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Singh VK, Wise SY, Fatanmi OO, Petrus SA, Carpenter AD, Lee SH, Hauer-Jensen M, Seed TM. Histopathological studies of nonhuman primates exposed to supralethal doses of total- or partial-body radiation: influence of a medical countermeasure, gamma-tocotrienol. Sci Rep 2024; 14:5757. [PMID: 38459144 PMCID: PMC10923821 DOI: 10.1038/s41598-024-56135-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Accepted: 03/01/2024] [Indexed: 03/10/2024] Open
Abstract
Despite remarkable scientific progress over the past six decades within the medical arts and in radiobiology in general, limited radiation medical countermeasures (MCMs) have been approved by the United States Food and Drug Administration for the acute radiation syndrome (ARS). Additional effort is needed to develop large animal models for improving the prediction of clinical safety and effectiveness of MCMs for acute and delayed effects of radiation in humans. Nonhuman primates (NHPs) are considered the animal models that reproduce the most appropriate representation of human disease and are considered the gold standard for drug development and regulatory approval. The clinical and histopathological effects of supralethal, total- or partial-body irradiations (12 Gy) of NHPs were assessed, along with possible protective actions of a promising radiation MCM, gamma-tocotrienol (GT3). Results show that these supralethal radiation exposures induce severe injuries that manifest both clinically as well as pathologically, as evidenced by the noted functionally crippling lesions within various major organ systems of experimental NHPs. The MCM, GT3, has limited radioprotective efficacy against such supralethal radiation doses.
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Affiliation(s)
- Vijay K Singh
- Division of Radioprotectants, Department of Pharmacology and Molecular Therapeutics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814-2712, USA.
- Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA.
| | - Stephen Y Wise
- Division of Radioprotectants, Department of Pharmacology and Molecular Therapeutics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814-2712, USA
- Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Oluseyi O Fatanmi
- Division of Radioprotectants, Department of Pharmacology and Molecular Therapeutics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814-2712, USA
- Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Sarah A Petrus
- Division of Radioprotectants, Department of Pharmacology and Molecular Therapeutics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814-2712, USA
- Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Alana D Carpenter
- Division of Radioprotectants, Department of Pharmacology and Molecular Therapeutics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814-2712, USA
- Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Sang-Ho Lee
- Pathology Department, Research Services, Naval Medical Research Center, Silver Spring, MD, 20910, USA
| | - Martin Hauer-Jensen
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA
| | - Thomas M Seed
- Tech Micro Services, 4417 Maple Avenue, Bethesda, MD, 20814, USA
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Shrum SA, Nukala U, Shrimali S, Pineda EN, Krager KJ, Thakkar S, Jones DE, Pathak R, Breen PJ, Aykin-Burns N, Compadre CM. Tocotrienols Provide Radioprotection to Multiple Organ Systems through Complementary Mechanisms of Antioxidant and Signaling Effects. Antioxidants (Basel) 2023; 12:1987. [PMID: 38001840 PMCID: PMC10668991 DOI: 10.3390/antiox12111987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 10/31/2023] [Accepted: 11/07/2023] [Indexed: 11/26/2023] Open
Abstract
Tocotrienols have powerful radioprotective properties in multiple organ systems and are promising candidates for development as clinically effective radiation countermeasures. To facilitate their development as clinical radiation countermeasures, it is crucial to understand the mechanisms behind their powerful multi-organ radioprotective properties. In this context, their antioxidant effects are recognized for directly preventing oxidative damage to cellular biomolecules from ionizing radiation. However, there is a growing body of evidence indicating that the radioprotective mechanism of action for tocotrienols extends beyond their antioxidant properties. This raises a new pharmacological paradigm that tocotrienols are uniquely efficacious radioprotectors due to a synergistic combination of antioxidant and other signaling effects. In this review, we have covered the wide range of multi-organ radioprotective effects observed for tocotrienols and the mechanisms underlying it. These radioprotective effects for tocotrienols can be characterized as (1) direct cytoprotective effects, characteristic of the classic antioxidant properties, and (2) other effects that modulate a wide array of critical signaling factors involved in radiation injury.
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Affiliation(s)
- Stephen A. Shrum
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (U.N.); (S.S.); (E.N.P.); (K.J.K.); (S.T.); (D.E.J.); (R.P.); (P.J.B.); (N.A.-B.)
- Tocol Pharmaceuticals, LLC, Little Rock, AR 77205, USA
| | - Ujwani Nukala
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (U.N.); (S.S.); (E.N.P.); (K.J.K.); (S.T.); (D.E.J.); (R.P.); (P.J.B.); (N.A.-B.)
