John R. Totter

Pteroylglutamic Acid-like Effect of Dehydroisoandrosterone on Growth of Certain Microorganisms.

Summary Dehydroisoandrosterone acetate was found to have pterovlglutamic acid-like activity for Streptococcus jaecalis, Lactobacillus casei and sulfonamide-treated Escherichia coli. The activity of the steroid differs from that of thymine but is of the same order of magnitude. We are indebted to Lederle Laboratories Division, American Cyanimid Company for the supplies of pteroylglutamic acid and pteroylglutamic acid antagonists used in this study.

Urinary Excretion of Orally Administered Pteroylglutamic Acid.

Summary Fifty-four urine samples for 24-hour periods have been assayed microbiologically for free pteroylglutamic acid. For normal subjects the average 24-hour excretion was 2.3γ. Following an oral dose of pteroylglutamic acid the mean percentage recovery was 28.5%. Although the hospitalized patients studied had a similar excretion level (average 2.3 γ for 24hours) prior to dosage with pteroylglutamic acid, the percentage returns from single oral doses were much lower than in the normal subjects, a finding which is possibly indicative of a low degree of saturation.

Biochemical Studies on Livers of Chicks Receiving Graded Levels of Pteroylglutamic Acid.

Summary Determinations of desoxypentose nucleic acid and pentose nucleic acid, pteroylglutamic acid (PGA), and conjugase have been made on the livers of chicks receiving 0, 5, 10, 20, 40, 80, 200, and 1000 pg of PGA per 100 g of diet and on controls receiving a commercial diet. Desoxypentose nucleic acid was found to be somewhat low in the livers of the negative control group of chicks but differences between all other groups uere of doubtful significance. The liver conjugase levels of the various groups, whether determined at pH 4.5 or at pH 7.0, were found to be unrelated to the dietary intake of PGA and to the nucleic acid content of the livers. The liver PGA freed by autolysis was approximately the same as that determinable after treatment with either chick pancreas conjugase or hog kidney conjugase. The levels of PGA found in the chick livers indicate that storage of excess vitamin did not take place until the dietary level exceeded 40 μg per 100 g. The bearing that the findings have on the mode of action of dietary PGA in reducing liver xanthine oxidase is briefly discussed.

Effect of aminopterin on radioactivity of rat liver- and intestinal-ribonucleic acid after C14 formate injection.

Summary Treatment of albino rats four times with 100 μg of aminopterin during a 68-hour period resulted in a severely lowered white blood cell count. The treated animals showed a reduced uptake of C14 formate in intestinal ribonucleic acid while their liver ribonucleic acid showed a markedly increased specific activity as compared with controls.

The relation of pteroylglutamic acid to metal-porphyrin enzymes.

Summary Streptococcus faccalis was grown in the usual PGA-deficient medium containing graded amounts of PGA, to which either 0.05% potassium cyanide, 0.5% caffeine, or 0.012% hydrogen peroxide was added as an inhibitor. The inhibition induced by any of these three substances was partially reversed by large amounts of PGA. In control experiments where the Ca pantothenate content of the medium was varied but the PGA content kept constant, no such reversal of inhibition was found even with high levels of Capantothenate. these data lend additional support to the suggestion that PGA is involved in thc synthesis of the porphyrin portions of metal-porphyrin enzymes.