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Melibiosamine (Gal-α(1,6)-GlcNH 2 ), consisting of galactose and glucosamine linked by an α(1,6)-glycosidic bond, is an artificial disaccharide derivative that selectively inhibits the proliferation of K562 tumor cells relative to HUC-F2 normal cells. In this study, we employed a linkage-editing strategy to synthesize CH 2 - and CHF-linked melibiosamine analogs through chemo- and stereoselective hydrogenation of fluorovinyl- C -glycoside. ( R )-CHF-Melibiosamine exhibited more potent antiproliferative activity than O -linked melibiosamine, while ( S )-CHF-melibiosamine was less potent.

The acetal ( O -glycoside) bonds of glycans and glycoconjugates are chemically and biologically vulnerable, and therefore C -glycosides are of interest as more stable analogs. We hypothesized that, if the O -glycoside linkage plays a vital role in glycan function, the biological activities of C -glycoside analogs would vary depending on their substituents. Based on this idea, we adopted a "linkage-editing strategy" for the creation of glycan analogs (pseudo-glycans). We designed three types of pseudo-glycans with CH 2 and CHF linkages, which resemble the O -glycoside linkage in terms of bond lengths, angles, and bulkiness, and synthesized them efficiently by means of fluorovinyl C -glycosylation and selective hydrogenation reactions. Application of this strategy to isomaltose (IM), an inducer of amylase expression, and α-GalCer, which activates iNKT cells, resulted in the discovery of CH 2 -IM, which shows increased amylase production ability, and CHF-α-GalCer, which shows activity opposite that of native α-GalCer, serving as an antagonist of iNKT cells.

We monitored the levels of cesium-137 ( 137 Cs) in the soils of five orchards for six years following the Fukushima Daiichi Nuclear Power Plant accident on 11 March 2011 and found that the vertical distribution of accident-derived 137 Cs varied significantly among the orchards with varying land-use and fertilizer management. Based on these results, this study evaluated how nitrogen (N) fertilizer management may have affected the vertical migration of 137 Cs in the orchard soils. We selected an experimental orchard producing 'Jonathan' apples, where a long-term N-fertilizer trial has continued since 1973, with an N-fertilized plot (N plot; N added at 20 g m -2 y -1 ) and a non-fertilized plot (0 N plot). Five years after the accident, the vertical migration of accident-derived 137 Cs was significantly lower in the N plot (2.3 cm) than in the 0 N plot (4.3 cm), suggesting greater 137 Cs retention in the surface of the N plot. Application of a cesium bromide ( 133 CsBr) tracer suggested that the retarded vertical migration of 137 Cs in the N plot may be related to significantly lower amounts of exchangeable 133 Cs and significantly higher proportions of non-exchangeable 133 Cs in the upper 2 cm. We did not find any evidence of the aboveground plants contributing to more 133 Cs retention in the N plot. However, greater 137 Cs retention in the surface (0-2 cm) of the N plot may be due to more dissolved organic carbon (DOC), and high DOC may have contributed to deeper 137 Cs migration in both the plots. Our results suggest that continuous N fertilizer application significantly retarded the migration of 137 Cs by approximately one-half and resulted in less 137 Cs reaching the mobile exchangeable form in the deeper root-zone layers., Competing Interests: Declaration of competing interest No conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)