Warfarin/coumadin has historically been used in rodenticides -> induces lethal hemorrhage
Some of the newer rodenticides contain such long-acting vitamin K antagonists that they not only kill the rodent, but they can also kill dogs/cats that may eat them
Sources of Vitamin K
Bacterial Synthesis of Vitamin K in Colon: represents the major source of vitamin K
Dietary Vitamin K: decreased dietary vitamin K has a minimal impact on vitamin K stores (since most vitamin K is obtained from colonic bacterial sources)
Average daily vitamin K intake (in USA): 100 ug/day
Ileum is the major site of vitamin K absorption: hepatically-synthesized bile acids are secreted into the small intestine, where they are required for fat absorption (vitamin K is a fat soluble vitamin)
Food Sources
Cauliflower
Green, Leafy Vegetables: kale, spinach
Liver
Margarine
Vegetable Oils: olive, canola, soybean
Physiology
Forms of Vitamin K: phylloquinone can be converted to menaquinone in some organs
Phylloquinone (Vitamin K1): natural form found in animal and vegetable sources
Menaquinone (Vitamin K2): natural form synthesized by intestinal bacterial flora, found in hepatic tissues
Menadione (Vitamin K3): synthetic, water-soluble form
Function: vitamin K is required for the post-translational carboxylation of glutamic acid (via vitamin K epoxide reductase) in the vitamin K-dependent clotting factors (factor II/prothombin, factor VII, factor IX, and factor X), the vitamin K-dependent anticoagulant factors (protein C, protein S, and protein Z), select bone proteins (osteocalcin, matrix-Gla protein), and some ribosomal proteins
Gamma carboxyglutamic acid is necessary to allow the protein to bind to membranes: gamma carboxyglutamic acid chelates positively-charged calcium, allowing binding to the negatively-charged phosphate head groups of membrane phospholipids)
Gamma carboxyglutamic acid assists in forming the necessary structure of such proteins by forming calcium-mediated intrachain interactions that link two gamma-carboxyglutamic acids to a calcium ion