Lactose-derived oligosaccharides in the milk of elephants: comparison with human milk

Abstract

Human milk is commonly considered to be unique when compared with the milk of other species with regard to its high content of complex fucosylated and sialylated lactose-derived oligosaccharides. We describe the application of high-pH anion-exchange chromatography with pulsed amperometric detection and TLC to characterize and quantitate neutral and sialylated lactose-derived oligosaccharides in milk from three Asian elephants and human milk. The lactose contents of elephant and human milks were 25–30 g/l and about 66 g/l respectively, whereas total oligosaccharide concentration was about three times higher in elephant milk and comprised up to 40% (10% in human milk) of the carbohydrate content. The ratio neutral: acidic components was different in the milk of the two species; in elephant milk, the N-acetylneuraminic acid-containing oligosaccharides made up almost half of the total amount v. 30% in human milk. Most oligosaccharides in elephant milk were more fucosylated and/or sialylated compared with human milk components. By mild acid hydrolysis, fucose and N-acetylneuraminic acid were cleaved off from complex components, and this resulted in increased amounts of fucose, galactose, N-acetylneuraminic acid, lactose and lacto-N-neo-tetraose. Unique to elephant milk are the high levels of 3′-galactosyllactose (up to 4 g/l) and lacto-N-neo-tetraose which are present in human milk only in trace amounts. Elephant and human milks have high levels and unique patterns of oligosaccharides which may reflect the relative importance of these components in neonatal host defence, in endothelial leucocyte interactions or in brain development.

Analysis of native milk oligosaccharides directly from thin-layer chromatography plates by matrix-assisted laser desorption/ionization orthogonal-time-of-flight mass spectrometry with a glycerol matrix

“…A milk sample from an individual Asian elephant (Elephas maximus) was kindly provided by Dr. Michael Flügger (Tierpark Hagenbeck, Hamburg, Germany). Oligosaccharide fractions were obtained by a modified procedure of Kunz et al [2]. Milk samples were defatted by centrifugation as described above.…”

“…Technically, this approach is in a close analogy to earlier studies in which fast-atom bombardment (FAB) was used to generate molecular ions of glycoconjugates directly from TLC plates [20,21]. In comparison to FAB, IR-MALDI, in combination with the glycerol matrix, provides considerably softer desorption/ionization conditions; this has been demonstrated for various classes of biomolecules [22] including complex carbohydrates [23].More than 130 different oligosaccharide structures have so far been described for human milk [2,24]. The exact composition varies between individuals and in the time-course of lactation [25].…”

“…This complex oligosaccharide content in human milk has been previously recognized for its role in the immune system of the infant [24]. Whereas human milk was considered to be unique in terms of its complex oligosaccharide content for some time, more recently elephant milk has been shown to represent another exception [2]. Previous studies, performed in our laboratory employing FAB high-energy collision-induced (CID) tandem MS on permethylated oligosaccharides, have revealed that in elephant milk only oligosaccharides of the neo-lacto (Type II) series are expressed (Pohlentz et al, unpublished data).…”

“…(J Am Soc Mass Spectrom 2006, 17, 139 -150) © 2006 American Society for Mass Spectrometry T he combination of robust and low-cost, but rather low-resolving high-performance thin-layer chromatography (HPTLC) with mass spectrometry (MS) systems for the precise analysis of samples of particular interest offers an attractive hybrid technique. HPTLC is frequently used for separation and partial characterization of neutral and acidic oligosaccharides from mixtures [1,2]. The low resolving power of the method, however, does not usually permit differentiation of species of similar structure and "mobility", and the chromatograms serve mostly for visualization and as a finger-print.…”

“…More than 130 different oligosaccharide structures have so far been described for human milk [2,24]. The exact composition varies between individuals and in the time-course of lactation [25].…”