Vitamin K denotes a group of lipophilic, hydrophobic vitamins, that are cofactors in many reactions.
This vitamin occurs naturally
- in vegetable food (green leaves) as a vitamin K1 (phylloquinone).
- In the large intestine, it is produced by our intestinal bacteria as vitamin K2 (menaquinone). Parasites or Cohabitants: Cruel Omnipresent Usurpers or Creative “Éminences Grises”?, 2011
Vitamin K (menaquinones) is produced by intestinal bacteria such as Bacteroides, Eubacterium, Propionibacterium, Fusobacterium, Bifidobacterium, Lactobacillus, Clostridium, Enterococcus, Streptococcus, and others.
Dietary deficiency is extremely rare unless the intestines are heavily damaged, are unable to absorb the molecule, or due to decreased production by normal flora, as seen in broad spectrum antibiotic use.
Synthetic vitamin K is called vitamin K3 (menadione), our body converts this vitamin into active vitamin K.
Linus Pauling Institute: Vitamin K
Chemically they are 2-methyl-1,4-naphthoquinone derivatives, that can undergo redox reactions. The side chain is composed of a varying number of isoprenoid residues.
Vitamin K shows strong similarity to Vitamin E. The structural analog Warfarin is a competitive inhibitor.
Menaquinone-n: usually n=7-9
Are menaquinones from different bacteria equivalents?
An Alternative Menaquinone Biosynthetic Pathway Operating in Microorganisms 2008
vitamin k2 and respiratory chain eukaryotes
Vitamin K3 is an alternative name of Menadione a precursor or menaquinones, that can be synthesized in humans from menadione
Papers Vitamin K3
5-hydroxy-2-methyl-1,4-naphthoquinone, a vitamin K3 analogue, suppresses STAT3 activation pathway through induction of protein tyrosine phosphatase, SHP-1: potential role in chemosensitization. 2010
5-hydroxy-2-methyl-1,4-naphthoquinone (plumbagin) , an analogue of vitamin K, and isolated from chitrak (Plumbago zeylanica), an Ayurvedic medicinal plant, can modulate the STAT3 pathway. We found that plumbagin inhibited both constitutive and interleukin 6-inducible STAT3 phosphorylation in multiple myeloma (MM) cells and this correlated with the inhibition of c-Src, Janus-activated kinase (JAK)1, and JAK2 activation. Vanadate, however, reversed the plumbagin-induced downregulation of STAT3 activation, suggesting the involvement of a protein tyrosine phosphatase. Indeed, we found that plumbagin induced the expression of the protein tyrosine phosphatase, SHP-1, and silencing of the SHP-1 abolished the effect of plumbagin.
Vitamin K(3) attenuates lipopolysaccharide-induced acute lung injury through inhibition of nuclear factor-kappaB activation. 2010
Vitamin K content in vegetables
Vitamin K supplements