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Micronutrients
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
Vitamin E has two main functions including enzymatic and antioxidant activities (23, 69–74). As an enzymatic activity regulator, vitamin E inhibits the activity of protein kinase C (PKC), an enzyme involved in cell proliferation and differentiation in smooth muscle cells, platelets, and monocytes (69–74). Vitamin E also increases the expression of two enzymes, namely cytosolic phospholipase A2 and cyclooxygenase-1, that suppress arachidonic acid metabolism, thereby increasing the release of prostacyclin from the endothelium, which, in turn, dilates blood vessels and inhibits platelet aggregation in humans (70–71). A few other studies suggest that tocopherols appear to inhibit platelet aggregation through the inhibition of protein kinase C (PKC) and the increased action of nitric oxide synthase (71). Another main activity of vitamin E is its antioxidant property. Alpha-tocopherol is a strong peroxyl radical scavenger and an inhibitor of oxidative stress, which can cause numerous chronic diseases like cancer, inflammatory diseases, and CVD. Thanks to its antioxidant effect, natural vitamin E in foods may prevent cardiovascular disease (CVD) and cancer. Details of the antioxidant property of vitamin E and its mechanism are developed in Chapter 4 of this book. In addition, natural vitamin E (RRR-α-tocopherol) possesses anti-inflammatory, anti-platelet aggregating, and immunostimulant properties, and is a regulating cell signaling agent as well as a modulating gene transcription compound (69–74).
Effects of Food Processing, Storage, and Cooking on Nutrients in Plant-Based Foods
Published in Nicole M. Farmer, Andres Victor Ardisson Korat, Cooking for Health and Disease Prevention, 2022
Alpha-tocopherol (vitamin E) is the name of a group of eight different molecules that exhibit the antioxidant activity of alpha-tocopherol. The main source of vitamin E in the diet is vegetable oils, especially safflower and sunflower oils (Traber, 2006). Vitamin E is lipid-soluble and, like carotenoids, does not tend to leach out during processing, especially in those unit operations such as washing and blanching, which require the product to be immersed in water. Alpha-tocopherol levels actually increase immediately after blanching which may be explained by increased availability to the assay due to rupture of cell wall materials and remain relatively constant during frozen storage (Bouzari et al., 2015b). However, more severe heat processing, such as the conditions found in canning operations, seems to decrease levels of alpha-tocopherol to their fresh counterparts. For instance, alpha-tocopherol levels decreased by as much as 15%–20% during canning of tomato paste and asparagus compared to their fresh versions, whereas no decreases were detected in canned spinach or sweet potatoes (Rickman, Bruhn, et al., 2007). Conversely, alpha-tocopherol is well preserved in fruits and vegetables during freezing.
Tocotrienol Vitamin E and Neurodegenerative Disorders
Published in Abhai Kumar, Debasis Bagchi, 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].
The Vitamin E Isoform α-Tocopherol is Not Effective as a Complementary Treatment in Cancer Treatment: A Systematic Review
Published in Nutrition and Cancer, 2022
Dorothee Retzlaff, Jennifer Dörfler, Sabine Kutschan, Maren Freuding, Jens Büntzel, Jutta Hübner
Vitamin E is a generic term for tocopherols and tocotrienols, which due to their chemical variations, differ in their various efficacies, including as antioxidants. The main effect of the isoform α-tocopherol in the body is an antioxidant property and the protection of body cells from free radicals, so many cancer patients aim to take α-tocopherol as a dietary supplement to improve the outcome of their therapy and reduce adverse reactions, like peripheral neuropathy or mucositis (1, 2). Alpha-tocopherol is known to protect against lipid peroxidation and to reduce stress-induced apoptosis (3). However, some studies have observed that α-tocopherol can have harmful effect on survival (4, 5) and one study reported that α-tocopherol might increase all-cause mortality of cancer patients (6). This systematic review was conducted to assess and evaluate which positive and harmful effects α-tocopherol can have on the clinical course of cancer therapy.
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.
Pesticides induced oxidative stress and female infertility: a review
Published in Toxin Reviews, 2020
Jitender Kumar Bhardwaj, Meenu Mittal, Priyanka Saraf, Priya Kumari
Alpha-tocopherol one of the most widely distributed and naturally occurring biologically active antioxidant that acts as protectant against lipid peroxidation through its chain breaking action (Oral et al.2006). Tocopherol protects GPx4 (an isoform of glutathione peroxidase) deficient cells from cell death (Agarwal et al.2012). In contrast to alpha-tocopherol, ascorbic acid is hydrophilic in nature and functions better in an aqueous environment than does alpha-tocopherol. It has been found that ascorbates can restore the antioxidant property of oxidized tocopherol, which indicates that ascorbic acid function mainly to recycle tocopheroxyl radical (Serbecic and Beutelspacher 2005). Furthermore, vitamin C acts as an antioxidant, blocking the formation of nitrosanimes, causing enhancement of the immune response, and detoxify liver enzymes (Glatthaar et al.1986). Ascorbates are present in millimolar and micromolar concentration in ovarian and human follicular fluid, respectively (Devine et al.2012), which detoxifies ROS, as do tocopherols, and inhibits cell death (Ramanathan et al.2005). Similarly, antioxidant property of vitamin E has been found to mediate inhibition of carcinogenesis, repair of DNA membranes (Sokol 1988). It is also known to be most potent radical scavenging lipophilic antioxidant.