C I . C I H C I H 772 MAN'S PHYSICAL WELFARE H— H— OH OH OH c c c C—CH3 H— / \ / \ / \ C—H H— C—H H— C— H— % / \ / % / c c c I II I II I II I CH3 I H I H para-cresol ortho-cresol meta-cresol C— C—CH3 The position of a substituted group often determines the effect of a substance on the human body; thus, of the three isomeric compounds, resorcinol, hydroquinone, and pyrocatechin, hydroquinone is more toxic and pyrocatechin is much more toxic than resorcinol. Pyrogallol is too toxic to be used as an internal medicine, but it is used in the treatment of parasitic skin diseases. Many Powerful Disinfectants and Antiseptics Have Been Discovered in Recent Years. Ehrlich's original idea that certain dyes should be effective in killing bacteria has borne fruit in the research laboratories during the past few years. The yellow dye, picric acid, has been used in disinfecting surfaces of the body in preparation for operations. Another dye, acriflavine, used during the World War of 1914—1918, was found to possess disinfecting properties. Paracelsus, the original chemotherapist of the Middle Ages, used mercury as one of his chief medicines. Mercuric chloride is a fair disinfectant often used by physicians in washing their hands before an operation, but compounds of mercury are not penetrating. By combining mercury with the very penetrating dye, fluorescein, an antiseptic, mereurochrome, was produced. In the proper concentrations mercurochrome can be used on the mucous membranes of the eye or of the bladder. Three other compounds of mercury — merthiolate, phenyl mercuric nitrate, and metaphen — have come into use recently. Other dyes which have been used as antiseptics are brilliant green, gentian violet, acriviolet, and rivanol. These dyes are both disinfectants and antiseptics In 1935 mandelic acid came into use for urinary infections. Mandelic acid, taken with an acid-producing diet or other acidifying agents such as sodium acid phosphate, produces an acid condition in the urine that inhibits bacterial growth. Methenamine (urotropin) has also been used in the treatment of urinary infections.
C I I I H CHEMISTRY AND THE CONTROL OF DISEASE 773 H— H— OH OH H—C—C=0 I c / \ C— II C— \ / C H mandelic acid It was found that maggots hatched from eggs laid in wounds by blowflies, while repulsive to contemplate, caused suppurating wounds to heal. A great deal of research led to the discovery that it is the urea produced by these maggots that is the active agent. Later it was shown that the still simpler substance, ammonium bicarbonate, is equally effective. Ammonium bicarbonate has been used with success for such infections as chronic osteomyelitis, varicose ulcers, middle-ear infections, and suture abscesses. Some compounds of silver are effective disinfectants. Water may be sterilized by the use of silver ions in the ratio of one part to 20,000,000 parts of water at a cost of only a few dollars per million gallons of water. Silver nitrate is corrosive to the tissues unless used in very dilute concentrations. born from mothers infected with gonorrhea. It has saved the eyesight of thousands of babies Colloidal silver (argyrol) and colloidal silver bromide (argental) are used in the treatment of infections of the mucous membranes. Sulfanilamide and Its Derivatives Introduced a New Era in Chemotherapy. Within the five-year period, 1935-1940, the unbelievable achievements of sulfanilamide in the treatment of formerly unconquerable diseases were quickly followed by the preparation of several derivatives of sulfanilamide which proved to be even better than the parent substance in some diseases. The discovery of these new wonder drugs is one of the greatest events since the preparation of arsphenamine by Ehrlich. Truly it represents the beginning of a new era in chemotherapy. Prontosil and similar dyes containing the NH2C6H4-SO2NH2 group were found by the German, Domagk, and his co-workers, Klarer and Mietzsch, to be effective in the treatment of streptococcic infections. Later in 1935 the Trefonels and their associates showed that all of these prontosil dyes owed their chemotherapeutic properties to a simpler substance contained in their molecules; this was sulfanilamide.