Preparation ofN-acetylneuraminic acid from delipidated egg yolk

Egg yolk, a large proportion of the egg, was studied for the preparation ofN-acetylneuraminic acid (Neu5Ac). The delipidated hen egg yolk (DEY; 500 kg containing 0.2% w/w, Neu5Ac) was hydrolysed with HCl (pH 1.4) at 80 °C and neutralized with NaOH (pH 6.0). The mixture was filtered and electrodialysed until the conductivity was 240 µS cm⁻¹. The filtrate was applied on a column of Dowex HCR-W2 (20–50 mesh), followed by a column of Dowex 1-X8 (200–400 mesh). The latter column was washed with water, and then eluted with a linear gradient of HCO₂H (0–2m). The eluates containing Neu5Ac were concentrated using a reverse osmosis membrane and, finally, rotary evaporated at 40 °C. The residue was then lyophilized to yield 500 g Neu5Ac. The purity of Neu5Ac was >98% (TBA method). HPLC, NMR spectroscopy and TLC chromatography of the product obtained from the DEY showed that Neu5Ac was the sole derivative present in egg yolk. The DEY, a byproduct from egg processing plants, was found to be an excellent source for the large-scale preparation of Neu5Ac.

Neu5Ac:

N-acetylneuraminic acid

Neu5Gc:

N-glycolylneuraminic acid

DEY:

delipidated egg yolk

HPLC:

high performance liquid chromatography

TLC:

thin layer chromatography

NMR:

nuclear magnetic resonance

IR:

infrared spectroscopy

Authors and Affiliations

1. Basic Research Laboratories, Taiyo Kagaku Co. Ltd, 1-3 Takaramachi, 510 (Mie), Yokkaichi, Japan

   Mamoru Koketsu, Lekh Raj Juneja, Hiroshi Kawanami & Mujo Kim

2. Department of Biotechnology, Fukuyama University, Fukuyama, 729-02, Hiroshima, Japan

   Takehiko Yamamoto

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