Search results for "Dioscorea"

A New Steroidal Saponin from Dioscorea cayenensis

2004

The new 26-O-beta-D-glucopyranosyl-3beta,26-dihydroxy-20,22-seco-25(R)-furost-5-en-20,22-dione-3-O-alpha-L-rhamnopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->4)-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-glucopyranoside (1), along with the known methyl protodioscin (2), asperoside (3) and prosapogenin A of dioscin (4) were isolated from the rhizomes of Dioscorea cayenensis LAM.-HOLL (Dioscoreaceae). Their structures were established mainly on the basis of 600 MHz 2D-NMR spectral data. 4 exhibited antifungal activity against the human pathogenic yeasts Candida albicans, C. glabrata and C. tropicalis (MICs of 20.8, 6.25, 25 microg/ml, respectively), whereas saponins 1-3 were inactive.

Steroidal saponins and flavan-3-ol glycosides from Dioscorea villosa

2006

RAPD differentiation between Borderea pyrenaica and B. chouardii (Dioscoreaceae), two relict endangered taxa

2001

As currently circumscribed, the genus Borderea Mieg. comprises two narrowly distributed European taxa, Borderea pyrenaica (Bub.) Mieg. and B. chouardii (Gaussen) Heslot. An accumulation of facts such as that both species share a very close overall morphology, that only a single population of Borderea chouardii is known, and that they live in contrasting environments has led some authors to suggest that B. chouardii is a mere ecotype of the more widespread B. pyrenaica. We tested this hypothesis using RAPD markers in four populations of Borderea, three of them identified as B. pyrenaica and the other one representing the only known population of B. chouardii. Eleven out of twenty assayed pri…

Nunatak survival vs. tabula rasa in the Central Pyrenees: a study on the endemic plant species Borderea pyrenaica (Dioscoreaceae)

2007

14 páginas, 4 figuras, 2 tablas.