B-amino acids are key structural elements of peptides, peptidomimetics and many other physiologically active compounds. Notably, b-amino acids are precursors for b-lactams, the most important class of antibiotics. Although some b-amino acids themselves show interesting pharmacological properties, usually they are intermediates en route to more complex products with biological and pharmacological activity. In recent years, it has become clear that peptides based on B-amino acids have secondary structures comparable to their a-amino acid analogues, but are not vulnerable towards proteases.

In polymer chemistry, polyols are a type of compounds with multiple hydroxyl functional groups available for organic reactions. A compound with two hydroxyl groups is a diol, one with three is a triol, one with four is a tetrol, and so on.

Glycosaminoglycans are large complex carbohydrate molecules that interact with a wide range of proteins involved in physiological and pathological processes. Glycosaminoglycans are sometimes known as mucopolysaccharides because of their viscous, lubricating properties, as found in mucous secretions. These molecules are present on all animal cell surfaces in the extracellular matrix, and some are known to bind and regulate a number of distinct proteins, including chemokines, cytokines, growth factors, morphogens, enzymes and adhesion molecules.

Ubiquinone is 2,3-dimethoxy-5-methyl-6-multiprenyl-1, 4-benzoquinone, also known as CoEnzyme Q (CoQ10, Q). The reduced form (QH2) is called ubiquinol and the partially reduced free-radical form is called semiquinone. The quinone group allows CoEnzyme Q to function as an electron-carrier, while the highly hydrophobic tail of isoprene units helps to confine CoEnzyme Q to lipid-rich areas of cells.

It is now well established that deficiencies of the major dietary sources of methyl donors, methionine and choline, lead to the formation of liver cancer in rodents.

Retinoic acid is a member of the over 4,000-strong family of retinoids, which are compounds derived from retinol or vitamin A, or compounds structurally similar to it. Vitamin A itself is derived only from food, and cannot be made in the body of any animal. It is esterified and stored in the liver, the richest source of vitamin A apart from supplements. Retinoic acid is synthesized from retinol via two enzymatic reactions, involving first reversible oxidation of retinol to retinal, and then a second oxidation, this time irreversibly, to retinoic acid.

Flavin is the common name for a group of organic compounds based on pteridine, formed by the tricyclic heterocycle isoalloxazine. The riboflavin (RF), vitamin B2, is an essential precursor of flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) co-enzymes.

Choline is found in various forms in humans and animals. The water-soluble choline metabolites include acetylcholine (ACho), an important neurotransmitter for brain and neuromuscular function, betaine (Bet), an oxidative intermediate of choline which supplies a methyl group for the conversion of homocysteine to methionine, and glycerophosphocholine (GPCho), which like Bet acts as an organic osmolyte in cells. The lipid-soluble choline-containing metabolites phosphatidylcholine (PC), sphingomyelin (SM), and lysophosphatidylcholine (LPC) are all structural components of mammalian membranes.

Sugar alcohols are acyclic polyols. The term acyclic polyol refers to a straight-chain, polyhydric alcohol, and, along with alditol, sugar alcohol, polyalcohol and polyhydric alcohol is commonly used in reference to the reduction products of sugars and closely related derivatives.

Thiols, also named as mercaptan, are a class of organic compounds containing a sulfhydryl group (SH). They are similar to the alcohols and phenols but with the oxygen atom replaced by a sulfur atom.