Les Flavonols d'Asclepias Syriaca

Eight flavonoids are present in the leaves of Asclepias syriaca. Three have been identified as quercetin, kaempferol, isorhamnetin; a structure of a fourth, 3,5,3′,4′-tetrahydroxy-7,8-(2″,2″-dimethyl-4″-methyl-5″,6″) pyranoflavone(I), has been established by study of its spectral properties (UV, IR, MS, NMR) and those of its acetate.     

Individual variation of flavonoid glycosides in Chaerophyllum aureum

Individuals (45) of Chaerophyllum aureum collected from six stations in a 1500 m perimeter of the Ubaye Valley (southern Alps, France) were surveyed for their flavonoid glycoside content. Factor analysis of correspondence applied to the distribution of these compounds showed—as noted before—luteolin-7 diglucoside is a discriminating factor of specimens from tall grass prairies (Adenostylion) against those from meadows (Triseto-Polygonion). In addition, populations of Triseto-Polygonion and Adenostylion differ in their chemical homogeneity: those from meadows display a far greater heterogeneity than those growing in the tall grass prairies. This can be interpreted as the result of a stronger selective pressure in the meadows, from human activities.     

Sur l'analyse qualitative des aglycones flavoniques dans une optique chimiotaxinomique

A qualitative method is described for the analysis of flavonols and flavones in hydrolysed extracts of plant organs; the procedure involves thin layer and column chromatography of plant extracts on polyamide. Physicochemical data are given for about eighty flavonoids.     

La variation flavonique chez les sous-especes de l'Anthyllis vulneraria

Nine infraspecific taxa of Anthyllis vulneraria have been investigated for leaf flavonoids. The distribution of 35 flavonol glycosides within 26 populations, indicated the presence of four chemical taxa, each based on different glycosides of 7-methylkaempferol.     

The role of high-mannose and complex asparagine-linked glycans in the secretion and stability of glycoproteins

Suspension-cultured cells of sycamore (Acer pseudoplatanus L.) secrete a number of acid hydrolases and other proteins that have both highmannose and complex asparagine-linked glycans. We used affinity chromatography with concanavalin A and an antiserum specific for complex glycans in conjunction with in vivo-labeling studies to show that all of the secreted proteins carry glycans. The presence of complex glycans on secretory proteins indicates that they are passing through the Golgi complex on the way to the extracellular compartment. The sodium ionophore, monensin, did not block the transport of proteins to the extracellular medium, even though monensin efficiently inhibited the Golgi-mediated processing of complex glycans. The inhibition of N-glycosylation by tunicamycin reduced by 76% to 84% the accumulation of newly synthesized (i.e. radioactively labeled) protein that was secreted by the sycamore cells, while cytoplasmic protein biosynthesis was not affected by this antibiotic. However, in the presence of glycoprotein-processing inhibitors, such as castanospermine and deoxymannojirimycin, the formation of complex glycans was prevented but glycoprotein secretion was unchanged. These results support the conclusion that N-linked glycan processing is not necessary for sorting, but glycosylation is required for accumulation of secreted proteins in the extracellular compartment.