Question: What is B17? 

Answer: "Vitamin B17", a name given to a substance called Laetrile by those who claim it prevents and cures cancer. Read more in detail-\n\nAmygdalin, C20H27NO11, is a glycoside isolated from bitter almonds by H. E. Robiquet and A. F. Boutron-Charlard in 1830, and subsequently investigated by Liebig and Wöhler, and others. Some sources claim Ernst T. Krebs was the discoverer of the substance, and Krebs is generally credited with popularizing it as a purported cancer cure and as "Vitamin B17." It is extracted from almond cake by boiling alcohol; on evaporation of the solution and the addition of ether, amygdalin is precipitated as white minute crystals. Sulfuric acid decomposes it into d-glucose, benzaldehyde, and prussic acid (hydrogen cyanide); while hydrochloric acid gives mandelic acid, d-glucose, and ammonia. The decomposition induced by enzymes may occur in two ways. Maltase partially decomposes it, giving d-glucose and mandelic nitrile glucoside, C6H5CH(CN)O·C6H11O5; this compound is isomeric with sambunigrin, a glucoside found by E.E. Bourquelot and Danjou in the berries of the common elder, Sambucus nigra. Emulsin, on the other hand, decomposes it into benzaldehyde, cyanide, and two molecules of glucose; this enzyme occurs in the bitter almond, and consequently the seeds invariably contain free cyanide and benzaldehyde. An "amorphous amygdalin" is said to occur in the cherry-laurel. Closely related to these glucosides is dhurrin, C14H17O7N, isolated by W. Dunstan and T. A. Henry from the common sorghum or "great millet," Sorghum vulgare; this substance is decomposed by emulsin or hydrochloric acid into d-glucose, cyanide, and p-hydroxybenzaldehyde-.
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