Classification Term: 1556
Tocopherols (ontology term: CHEMONTID:0000201)
Vitamin E derivatives containing a saturated trimethyltridecyl chain attached to the carbon C6 atom of a benzopyran ring system. The differ from tocotrienols that contain an unsaturated trimethyltrideca-3,7,11-trien-1-yl chain." []
found 12 associated metabolites at family metabolite taxonomy ontology rank level.
Ancestor: Vitamin E compounds
Child Taxonomies: There is no child term of current ontology term.
alpha-Tocopherol
Alpha-tocopherol is a pale yellow, viscous liquid. (NTP, 1992) (R,R,R)-alpha-tocopherol is an alpha-tocopherol that has R,R,R configuration. The naturally occurring stereoisomer of alpha-tocopherol, it is found particularly in sunflower and olive oils. It has a role as an antioxidant, a nutraceutical, an antiatherogenic agent, an EC 2.7.11.13 (protein kinase C) inhibitor, an anticoagulant, an immunomodulator, an antiviral agent, a micronutrient, an algal metabolite and a plant metabolite. It is an enantiomer of a (S,S,S)-alpha-tocopherol. In 1922, vitamin E was demonstrated to be an essential nutrient. Vitamin E is a term used to describe 8 different fat soluble tocopherols and tocotrienols, alpha-tocopherol being the most biologically active. Vitamin E acts as an antioxidant, protecting cell membranes from oxidative damage. The antioxidant effects are currently being researched for use in the treatment of diseases causing bone loss, cardiovascular diseases, diabetes mellitus and associated comorbidities, eye diseases, inflammatory diseases (including skin conditions), lipid disorders, neurological diseases, and radiation damage. Though this research is so far inconclusive, vitamin E remains a popular supplement and is generally considered safe by the FDA. Vitamin E is a natural product found in Monteverdia ilicifolia, Calea jamaicensis, and other organisms with data available. Alpha-Tocopherol is the orally bioavailable alpha form of the naturally-occurring fat-soluble vitamin E, with potent antioxidant and cytoprotective activities. Upon administration, alpha-tocopherol neutralizes free radicals, thereby protecting tissues and organs from oxidative damage. Alpha-tocopherol gets incorporated into biological membranes, prevents protein oxidation and inhibits lipid peroxidation, thereby maintaining cell membrane integrity and protecting the cell against damage. In addition, alpha-tocopherol inhibits the activity of protein kinase C (PKC) and PKC-mediated pathways. Alpha-tocopherol also modulates the expression of various genes, plays a key role in neurological function, inhibits platelet aggregation and enhances vasodilation. Compared with other forms of tocopherol, alpha-tocopherol is the most biologically active form and is the form that is preferentially absorbed and retained in the body. A generic descriptor for all tocopherols and tocotrienols that exhibit alpha-tocopherol activity. By virtue of the phenolic hydrogen on the 2H-1-benzopyran-6-ol nucleus, these compounds exhibit varying degree of antioxidant activity, depending on the site and number of methyl groups and the type of isoprenoids. See also: Alpha-Tocopherol Acetate (is active moiety of); Tocopherol (related); Vitamin E (related) ... View More ... alpha-Tocopherol is traditionally recognized as the most active form of vitamin E in humans and is a powerful biological antioxidant. The measurement of "vitamin E" activity in international units (IU) was based on fertility enhancement by the prevention of spontaneous abortions in pregnant rats relative to alpha-Tocopherol. Natural vitamin E exists in eight different forms or isomers: four tocopherols and four tocotrienols. In foods, the most abundant sources of vitamin E are vegetable oils such as palm oil, sunflower, corn, soybean, and olive oil. Nuts, sunflower seeds, and wheat germ are also good sources. Constituent of many vegetable oils such as soya and sunflower oils. Dietary supplement and nutrient. Nutriceutical with anticancer and antioxidant props. Added to fats and oils to prevent rancidity. The naturally-occurring tocopherol is a single stereoisomer; synthetic forms are a mixture of all eight possible isomers An alpha-tocopherol that has R,R,R configuration. The naturally occurring stereoisomer of alpha-tocopherol, it is found particularly in sunflower and olive oils. α-Tocopherol (alpha-tocopherol) is a type of vitamin E. Its E number is "E307". Vitamin E exists in eight different forms, four tocopherols and four tocotrienols. All feature