trend of using environmentally friendly technologies is becoming stronger [4]. Extraction is designed to separate bioactive compounds from raw materials. Primarily, different variants of solvent extraction are used. Chemicals diffuse into the solvent, and the extract is collected. The greater the diffusivity and solubility of the active substances, the greater the extraction efficiency is. The improvement of extraction parameters is influenced by many factors, not only the chemical nature, size of particles, the type and amount of the solvent but also the temperature and the type and time of extraction. Classic extraction methods are often less effective; they require a relatively long extraction time and a larger amount of solvent. These are, e.g., maceration, reflux extraction, and percolation [5]. New extraction methods, e.g., ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), enzyme-assisted extraction (EAE), micellar extraction (MAME), or supercritical fluid extraction (SFE), are often characterized by higher speed, reduced solvent consumption, and higher elution of bioactive compounds [6]. Regardless of the extraction method used, there are some natural mechanical barriers hindering the extraction process. These include cell structures that need to be overcome to elute the metabolites of interest. Many components of the cell wall, such as lignins, cellulose, or some proteins, give cells strength but constitute an impediment during extraction of bioactive components. Some active metabolites are present in the cytoplasm, some are stored in vacuoles or plastids, and others are bound in a polysaccharide-lignin network by hydrogen bonds, which makes them not always available for conventional solvents [7; 8; 9]. In every case, the enzyme-assisted extraction method allows reducing the resistance of natural matter. The EAE is based on the use of enzymes that catalyse the cleavage of covalent bonds in the presence of water. This disintegrates cell structures and increases the permeability of the material. The enzyme-assisted extraction can be a standalone method or a pretreatment for conventional extractions. Enzymes are highly specific in appropriate conditions. Particle size, time, pH, and temperature must be considered. Enzymatic reactions proceed effectively at a relatively low temperature and moderate pH and in a relatively short time (up to few hours) and do not require expensive equipment. The duration and mild conditions allow minimizing degradation or isomerisation of active molecules. In the majority of cases, a positive or even highly positive effect of enzymatic pretreatment on extraction efficacy is observed [10; 11; 12; 13]. Optimization of key conditions often results in lowering the costs and energy consumption of the whole extraction process [14; 15]. Moreover, enzymolysis takes place in a water solution or in a buffer [16]. Therefore, no additional portion of organic solvent is needed. All the abovementioned conditions make the enzymatic pretreatment of the solution match the assumptions of green chemistry.