In vitro cytotoxic, antileishmanial and antifungal activities of ethnopharmacologically selected Gabonese plants.

Seventy-seven crude extracts from leaves and stem barks of 15 Gabonese plants used in traditional medicine were evaluated for their cytotoxic, antileishmanial and antifungal activities. Most of the extracts exhibited cytotoxic activities toward human monocytes, and most particularly the hydromethanolic 50% (v/v) fraction of Ganophyllum giganteum leaves (IC(50)=1.3 microg/ml) as well as the methanolic extracts of Polyalthia suaveolens, Dioscorea preussii, Augouardia letestui leaves and Cola lizae stem barks (IC(50)<5 microg/ml). The methanolic extract of Polyalthia suaveolens displayed a strong antiproliferative activity against the promastigote form of Leishmania infantum parasites and presented a good antifungal activity on all the tested strains (IC(50)<1mg/ml). This extract was divided into six fractions: fraction F6 demonstrated a cytotoxic activity stronger than those of the crude extract (IC(50)=0.6 microg/ml), fractions F4 and F5 were devoid of cytotoxicity (IC(50)>100 microg/ml) and displayed interesting antileishmanial activity against the intracellular amastigote form of the parasite (IC(50)=5.6 and 12.4 microg/ml), respectively. However, the antifungal activity observed for the crude extract could not be recovered in the corresponding fractions.

Gluco-indole alkaloids from the bark of Nauclea diderrichii. 1H and 13C NMR assignments of 3alpha-5alpha-tetrahydrodeoxycordifoline lactam and cadambine acid.

Detailed (1)H and (13)C NMR assignments of 3alpha-5alpha-tetrahydrodeoxycordifoline lactam and cadambine acid, isolated from the bark of the Nauclea diderrichii (de Wild.) Merr. (Rubiaceae) were achieved by 1D and 2D techniques such as DEPT, HMBC, HMQC, COSY and NOESY.

Revised structures of four saponins from Nauclea diderrichii.

The interglycosidic linkages of four quinovic acid glycosides previously described from the bark of Nauclea diderrichii (de Wild) Merr. (Rubiaceae) are revised on the basis of 2D-NMR spectroscopic results. The structures were established as: quinovic acid 3-O-beta-glucopyranosyl(1-->4)-beta-fucopyranosyl-(28-->1)-beta -glucopyranosyl ester, quinovic acid 3-O-beta-glucopyranosyl-(1-->4)-alpha-rhamnopyranosyl-(28-->1)-beta-glucopyranosyl ester, quinovic acid 3-O-beta-glucopyrnaosyl-(1-->4)-beta-fucopyranoside, and quinovic acid 3-O-beta-glucopyranosyl-(1-->4)-alpha-rhamnopyranoside. The first three saponins are new compounds.

Quinovic acid glycosides from Nauclea diderrichii.

From the bark of Nauclea diderrichii (de Wild) Merr. seven saponins were isolated and characterized by 2D-NMR and FABMS. These compounds are quinovic acid glycosides previously reported for the Rubiaceae, six of them are described for the first time in this drug.

A new terpenoid glycoside from Nauclea diderrichii bark.

A new terpenoid glycoside, marounoside [1], was isolated from the bark of Nauclea diderrichii and characterized by 1D and 2D nmr spectroscopy. The aglycone, a terpene with an unusual carbon skeleton, is linked to glucose, which, in turn, is connected to an apiofuranose residue.