The Chemistry of Vitamin E. I. The Structure and Synthesis of α-Tocopherol

Smith, Lee Irvin; Ungnade, Herbert E.; Prichard, W. W.

doi:10.1126/science.88.2271.37

Cited by 34 publications

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“…Particularly on resistant plants closely related to congenial hosts, considerable development of mycelium may be permitted before the aspiring parasite is finally stopped. Where penetration occurs, and occasionally even without penetration of a host cell (31), the parasite elicits marked responses from the invaded cell. Changes in the staining reactions of both host and parasite occur at once, whether the host is congenial or not (25,31).…”

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“…Where penetration occurs, and occasionally even without penetration of a host cell (31), the parasite elicits marked responses from the invaded cell. Changes in the staining reactions of both host and parasite occur at once, whether the host is congenial or not (25,31). The haustoria of many obligate parasites become associated with or actually enveloped by the host nucleus (39,40,41), but this has rarely been seen with powdery mildews.…”

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“…The haustoria of many obligate parasites become associated with or actually enveloped by the host nucleus (39,40,41), but this has rarely been seen with powdery mildews. Changes in appearance and composition, followed by death of the attacked cell, occur in many immune and resistant plants, either before or after penetration (18,30,31,37,42). In others, death of the host cells is delayed and some myce lium develops, but more host cells are eventually involved in necrosis.…”

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Physiological Aspects of Fungus Diseases of Plants

Allen¹

1954

Annu. Rev. Plant. Physiol.

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The present review will be concerned with the inception and results of diseases of higher plants caused by obligately parasitic fungi. The term "ob ligate parasite" refers to those fungi which have not yet been cultured even in their vegetative phase except on a living host plant and whose nutrient re quirements and physiology are therefore largely unknown. Particular em phasis will be placed on diseases caused by rusts (Uredinales) and powdery mildews (Erysiphaceae), but occasional reference will also be made to other obligate parasites, particularly the downy mildews (Peronosporaceae) .Some physiological aspects of these diseases are included in recent re views (1, 2), and the literature on variation in rusts has been reviewed by Johnson (3). Gaumann's Pjlanzliche Infektionslehre (4) is an extensive and provocative collation of many aspects of plant diseases, and is available in English translation (5) , and in a second edition in German (6) . In a mono graph on The Cereal Rusts, Chester has presented a comprehensive sur vey and analysis of the litereature on stem rust of wheat and some allied diseases (7), and Volume VII of Buller's Researches on Fungi, published posthumous ly, has many interesting observations on certain aspects of the biology of the Uredinales (8). A monograph in Russian is concerned primarily with the au thor's investigations on the metabolism of plants infected with obligate par asites (9).The terminology used to describe attributes of host and parasite has been reduced to a minimum for purposes of this review. "Susceptibility" and "re sistance" will be used to designate conditions of the host which, respective ly, favor or do not favor development of a parasite. Plants showing extremes of these conditions will sometimes be referred to as "congenial" and "im mune," respectively. "Virulence" and "avirulence" will designate the com plementary conditions of the parasite. The term "infection" will be used to designate the penetration of a host cell and whatever subsequent progress the parasite makes.The literature on these diseases will be considered in three sections cor responding to three aspects of the origin and development of disease: (a) the inception of disease, (b) environmental factors affecting the host's suitability as a substrate for development of the parasite, and (c) changes in host phys iology resulting from infection. THn INCEPTION OF DISEASEGenetic basis of host restriction.-A given plant species is liable to attack only by certain parasites, but these parasites may come from the most di verse groups of the plant and animal kingdoms. A particular species of par-225 Annu. Rev. Plant. Physiol. 1954.5:225-248. Downloaded from www.annualreviews.org Access provided by Tufts University on 12/01/14. For personal use only.Quick links to online content Further ANNUAL REVIEWS

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Physiological Aspects of Fungus Diseases of Plants

Allen¹

1954

Annu. Rev. Plant. Physiol.

