Natural deep eutectic systems—A new era of cryopreservation

Human and animal cells are extremely important for research and many medical applications; however, they do not survive long-term storage with simple cooling or freezing. On the other hand, the increase in world's population along with the changes in feeding behaviors has led to the establishment of new plant varieties. Several plant species are endangered and germplasm conservation is far from developed, hence the search for new cryoprotectant agents became crucial. The metabolites produced by animals and plants to survive extreme cold temperatures served as starting point for the development of natural cryoprotectants. Natural Deep Eutectic Systems (NADES) emerged as alternative solvents and several reports show their low toxicity profile and biodegradability. The components present in organisms that survive extreme cold are potential candidates to prepare a wide variety of NADES. This review exploits NADES' potential as well, as their components, as new alternative cryoprotectant agents.