a chromane ring, with a hydroxyl group that can donate a hydrogen atom to reduce free radicals and a hydrophobic side chain which allows for penetration into biological membranes. Compared to the others, α-tocopherol is preferentially absorbed and accumulated in humans. Vitamin E is found in a variety of tissues, being lipid-soluble, and taken up by the body in a wide variety of ways. The most prevalent form, α-tocopherol, is involved in molecular, cellular, biochemical processes closely related to overall lipoprotein and lipid homeostasis. Ongoing research is believed to be "critical for manipulation of vitamin E homeostasis in a variety of oxidative stress-related disease conditions in humans."[2] One of these disease conditions is the α-tocopherol role in the use by malaria parasites to protect themselves from the highly oxidative environment in erythrocytes.[3] DL-α-Tocopherol. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=16826-11-2 (retrieved 2024-06-29) (CAS RN: 10191-41-0). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). DL-alpha-Tocopherol is a synthetic vitamin E, with antioxidation effect. DL-alpha-Tocopherol protects human skin fibroblasts against the cytotoxic effect of UVB[1]. DL-alpha-Tocopherol is a synthetic vitamin E, with antioxidation effect. DL-alpha-Tocopherol protects human skin fibroblasts against the cytotoxic effect of UVB[1]. rel-α-Vitamin E (rel-D-α-Tocopherol) is a vitamin with antioxidant properties and also a mixture[1]. α-Vitamin E ((+)-α-Tocopherol), a naturally occurring vitamin E form, is a potent antioxidant[1][2]. α-Vitamin E ((+)-α-Tocopherol), a naturally occurring vitamin E form, is a potent antioxidant[1][2].
Gamma-tocopherol/beta-tocopherol
Gamma-tocopherol is a tocopherol in which the chroman-6-ol core is substituted by methyl groups at positions 7 and 8. It is found particularly in maize (corn) oil and soya bean (soybean) oils. It has a role as a plant metabolite, a food antioxidant and an algal metabolite. It is a vitamin E and a tocopherol. gamma-Tocopherol is under investigation in clinical trial NCT00836368 (In Vitro Basophil Responsiveness to Allergen Challenge After Gamma-tocopherol Supplementation in Allergic Asthmatics). gamma-Tocopherol is a natural product found in Hypericum perfoliatum, Hypericum tomentosum, and other organisms with data available. Gamma-Tocopherol is the orally bioavailable gamma form of the naturally-occurring fat-soluble vitamin E, found in certain nuts and seeds, with potential antioxidant activity. Although the exact mechanism of action of this tocopherol has yet to be fully identified, gamma-tocopherol appears to have the ability to scavenge free radicals, thereby protecting against oxidative damage. A natural tocopherol with less antioxidant activity than ALPHA-TOCOPHEROL. It exhibits antioxidant activity by virtue of the phenolic hydrogen on the 2H-1-benzopyran-6-ol nucleus. As in BETA-TOCOPHEROL, it also has three methyl groups on the 6-chromanol nucleus but at different sites. gamma-Tocopherol, also known as 7,8-dimethyltocol, belongs to the class of organic compounds known as tocopherols. These are vitamin E derivatives containing a saturated trimethyltridecyl chain attached to the carbon C6 atom of a benzopyran ring system. They differ from tocotrienols which contain an unsaturated trimethyltrideca-3,7,11-trien-1-yl chain. It is estimated that 50\\\\\% of gamma-tocopherol is metabolized into gamma-CEHC and excreted into the urine. gamma-Tocopherol is the predominant form of vitamin E in plant seeds and derived products (e.g. nuts and vegetable oils). Unlike alpha-tocopherol, gamma-tocopherol inhibits cyclooxygenase activity and, therefore, exhibit anti-inflammatory properties (PMID: 11722951). Occurs in many nut and other vegetable oils such as soya and sunflower oil. It is used as antioxidant food additive. Member of Vitamin E group. Added to fats and oils to prevent rancidity. The naturally occurring tocopherol is a single steroisomer; synthetic forms are a mixture of all eight possible isomers [DFC] A tocopherol in which the chroman-6-ol core is substituted by methyl groups at positions 7 and 8. It is found particularly in maize (corn) oil and soya bean (soybean) oils. (+)-γ-Tocopherol. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=54-28-4 (retrieved 2024-07-01) (CAS RN: 54-28-4). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). γ-Tocopherol (D-γ-Tocopherol) is a potent cyclooxygenase (COX) inhibitor. γ-Tocopherol is a naturally occurring form of Vitamin E in many plant seeds, such as corn oil and soybeans. γ-Tocopherol possesses antiinflammatory properties and anti-cancer activity[1]. γ-Tocopherol (D-γ-Tocopherol) is a potent cyclooxygenase (COX) inhibitor. γ-Tocopherol is a naturally occurring form of Vitamin E in many plant seeds, such as corn oil and soybeans. γ-Tocopherol possesses antiinflammatory properties and anti-cancer activity[1].
