Riboflavin, also known as vitamin B2, is a vitamin found in food and sold as a dietary supplement. It is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide. These coenzymes are involved in energy metabolism, cellular respiration, and antibody production, as well as normal growth and development. The coenzymes are also required for the metabolism of niacin, vitamin B6, and folate. Riboflavin is prescribed to treat corneal thinning, and taken orally, may reduce the incidence of migraine headaches in adults.
Vitamin B6 is one of the B vitamins, and is an essential nutrient for humans. The term essential nutrient refers to a group of six chemically similar compounds, i.e., "vitamers", which can be interconverted in biological systems. Its active form, pyridoxal 5′-phosphate, serves as a coenzyme in more than 140 enzyme reactions in amino acid, glucose, and lipid metabolism.
Ginkgo biloba, commonly known as ginkgo or gingko, also known as the maidenhair tree, is a species of gymnosperm tree native to East Asia. It is the last living species in the order Ginkgoales, which first appeared over 290 million years ago, and fossils very similar to the living species, belonging to the genus Ginkgo, extend back to the Middle Jurassic epoch approximately 170 million years ago. The tree was cultivated early in human history and remains commonly planted, and is widely regarded as a living fossil.
Homocystinuria (HCU) is an inherited disorder of the metabolism of the amino acid methionine due to a deficiency of cystathionine beta synthase or methionine synthase. It is an inherited autosomal recessive trait, which means a child needs to inherit a copy of the defective gene from both parents to be affected. Symptoms of homocystinuria can also be caused by a deficiency of vitamins B6, B12, or folate.
Pyridoxal phosphate (PLP, pyridoxal 5'-phosphate, P5P), the active form of vitamin B6, is a coenzyme in a variety of enzymatic reactions. The International Union of Biochemistry and Molecular Biology has catalogued more than 140 PLP-dependent activities, corresponding to ~4% of all classified activities. The versatility of PLP arises from its ability to covalently bind the substrate, and then to act as an electrophilic catalyst, thereby stabilizing different types of carbanionic reaction intermediates.
Bilobalide is a biologically active terpenic trilactone present in Ginkgo biloba.
Ginkgolides are biologically active terpenic lactones present in Ginkgo biloba. They are diterpenoids with 20-carbon skeletons, which are biosynthesized from geranylgeranyl pyrophosphate.
Pyridoxine 5′-phosphate oxidase is an enzyme, encoded by the PNPO gene, that catalyzes several reactions in the vitamin B6 metabolism pathway. Pyridoxine 5′-phosphate oxidase catalyzes the final, rate-limiting step in vitamin B6 metabolism, the biosynthesis of pyridoxal 5′-phosphate, the biologically active form of vitamin B6 which acts as an essential cofactor. Pyridoxine 5′-phosphate oxidase is a member of the enzyme class oxidases, or more specifically, oxidoreductases. These enzymes catalyze a simultaneous oxidation-reduction reaction. The substrate oxidase enzymes is hydroxylated by one oxygen atom of molecular oxygen. Concurrently, the other oxygen atom is reduced to water. Even though molecular oxygen is the electron acceptor in these enzymes' reactions, they are unique because oxygen does not appear in the oxidized product.
In enzymology, an erythrose-4-phosphate dehydrogenase (EC 1.2.1.72) is an enzyme that catalyzes the chemical reaction
The enzyme pyridoxal phosphatase (EC 3.1.3.74) catalyzes the reaction
In enzymology, a pyridoxine 5'-phosphate synthase (EC 2.6.99.2) is an enzyme that catalyzes the chemical reaction
In enzymology, a pyridoxal kinase is an enzyme that catalyzes the chemical reaction
Pyridoxal kinase is an enzyme that in humans is encoded by the PDXK gene.
Vitamins occur in a variety of related forms known as vitamers. A vitamer of a particular vitamin is one of several related compounds that performs the functions of said vitamin and prevents the symptoms of deficiency of said vitamin.
4-Deoxypyridoxine is a vitamin B6 antagonist. It may be toxic to developing embryos since it can have negative effects on collagen and elastin during development. The presence of this compound can produce vitamin B6 deficiency, which suppresses the immune system. 4-Deoxypyridoxine lowers vitamin B6 concentration by competitively inhibiting some of the enzymes necessary for the regeneration of vitamin B6. The related immunosuppression can be beneficial in animal models of Trichinella spiralis infections. 4-Deoxypyridoxine has also been described as an inhibitor of sphingosine-1-phosphate lyase. The inhibition of sphingosine-1-phosphate lyase by 4-deoxypyridoxine has been shown to prevent cell death of ex vivo animal pancreatic islets. The use of 4-deoxypyridoxine to prevent stress-induced apoptosis is suggest that the compound, as well as other inhibitors of sphingosine-1-phosphate lyase, could be used to increase the viability of donor pancreatic tissue in the treatment of diabetes.
Pyridoxine-dependent epilepsy (PDE) is a rare genetic disorder characterized by intractable seizures in the prenatal and neonatal period. The disorder was first recognized in the 1950s, with the first description provided by Hunt et al. in 1954. More recently, pathogenic variants within the ALDH7A1 gene have been identified to cause PDE.
In molecular biology, the Cys/Met metabolism PLP-dependent enzyme family is a family of proteins including enzymes involved in cysteine and methionine metabolism which use PLP (pyridoxal-5'-phosphate) as a cofactor.
Phosphoserine transaminase is an enzyme with systematic name O-phospho-L-serine:2-oxoglutarate aminotransferase. This enzyme catalyses the following chemical reaction
Megavitamin-B6 syndrome, also known as hypervitaminosis B6, vitamin B6 toxicity, and vitamin B6 excess, is a medical condition characterized by adverse effects resulting from excessive intake of vitamin B6. Primarily affecting the nervous system, this syndrome manifests through symptoms such as peripheral sensory neuropathy, characterized by numbness, tingling, and burning sensations in the limbs. The condition is usually triggered by chronic dietary supplementation of vitamin B6 but can also result from acute over-dosages, whether orally or parenterally.
3-Hydroxyisonicotinaldehyde (HINA), also known as 3-hydroxypyridine-4-carboxaldehyde, is a derivative of pyridine, with hydroxyl and aldehyde substituents. It has been studied as a simple analogue of vitamin B6. In 2020, it was reported as having the lowest molecular weight of all dyes which exhibit green fluorescence.
