Natural deep eutectic systems inspired in animals living in extreme environments: cytotoxicity profile

Several publications have related the presence of considerable amounts of simple molecules (i.e., sugars, polyols and amino acids) in all microbial, mammalian and plant cells, that are crucial for their survival.1,2 Natural deep eutectic systems (NADES) have been pointed as responsible for survival of animals and plant at negative temperatures during winter.3
NADES are the result of the creation of intermolecular hydrogen bonds between two and/or three components and are mostly composed of natural primary metabolites such as sugars, sugar alcohols, organic acids, amino acids, amines. Additionally, NADES may contain water in certain molar ratios.4,5
Our work focused on the possible application of NADES in cryopreservation process as cryoprotective agents (CPA).6,7 In this sense, we tested various combinations of components, that are reported to be present in different organisms which survive to extreme temperatures amplitudes, until the correct molar ratio that forms the NADES was found.8
Through differential scanning calorimetric it was possible to confirm the successful production of eutectic mixtures, as there is a strong depression on the melting point of the raw materials due to the establishment of hydrogen bonds between counterparts of each component. The NADES prepared, based in urea, amino acids, sugars and polyols, we evaluated in terms of their cytotoxic profile in vitro against L929 cells using different percentages of each NADES and DMSO, which as used as gold standard.
Since NADES acts in the same principle as a CPA in cryopreservation process, inhibiting the crystallization of water, formation of ice and the freezing process will not compromise the cells.
Our investigation proposes the identification of new NADES as a promising green alternative to the conventional CPA used in cryopreservation methods.