Delta-Tocopherol
Tocopherol, or Vitamin E, is a fat-soluble vitamin in eight forms that is an important antioxidant. Vitamin E is often used in skin creams and lotions because it is believed to play a role in encouraging skin healing and reducing scarring after injuries such as burns. -- Wikipedia; Natural vitamin E exists in eight different forms or isomers, four tocopherols and four tocotrienols. All isomers have a chromanol ring, with a hydroxyl group which can donate a hydrogen atom to reduce free radicals and a hydrophobic side chain which allows for penetration into biological membranes. There is an alpha, beta, gamma and delta form of both the tocopherols and tocotrienols, determined by the number of methyl groups on the chromanol ring. Each form has its own biological activity, the measure of potency or functional use in the body. -- Wikipedia; Alpha-tocopherol is traditionally recognized as the most active form of vitamin E in humans, and is a powerful biological antioxidant. The measurement of "vitamin E" activity in international units (IU) was based on fertility enhancement by the prevention of spontaneous abortions in pregnant rats relative to alpha tocopherol. It increases naturally to about 150\\\\\% of normal in the maternal circulation during human pregnancies. 1 IU of vitamin E is defined as the biological equivalent of 0.667 milligrams of d-alpha-tocopherol, or of 1 milligram of dl-alpha-tocopherol acetate. The other isomers are slowly being recognized as research begins to elucidate their additional roles in the human body. Many naturopathic and orthomolecular medicine advocates suggest that vitamin E supplements contain at least 20\\\\\% by weight of the other natural vitamin E isomers. Commercially available blends of natural vitamin E include "mixed tocopherols" and "high gamma tocopherol" formulas. Also selenium, Coenzyme Q10, and ample vitamin C have been shown to be essential cofactors of natural tocopherols. -- Wikipedia; Synthetic vitamin E, usually marked as d,l-tocopherol or d,l tocopheryl acetate, with 50\\\\\% d-alpha tocopherol moiety and 50\\\\\% l-alpha-tocopherol moiety, as synthesized by an earlier process is now actually manufactured as all-racemic alpha tocopherol, with only about one alpha tocopherol molecule in 8 molecules as actual d-alpha tocpherol. The synthetic form is not as active as the natural alpha tocopherol form. The 1950s thalidomide disaster with numerous severe birth defects is a common example of d- vs l- epimer forms type problem with synthesized racemic mixtures. Information on any side effects of the synthetic vitamin E epimers is not readily available. Naturopathic and orthomolecular medicine advocates have long considered the synthetic vitamin E forms to be with little or no merit for cancer, circulatory and heart diseases. -- Wikipedia; Abetalipoproteinemia is a rare inherited disorder of fat metabolism that results in poor absorption of dietary fat and vitamin E. The vitamin E deficiency associated with this disease causes problems such as poor transmission of nerve impulses, muscle weakness, and degeneration of the retina that can cause blindness. Individuals with abetalipoproteinemia may be prescribed special vitamin E supplements by a physician to treat this disorder. -- Wikipedia; Recent studies also show that vitamin E acts as an effective free radical scavenger and can lower the incidence of lung cancer in smokers. The effects are opposite to that of the clinical trials based on administering carotenoid to male smokers, that resulted in increased risk of lung cancer. Hence vitamin E is an effective antagonist to the oxidative stress that is imposed by high carotenoids in certain patients. -- Wikipedia; A cataract is a condition of clouding of the tissue of the lens of the eye. They increase the risk of disability and blindness in aging adults. Antioxidants are being studied to determine whether they can help prevent or delay cataract growth. Observational studies have found that lens clarity, wh... Delta-Tocopherol is an isomer of Vitamin E. Delta-Tocopherol is an isomer of Vitamin E.
