A cryoprotectant is a substance that is used to protect biological tissue from freezing damage (i.e. that due to ice formation). Arctic and Antarctic insects, fish and amphibians create cryoprotectants (antifreeze compounds and antifreeze proteins) in their bodies to minimize freezing damage during cold winter periods. Insects most often use sugars or polyols as cryoprotectants. One species that uses cryptopectant is Polistes exclamans. In this species the different levels of cryptopectant can be used to distinguish between morphologies. Arctic frogs use glucose, but Arctic salamanders create glycerol in their livers for use as a cryoprotectant. Cryoprotectants operate simply by increasing the solute concentration in cells. However, in order to be biologically viable they must (1) easily penetrate cells, and (2) not be toxic to the cell.
Read more about Cryoprotectant: Conventional Cryoprotectants, Toxicity, Glass Transition Temperature, Food Preservers, Common Cryoprotectants