Glycosides from Muscaricomosum. 5. Structure of muscaroside B

Abstract

A further component of the glycoside mixture extracted from the bulbs of Muscaricomosum has been completely characterized by chemical degradative study and spectral investigation. This glycoside, 2, termed muscaroside B, possesses an α-L-arabinofuranosyl(1 → 2)-α-L-arabinopyranosyl(1 → 3)[α-L-rhamnopyranosyl(1 → 2)]-β-D-glucopyranosyl(1 → 2)-α-L-arabinopyranosyl(1 → 6)-β-D-glucopyranosyl chain linked at the 3-position of eucosterol.

Glycosides from Muscaricomosum. 6. Use of homo- and heteronuclear two-dimensional nuclear magnetic resonance spectroscopy for the structure determination of the novel glycoside muscaroside C

“…In connection with our studies (1)(2)(3)(4)(5) on the glycoside fraction of Muscari comosum we recently reported the isolation and structure determination of muscarosides A (4) and B (5). In this paper we describe the structure elucidation of a minor glycoside, muscaroside C, 1, which possesses a P-D-apio-Dfuranosyl( 142)-P-D-glucopyranosyl-(1-2)-a-L-arabinopyranosyl(l+6)-P-D-glucopyranosyl chain linked at the 3-position of (23S)-17,23-epoxy-3~,30,31-trihydroxy-27-nor5a-lanost-8-ene 2 (2).…”

“…No direct evidence for the a-configuration of the L-arabinopyranosyl unit was found, owing to its high conformational mobility (4,5,17). However, an a-configuration was inferred from the striking similarity between the I " data of the L-arabinopyranosyl unit of 1 and those found for the a-L-arabinopyranosyl residues identically located in muscarosides A and B (4, 5).…”

Full Structural Characterization of an Extracellular Polysaccharide Produced by the Freshwater Cyanobacterium Oscillatoria planktothrix FP1

“…Klyne's rule; [12,14] the application of which firmly indicated a -configuration for E (Table 3). In fact, the two alternative combinations (obtained by supposing the presence of residue E with -or -configuration in the pentasaccharide chain) gave calculated [M] D values of -22.1°for the -configuration of E and +166.7°for the -configuration of E Ϫ both of which differ considerably from the observed value of 192.2°.…”

“…[12,14] These methods overcame the problems associated with the lack of monosaccharide references and the difficulties associated with its isolation. Lipkind et al [9] exploited the relative intensities of the inter-residual NOE effects by analyzing the structural and stereochemical factors determining the conformation of the glycosidic linkages; data showed that the main structural factors determining the NOE and the preferred conformation in disaccharide units were the configuration of the glycosidic linkage, the nature of the sugar, the position of glycosidation, and the absolute configuration of the constituent residues.…”

The chemistry and biological activity of the Hyacinthaceae

“…76,[81][82][83][84] Extensive work on the bulbs by Adinol et al resulted in the isolation of the free aglycones present in the bulbs (20,21,22,54,(169)(170)(171)(172)(173)(174)(175) [85][86][87][88][89] as well as the full structural elucidation of the glycosides (86, 87, 102, 103 and 176). [90][91][92][93][94] All the nortriterpenes isolated from Leopoldia comosa mentioned so far have S conguration at C-23, three compounds with R conguration have also been identied, 177, 91 178 (23R 20) and 179 (23R 170). 89 Two classes of homoisoavanones have been isolated from the bulbs of L. comosa, the 3-benzyl-4-chromones (30, 58, 59, 61, 62, 80, 97, 180-181) 95,96 and the scillascillin type (55, 104-107 and 182).…”