Uptake, Metabolism and Excretion of Orally and Intravenously Administered, Double‐Labeled N‐GIycoloylneuraminic Acid and Single‐Labeled 2‐Deoxy‐2,3–dehydro‐N‐acetylneuraminic Acid in Mouse and Rat

Abstract

N-Glycoloyl-~-[2-' 4C,9-3H]neuraminic acid enzymically prepared from sodium 12-l 4C]pyruvate and Nglycoloyl-~-[6-~H]mannosamine by N-acetylneuraminate lyase in 52 % yield was orally administered to 20-day-old fasted mice. In the course of 6 h 98 "/, of the total radioactivity belonging to the originally administered N-glycoloylneuraminic acid was resorbed from the intestine and appeared in the urine. 6 h after application total 0.7 % of the 3H and 0.5 % of the I4C radioactivity were recovered in blood, liver, spleen, kidney and brain. The difference between the 14C and the 3H quantities was detected as exhaled 14C02. After intravenous injection of N-glycoloylneuraminic acid into rats, 90 % of the radioactivity was excreted in the urine within 10 min corresponding to the originally applied substance. After 6 h, 1.3 "/, of the 3H and 1 "/, of the 14C radioactivity were left in blood and in liver, spleen, kidney and brain.An efficient preparation of 2-deoxy-2,3-dehydro-N-acetylneuraminic acid and 2-deoxy-2,3-dehydroneuraminic acid from N-acetylneuraminic acid is described, as well as the synthesis of a tritium-labelled 2-deoxy-2,3-dehydro-N-acetylneuraminic acid. The unsaturated neuraminic acid derivative behaved similarly to N-glycoloylneuraminic acid after oral and intravenous application. 99 % of the radioactivity orally administered was resorbed from the intestine and excreted in the urine without chemical alteration in the course of 6 h. About 1 % of the radioactivity administered orally to mice and 1.7 % of the same compound administered intravenously to rats were still found in blood, liver, spleen, kidney and brain after this time.The results suggest that the small amount of N-glycoloylneuraminic acid retained in the organism was at least partially cleaved by N-acetylneuraminate lyase. The high excretion rate of unchanged 2-deoxy-2,3-dehydro-Nacetylneuraminic acid and the fact that it does not act as a substrate for the lyase supposes that there is no further metabolism of this sialic acid under the conditions described. It may be concluded from these observations that Nglycoloylneuraminic acid occurring in food cannot be used directly for the biosynthesis of glycoconjugates, which is important from an immunological point of view. The results presented here are compared with those obtained after application of double-labeled N-acetylneuraminic acid in former studies [U. Nohle and R. Schauer (1981) HoppeSeyler's 2. Pkysiol. Ckem. 362, 1495 -15061. N-Glycoloylneuraminic acid is found as a terminal sugar in various glycoconjugates and oligosaccharides. Though biosynthesis has already been investigated [I, 21, nothing is known about the metabolism of extracellular free Neu5Gc. We have reported the fate of orally and intravenously administered, double-labeled Neu5Ac in mouse and rat [3]. It was concluded from the observations that the bulk of free Neu5Ac is excreted unchanged in the urine and to a smaller amount cleaved by Nacetylneuraminate lyase suggesting that this sialic acid cannot be directly used for ...

Distribution of N-acetyl (4,5,6,7,8,9-14C) neuraminic acid in mice studied by whole-body autoradiography.

“…Biochemical data showed that a large part of administered radioactive NeuNAc was excreted in a short time (8,23,24). Approximately 90% of NeuNAc was found in the urine between 10 min and 1 hr after intravenous injection (8) and only a small per cent of the applied radioactivity was left in the blood, liver, spleen, kidney and brain at 4 hr after injection (23,24). In our observations, only the kidney, distal portion of small intestine and urine showed substantial radioactivity until 3 hr after injection.…”

“…NeuNAc is a terminal sugar in many glycoconjugates (23), but the previous investigations of NeuNAc metabolism are limited to only a few tissues and organs (10,13,23,24,29,40,41), and there is no study on the tissue distribution of this compound. Whole-body autoradiography developed by Ullberg (36) makes it possible to examine and compare the radioactivities of many organs and tissues under identical conditions.…”

Approaches and Strategies for the Treatment of Influenza Virus Infections

“…The lack of in vivo activity for FANA led to the generally accepted belief that potent synthetic analogues such as DANA would not have in vivo activity. In addition, subsequent work demonstrated that sialic acid analogues were rapidly excreted (Nohle et al, 1982), leading to the notion that DANA (Neu5Ac2en) analogues would not have potential clinical utility without modification of these molecules that would reduce the rapid excretion (reviewed in von Itzstein et al, 1993a).…”

“…The lack of in vivo activity for FANA led to the generally accepted belief that potent synthetic analogues such as DANA would not have in vivo activity. In addition, subsequent work demonstrated that sialic acid analogues were rapidly excreted (Nohle et al, 1982), leading to the notion that DANA (Neu5Ac2en) analogues would not have potential clinical utility without modification of these molecules that would reduce the rapid excretion (reviewed in von Itzstein et al, 1993a).The elucidation of the X-ray crystallographic structure of influenza NA ushered in a new era of structure-based drug design for inhibitors of this enzyme. Early work that showed the HA and NA activities of influenza virus resided in two morphologically distinct surface 'spikes' (Laver & Valentine, 1969) Colman, 1991).…”

Structural parameters and natural occurrence of 2-deoxy-2, 3-didehydro-N-glycoloyneuraminic acid

“…Neu2enSGc was prepared in analogy to the synthesis of Neu2en5Ac as reported by Nohle et al [16]. To this end Neu5Gc was converted into the penta-0-p-nitrobcn7oyl derivative of its methyl ester.…”