Characterization of lyso-galactolipids, C-2 and C-3O-acyl trigalactosylglycerol isomers, obtained from the lichenized fungusDictyonema glabratum

Abstract

A mixture of two lyso isomers of a galactolipid was obtained from Dictyonema glabratum. Aqueous hydrolysis gave rise to galactose and glycerol in a 3:1 molar ratio. ESI-MS spectroscopy gave, in the positive-ion mode, a pseudomolecular ion at m/z 839 and daughter ions with m/z 677, 600, 515 and 353, suggesting three galactosyl units linked to a glycerol moiety, substituted by one O-acyl group. 1D and 2D NMR experiments were used to characterize the glycolipid, and HMQC examination showed three anomeric signals, corresponding to two alpha-Galp and one beta-Galp residue liked to glycerol. The glycolipid structure was shown to be O-alpha-D-Galp-(1-->6)-O-alpha-D-Galp-(1-->6)-O-beta-D-Galp-(1<-->1)-2- and -3-monoacyl-D-glycerol, the latter structures not having been previously found in nature. The fatty acid composition was determined by GC-MS of derived methyl esters: that of palmitic acid C(16:0) was the most abundant, although the presence of C(12:0), C(14:0), C(16:1) and C(18:0) esters was observed.

Characterization and Antineoplasic Effect of Extracts Obtained from Pleurotus sajor-caju Fruiting Bodies

“…A small signal in the region of δ 174.5 (Fig. 4a) an ester carbonyl group [24]. FII fraction shows a more intense anomeric signal in the β configuration region of the spectrum (δ 103.7) than FI fraction (Fig.…”

Isolation of Araguspongine M, a New Stereoisomer of an Araguspongine/Xestospongin alkaloid, and Dopamine from the Marine Sponge Neopetrosia exigua Collected in Palau

“…The EtOH extract of the sponge was partitioned between water and 1-butanol. The butanol extract was subjected to repeated chromatographic separations to give the new compound, araguspongine M ( 1 ), araguspongines B ( 2 ) and D ( 3 ) [ 7 , 8 ], dopamine ( 4 ), three galactosyl diacylglycerols ( 5–7 ) [ 9 – 13 ], 24-methyl cholesterol ( 8 ), 5, 6-dihydrocholesterol ( 9 ), β-sitosterol ( 10 ) [ 14 – 16 ], and three 5α,8α-epidioxy sterols ( 11 – 13 ) [ 17 , 18 ]. The structures of known compounds were determined on the basis of their spectral data and comparison with the previously reported values.…”

“…These compounds were also isolated from marine sponges, Phyllospongia foliascens [ 37 ] and Pseudoceratina sp. [ 38 ], and marine microorganisms, such as cyanobacteria [ 9 – 10 ], dinoflagellates [ 11 , 12 ], and a lichenized fungus [ 13 ]. HPLC analysis of the glycolipids fractions revealed that there were at least seven minor monogalactosyl and digalactosyl diacylglycerols, and several trigalactosyl diacylglycerols in this sponge.…”