Browsing by Autor "Nancy Vera"

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    Active sesquiterpene lactones against <i>Leishmania amazonensis</i> and <i>Leishmania braziliensis</i>
    (Taylor & Francis, 2016) A Sosa; Susana Amaya; Efraín Salamanca; Miguel Gilabert; Alicia Bardón; Alberto Giménez; Nancy Vera; Susana Borkosky
    Seventeen sesquiterpene lactones (SLs) isolated from five species of the tribe Vernonieae were evaluated for their in vitro activity against promastigotes of Leishmania amazonensis and Leishmania braziliensis. Additionally, a quantitative structure activity relationship has been made, since all these natural compounds were found to have potent to mild antileishmanial properties. The most active compounds against L. braziliensis were 16 and 17 (IC<sub>50</sub> values 1.45 and 1.34 μM, respectively), followed by compound 15 with IC<sub>50</sub> value of 1.60 μM against L. amazonensis. The three glaucolide-type SLs (4-6) were the least active against both parasites. The computational study allowed us to establish that lipophilicity and polarisability play an important role in the antiparasitic activity. This is the first report of the known germacradiendiolides 16 and 17 from Elephantopus mollis. The activity data of the compounds 1-17 assayed against Leishmania parasites are reported here for the first time.
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    Trypanocidal activity of South American Vernonieae (Asteraceae) extracts and its sesquiterpene lactones
    (Taylor & Francis, 2020) A Sosa; Efraín Salamanca; Susana Amaya; Alicia Bardón; Alberto Giménez-Turba; Nancy Vera; Susana Borkosky
    Chagas disease is caused by <i>Trypanosoma cruzi</i> and affects the poorest population in the Americas. Fourteen plant extracts and seventeen sesquiterpene lactones from the tribe Vernonieae (Asteraceae), were evaluated for the first time against <i>T. cruzi</i>. Cytotoxicity employing HeLa cells was also assessed. The best results were obtained with leaves and flowers rinse extracts from <i>Vernonanthura nebularum</i> (E-1 and E-3) and <i>Elephantopus mollis</i> (E-11 and E-13), with IC<sub>50</sub> values <2 µg/mL, being E-1 the most active (IC<sub>50</sub> = 0.8 µg/mL). Additionally, these extracts displayed a good selectivity (SI > 10). The most active sesquiterpene lactones, isolated from the extracts, were 2 (2<b>-</b>methoxy-2,5-epoxy-8-methacryloxygermacra-3Z,11(13)-dien-6,12-olide) and 6 (2<b>-</b>ethoxy-2,5-epoxy-8-angeloxygermacra-3Z,11(13)-dien-6,12-olide) from <i>V. nebularum</i> and 12 (8α-methacryloxyhirsutinolide 13-O-acetate) from <i>V. pinguis</i>, with IC<sub>50</sub> of 1.5, 2.1 and 2.0 µM, respectively. These compounds showed SI values >14, better than those of the reference drug nifurtimox. Plants living in South American ecosystems could become a potential source of trypanocidal agents.