Beta-tocopherol
beta-Tocopherol is an antioxidant which is synthesized by photosynthetic organisms and plays an important role in human and animal nutrition. beta-Tocopherols can be oxidized in dry CH2Cl2 or CH3CN by one electron to form cation radicals that deprotonate to form the neutral phenoxyl radicals, which are then immediately further oxidized by one electron to the phenoxonium cations (an ECE electrochemical mechanism, where E signifies an electron transfer and C represents a chemical step, with the electrochemical mechanism having been determined by in situ spectroscopic analysis). The phenoxonium cation of beta-tocopherol is stable for several minutes (PMID: 16771430). beta-Tocopherol has been identified in the human placenta (PMID: 32033212). (rel)-β-Tocopherol is a relative configuration of β-Tocopherol.(±)-β-Tocopherol is a lipid-soluble form of vitamin E with antioxidant activity. β-Tocopherol can inhibit tyrosinase activity and melanin synthesis. β-Tocopherol also can prevent the inhibition of cell growth and of PKC activity caused by d-alpha-tocopherol[1].
Substance P
C63H98N18O13S (1346.7281097999999)
Entamoeba histolytica is a single-celled parasitic protozoan that infects the lower gastrointestinal tract of humans. The symptoms of infection are diarrhea, constipation, and abdominal pain. This protozoan was found to secrete serotonin as well as substance P and neurotensin.; In the field of neuroscience, substance P (SP) is a neuropeptide: an undecapeptide that functions as a neurotransmitter and as a neuromodulator. It belongs to the tachykinin neuropeptide family. Substance P and its closely related neuropeptide neurokinin A (NKA) are produced from a polyprotein precursor after differential splicing of the preprotachykinin A gene. The deduced amino acid sequence of substance P is as follows:; Substance P (SP), is an 11-amino acid neuropeptide. SP is a member of the tachykinin family of peptides because it induces rapid smooth muscle contraction in guinea pig ileum and rat duodenum. Other members of the tachykinin family, sharing common carboxyl terminal Phe-X-Gly-Leu-met-NH2 sequences in mammals, include neurokinin A and neurokinin B. In mammals, tachykinins are produced by two genes, preprotachykinin-A (PPT-A) and preprotachykinin-B (PPT-B), and SP is a product of the PPT-A gene. SP is localized in the central nervous system as well as in several peripheral tissues, including the entire length of the gastrointestinal tract as well as the colon. The main sources of SP in the gut include the myenteric and submucosal plexus, intrinsic sensory neurons, as well as sensory neurons originating from the dorsal root ganglia. A newly identified gene, preprotachykinin C gene, encodes for the sequence of a new preprotachykinin protein designated hemokinin (HK) and produced primarily by hematopoietic cells. HK binds with high selectivity to NK-1R and has similar in vivo potency to SP. Like SP, HK is an 11-amino acid peptide having ~55\\\\% amino acid similarity to SP.; The effects of SP are mediated by three different G-protein-coupled receptors (GPCRs), namely neurokinin (NK)-1, 2, and 3. SP binds with high affinity to NK-1 receptor (NK-1R), and with low affinity to NK-2 and 3 receptors. NK-1 receptors are present in both small intestine and colon of animals and humans and are localized in a variety of cells, including nerves, smooth muscle, immune cells, glands, endothelial cells, as well as epithelial cells. Although NK-1 receptors have been associated with several intestinal pathophysiologic conditions (see below), NK-2 receptors have been linked mostly with circular muscle contraction, and are localized in circular muscle and muscularis mucosae. Although NK-2 receptors are present predominantly on smooth muscle and, like NK-1, can affect gut motility, NK-3 receptors are expressed predominantly in neurons and can stimulate or diminish muscle contraction indirectly following SP binding to neuronal cells in the submucosal and myenteric