lipofiilisyyttä

Lipofiilisyyttä, often translated as lipophilicity, is a fundamental property of a chemical substance that describes its tendency to dissolve in fats, oils, and lipids. It is essentially the opposite of hydrophilicity, which is the tendency to dissolve in water. Lipophilicity is a crucial factor influencing how a substance behaves in biological systems, its distribution in the body, and its interaction with cell membranes.

The degree of lipophilicity is often quantified using the octanol-water partition coefficient (Kow). This coefficient represents the ratio of a substance's concentration in octanol (a surrogate for lipids) to its concentration in water at equilibrium. A higher Kow value indicates greater lipophilicity. Another related measure is the partition coefficient of a neutral molecule between octanol and aqueous buffer at pH 7.4, often denoted as LogP.

Substances with high lipophilicity tend to cross biological membranes more readily, as these membranes are primarily composed of lipid bilayers. This property is therefore important in pharmacology for determining drug absorption, distribution, metabolism, and excretion (ADME). It also plays a role in environmental science, affecting how pollutants persist and accumulate in organisms. Conversely, very high lipophilicity can lead to poor water solubility, which can hinder administration and distribution in certain applications.