- Joint Bioinformatics Graduate Program, University of Arkansas at Little Rock, Little Rock, AR 72204, USA
| | - Shivangi Shrimali
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (U.N.); (S.S.); (E.N.P.); (K.J.K.); (S.T.); (D.E.J.); (R.P.); (P.J.B.); (N.A.-B.)
- Joint Bioinformatics Graduate Program, University of Arkansas at Little Rock, Little Rock, AR 72204, USA
| | - Edith Nathalie Pineda
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (U.N.); (S.S.); (E.N.P.); (K.J.K.); (S.T.); (D.E.J.); (R.P.); (P.J.B.); (N.A.-B.)
- Joint Bioinformatics Graduate Program, University of Arkansas at Little Rock, Little Rock, AR 72204, USA
| | - Kimberly J. Krager
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (U.N.); (S.S.); (E.N.P.); (K.J.K.); (S.T.); (D.E.J.); (R.P.); (P.J.B.); (N.A.-B.)
| | - Shraddha Thakkar
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (U.N.); (S.S.); (E.N.P.); (K.J.K.); (S.T.); (D.E.J.); (R.P.); (P.J.B.); (N.A.-B.)
| | - Darin E. Jones
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (U.N.); (S.S.); (E.N.P.); (K.J.K.); (S.T.); (D.E.J.); (R.P.); (P.J.B.); (N.A.-B.)
| | - Rupak Pathak
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (U.N.); (S.S.); (E.N.P.); (K.J.K.); (S.T.); (D.E.J.); (R.P.); (P.J.B.); (N.A.-B.)
| | - Philip J. Breen
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (U.N.); (S.S.); (E.N.P.); (K.J.K.); (S.T.); (D.E.J.); (R.P.); (P.J.B.); (N.A.-B.)
| | - Nukhet Aykin-Burns
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (U.N.); (S.S.); (E.N.P.); (K.J.K.); (S.T.); (D.E.J.); (R.P.); (P.J.B.); (N.A.-B.)
| | - Cesar M. Compadre
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (U.N.); (S.S.); (E.N.P.); (K.J.K.); (S.T.); (D.E.J.); (R.P.); (P.J.B.); (N.A.-B.)
- Tocol Pharmaceuticals, LLC, Little Rock, AR 77205, USA
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Singh VK, Seed TM. Development of gamma-tocotrienol as a radiation medical countermeasure for the acute radiation syndrome: current status and future perspectives. Expert Opin Investig Drugs 2023; 32:25-35. [PMID: 36655861 DOI: 10.1080/13543784.2023.2169127] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
INTRODUCTION The possibility of exposure to high doses of total- or partial-body ionizing radiation at a high dose rate due to radiological/nuclear accidents or terrorist attacks is increasing. Despite research and development during the last six decades, there is a shortage of nontoxic, safe, and effective radiation medical countermeasures (MCMs) for radiological and nuclear emergencies. To date, the US Food and Drug Administration (US FDA) has approved only four agents for the mitigation of hematopoietic acute radiation syndrome (H-ARS). AREA COVERED We present the current status of a promising radiation countermeasure, gamma-tocotrienol (GT3; a component of vitamin E) as a radiation MCM that has been investigated in murine and nonhuman primate models of H-ARS. There is significant work with this agent using various omic platforms during the last few years to identify its efficacy biomarkers. EXPERT OPINION GT3 is a newer type of radioprotector having significant injury-countering potential and is currently under advanced development for H-ARS. As a pre-exposure drug, it requires only single doses, lacks significant toxicity, and has minimal, ambient temperature storage requirements; thus, GT3 appears to be an ideal MCM for military and first responders as well as for storage in the Strategic National Stockpile.
