B Vitamins and Folate: Chemistry, Analysis, Function and Effects / Edition 1 available in Hardcover
B Vitamins and Folate: Chemistry, Analysis, Function and Effects / Edition 1
- ISBN-10:
- 1849733694
- ISBN-13:
- 9781849733694
- Pub. Date:
- 10/23/2012
- Publisher:
- RSC
B Vitamins and Folate: Chemistry, Analysis, Function and Effects / Edition 1
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About the Author
Victor Preedy is currently Professor of Nutritional Biochemistry and Director of Genomics Centre, King's College London and Professor of Clinical Biochemistry at King's College Hospital London. After graduating with a BSc degree in Physiology with Pharmacology and Biology, Professor Preedy carried out a period of research on protein metabolism in the Department of Nutrition at the London School of Hygiene and Tropical Medicine. After the successful award of his PhD he studied aspects of cardiac protein metabolism at the National Heart Hospital. After 4 years, he then moved to the MRC Clinical Research Centre in Harrow, which was followed by his appointment as a lecturer to Kings College in 1988. He was promoted to Reader in 1995 and Professor in 2003. Professor Preedy has published over 550 articles, which includes over 160 peer-reviewed manuscripts based on original research and 90 reviews as well as 35 books.
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B Vitamins and Folate
Chemistry, Analysis, Function and Effects
By Victor R. Preedy
The Royal Society of Chemistry
Copyright © 2013 The Royal Society of ChemistryAll rights reserved.
ISBN: 978-1-84973-369-4
CHAPTER 1
Historical Context of Vitamin B
HIDEYUKI HAYASHI
Department of Chemistry, Osaka Medical College, 2-7 Daigakumachi, Takatsuki, Osaka 569-8686, Japan Email: hayashi@art.osaka-med.ac.jp
1.1 Evidence for the Presence of Unidentified Factors Essential for Life
From ancient times, people were aware of the presence of a specific type of disease, beriberi, which affected people mainly in the East and South Asia. As early as 2600 BC, a Chinese account described that beriberi was caused by long-term rice eating but could be prevented by taking rice bran simultaneously. This finding was not recognized in modern medicine. However, in a similar context, the antiscorbutic effect of citrus fruits was already empirically known in the 17th century when James Lind of the Royal Navy systematically carried out experiments to demonstrate the beneficial effect of orange and lemon. Although he never thought that citrus juice is the only solution to scurvy, the surgeons of the Royal Navy were by experience convinced of the efficacy of citrus juice even if the reason was unknown. In the early 1880s, the Surgeon General of the Imperial Japanese Navy, Kanehiro Takagi, noticed that beriberi was common among crews and lower rank officers but not among officers who ate a Western-style diet. He considered that the low-protein diet was the cause of beriberi and performed an experiment in 1884 in which crews of a battleship were given bread and meat during a nine-month mission. Only 16 out of 333 developed beriberi and no one died, compared with a similar mission in the previous year, in which 169 out of 376 developed the disease and 25 died. The Japanese Navy adopted the Western-style diet (bread was later replaced by rice cooked with barley) and eliminated beriberi after 1885. This important lesson, however, was dismissed by the surgeons of the Imperial Japanese Army, who considered beriberi as an infectious disease and criticized Takagi for insufficiency of data and lack of theory that could explain the results. As a result, the army lost 28 000 soldiers due to beriberi in the Russo-Japanese War.
Independently of this, in 1887 a Dutch physician Christiaan Eijkman found an animal model for beriberi when he was in Dutch East Indies (Indonesia). As a former student of Robert Koch, he had been trying to isolate and infect chickens with 'beriberi bacteria'. As he had expected, all the chickens developed polyneuritis gallinarum, the bird counterpart of human beriberi, but soon recovered spontaneously. He noticed that chickens were sick while they were fed polished rice, but recovered after the diet was inadvertently changed to unpolished rice. He conducted detailed experiments to exclude other possibilities, such as that polished rice promotes the growth of bacteria during storage, and concluded around 1895 that what made the difference was the presence or absence of the silver layer of rice. He hypothesized that rice contains some toxin and a substance in the silver layer — he called this the anti-beriberi factor — neutralizes its virulence (Eijkman 1897). In 1901, Gerrit Grijns, who was an assistant to Eijkman, observed that chickens fed on raw meat did not develop polyneuritis whereas those exclusively fed on meat that had been heated long enough at 120 °C developed the disease. This clearly showed that neither polyneuritis nor beriberi was caused by some substances in rice. From this result, and by taking Takagi's observations into account, he interpreted Eijkman's results in another way: polyneuritis is a deficiency syndrome of a still unknown substance that is essential for life and destroyed by moist heat (Grijns 1901). His theory was later adopted by Eijkman in 1906.
