An expeditious route to the synthesis of kelampayosides A and B

Phenolic glycosides from sugar maple (Acer saccharum) bark

Four new phenolic glycosides, saccharumosides A-D (1-4), along with eight known phenolic glycosides, were isolated from the bark of sugar maple (Acer saccharum). The structures of 1-4 were elucidated on the basis of spectroscopic data analysis. All compounds isolated were evaluated for cytotoxicity effects against human colon tumorigenic (HCT-116 and Caco-2) and nontumorigenic (CCD-18Co) cell lines.

Synthesis of apiose-containing oligosaccharide fragments of the plant cell wall: fragments of rhamnogalacturonan-II side chains A and B, and apiogalacturonan

Fragments of pectic polysaccharides rhamnogalacturonan-II (RG-II) and apiogalacturonan were synthesised using p-tolylthio apiofuranoside derivatives as key building blocks. Apiofuranose thioglycosides can be conveniently prepared by cyclization of the corresponding dithioacetals possessing a 2,3-O-isopropylidene group, which is required for preservation of the correct (3R) configuration of the apiofuranose ring. The remarkable stability of this protecting group in apiofuranose derivatives requires its replacement with a more reactive protecting group, such as a benzylidene acetal which was used in the synthesis of trisaccharide β-Rhap-(1→3')-β-Apif-(1→2)-α-GalAp-OMe. The X-ray crystal structure of the protected precursor of this trisaccharide has been elucidated.

Heterocyclic compounds and aromatic diglycosides from Bretschneidera sinensis

Two new heterocyclic compounds, bretschneiderazines A and B (1, 2), three new aromatic diglycosides, bretschneiderosides A-C (3-5), and three known aromatic diglycosides, 6-8, were isolated from Bretschneidera sinensis. The structure of bretschneiderazine A (1) was confirmed by single-crystal X-ray diffraction analysis. Bretschneiderazine A (1) showed moderate activity against the NCI-H446 cell line.

Phenolic and iridoid glycosides from Strychnos axillaris

Five phenolic glycosides 1-5 and an iridoid glucoside 6 were isolated, together with 22 known compounds, from the dried barks and woods of Strychnosaxillaris. Their structures were determined by application of spectroscopic (NMR, MS) and chemical methodologies.

Synthesis of a disaccharide fragment of rhamnogalacturonan II

A disaccharide portion of the A-side chain of the rhamnogalacturonan II oligosaccharide has been prepared. Glycosylation of methyl (methyl 3,4-O-isopropylidene-alpha-D-galactopyranosid)uronate with p-tolyl 2,3-di-O-acetyl-3-C-(benzyloxymethyl)-1-thio-alpha/beta-D-erythrofuranoside was carried out using N-iodosuccinimide as promoter and silver trifluoromethanesulfonate as catalyst. Removal of the protecting groups gave the beta-d-Apif-(1-->2)-alpha-D-GalpA-OMe disaccharide.