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Affiliation(s)
- Vijay K Singh
- Division of Radioprotectants, Department of Pharmacology and Molecular Therapeutics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.,Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
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Singh VK, Seed TM. Repurposing Pharmaceuticals Previously Approved by Regulatory Agencies to Medically Counter Injuries Arising Either Early or Late Following Radiation Exposure. Front Pharmacol 2021; 12:624844. [PMID: 34040517 PMCID: PMC8141805 DOI: 10.3389/fphar.2021.624844] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 04/26/2021] [Indexed: 12/12/2022] Open
Abstract
The increasing risks of radiological or nuclear attacks or associated accidents have served to renew interest in developing radiation medical countermeasures. The development of prospective countermeasures and the subsequent gain of Food and Drug Administration (FDA) approval are invariably time consuming and expensive processes, especially in terms of generating essential human data. Due to the limited resources for drug development and the need for expedited drug approval, drug developers have turned, in part, to the strategy of repurposing agents for which safety and clinical data are already available. Approval of drugs that are already in clinical use for one indication and are being repurposed for another indication is inherently faster and more cost effective than for new agents that lack regulatory approval of any sort. There are four known growth factors which have been repurposed in the recent past as radiomitigators following the FDA Animal Rule: Neupogen, Neulasta, Leukine, and Nplate. These four drugs were in clinic for several decades for other indications and were repurposed. A large number of additional agents approved by various regulatory authorities for given indications are currently under investigation for dual use for acute radiation syndrome or for delayed pathological effects of acute radiation exposure. The process of drug repurposing, however, is not without its own set of challenges and limitations.
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Affiliation(s)
- Vijay K. Singh
- Division of Radioprotectants, Department of Pharmacology and Molecular Therapeutics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
- Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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Singh VK, Seed TM. Pharmacological management of ionizing radiation injuries: current and prospective agents and targeted organ systems. Expert Opin Pharmacother 2020; 21:317-337. [PMID: 31928256 PMCID: PMC6982586 DOI: 10.1080/14656566.2019.1702968] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 12/06/2019] [Indexed: 12/20/2022]
Abstract
Introduction: There is a limited array of currently available medicinals that are useful for either the prevention, mitigation or treatment of bodily injuries arising from ionizing radiation exposure.Area covered: In this brief article, the authors review those pharmacologic agents that either are currently being used to counter the injurious effects of radiation exposure, or those that show promise and are currently under development.Expert opinion: Although significant, but limited progress has been made in the development and fielding of safe and effective pharmacotherapeutics for select types of acute radiation-associated injuries, additional effort is needed to broaden the scope of drug development so that overall health risks associated with both short- and long-term injuries in various organ systems can be reduced and effectively managed. There are several promising radiation countermeasures that may gain regulatory approval from the government in the near future for use in clinical settings and in the aftermath of nuclear/radiological exposure contingencies.
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Affiliation(s)
- Vijay K. Singh
- Division of Radioprotectants, Department of Pharmacology and Molecular Therapeutics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
- Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Thomas M Seed
- Tech Micro Services, 4417 Maple Avenue, Bethesda, MD 20814, USA
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Utilization of Vitamin E Analogs to Protect Normal Tissues While Enhancing Antitumor Effects. Semin Radiat Oncol 2019; 29:55-61. [PMID: 30573184 DOI: 10.1016/j.semradonc.2018.10.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Despite advances in radiation delivery techniques, side effects of radiation therapy due to radiation exposure of normal tissues are common and can limit the deliverable dose to tumors. Significant interests lie in pharmacologic modifiers that may protect against normal tissue toxicity from cancer treatment while simultaneously enhancing the tumor response to therapy. While no such treatments are available in the clinic, this is an area of active preclinical and clinical research. This review summarizes research studies that provide evidence to indicate that tocotrienols, natural forms of vitamin E, are potent radiation protectors and may also have antitumor effects. Hence, several current clinical trials test tocotrienols as concomitant treatment in cancer therapies.
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Singh VK, Hauer-Jensen M. γ-Tocotrienol as a Promising Countermeasure for Acute Radiation Syndrome: Current Status. Int J Mol Sci 2016; 17:E663. [PMID: 27153057 PMCID: PMC4881489 DOI: 10.3390/ijms17050663] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 04/03/2016] [Accepted: 04/25/2016] [Indexed: 01/13/2023] Open
Abstract
The hazard of ionizing radiation exposure due to nuclear accidents or terrorist attacks is ever increasing. Despite decades of research, still, there is a shortage of non-toxic, safe and effective medical countermeasures for radiological and nuclear emergency. To date, the U.S. Food and Drug Administration (U.S. FDA) has approved only two growth factors, Neupogen (granulocyte colony-stimulating factor (G-CSF), filgrastim) and Neulasta (PEGylated G-CSF, pegfilgrastim) for the treatment of hematopoietic acute radiation syndrome (H-ARS) following the Animal Efficacy Rule. Promising radioprotective efficacy results of γ-tocotrienol (GT3; a member of the vitamin E family) in the mouse model encouraged its further evaluation in the nonhuman primate (NHP) model. These studies demonstrated that GT3 significantly aided the recovery of radiation-induced neutropenia and thrombocytopenia compared to the vehicle controls; these results particularly significant after exposure to 5.8 or 6.5 Gray (Gy) whole body γ-irradiation. The stimulatory effect of GT3 on neutrophils and thrombocytes (platelets) was directly and positively correlated with dose; a 75 mg/kg dose was more effective compared to 37.5 mg/kg. GT3 was also effective against 6.5 Gy whole body γ-irradiation for improving neutrophils and thrombocytes. Moreover, a single administration of GT3 without any supportive care was equivalent, in terms of improving hematopoietic recovery, to multiple doses of Neupogen and two doses of Neulasta with full supportive care (including blood products) in the NHP model. GT3 may serve as an ultimate radioprotector for use in humans, particularly for military personnel and first responders. In brief, GT3 is a promising radiation countermeasure that ought to be further developed for U.S. FDA approval for the ARS indication.
