Niedermolekulare

Niedermolekulare is a German term used in chemistry, biochemistry, and pharmacology to describe substances with low molecular weight, i.e., small molecules. In English-language contexts the term is often translated as low-molecular-weight substances or small molecules. Although there is no strict universal boundary, compounds typically considered niedermolekulare possess molecular weights ranging from a few hundred up to about 1,000 daltons.

These substances are usually non-polymeric and consist of a limited number of atoms. They exhibit diverse functional groups and properties, including polar, nonpolar, acidic or basic characters, and can be soluble in water or organic solvents. Their small size enables rapid diffusion and often allows crossing biological membranes, influencing metabolism, signaling, or pharmacokinetics.

Niedermolekulare play essential roles as nutrients, metabolites, cofactors, drugs, and signaling molecules. Examples include glucose, amino acids, vitamins (e.g., ascorbic acid), nucleotides (ATP), cofactors (NAD+, FAD), organic acids, and many drugs such as acetylsalicylic acid or caffeine.

In research and industry, niedermolekulare are analyzed using mass spectrometry, nuclear magnetic resonance, or chromatographic techniques (HPLC, GC). They are distinguished from hochmolekulare or macromolecular substances such as proteins, nucleic acids, or polysaccharides by their lower molecular weight and simpler structures.