Ectoin

Ectoin is a small molecule produced by microorganisms living in extreme environments, where it protects their cells against salt, heat and dehydration. It works by organising water rather than by binding it directly.

How it works

Most humectants hold water by attracting it to themselves. Ectoin behaves differently. It is excluded from the immediate surface of proteins and cell membranes, and in being pushed away it concentrates water molecules into an ordered shell around those structures.

This is described as preferential exclusion or the formation of an ectoin hydration complex. The practical effect is that proteins and membranes sit within a stabilised layer of water, which helps them retain their structure under stress from dehydration, heat or osmotic change.

Where it comes from

Ectoin was first identified in halophilic bacteria, microorganisms that survive in salt lakes and other high-salinity environments where ordinary cells would dehydrate. The ectoin used in cosmetics is produced by fermentation rather than extraction.

In formulation

Ectoin is water-soluble, stable across a wide pH and temperature range, and used at low concentrations. It appears frequently in formulas built around actives that can disturb the barrier, such as retinoids and exfoliating acids, where the aim is to support skin through the adjustment period.