1.2 Establishment of the Concept of Vitamins
In the 19th century, chemists knew that food contains carbohydrates, proteins and lipids. They imagined that it could be possible to make artificial food by properly mixing these nutrients. Ironically, it became a practical issue to test this idea during the Siege of Paris in 1870. A French chemist Jean Dumas made an artificial milk, but infants fed the milk did not survive. This observation attracted the attention of Gustav von Bunge who, believing that minerals are critical for preparing efficient artificial food, ordered his student Nicholas Lunin to study the effect of salt content on mice maintained on artificial food. The mice, however, could not survive for very long, irrespective of the salt content of the food. Lunin concluded that 'a natural food such as milk must therefore contain besides these known principal ingredients small quantities of unknown substances essential to life' (Lunin 1881). Unfortunately, his view was not supported by Bunge and the true significance of this report was not recognized in the scientific community, partly due to the title ('On the importance of inorganic salts in the diet of the animal') reflecting the thought of Bunge's school. In 1905, Cornelius Pekelharing, who had been a predecessor of Eijkman in Java, carried out similar experiments and reached the same conclusion. His report was published in Dutch and was not circulated widely. It was only in 1912 that the idea of 'unknown substances essential to life' was made widely known by the famous paper of Sir Frederick Hopkins (Hopkins 1912). Hopkins was studying the nutritional effect of tryptophan, which he had discovered in 1901, and noticed that animals fed with the tryptophan-deficient 'synthetic' diet could not live long, even if tryptophan was added to the diet. Perhaps without knowing the works of Lunin and Pekelharing (Hopkins 1929), he proposed the notion of 'deficiency diseases' — beriberi, scurvy and rickets as distinct entities. He further forecast that there were many other nutritional errors dependent on unknown dietary factors.
The next step was, undoubtedly, to isolate these substances. Umetaro Suzuki was probably the first to extract the anti-beriberi factor in a concentrated form from rice bran. He presented his results, in December 1910, at the meeting of the Tokyo Chemical Society, and published them in the January issue of the Society's journal in 1911. Because it was written in Japanese, his work was not known outside Japan. In December 1911, Casimir Funk published a paper describing the extraction of the factor using a similar method to Suzuki (Funk 1911). In the following year, Suzuki published in German a paper combining his collective works (Suzuki et al. 1912). At this point, he was aware that the material he had previously extracted was largely nicotinic acid and that this had misled him to name the compound 'aberic acid'. He could precipitate the effective component with picric acid and succeeded in concentrating the active substance. He then corrected the name to 'oryzanin' (from the Latin oryza meaning rice). Funk published a paper in the same year describing the concept of 'deficiency disease'. Although it was not different from that proposed by Hopkins, the name vitamine ('vital amine') he used in his paper was soon adopted by researchers in this field. However, as Funk himself admitted these essential substances (a fat-soluble substance necessary for preventing xerophthalmia had been found by Elmer McCollum) did not need to be organic bases. Therefore, in 1920 Jack Drummond recommended dropping the final 'e' of 'vitamine'. He also proposed discontinuing the use of the term 'fat-soluble A' and 'water-soluble B' suggested by McCollum as the unidentified substances necessary for growth, and instead calling these substances 'vitamin A', 'vitamin B', etc., until their true structures were determined.
The pure crystalline vitamin was obtained in Java in 1927 by Barend Jansen and William Donath, who were both students of Eijkman (Jansen and Donath 1927). RobertWilliams developed an effective method to isolate vitamin B from rice bran, proposed its structure, and confirmed it by synthesizing the compound (Williams and Cline 1936). The compound, then already given the name vitamin B1, had a thiazole ring and therefore was named 'thiamine' (Figure 1.1). (As with 'vitamin', 'thiamine' later lost its 'e' to 'thiamin', although the spelling 'thiamine' is still frequently used.)