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“…Aminoalkylation (29) is covered by another patent (29). Recently, we prepared 2,2,7, in analytically pure form as well as the corresponding 0t-tocopherol derivative.…”

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“…Found: C,71.77;H,8.91. Tris(2,2,f,7,8-pentamethyl-6-chromanol) phosphate 2,2,5,7, was dissolved in hexane and 0.24 g of sodium hydride was added while stirring under nitrogen. After 1/2 hr a slight excess of POC13 was slowly added to the stirring slurry.…”

Section: 278-tetramethyl-5-bromomethyl-6-ch Romanolmentioning

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Reaction products of tocopherols

Skinner

Parkhurst

1971

Lipids

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Tocopherols readily undergo oxidation with a variety of oxidizing agents. Considerable effort has gone into isolation and identification of these various oxidation products. In many cases they can undergo further transformations upon treatment with various chemical reagents. This review will focus on the oxidation of α‐tocopherol and transformation of its oxidation products to new derivatives. Dimeric and trimeric oxidation products will not be covered. Early work on the oxidation of α‐tocopherol led to identification of α‐tocopherol quinone as an oxidation product formed by FeCl3 oxidation. Stronger oxidizing conditions with FeCl3 or oxidation with AgNO3 or HNO3 led to the orthoquinone and the hydroxy‐p‐quinone due to loss of one or two methyl groups from the aromatic ring. These early studies pointed out the unusual reactivity of the 5‐methyl group of α‐tocopherol. Oxidation of α‐tocopherol with benzoyl peroxide led to substitution of a benzoate on the 5‐methyl group. A similar reaction occurs when diasobisisobutyronitrile is used as the oxidizing agent. The oxidation of α‐tocopherol by tetrachloro‐o‐quinone in aqueous acetonitrile resulted in the formation of 9‐hydroxy‐α‐tocopherone. When FeCl3 was used as the oxidizing agent in the presence of α,α'‐bibyridyl in ethanol, 9‐ethoxy‐α‐tocopherone was formed. α‐Tocopherolquinone can be reduced with Zn−HOAc or by catalytic hydrogenation to the hydroquinone or reductively cyclized to α‐tocopherol with Zn−HBr. Reaction of α‐tocopherolquinone with acetyl chloride resulted in the 5‐chloromethyl‐6‐acetoxy derivative which has been converted to a variety of 5‐methylsubstituted derivatives. Reaction of α‐tocopherol with Br2 led to the 5‐bromomethyl derivative. When α‐tocopherolquinone was treated with hydrochloric, phosphoric, citric or tartaric acid, in the absence of oxygen, a disproportionation took place forming α‐tocopherol, α‐tocored and other oxidation products. An interesting isomerization of α‐tocored, the orthoquinone, occurs in the presence of aqueous HCl to yield the yellowp‐quinone with the chroman ring closed. The 5‐benzoyloxymethyl derivative upon treatment with HCl generateso‐quinone methide which can be trapped by reaction with tetracyanoethylene or dihydropyran. Treatment of the 5‐benzoyloxmethyl derivative with HCl in ethanol followed by sublimation yielded the 5‐aldehyde of α‐tocopherol. Recently, a series of phosphate derivatives of α‐tocopherol or its model, 2,2,5,7,8‐pentamethyl‐6‐chromanol, were synthesized. Tris (6‐acetoxy‐5‐methyleneoxy‐7,8‐dimethyltocol)phosphate, tris(2,2,5,7,8‐pentamethyl‐6‐chromanol)phosphate, 5‐hydroxymethyl‐2,2,7,8‐tetramethyl‐6‐chromanol phosphate and the cyclic 5‐methylenoxy‐2,2,7,8‐tetramethyl‐6‐chromanol phosphate, were prepared. These phosphates are of interest in view of a possible role of α‐tocopherol in oxidative phosphorylation.

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Vitamin E

Casani¹

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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A brief history of the vitamin from its discovery to the present is given. An overview of synthetic approaches to vitamin E is presented starting with the original work in the late 1930s. A review of the literature indicates emphasis on the development of the synthesis of the trimethylhydroquinone intermediate and of the critical condensation reaction to tocopherol. The occurrence of vitamin E and compounds with vitamin E activity in natural sources along with the isolation of natural forms of vitamin E from vegetable oil sources has been summarized. The greater prevalence of compounds with vitamin E activity in vegetable sources compared to animal sources is shown. A brief review of the physiological role of vitamin E is given. In addition to research on its historical role in reproduction, a discussion of recent activity on the antioxidant properties is presented. The uses and commercial forms of vitamin E are discussed. Its role in animal feed fortification, food preservation, and polymer applications is summarized. The traditional colorimetric analysis for vitamin E in foods, feeds, and product forms is reviewed. More modern chromatographic methods for various sample matrices are presented.

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The Chemistry of Vitamin E. I. The Structure and Synthesis of α-Tocopherol

Cited by 34 publications

References 6 publications

Physiological Aspects of Fungus Diseases of Plants

Physiological Aspects of Fungus Diseases of Plants

Reaction products of tocopherols

Vitamin E

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