Description Application D-Mannitol is used as an osmolyte and transport facilitator in a variety of biological in vivo and in vitro applications, such as improvement of blood-brain barrier transport and hyperosmolar therapy. D-Mannitol is used as a substrate to identify, differentiate and characterized enzymes such as mannitol dehydrogenase(s). D-Mannitol is used in identify mannitol metabolizing bacteria. Biochem/physiol Actions A sugar alcohol sweet tastant. Used in sweetness inhibition studies. Other Notes Used in discontinuous gradient centrifugation for purification of plant protoplasts. Plasmolyticum that reversibly inhibits phenylalanine ammonia-lyase activity of protoplasts at concentrations exceeding 50 mM. Component of the liquid stationary phase in the GLC separation of nitroxylene and xylenol isomers.