Vitamin K – sources, physiological role, kinetics, deficiency, detection, therapeutic use, and toxicity

Abstract

Vitamin K is traditionally connected with blood coagulation, since it is needed for the posttranslational modification of 7 proteins involved in this cascade. However, it is also involved in the maturation of another 11 or 12 proteins that play different roles, encompassing in particular the modulation of the calcification of connective tissues. Since this process is physiologically needed in bones, but is pathological in arteries, a great deal of research has been devoted to finding a possible link between vitamin K and the prevention of osteoporosis and cardiovascular diseases. Unfortunately, the current knowledge does not allow us to make a decisive conclusion about such a link. One possible explanation for this is the diversity of the biological activity of vitamin K, which is not a single compound but a general term covering natural plant and animal forms of vitamin K (K1 and K2) as well as their synthetic congeners (K3 and K4). Vitamin K1 (phylloquinone) is found in several vegetables. Menaquinones (MK4–MK13, a series of compounds known as vitamin K2) are mostly of a bacterial origin and are introduced into the human diet mainly through fermented cheeses. Current knowledge about the kinetics of different forms of vitamin K, their detection, and their toxicity are discussed in this review.

Biological Role of Vitamin K—With Particular Emphasis on Cardiovascular and Renal Aspects

“…This enzyme catalyzes the attachment of carboxyl groups to Glu residues in proteins, whose carboxylation is vitamin K dependent [3,12,13]. This group consists of at least 18 proteins which include several proteins involved in blood clotting (protein C, S, M, Z, factors VII, IX, X and prothrombin), Gas6 (Growth Arrest-Specific 6 Protein), bone Gla protein (BGP or osteocalcin OC), matrix Gla protein (MGP), periostin and GRP (Gla Rich Protein) [6,7,[9][10][11][12][13]. The most important VKDPs are prothrombin, MGP and OC [6,7,10,11].…”

“…Vascular calcification is a dynamic process with the participation of calcification promoters and inhibitors and, at present, no particular therapy is known [2,11]. The mechanism of this process involves matrix-Gla protein (MGP), which is the most potent inhibitor of arterial calcification which belongs to Gla-containing proteins also known as Gla-rich protein GRP [1,3,4,7,11,13,16]. GRPs are dependent on vitamin K which is a cofactor of conversion of glutamate into Gla [1,3,16].…”

“…In recent years, there has been a growing interest in the role of vitamin K in the calcification of arteries, especially in patients with CKD [1][2][3][4][5]7,8,[11][12][13]16]. In patients with CKD, VC occurs widely even at early stages [1,2].…”

Personalized Medicine in Mitochondrial Health and Disease: Molecular Basis of Therapeutic Approaches Based on Nutritional Supplements and Their Analogs

“…Menadione, which is sometimes called vitamin K3, is another synthetic form of vitamin K. It was shown to damage hepatic cells, so it is no longer used in dietary supplements or fortified foods. Vitamin K shows very low toxicity levels also in the case of long-term supplementations [ 110 ]. Phylloquinone was used in combination with other vitamins or drugs for the treatment of primary mitochondrial disorders [ 63 , 111 , 112 , 113 ], although it cannot replace coenzyme Q10 in the mitochondrial respiratory chain of mammalian cells [ 114 ], despite what was observed in drosophila models [ 115 ].…”

Antitumor Activities of tRNA-Derived Fragments and tRNA Halves from Non-pathogenic Escherichia coli Strains on Colorectal Cancer and Their Structure-Activity Relationship

“…Advanced studies have revealed that PECSs containing the peptide synthetase-polyketide synthetase (PKS) island could induce DNA double-strand breaks in human cell lines, and thus, PECSs may be able to accelerate the development of colorectal cancer ( 12 – 14 ), which is a leading cause of cancer-related deaths worldwide ( 15 , 16 ). On the other hand, E. coli strains of groups A and D are not known to cause diseases and can even be beneficial to their hosts, e.g., by producing vitamin K 2 ( 5 , 17 , 18 ). Thus, the functions of these non-pathogenic E. coli strains (NPECSs) demand attention from researchers.…”