Carola Kraft

Antiplasmodial activity of naphthoquinones and one anthraquinone from Stereospermum kunthianum.

A lipophilic extract of the root bark of Stereospermum kunthianum revealed antiplasmodial activity in vitro. Bioassay-guided fractionation led to the isolation of four novel naphthoquinones (sterekunthals A and B, pyranokunthones A and B) and one novel anthraquinone (anthrakunthone) together with the known naphthoquinone pinnatal. The structures of the novel compounds were determined by comprehensive analyses of their 1D and 2D NMR data. The antiplasmodial activities and toxicity against the endothelial cell line ECV-304 of the isolated compounds have been assessed.

Herbal Remedies Traditionally Used Against Malaria in Ghana: Bioassay-Guided Fractionation of Microglossa pyrifolia (Asteraceae)

Different extracts from 11 West African plants traditionally used against malaria in Ghana were tested against both the chloroquine-sensitive strain PoW and the chloroquine-resistant clone Dd2 of Plasmodium falciparum. Due to the promising in vitro activity of the lipophilic extract [IC50: 10.5 μg/ml (PoW); 13.1 μg/ml (Dd2)], Microglossa pyrifolia (Lam.) Kuntze (Asteraceae) was chosen for further phytochemical investigation. From active fractions 13 compounds were isolated; their structures were established on the basis of spectroscopic methods. 1-Acetyl-6E-geranylgeraniol-19-oic acid and sinapyl diangelate represent new natural compounds. The two diterpenes E-phytol [IC50: 8.5 μм (PoW); 11.5 μм (Dd2)], and 6Egeranylgeraniol- 19-oic acid [IC50: 12.9 μм (PoW); 15.6 μм (Dd2)] proved to be the most active constituents in our test system.

Sipaucins A-C, sesquiterpenoids from Siparuna pauciflora.

The phytochemical investigation of the leaves of Siparuna pauciflora yielded three novel sesquiterpenoids: the germacrane sipaucin A, the elemane sipaucin B and sipaucin C, comprising a new type of carbon skeleton. In addition, four known aporphine alkaloids-nor-boldine, boldine, laurotetanine, and N-methyl-laurotetanine-were obtained. The evaluation of the antiplasmodial activity of the isolated compounds against two strains of Plasmodium falciparum (PoW, Dd2) showed a moderate activity of nor-boldine.

Cornutins C-L, neo-clerodane-type diterpenoids from Cornutia grandifolia var. intermedia.

Ten novel neo-clerodane diterpenoids, named cornutins C-L, have been isolated from the leaves of Cornutia grandifolia var. intermedia. Their structures have been elucidated by detailed spectroscopic analysis. In addition, the in vitro antiplasmodial activity of four isolated compounds (cornutin C-F) has been evaluated, revealing only a marginal activity.

Andirol A and B, Two Unique 6-Hydroxymethylpterocarpenes from Andira inermis§

From a methanolic extract of the leaves of Andira inermis (Fabaceae), andirol A and B, two compounds with a novel type of a rotenoid-related skeleton and andinermol, a new 2-aryl-3-hydroxymethyl-benzofuran could be isolated. Characterisation and structure elucidation of these compounds was achieved on the basis of their spectral data. In addition, the in vitro activities of the isolated compounds against both the chloroquine-sensitive strain PoW and the chloroquine-resistant clone Dd2 of Plasmodium falciparum have been evaluated.