Browsing by Autor "Ana Simonet"

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    Characterization of three saponins from a fraction using 1D DOSY as a solvent signal suppression tool. Agabrittonosides E–F. Furostane Saponins from <i>Agave brittoniana</i> Trel. spp. <i>Brachypus</i>
    (Wiley, 2010) Francisco A. Macı́as; José O. Guerra; Ana Simonet; Andy J. Pérez; Clara Nogueiras
    A careful NMR analysis, especially by 1D TOCSY and 1D ROESY, of a refined saponin fraction allowed us to determine the structure of three saponins from a polar extract of Agave brittoniana Trel. spp. Brachypus leaves. The use of 1D DOSY for the suppression of the solvent signal was useful to obtain the chemical shifts of anomeric signals. A full assignment of the (1)H and (13)C spectral data for the new saponins, agabrittonosides E-F (1-2) and the well-known Karatavioside C (3) and their methoxyl derivatives, is reported. The structures were established using a combination of 1D and 2D ((1)H, (1)H-COSY, TOCSY, ROESY, g-HSQC, g-HMBC and g-HSQC-TOCSY) NMR techniques and ESI-MS. In addition, the methoxylation of these furostane saponins in the presence of MeOH was studied.
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    Saponinas esteroidales de la planta Agave brittoniana (Agavaceae) con actividad contra el parásito Trichomona vaginalis
    (Vicerractoría Investigación, 2007) José O. Guerra; Alfredo Meneses; Ana Simonet; Francisco A. Macı́as; Clara Nogueiras; Alicia Gómez; José Antonio Escario
    The genus Agave (Agavaceae), includes more than 300 species; around 16 of them show an homogeneous distribution throughout Cuba. Agave brittoniana (ssp. brachypus), is an endemic subspecies that grows in the central region of the country and its leaves are traditionally used in the treatment of parasitic diseases. The parasite Trichomonas vaginalis causes the disease known as trichomoniasis, that infects the genital tract. To test in vitro the plant against Trichomona vaginalis, the dried and powdered leaves were extracted three times with ethanol-water (7:3) by maceration at room temperature. The solvent was removed under reduced pressure and the extract was suspended in distilled water, defatted with n-hexane, and extracted with water-saturated n-butanol. After solvent removal, a portion of the n-butanol extract was hydrolyzed. After extraction with ethyl acetate the hydrolysis products were compared with authentic sapogenins samples using thin layer chromatography (TLC). Most of the sapogenins (yuccagenin and diosgenin) were isolated and their structures were confirmed. using nuclear magnetic resonance (NMR) experiments. The n-butanol extract was subjected to a separation process through column chromatography to obtain five fractions. After multiple separation processes by reversed phase high performance liquid chromatography (HPLC), the most active one produced one refined fraction that contained two saponins with the same aglycone (diosgenin) and one yuccagenin based saponin. Best results of the activity were obtained with the yuccagenin derived glycoside.