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Article Evaluation (Asima Chatterjee)


 * there could be more information about her findings and applications
 * further development on her epilepsy drug
 * further development on role in organic chemistry
 * all links work, except no exiting link for the drug she developed
 * there are conflicts on whether she was the first or second women to conferred a doctorate in Science from an Indian University
 * Wikiprojects: women scientists, India / West Bengal, Science and Academia

Article Selection


 * Adolf Windaus - https://www.britannica.com/science/steroid
 * explain the process of transforming cholesterol to vitamin D3
 * Asima Chatterjee
 * Heinrich Otto Wieland

Bibliography


 * https://doi.org/10.1093/jn/134.6.1299
 * https://www.mayoclinicproceedings.org/article/S0025-6196(11)63115-7/fulltext

DRAFT - Adolf Windaus

Biography

Adolf Windaus was born in Berlin, Germany on December 25, 1876 to a family who owned a drapery business. He attended a prestigious French grammar school, where he focused primarily on literature. Windaus began studying medicine at the University of Berlin in about 1895 then proceeded to study chemistry at the University of Freiburg. He married Elizabeth Resau in 1915 and they had three children together, Gunter, Gustav, and Margarete. After earning his PhD in medicine, Windaus became the head of the chemical institute at the University of Gottingen from 1915 to 1944. Throughout his life, Windaus won many awards including the Geothe Medal, the Pasteur Medal, and the Nobel Prize for Chemistry. In addition to his many accomplishments and discoveries in science, Windaus was also one of the very few German chemists who did not work with the Nazis and openly opposed their regime. As the head of the chemical institute at the University of Gottingen, Windaus personally defended one of his Jewish graduate students from dismissal. Windaus believed that while every man had a moral code, his science was motivated by curiosity, and was not driven by politics, ethics, and applications of his discoveries. This viewpoint caused Windaus to decline to research poison gas during World War I.

Sterols

The best known sterol, nitrogen-free secondary alcohols containing alicyclics systems, is cholesterol (C27H46O). It was first discovered in human gallstones and is a mono-unsaturated alcohol found in all higher animals, both as a free alcohol and fatty acid ester.

Vitamin D2 and D3

Rickets, a bone disease resulting from vitamin D deficiency, was originally treated in the early 1900s through essential dietary factors such as whole milk or cod-liver oil. It was also postulated that increase sunlight was improving conditions, but was improperly concluded that cholesterol was the precursor activated via UV light. In testing this, investigators under Windaus’ instruction found that completely pure cholesterol - converted into its dibromide and recrystallized - had lost its antirachitic effects upon irradiation. It was then postulated that a different substance associated with ‘chemically pure’ cholesterol through all usual stages of purification is the precursor to vitamin D.

The impurity was able to precipitate with digitonin, showing chemical properties of a steroid with three double bonds. The three UV absorption peaks of the active impurity was used to purify, and become highly concentrated through high-vacuum distillation and charcoal adsorption techniques. In evaluating a variety of sterols that showed antirachitic activity upon irradiation, done so in consultation with A.F. Hess, O. Rosenheim, and T.A. Webster, ergosterol (Ca27H42) was found to be the only precursor of vitamin D, convertible under wavelength between 253 and 302 nm. Similarities of ergosterol to that of the active fraction from cholesterol included math UV spectrums, rapid destruction by oxidation, and production of the same color reaction with sulfuric acid.

This production of Vitamin D2, or calciferol, was a complete cure to rachitic - 100,000 times more effective than fish liver oil - and Windaus and his group were able to determine its chemical properties. This included being isomeric with ergosterol with a hydroxyl group and three conjugated double bonds; the correct structure was confirmed in 1936. The possibility of polymerization was tested to be inaccurate through evaluating the molecular weight, and were also able to denounce certain isomerization The secondary alcohol displacing to a double bond was shown to not occur through Zerewitinoff’s method and a double bond to a steric rearrangement didn’t occur under observance of titration and catalytic hydrogenation.

Ergosterol was originally found in fungi and not animal organisms, so the question of obtaining Vitamin D from sunlight was still in question and studied by Windaus long after receiving the Nobel Prize. In isolating and identifying 7-dehydrocholesterol in hog skin, and later human skin, whole milk, and animal liver, it too was antirachitic upon irradiation. This was already a known compound derived from cholesterol, and the new irradiation product was named Vitamin D3, or cholecalciferol. Windaus established the structure by investigating the photochemical reactions within its formation.

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