nerve plexuses of the gastrointestinal tract. NK-3 receptors also provide slow excitatory synaptic input to neurons in ganglia of the sphincter of Oddi. Thus, both NK-2 and NK-3 receptors affect motility responses in the GI, but there is very little evidence that they are involved in neuroimmune interactions. (PMID: 17192554); Substance P is an important element in pain perception. The sensory function of substance P is thought to be related to the transmission of pain information into the central nervous system. Substance P coexists with the excitatory neurotransmitter glutamate in primary afferents that respond to painful stimulation. SP has been associated with the regulation of mood disorders, anxiety, stress, reinforcement, neurogenesis, respiratory rhythm, neurotoxicity, nausea/emesis, pain and nociception. Substance P and other sensory neuropeptides can be released from the peripheral terminals of sensory nerve fibers in the skin, muscle and joints. It is proposed that this release is involved in neurogenic inflammation which is a local inflammatory response to certain types of infection or injury... Substance P (SP), is an 11-amino acid neuropeptide. SP is a member of the tachykinin family of peptides because it induces rapid smooth muscle contraction in guinea pig ileum and rat duodenum. Other members of the tachykinin family, sharing common carboxyl terminal Phe-X-Gly-Leu-met-NH2 sequences in mammals, include neurokinin A and neurokinin B. In mammals, tachykinins are produced by two genes, preprotachykinin-A (PPT-A) and preprotachykinin-B (PPT-B), and SP is a product of the PPT-A gene. SP is localized in the central nervous system as well as in several peripheral tissues, including the entire length of the gastrointestinal tract as well as the colon. The main sources of SP in the gut include the myenteric and submucosal plexus, intrinsic sensory neurons, as well as sensory neurons originating from the dorsal root ganglia. A newly identified gene, preprotachykinin C gene, encodes for the sequence of a new preprotachykinin protein designated hemokinin (HK) and produced primarily by hematopoietic cells. HK binds with high selectivity to NK-1R and has similar in vivo potency to SP. Like SP, HK is an 11-amino acid peptide having ~55\\\\% amino acid similarity to SP. The effects of SP are mediated by three different G-protein-coupled receptors (GPCRs), namely neurokinin (NK)-1, 2, and 3. SP binds with high affinity to NK-1 receptor (NK-1R), and with low affinity to NK-2 and 3 receptors. NK-1 receptors are present in both small intestine and colon of animals and humans and are localized in a variety of cells, including nerves, smooth muscle, immune cells, glands, endothelial cells, as well as epithelial cells. Although NK-1 receptors have been associated with several intestinal pathophysiologic conditions (see below), NK-2 receptors have been linked mostly with circular muscle contraction, and are localized in circular muscle and muscularis mucosae. Although NK-2 receptors are present predominantly on smooth muscle and, like NK-1, can affect gut motility, NK-3 receptors are expressed predominantly in neurons and can stimulate or diminish muscle contraction indirectly following SP binding to neuronal cells in the submucosal and myenteric nerve plexuses of the gastrointestinal tract. NK-3 receptors also provide slow excitatory synaptic input to neurons in ganglia of the sphincter of Oddi. Thus, both NK-2 and NK-3 receptors affect motility responses in the GI, but there is very little evidence that they are involved in neuroimmune interactions. (PMID: 17192554). Substance P (Neurokinin P) is a neuropeptide, acting as a neurotransmitter and as a neuromodulator in the CNS. The endogenous receptor for substance P is neurokinin 1 receptor (NK1-receptor, NK1R). Substance P (Neurokinin P) is a neuropeptide, acting as a neurotransmitter and as a neuromodulator in the CNS. The endogenous receptor for substance P is neurokinin 1 receptor (NK1-receptor, NK1R).
