Basic Facts about Micronutrients
Kedar N. Prasad in Micronutrients in Health and Disease, 2019
Vitamin E: Among vitamin E isomers, alpha-tocopherol is biologically more active than others. In recent years, the research on tocotrienols has also revealed some important biological functions. Synthetic vitamin E is referred to as the dl-form; the natural form is termed as the d-form. Vitamin E is commercially sold as d- or dl-alpha-tocopherol, alpha-tocopheryl acetate (alpha-TA), or alpha-tocopheryl succinate (alpha-TS). The esterified form of vitamin E (alpha-TA and alpha-TS) are more stable than alpha-tocopherol. Alpha-TA has been widely used in the basic research and clinical studies. It has been presumed that alpha-TA or alpha-TS is converted to alpha-tocopherol before absorption. This assumption may be true as long as the stores of alpha-tocopherol in the body are not saturated; however, if the body stores of alpha-tocopherol are saturated, alpha-TS can be absorbed as alpha-TS. Alpha-TS enters the cells more easily than alpha-tocopherol because of its greater solubility. Alpha-TS have some unique functions that cannot be produced by alpha-T. Alpha-TS is now considered the most effective form of vitamin E, but it cannot act as an antioxidant until converted to alpha-T. Alpha-T is located primarily in the membranous structures of the cells. The level of vitamin E can be determined in the plasma.
Tocotrienol Vitamin E and Neurodegenerative Disorders
Abhai Kumar, Debasis Bagchi in Antioxidants and Functional Foods for Neurodegenerative Disorders, 2021
Alpha tocopherol is the most studied form of natural vitamin E in animal tissues, occurring as a chain-breaking antioxidant in cell membranes and lipoproteins, limiting lipid peroxidation, and sustaining membrane integrity. Recently, studies have established that tocotrienols have an overall positive effect on human health and have more potent antioxidant capacity compared to tocopherols [5,6]. The U.S. Food and Drug Administration (FDA) classifies α-tocotrienol as Generally Recognized as Safe (GRN307), and recognizes that tocotrienol is not a drug with adverse side effects [7]. Tocotrienols are found in the seed endosperm of most monocots with agronomically vital cereal grains such as wheat, rice, and barley. Palm oil is the richest source of tocotrienols [2,8]. Several studies have shown that tocotrienols possess numerous biological functions often not shared by tocopherols. At nanomolar concentration, α-tocotrienol, uniquely inhibits inducible neurodegeneration by modifying specific mediators of cell death (Figure 14.1) [9,10].
Prospects of Local Flora of Trans-Himalayan Region of Ladakh for Various Medicinal Uses
Parimelazhagan Thangaraj in Medicinal Plants, 2018
Sea buckthorn oil is a valuable product used in medicine as a nutraceutical supplement and in cosmetics. Lipids from sea buckthorn leaves have been recommended for anti-burn and wound healing properties. The presence of a high content of α-tocopherol has significant healthful effects which act as natural antioxidants in the human body. The carotenoid content of sea buckthorn oil ranges from 314–2139 mg/100g (Zhang et al. 1989). It is indicated that the carotenoids consist of approximately 20% β-carotene, 30% γ-carotene, 30% lycopene and 15% oxygen-containing carotenoids. Phytosterol is also constituents of sea buckthorn oil which are capable of lowering plasma cholesterol on consumption by humans. The major phytosterol is sitosterol (β-sitosterol) and 5-avenasterol. The total quantity of phytoesterol in whole sea buckthorn fruits ranges from 340–520 mg/kg and is 4 to 20 times more than soybean oil. A novel triglyceride, 1,3-dicapryloyl-2-linoleoyl glycerol has been isolated and its structure was elucidated by Swaroop et al. (2005).
Inhibition of platelet activation using vitamins
Published in Platelets, 2020
It should be noted that in some works, dietary supplementation with α-tocopherol [26,27] or palm-based tocotrienols and tocopherol mixtures [28] was not effective. α-Tocopherol is the prevalent form of vitamin E in plasma and is believed to be mainly responsible for the biological activity of the vitamin. Therefore, in most studies, the effect of only α-tocopherol was studied. However, it was found that other tocopherols are also active as inhibitors of platelet aggregation. In in vitro studies with human PRP, α-, γ- and δ-tocopherol have similar inhibitory effects on platelet aggregation induced by 5 µM of ADP[16]. Dietary supplementation of 100 and 200 mg/day γ-tocopherol for five weeks decreased the ex vivo whole blood platelet aggregation induced by 2 µg/ml of collagen[29]. Liu et al [30]. suggested that the absence of tocopherols other than α-tocopherol in the preparations used in the clinical studies might account for the conflicting results with the supplementation of vitamin E. They found that platelet aggregation was inhibited more potently in platelets isolated from humans supplemented with a mixed tocopherol preparation than in platelets isolated from humans supplemented with α-tocopherol alone.
Pharmacological potential of tocopherol and doxycycline against traumatic brain injury-induced cognitive/motor impairment in rats
Published in Brain Injury, 2020
Arti Rana, Shamsher Singh, Rahul Deshmukh, Anoop Kumar
Alpha-tocopherol is an active form of vitamin E which has diverse biological activities including potent antioxidant, anti-inflammatory, anticancer, and anti-angiogenic activities (10). In literature, various reports have indicated the neuroprotective role of tocopherol in various neurodegenerative disorders. Saha et al. (11), have suggested the neuroprotective role of alpha-tocopherol against a wide variety of neurodegenerative diseases (Huntington disease, Alzheimer's disease) (11). Ishaq et al. (12), have reported a reduction in the mortality rate of TBI rats after treatment with ascorbic acid and tocopherol (12). Alpha-tocopherol is known to provide a neuroprotective effect in TBI by suppressing the level of Nogo-A and NgR in the brain (13). In literature, various reports have indicated the neuroprotective effect of doxycycline and tocopherol against various neurodegenerative disorders. However, the neuroprotective mechanism of tocopherol and doxycycline in TBI is still unclear. Thus, in the current investigation, we have tested the pharmacological potential of tocopherol and doxycycline (alone and in combination) as a neuroprotective and neuromodulatory agent in TBI.
A meta-analysis of peripheral tocopherol levels in age-related cognitive decline and Alzheimer’s disease
Published in Nutritional Neuroscience, 2021
Stephanie Ashley, Steven Bradburn, Chris Murgatroyd
Dietary intake has been progressively examined as a potential independent risk factor of the age-related cognitive decline and dementia, and the intake of certain nutrients such as vitamin E have been implicated in healthy brain function, though results are conflicting [2,3]. Vitamin E is an essential dietary micronutrient comprising a group of structurally-related forms including four different tocopherols. α–tocopherol is the most bioavailable antioxidant isoform of vitamin E in the human body and most often used in supplements. Vitamin E is found in vegetable oils and products derived from vegetables whole grains, nuts and seeds, animal fats and meats, with variations in levels of tocopherols between food sources for examples while some oils, such as soybean oil, contain a mix of tocopherols, others, such as sunflower oil, contain almost exclusively α-tocopherol (for further review see [4]).
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