A betaine () in chemistry is any neutral chemical compound with a positively charged functional group that bears no hydrogen atom, such as a quaternary ammonium or phosphonium cation (generally: Onium compounds ions), and with a negatively charged functional group, such as a carboxylate group that may not be adjacent to the cationic site.
Pronunciation
The pronunciation of the compound reflects its origin and first isolation from sugar
beets (
Beta vulgaris subsp.
vulgaris), and does not derive from the Greek letter beta (β). It is commonly pronounced
beta-INE or
BEE-tayn.
Glycine betaine
The original betaine,
N,
N,
N-trimethylglycine, was named after its discovery in
sugar beet (
Beta vulgaris subsp.
vulgaris) in the nineteenth century.
[ DNA Methylation and Complex Human Disease, Michel Neidhart] It is a small
N-trimethylated
amino acid. It is a
zwitterion, which cannot isomerize because there is no labile hydrogen atom attached to the nitrogen atom. This substance may be called
glycine betaine to distinguish it from other betaines.
Uses
Biochemistry
Phosphonium betaines are intermediates in the some
Wittig reaction. The addition of betaine to polymerase chain reactions improves the amplification of DNA by reducing the formation of secondary structure in GC-rich regions. The addition of betaine may enhance the specificity of the polymerase chain reaction by eliminating the base pair composition dependence of DNA melting.
Food additive
In 2017, the European Food Safety Authority concluded that betaine was safe "as a novel food to be used at a maximum intake level of 6 mg/kg body weight per day in addition to the intake from the background diet."
Approved drug
A prescription drug (
Cystadane)
[ containing betaine has limited use for oral treatment of genetic disorder homocystinuria to lower levels of homocysteine in circulating blood.][
]
Dietary supplement
Trimethylglycine, a betaine, is used as a dietary supplement, although there is no evidence that it is effective or safe.
See also
Further reading
