Planta Med 2006; 72 - P_030
DOI: 10.1055/s-2006-949830

Hyraceum, the fossilised metabolic products of rock hyraces, shows affinity to the GABA-benzodiazepine receptor

AK Jäger 1, A Olsen 1, LC Prinsloo 2, L Scott 3
  • 1Department of Medicinal Chemistry, The Danish University of Pharmaceutical Sciences, Universitetsparken 2, DK-2100 Copenhagen O, Denmark
  • 2Department of Physics, University of Pretoria 0002, South Africa
  • 3Department of Plant Sciences, University of the Free State, Nelson Mandela Avenue, PO Box 339; Bloemfontein 9300, South Africa

Hyraceum, the fossilised urine and dung of rock hyraces (Procavia capensis), was traditionally used in South Africa by Hottentots and Afrikaner settlers for the treatment of epilepsy. 14 hyraceum samples were collected at different geographical locations in South Africa and tested for affinity to the GABA-benzodiazepine receptor using flumazenil Ro-15 1788 as ligand [1]. The clinically used benzodiazepines bind to the GABA-benzodiazepine site and exert their anti-epileptic effect via the GABAergic system. Ethanolic extracts of 4 of the hyraceum samples showed affinity to the GABA-benzodiazepine site, displacing over 50% of the flumazenil at 0.45mg/mL extract (in total assay volume); whilst aqueous extracts were inactive. One of the active samples was carbon-dated to be about 10.000 year old. A TLC analysis of the ethanolic extracts showed a complex pattern of compounds with no constituents present in all the 4 active samples, but absent in the inactive samples. Infrared spectra did not indicate similarity between the 4 active samples, and also showed that the heterogeneity of the samples can influence the concentration of the active ingredient.

Reference: 1. Risa, J. et al. (2004), J. Ethnopharmacol. 93: 177–182.