Two highly potent cytotoxic 26-membered macrolides, isocaribenolide-I (1) and a chlorohydrin 2, together with known amphidinolide N (3), have been isolated from a free-swimming dinoflagellate Amphidinium species (KCA09053 and KCA09056 strains) collected off Iriomote Island, Japan. The structures of 1 and 2 were determined to be a congener of 3 with an isobutyl terminus and the chlorohydrin form of 3, respectively, by detailed analyses of spectroscopic data. The relative stereochemistries of 1 and 2 were elucidated by the conformational analyses based on NMR data.
A fermented beverage of plant extracts (Super Ohtaka®) was prepared from about 50 kinds of fruits and vegetables. This natural fermentation was performed by yeast (Zygosaccharomyces spp. and Pichia spp.) and lactic acid bacteria (Leuconostoc spp.) and resulted in the production of a novel fructopyranose-containing saccharide, which was subsequently isolated using carbon-Celite column chromatography and preparative-HPLC. The structure of the saccharide was determined using MALDI-TOF MS and NMR, and the saccharide was identified as β-D-fructopyranosyl-(2→6)-β-D-fructofuranosyl-(2↔1)-α-D-glucopyranoside. This is the first description of this novel saccharide and its isolation from a natural source.
Ten difructose anhydrides (DFAs) were the predominant products formed from the thermal treatment of equal amounts of D-glucose and D-fructose under melting conditions at 150°C for 60 min. The DFAs were isolated from the reaction mixture by carbon-Celite column chromatography and preparative high-performance liquid chromatography. The structures of the saccharides were confirmed by NMR measurements. We present the complete assignments of the 1H- and 13C-NMR signals of two of these DFAs for the first time.