###### Abstract
They show the interesting characteristics of ILs but present unique advantages. In this sense, they are not always formed through ionic interactions but also hydrogen bonds and other kinds of interactions. DESs include salts and also carbohydrates, amino acids, polyols, and others. DESs easily integrate, are less toxic, and more environmentally friendly than ILs. They are usually composed of hydrogen bond acceptors (HBA), such as quaternary ammoniums, and hydrogen bond donors (HBD) as, for example, urea, carboxylic acids, or amines. Its main advantage above ILs is that they can be easily eliminated. It is because when forming eutectic solvents, no chemical reaction occurs, so their interactions can be broken under appropriated conditions without the necessity of applying complex procedures. DESs are generally composed of asymmetric components, which reduce energy, characterizing the ionic structure's stability, resulting in a lower melting temperature. DESs are characterized by being more viscous than water and conventional organic solvents [4]. When DESs are formed of natural eutectic compounds from plant metabolites or their derivatives, they are referred to as NADESs. The most common are choline chloride (ChCl), citric acid, malic acid, maleic acid, acetic acid, glucose, fructose, sucrose, trehalose, terpenoids or water, among others. NADESs are readily biodegradable and have less toxicity, if not almost zero. NADESs can act as natural solvents (as it happens in natural matrices) [2]. Some examples of NADESs can be seen in Figure 1.  
In a global view, DESs and NADESs are prepared by HBDs and HBAs with a specific molar ratio. Each mixture is placed in a flask at temperatures ranging around 50-85 \({}^{\circ}\)C, with continuous stirring until a homogeneous liquid appears. After the formation of the NADES, it generally needs water to reduce the viscosity and help the extraction process, as water facilitates mass transfer. It needs conditioning such as drying and grinding, or even high voltage electric discharges can be used as a pretreatment. In some articles NADESs are prepared in a different way, dissolving individual components in water, then mixing and removing water or not, depending on the subsequent use. The viscosity of DESs/NADESs also changes significantly depending on their composition and both parameters, nature of components and water can be modified to reach the most adequate extraction conditions. For example, in the study in which the extraction efficiency of phenolic compounds in leaves of _C. cajan_ was valuated [6]. Fourteen NADESs were prepared with a molar ratio (1:2) and, for increasing mass transfer, 20% (\(v/v\)) of water was used in the NADESs solutions. In the experiment, it was found to contain 6978 mg/g stillenes cajan in stilbene and 4370 mg/g of acid and longsitislin C. However, a high excess of water addition can negatively impact the solvent's interactions and the compounds. Changing the water content makes NADESs more polar or less polar if desired. Likewise, the viscosity of these solvents can also change with temperature. When temperature increases, it can cause a decrease in viscosity and better extraction performances. Nevertheless, this increase in temperature must be moderate because it can damage the thermolabile compounds.