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Affiliation(s)
- Vijay K Singh
- Department of Pharmacology and Molecular Therapeutics, F. Edward Hébert School of Medicine, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, MD 20889, USA.
| | - Martin Hauer-Jensen
- Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences and Central Arkansas Veterans Healthcare Systems, Little Rock, AR 72205, USA.
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Abstract
The discovery of vitamin E (α-tocopherol) began in 1922 as a vital component required in reproduction. Today, there are eight naturally occurring vitamin E isoforms, namely α-, β-, γ- and δ-tocopherol and α-, β-, γ- and δ-tocotrienol. Vitamin E is potent antioxidants, capable of neutralizing free radicals directly by donating hydrogen from its chromanol ring. α-Tocopherol is regarded the dominant form in vitamin E as the α-tocopherol transfer protein in the liver binds mainly α-tocopherol, thus preventing its degradation. That contributed to the oversight of tocotrienols and resulted in less than 3% of all vitamin E publications studying tocotrienols. Nevertheless, tocotrienols have been shown to possess superior antioxidant and anti-inflammatory properties over α-tocopherol. In particular, inhibition of 3-hydroxy-3-methylglutaryl-coenzyme A reductase to lower cholesterol, attenuating inflammation via downregulation of transcription factor NF-κB activation, and potent radioprotectant against radiation damage are some properties unique to tocotrienols, not tocopherols. Aside from cancer, vitamin E has also been shown protective in bone, cardiovascular, eye, nephrological and neurological diseases. In light of the different pharmacological properties of tocopherols and tocotrienols, it becomes critical to specify which vitamin E isoform(s) are being studied in any future vitamin E publications. This review provides an update on vitamin E therapeutic potentials, protective effects and modes of action beyond cancer, with comparison of tocopherols against tocotrienols. With the concerted efforts in synthesizing novel vitamin E analogs and clinical pharmacology of vitamin E, it is likely that certain vitamin E isoform(s) will be therapeutic agents against human diseases besides cancer.
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Affiliation(s)
- Hong Yong Peh
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, Singapore
| | - W S Daniel Tan
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, Singapore
| | - Wupeng Liao
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, Singapore
| | - W S Fred Wong
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, Singapore; Immunology Program, Life Science Institute, National University of Singapore, Singapore.
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Kumar S, Tiku AB. Immunomodulatory potential of acemannan (polysaccharide fromAloe vera) against radiation induced mortality in Swiss albino mice. FOOD AGR IMMUNOL 2015. [DOI: 10.1080/09540105.2015.1079594] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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Ahsan H, Ahad A, Iqbal J, Siddiqui WA. Pharmacological potential of tocotrienols: a review. Nutr Metab (Lond) 2014; 11:52. [PMID: 25435896 PMCID: PMC4247006 DOI: 10.1186/1743-7075-11-52] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 10/15/2014] [Indexed: 02/06/2023] Open
Abstract
Tocotrienols, members of the vitamin E family, are natural compounds found in a number of vegetable oils, wheat germ, barley, and certain types of nuts and grains. Like tocopherols, tocotrienols are also of four types viz. alpha, beta, gamma and delta. Unlike tocopherols, tocotrienols are unsaturated and possess an isoprenoid side chain. Tocopherols are lipophilic in nature and are found in association with lipoproteins, fat deposits and cellular membranes and protect the polyunsaturated fatty acids from peroxidation reactions. The unsaturated chain of tocotrienol allows an efficient penetration into tissues that have saturated fatty layers such as the brain and liver. Recent mechanistic studies indicate that other forms of vitamin E, such as γ-tocopherol, δ-tocopherol, and γ-tocotrienol, have unique antioxidant and anti-inflammatory properties that are superior to those of α-tocopherol against chronic diseases. These forms scavenge reactive nitrogen species, inhibit cyclooxygenase- and 5-lipoxygenase-catalyzed eicosanoids and suppress proinflammatory signalling, such as NF-κB and STAT. The animal and human studies show tocotrienols may be useful against inflammation-associated diseases. Many of the functions of tocotrienols are related to its antioxidant properties and its varied effects are due to it behaving as a signalling molecule. Tocotrienols exhibit biological activities that are also exhibited by tocopherols, such as neuroprotective, anti-cancer, anti-inflammatory and cholesterol lowering properties. Hence, effort has been made to compile the different functions and properties of tocotrienols in experimental model systems and humans. This article constitutes an in-depth review of the pharmacology, metabolism, toxicology and biosafety aspects of tocotrienols. Tocotrienols are detectable at appreciable levels in the plasma after supplementations. However, there is inadequate data on the plasma concentrations of tocotrienols that are sufficient to demonstrate significant physiological effect and biodistribution studies show their accumulation in vital organs of the body. Considering the wide range of benefits that tocotrienols possesses against some common human ailments and having a promising potential, the experimental analysis accounts for about a small fraction of all vitamin E research. The current state of knowledge deserves further investigation into this lesser known form of vitamin E.
