Hypoglycemic Effect of D-Ribose in Man

Abstract

Ribose 5-phosphate occupies an important position as an intermediate in the oxidative or pentose phosphate pathway of glucose metabolism. In both plant and animal tissues ribose 5-phosphate forms fructose 6-phosphate ( 1 ) which may be readily converted to glucose. Recently Agranoff and Brady(2) have isolated an enzyme from mammalian liver capable of phosphorylating D-ribose to form ribose 5-phosphate, thus permitting ribose to enter into this pathway. The conversion of ribose to glucose has been demonstrated by Katz et d ( 3 ) who found that ribose l-C14 incubated with rat liver slices yielded glucose labeled in a pattern which agreed with predictions from known reactions. Intravenous infusion of known glycogenic sugars such as D-galactose (4) and D-fructose (5,6) have been shown to cause an increase in blood glucose levels in normal man. Occurrence of increases in blood glucose levels after infusion of the pentoses D-xylose and L-arabinose has been reported from this laboratory although no effect was observed after D-lyxose and Darabinose administration ( 7 ) .Bruck and Rapoport (8) have reported that D-galactose * Present address: Duke University School of Medicine, Durham, N. C.infusions cause a lowering of blood glucose levels in galactosemic individuals. Except for a single observation that infusion of Dfructose may have a glucose lowering effect (9) no sugars have been observed to cause decreases in blood glucose levels following infusion into normal man. This paper reports that following infusion of D-ribose into normal man, decreases in blood glucose levels occur despite the fact that this sugar is susceptible to conversion to glucose via known metabolic pathways.Methods. The D-ribose used was obtained from the Pfanstiehl Co., Waukegan, Ill. By the criteria of optical rotation and paper chromatography, the sugar was authentic Dribose. Fifteen infusions of D-ribose were performed in 5 fasting normal males, (ages 18-21 yrs.) 3 diabetics (ages 23, 31 and 53 yrs.) whose last insulin dose (NPH + crystalline) was given 24 hours prior to study and one 48 yr. old subject with liver disease proved by liver biopsy. D-ribose was autoclaved as a 7.576 solution and found sterile and pyrogen-free prior to use. In 13 studies, 10 to 20 g of D-ribose were infused intravenously over 10-25 minutes. Blood specimens were obtained from an indwelling plasat GEORGETOWN UNIV MED CTR on July 20, 2015 ebm.sagepub.com Downloaded from

The Metabolic Fate of C14 Labeled Pentoses in Man

“…After infusion of D-xylOse and L-arabinose in man a rise in blood glucose has been observed (10). Little or no change occurs upon infusion of D-arabinose or D-lyxose, whereas D-ribose has been observed to cause marked decreases in blood glucose level (17). Despite the hypoglycemia induced by ribose, D-ribose-i-C"4 has been shown to be converted to blood (16) and urinary glucose (12) via the pentose phosphate pathway.…”

The Metabolism of D-Ribose in Man

“…The effect of ribose on blood levels of glucose, pyruvate and inorganic phosphate It has been reported that the infusion of ribose into the normal and some diabetic individuals causes a lowering of blood glucose of about 30 mg. per cent (14). A typical response of blood glucose to ribose is demonstrated in Figure 7 of ribose is shown again in the same subject ( Figure 5) after a 4 Gm.…”

“…This paper presents data concerning the fate of ribose after its intravenous administration in both unlabeled and C14 labeled form to both normal and diabetic subjects. Preliminary results of these studies have been published (13), as well as a report of the hypoglycemia induced by ribose infusion (14). Previous publications (15,16) from this laboratory have described the physiologic disposition in man of the related pentoses D-Xylose, D-and L-arabinose, and D-lyxose, as well as the effects of insulin on the blood levels of these sugars.…”

“…Quantitative determination of urinary glucose after ribose infusion (14) eliminated glucosuria as a cause and indicated that the hypoglycemia might be the result of a defect in the hepatic homeostatic mechanism for maintenance of blood glucose.…”

Assessment of Hematological and Biochemical parameters with extended D-Ribose ingestion

“…Segal and Foley [21,22] found different levels of hypoglycemia with D-ribose supplementation depending upon dose with higher doses producing a greater decrease. Gross et al [23] has published similar findings.…”