Properties of arabinogalactan-proteins in European pear (Pyrus communis L.) fruits.

Arabinogalactans (AGs) and arabinogalactan-proteins (AGPs) were partially purified from an extract of fruits of the European pear (Pyrus communis L.) by DEAE-cellulose ion-exchange and Sepharose 6B gel-filtration chromatography. Among 7 AG(P)-containing fractions, a neutral AGP (SE-1) was confirmed to be highly purified (Mr 67,000) and rich in L-Ara and Gal; this fraction included a small amount (2.6%, w/w) of protein and showed the highest reactivity forming precipitate with ß-Glc Yariv reagent among the 7 fractions, the intensity of which was comparable to that of gum arabic, a standard AGP. Another accompanying minor low-Mr neutral AGP (SE-2; Mr approx. 7200) still contained other polysaccharide (starch fragments) and did not show Yariv reactivity. The carbohydrate moieties of SE-1 consisted of consecutive (1 → 3)-linked ß-galactosyl backbone chains substituted with side chains of (1 → 6)-linked ß-galactosyl residues at O-6, to which mainly single α-l-arabinofuranosyl residues were attached through O-3. This structural feature was also observed for SE-2. Successive digestion of SE-1 with α-l-arabinofuranosidase and exo-ß-(1 → 3)-galactanase with the aid of endo-ß-(1 → 3)-galactanase released most (more than 98%, w/w) of the carbohydrate moieties as low-Mr fragments. These consisted of free L-Ara and Gal, and a series of ß-(1 → 6)-galactooligosaccharides with degree of polymerization (dp) up to at least 17, indicative of attachment of (1 → 6)-linked ß-galactosyl side chains of varying length along the (1 → 3)-linked ß-galactosyl backbone chains.

Inhibitory analysis of the effect of polycyclic aromatic hydrocarbons on the activity of chitinase by means of liquid chromatography-mass spectrometry of chitin oligosaccharides.

The analytical method of determining enzyme activity by liquid chromatography-mass spectrometry (LC/MS) was developed and applied for investigation of the effect of polycyclic aromatic hydrocarbons (PAHs) on the enzyme activity of chitinase. The measurement of chitinase activity by LC/MS is useful in order to use the nonderivatized substrate, which can show in vivo chitinase activity. Substrate consumption and product formation were monitored in order to determine chitinase activity. It was shown that, for the first time, in vitro addition of PAHs inhibited the activity of chitinase in a noncompetitive manner. The IC(50) value of benzo[a]pyrene was 1.4 microM, and PAHs containing four or more aromatic rings showed the same or higher inhibitory effect, whereas PAHs with a lower number of aromatic rings showed lower inhibition of the chitinase activity than benzo[a]pyrene.

Design and synthesis of glycosidase inhibitor 5-amino-1,2,3,4-cyclohexanetetrol derivatives from (-)-vibo-quercitol.

In continuation of development of bioactive inositol derivatives, a 1-O-methyl derivative of 5-amino-5-deoxy-L-talo-quercitol was designed and synthesized as an analogue of the strong alpha-fucosidase inhibitor, 5a-carba-alpha-L-fucopyranosylamine, the methyl branch being replaced with methoxyl, and demonstrated to be a moderate alpha-fucosidase inhibitor. The present approach provides a possible route to apply alkyl ethers of aminodeoxyinositols as hexopyranose mimics of biological interest.

Synthesis and glycosidase inhibitory activity of some N-substituted 5a-carba-beta-fuco- and beta-galactopyranosylamines, and selected derivatives.

In the course of chemical modification of alpha-fucosidase inhibitors of 5a-carba-fucopyranosylamine type, an N-dodecyl derivative of the enantiomer 6-deoxy-5a-carba-beta-D-galactopyranosylamine demonstrated very strong inhibition of beta-galactosidase and beta-glucosidase. This finding led us to synthesize corresponding 6-hydroxy compounds, in order to elucidate structure-activity relationships for inhibitors of this type. Among four N-alkyl-5a-carba-beta-D-galactopyranosylamines prepared, the N-octyl derivative could be demonstrated to possess moderate activity toward alpha- and beta-galactosidases, and beta-glucosidase.

Convenient synthesis of (+)-valiolamine and (-)-1-epi-valiolamine from (-)-vibo-quercitol.

Convenient and practical synthesis of (+)-valiolamine and (-)-1-epi-valiolamine from (-)-vibo-quercitol, 1-deoxy-L-myo-inositol, readily obtained by bioconversion of myo-inositol, is described.