Medicinal Compounds and Toxic Esters

In 1719, J. T. Hensing detected phosphorus in the brain, in unexpectedly large quantities (Table 11.8). Subsequently, there arose a widespread but unsubstantiated belief that phosphorus was good for the brain as well as numerous other unwanted medical conditions. Extravagant and doubtful claims were made as to the medicinal value of the element, which persisted to late in the nineteenth century and even into the twentieth century [1,2]. 

During the eighteenth and nineteenth centuries, elemental phosphorus (as the P4 white form) was mistakenly prescribed for the treatment of a multitude of different illnesses, in spite of the fact that its high toxicity was sometimes recognised. The element, although used at very low concentrations, was probably responsible for many deaths rather than cures.  

Benefits were claimed in the treatment of skin complaints, colic, tetanus, epilepsy, apoplexy, gout, melancholia, migraine, TB, cholera, impotence and so on. Application of the element was usually in the form of pills or various ointments, the latter utilising olive oil, almond oil, turpentine, glycerol or other organic materials. A typical phosphorylated oil described in British Pharmacopea 1885 contained about 1% P dispersed in almond oil. Such concoctions were still around at the start of the twentieth century. 

About the middle of the nineteenth century, the use of certain phosphorus compounds (rather than the element) became the vogue. The laxative properties of sodium phosphates were recognised and in the same period hypophosphites (as Na, Mg or Ca salts) were introduced for the treatment of neurasthenia and other nervous deficiencies. These were all considerably less toxic than the element itself and were followed by glycerophosphates (as Na, Ca and other salts) which were believed to function as brain nutrients or nerve tonics . The use of hypophosphites and glycerophosphates persisted well into the twentieth century, but they are now considered to be of very limited value for these purposes. A syrup of phosphorus , described in British Pharmacopea 1885, contained phosphoric acid, sodium phosphate and iron sulphate among other ingredients. Commercial exploitation of products of this kind was inevitable (Hgure 12.22). Modem dietary supplements are often based on collections of vitamins which usually include Bg and B,2. These two vitamins form part of phosphate ester enzymes (e.g. Equation ll.lOSj). 

in spite of early false trails, phosphoras compounds are frequently found to play a key role in the treatment of disease or unwanted conditions. Their medicinal function may be in the form of drugs, dietary supplements, bioconstruction materials or in diagnostic or preventative procedures. Of increasing prominence are the many forms of DNA (Chapters 10 and 11). 

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