1.3 Resolution of Vitamin B
Although there had been a belief that the 'water-soluble B' necessary for growth was identical with the antineuritic vitamin, people became aware of the possibility that vitamin B is not a single entity. In 1927, following the crystallization of the antineuritic vitamin, the British Committee on Accessory Food Factors distinguished the heat-labile and heat-stable components of vitamin B, and named the former B1 and the latter B2.
In 1933 Richard Kuhn, Paul György and Theodor Wagner-Jauregg isolated from egg white a yellow pigment having vitamin B2 activity, which they crystallized and named 'ovo-flavin' (Kuhn et al. 1933). They noticed that the absorption spectra of ovo-flavin resembled those of the 'yellow enzyme' isolated by Warburg and Christian (see below). In the same year they also crystallized lacto-flavin, which had been reported by P. Ellinger and W. Koschara, and showed it was identical with ovo-flavin. Alkaline hydrolysis of lumiflavin (C13H12N4O2), the photolysis product of lacto-flavin (C17H20N4O6) in alkaline medium, afforded urea and a compound having the chemical formula C12H12N2O3, which yielded on thermal decomposition CO2 and C11H12N2O. These reactions were similar to those of alloxazine, which gave urea, CO2 and 2-hydroxyquinoxaline-3-carboxylic acid (C8H6N2O), suggesting that lumiflavin is a trimethyl derivative of alloxazine. Combining the observation by E. Holiday and K. Stern of the spectral similarities between lacto-flavin and alloxazine and its derivatives (Holiday and Stern 1934), Kuhn proposed the structure of lumiflavin to be 7,8,10-trimethylisoalloxazine (Kuhn and Rudy 1934). In 1935, Kuhn's group (Kuhn et al. 1935) and Karrer's group (Karrer et al. 1935) synthesized independently 7,8-dimethyl-10-D-1'-ribitylisoalloxazine, and confirmed its identity with lacto-flavin. Once the structure (Figure 1.2) was finally determined, the vitamin was called riboflavin thereafter.
1.4 Discovery that Vitamins act as Coenzymes
The 1930s saw the dawn of coenzyme research. In 1932, Otto Warburg obtained a yellow enzyme from yeast and showed that the yellow dye reversibly underwent oxidation and reduction while conducting the oxidation of glucose 6-phosphate (Warburg and Christian 1932). Hugo Theorell, working in Warburg's laboratory, crystallized the enzyme and showed that the pigment could be reversibly removed from the enzyme protein and the enzyme which lost the pigment was inactive (Theorell 1935). This was the first discovery of a 'coenzyme'. Theorell also determined the correct structure of the coenzyme, the phosphate ester of riboflavin, flavin mononucleotide (FMN) (Threorell 1937). The more abundant and complex form of the coenzyme was found by Warburg and Christian in D-amino acid oxidase, and was determined to be flavin adenine dinucleotide (FAD) (Warburg and Christian 1938).
Dating back to 1911, Neuberg had discovered that bacteria and plants have an enzyme that catalyses the decarboxylation of pyruvate to acetaldehyde and CO2. He named the enzyme 'carboxylase', which in today's nomenclature refers to an enzyme undergoing carboxylation but at that time meant decarboxylase. In 1932, Ernst Anhagen observed that yeast 'carboxylase' lost activity when treated with alkali (Auhagen 1932). The activity was restored by the addition of a heated solution of yeast extract. He then speculated that the 'carboxylase' contains a non-proteinous low-molecular weight compound, named 'cocarboxylase'. At the same time, R. Peters and colleagues observed that the brain extract of pigeons deficient of thiamin showed a decreased rate of lactate degradation, but that the rate was restored by the addition of 'concentrated vitamin B1' (crystalline thiamin was expensive) to the extract (Meiklejohn et al. 1932). Based on these observations, Lohman and Schuster isolated cocarboxylase from yeast and proposed its structure to be thiamin diphosphate (Lohman and Schuster 1937).
(Continues...)
Excerpted from B Vitamins and Folate by Victor R. Preedy. Copyright © 2013 The Royal Society of Chemistry. Excerpted by permission of The Royal Society of Chemistry.
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