In one sentence: Ectoine is a compatible solute in halophilic organisms. Now let’s take this fancy  sentence apart. Halophilic organisms (halophiles) live in environments with high salinity levels. It was  believed to be impossible to live in such hypersaline environments, but the discovery of  microorganisms inhabiting these environments in the beginning of the twentieth century suggested  otherwise. Ectoine was first discovered in the extreme microorganism Halorhodospira halochloris, which resides in the salt lakes of Wadi Natrun (Egypt). The air humidity is so dry and salt  concentration so high that plants and animals avoid this place and yet halophiles are able to survive  these conditions.

How is ectoine synthesized by the cell?  

The biosynthesis of ectoine was determined with the help of 13C-labeling techniques and proceeds  via the pathway in the below. The pathway starts with the phosphorylation of the amino acid L-aspartate in the presence of the enzyme aspartokinase and ends with the conversion of  diaminobutanoate to ectoine via ectoine synthase.

Uses

Now that ectoine can be produced in large quantities all that is left is to find use for it! Not just in  cosmetic products which stimulated the production of ectoine in large scales, but ectoine has also  found to be advantageous in therapeutic and medicinal products.  

Eye drops containing ectoine (Triofan?) are effective in preventing the eyes from drying out and helps fluidize the tear fluid lipid layer.

Ectoine nasal sprays (Triofan?naturel and Triofan? Heutschnupfen) are used in the  treatment of allergic rhinitis and rhinoconjunctivitis symptoms.

Mouth and throat sprays with ectoine are used to treat pharyngitis/laryngitis. 

Ectoine containing creams are used in the treatment of atopic dermatitis.

Ectoine is even found in ‘anti-aging’ creams as it hydrates the skin and improves its elasticity  and surface structure.