13'-Carboxy-alpha-tocopherol
13-carboxy-alpha-tocopherol is a dehydrogenation carboxylate product of 13-hydroxy-a-tocopherol by an unidentified microsomal enzyme(s) probably via an aldehyde intermediate. The tocopherols ( a-tocopherol , b-tocopherol ,r-tocopherol and d-tocopherol ) and their corresponding tocotrienols are synthesized by plants and have vitamin E antixoidant activity (see pathway vitamin E biosynthesis ). They differ in the number and location of methyl groups on the chromanol ring. The naturally occurring form of a-tocopherol is (2R,4R,8R)-a-tocopherol (synonym (R,R,R)-a-tocopherol). Synthetic a-tocopherols are a racemic mixture of eight different R and S stereoisomers. Only the 2R forms are recognized as meeting human requirements. The in vivo function of vitamin E is to scavenge peroxyl radicals via its phenolic (chromanol) hydroxyl group, thus protecting lipids against free radical-catalyzed peroxidation. The tocopheryl radical formed can then be reduced by reductants such as L-ascorbate. Other major products of a-tocopherol oxidation include α-tocopherylquinone and epoxy-a-tocopherols. The metabolites a-tocopheronic acid and its lactone, known as the Simon metabolites, are generally believed to be artefacts. In addition to these oxidation products, the other major class of tocopherol metabolites is the carboxyethyl-hydroxychromans.These metabolites are produced in significant amounts in response to excess vitamin E ingestion. Vitamin E is fat-soluble and its utilization requires intestinal fat absorption mechanisms. It is secreted from the intestine into the lymphatic system in chylomicrons which subsequently enter the plasma. Lipolysis of these chylomicrons can result in delivery of vitamin E to tissues, transfer to high-density lipoproteins (and subsequently to other lipoproteins via the phospholipid exchange protein), or retention in chylomicron remnants. These remnants are taken up by the liver. Natural (R,R,R)-α-tocopherol and synthetic 2R-α-tocopherols are then preferentially secreted from the liver into plasma as a result of the specificity of the α-tocopherol transfer protein. This protein, along with the metabolism of excess vitamin E in the liver and excretion into urine and bile, mediate the supply of a-tocopherol in plasma and tissues. 13-carboxy-alpha-tocopherol is a dehydrogenation carboxylate product of 13-hydroxy-a-tocopherol by an unidentified microsomal enzyme(s) probably via an aldehyde intermediate
13'-Carboxy-gamma-tocopherol
13-Carboxy-gamma-tocopherol is a dehydrogenation carboxylate product of 13-hydroxy-r-tocopherol by an unidentified microsomal enzyme(s) probably via an aldehyde intermediate. r-Tocopherol provides different antioxidant activities in food and in-vitro studies and showed higher activity in trapping lipophilic electrophiles and reactive nitrogen and oxygen species. From the metabolism end product, only that of r-tocopherol (2,7,8-trimethyl-2-(b-carboxyethyl)-6-hydroxychroman), but not that of a-tocopherol, was identified to provide natriuretic activity. Only the r-tocopherol plasma level served as biomarker for cancer and cardiovascular risk. 13-Carboxy-gama-tocopherol is a dehydrogenation carboxylate product of 13-hydroxy-r-tocopherol by an unidentified microsomal enzyme(s) probably via an aldehyde intermediate
13'-Hydroxy-alpha-tocopherol