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Affiliation(s)
- Haseeb Ahsan
- Department of Biochemistry, Faculty of Dentistry, Jamia Millia Islamia, New Delhi, 110025 India
| | - Amjid Ahad
- Department of Biochemistry, Jamia Hamdard (Hamdard University), New Delhi, 110062 India
| | - Jahangir Iqbal
- Department of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY 11203 USA
| | - Waseem A Siddiqui
- Department of Biochemistry, Jamia Hamdard (Hamdard University), New Delhi, 110062 India
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Ahsan H, Ahad A, Iqbal J, Siddiqui WA. Pharmacological potential of tocotrienols: a review. Nutr Metab (Lond) 2014. [PMID: 25435896 DOI: 10.1186/743-7075-11-52] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
Abstract
Tocotrienols, members of the vitamin E family, are natural compounds found in a number of vegetable oils, wheat germ, barley, and certain types of nuts and grains. Like tocopherols, tocotrienols are also of four types viz. alpha, beta, gamma and delta. Unlike tocopherols, tocotrienols are unsaturated and possess an isoprenoid side chain. Tocopherols are lipophilic in nature and are found in association with lipoproteins, fat deposits and cellular membranes and protect the polyunsaturated fatty acids from peroxidation reactions. The unsaturated chain of tocotrienol allows an efficient penetration into tissues that have saturated fatty layers such as the brain and liver. Recent mechanistic studies indicate that other forms of vitamin E, such as γ-tocopherol, δ-tocopherol, and γ-tocotrienol, have unique antioxidant and anti-inflammatory properties that are superior to those of α-tocopherol against chronic diseases. These forms scavenge reactive nitrogen species, inhibit cyclooxygenase- and 5-lipoxygenase-catalyzed eicosanoids and suppress proinflammatory signalling, such as NF-κB and STAT. The animal and human studies show tocotrienols may be useful against inflammation-associated diseases. Many of the functions of tocotrienols are related to its antioxidant properties and its varied effects are due to it behaving as a signalling molecule. Tocotrienols exhibit biological activities that are also exhibited by tocopherols, such as neuroprotective, anti-cancer, anti-inflammatory and cholesterol lowering properties. Hence, effort has been made to compile the different functions and properties of tocotrienols in experimental model systems and humans. This article constitutes an in-depth review of the pharmacology, metabolism, toxicology and biosafety aspects of tocotrienols. Tocotrienols are detectable at appreciable levels in the plasma after supplementations. However, there is inadequate data on the plasma concentrations of tocotrienols that are sufficient to demonstrate significant physiological effect and biodistribution studies show their accumulation in vital organs of the body. Considering the wide range of benefits that tocotrienols possesses against some common human ailments and having a promising potential, the experimental analysis accounts for about a small fraction of all vitamin E research. The current state of knowledge deserves further investigation into this lesser known form of vitamin E.
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Affiliation(s)
- Haseeb Ahsan
- Department of Biochemistry, Faculty of Dentistry, Jamia Millia Islamia, New Delhi, 110025 India
| | - Amjid Ahad
- Department of Biochemistry, Jamia Hamdard (Hamdard University), New Delhi, 110062 India
| | - Jahangir Iqbal
- Department of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY 11203 USA
| | - Waseem A Siddiqui
- Department of Biochemistry, Jamia Hamdard (Hamdard University), New Delhi, 110062 India
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