Nematicidal compound from the seeds of Balanites aegyptiaca. Isolation and structure elucidation

Testing for anthelmintic activity using the target species in its normal host requires relatively large quantities of chemicals and animals breeding facilities, which can be quite expensive. To circumvent this problem, Caenorhabditis elegans, a free-living soil nematode, susceptible to all commercially available anthelmintics, has been proposed for the development of in vitro drug screening assays [1], a fluorescence-based microscopy method has been recently developed and fully validated from the biological and analytical points of view [2].

Balanites aegyptiaca (L.) Delile (Zygophyllaceae) is a tropical plant largely used in Africa; every parts of the plant are medicinal and compose a number of remedies to treat various ailments. The seeds are notably used as anthelmintic against different nematode and cestode species. The crude aqueous extract of Balanites aegyptiaca seeds showed in vitro anthelmintic activity against Caenorhabditis elegans. Bioassay-directed fractionation based on this model led to the isolation of a known cytostatic steroidal saponin, balanitin 7 [3.] as the principal nematicidal agent. The structure elucidation was based on NMR spectroscopic analysis and chemical methods.

Preliminary testing for the mechanism of action of balanitin 7 shows that this “new“ anthelmintic agent does not inhibit acetyl cholinesterase and so differs from the well-known drugs pyrantel and piperazine.

Acknowledgement: C. Gnoula is a PhD scholarship recipient from the Université Libre de Bruxelles (ULB).

References: 1. O'Grady, J. et al. (2004), Exp. Parasitol.106: 164–72. 2. Gnoula, C. et al. (2006), Talanta (submitted). 3. Pettit, G.R. et al. (1991), J. Nat. Prod. 54: 1491–1502.