13-hydroxy-alpha-tocopherol is the precursor in dehydrogenation to 13-carboxy-alpha-tocopherol by an unidentified microsomal enzyme(s) probably via an aldehyde intermediate. The tocopherols ( a-tocopherol , b-tocopherol ,r-tocopherol and d-tocopherol ) and their corresponding tocotrienols are synthesized by plants and have vitamin E antixoidant activity (see pathway vitamin E biosynthesis ). They differ in the number and location of methyl groups on the chromanol ring. The naturally occurring form of a-tocopherol is (2R,4R,8R)-a-tocopherol (synonym (R,R,R)-a-tocopherol). Synthetic a-tocopherols are a racemic mixture of eight different R and S stereoisomers. Only the 2R forms are recognized as meeting human requirements. The in vivo function of vitamin E is to scavenge peroxyl radicals via its phenolic (chromanol) hydroxyl group, thus protecting lipids against free radical-catalyzed peroxidation. The tocopheryl radical formed can then be reduced by reductants such as L-ascorbate. Other major products of a-tocopherol oxidation include α-tocopherylquinone and epoxy-a-tocopherols. The metabolites a-tocopheronic acid and its lactone, known as the Simon metabolites, are generally believed to be artefacts. In addition to these oxidation products, the other major class of tocopherol metabolites is the carboxyethyl-hydroxychromans.These metabolites are produced in significant amounts in response to excess vitamin E ingestion. Vitamin E is fat-soluble and its utilization requires intestinal fat absorption mechanisms. It is secreted from the intestine into the lymphatic system in chylomicrons which subsequently enter the plasma. Lipolysis of these chylomicrons can result in delivery of vitamin E to tissues, transfer to high-density lipoproteins (and subsequently to other lipoproteins via the phospholipid exchange protein), or retention in chylomicron remnants. These remnants are taken up by the liver. Natural (R,R,R)-α-tocopherol and synthetic 2R-α-tocopherols are then preferentially secreted from the liver into plasma as a result of the specificity of the α-tocopherol transfer protein. This protein, along with the metabolism of excess vitamin E in the liver and excretion into urine and bile, mediate the supply of a-tocopherol in plasma and tissues. 13-hydroxy-alpha-tocopherol is the precursor in dehydrogenation to 13-carboxy-alpha-tocopherol by an unidentified microsomal enzyme(s) probably via an aldehyde intermediate
13'-Hydroxy-gamma-tocopherol
13-hydroxy-r-tocopherol is a precursor of dehydrogenation to form 13-Carboxy-gamma-tocopherol by an unidentified microsomal enzyme(s) probably via an aldehyde intermediate. r-Tocopherol provides different antioxidant activities in food and in-vitro studies and showed higher activity in trapping lipophilic electrophiles and reactive nitrogen and oxygen species. From the metabolism end product, only that of r-tocopherol (2,7,8-trimethyl-2-(b-carboxyethyl)-6-hydroxychroman), but not that of a-tocopherol, was identified to provide natriuretic activity. Only the r-tocopherol plasma level served as biomarker for cancer and cardiovascular risk. 13-hydroxy-r-tocopherol is a precursor of dehydrogenation to form 13-Carboxy-gama-tocopherol by an unidentified microsomal enzyme(s) probably via an aldehyde intermediate
(-)-1-[5-Chloro-1-(2,4-dimethoxyphenylsulfonyl)-3-(2-methoxyphenyl)-2-oxo-2,3-dihydro-1H-indol-3-yl]-4(R)-hydroxy-L-proline N,N-dimethylamide
(-)-alpha-Tocopherol
α-tocopherol is a member of the class of compounds known as tocopherols. Tocopherols are vitamin E derivatives containing a saturated trimethyltridecyl chain attached to the carbon C6 atom of a benzopyran ring system. The differ from tocotrienols that contain an unsaturated trimethyltrideca-3,7,11-trien-1-yl chain. α-tocopherol is practically insoluble (in water) and a very weakly acidic compound (based on its pKa). α-tocopherol can be found in a number of food items such as lime, rowanberry, horseradish tree, and pineappple sage, which makes α-tocopherol a potential biomarker for the consumption of these food products. α-tocopherol is a form of vitamin E that is preferentially absorbed and accumulated in humans. The measurement of "vitamin E" activity in international units (IU) was based on fertility enhancement by the prevention of spontaneous abortions in pregnant rats relative to α-tocopherol .