THE CONDUCT OF PHENOLPHTHALEIN IN THE ANIMAL ORGANISM. 
Several years ago Kastle and Shedd a proposed the use of phenol - 
phthalin, dioxytriphenylmethane carbonic acid, as a reagent for the 
oxidizing ferments. By means of the vegetable oxidases this com- 
pound is readily oxidized to phenolphthalein. On the other hand, all 
attempts to oxidize this compound with extracts of animal tissues have 
resulted thus far in failure, and even when injected into the animal 
subcutaneous^ it passes apparent!}' unchanged into the urine, and but 
little, if any, of it is oxidized to phenolphthalein. In the light of this 
fact, it occurred to me to ascertain whether the reverse of this change 
could be effected in the animal organism; that is, whether phenol- 
phthalein could be reduced to phenolphthalin. That powerful reduc- 
tions are accomplished in the animal organism is indicated by the work 
of Ehrlich, * 6 who showed that in the living animal various animal tissues 
can effect the reduction of indophenol and alizarin blue to their corre- 
sponding leuco-compounds. With the view, therefore, of determining 
whether phenolphthalein could be reduced in the organism, on Octo- 
ber 16, 1905, 0.5 gram of the compound was made into a suspension 
in water and injected into the peritoneal cavity of a guinea pig weigh- 
ing 325 grams. 
Apparently the injection caused no serious discomfort, and, except for 
some diuresis and some loss in weight, no unfavorable symptoms were 
observable at any time, and the animal is alive and apparently well at 
this time, viz, December 30, 1905. In one hour after the injection a 
specimen of the urine of the animal was obtained. This gave no test 
for phenolphthalein or phenolphthalin, nor for any conjugation prod- 
uct of either of these compounds. During the night of October 16 the 
pig passed a considerable quantity of urine. This was normal in 
appearance and gave no red color for phenolphthalein on the addition 
of caustic soda. Some of it was then boiled for a few minutes with 
dilute hydrochloric acid. This was then cooled and made alkaline with 
caustic soda, when the characteristic purplish red color of phenol- 
phthalein in alkali was obtained. This would seem to indicate that 
phenolphthalein, when injected into the peritoneal cavit}^ of an animal, 
forms some conjugated compound, which of itself gives no color reac- 
tion with caustic soda, but which is hydrotyzable by h} T drochloric acid, 
yielding phenolphthalein as one of the products of the hydrolysis. 
« Am. Chem. Jour., XXVI, 526-539. 
& “Das Sauerstoff Bedurfniss des Organismus. ,, Berlin, 1885. 
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