[mass noun] One of the K vitamins, a compound produced by bacteria in the large intestine and essential for the blood-clotting process. It is an isoprenoid derivative of menadione.
- ‘For example, menaquinone 7 could also be written as K [2.sub.35].’
- ‘When administered, vitamin K 3 is alkylated to one of the vitamin K 2 forms of menaquinone.’
- ‘Mutant M249 preferentially accumulated menaquinone, which contains tetrahydrogeranylgeraniol as its side chain.’
- ‘The most common form of vitamin K in animals is menaquinone 4, produced by intestinal bacteria from exogenous naphthoquinones and transformed endogenously in our own cells.’
- ‘The most common form of vitamin K2 in animals is menaquinone 4, produced by the processing of exogenous and bacterial naphthoquinones.’
1940s: from the chemical name me(thyl)-na(phtho)quinone.