J Ethnopharmacol. 1985 May; 13(2): 201-8.

A drug used in traditional medicine: Harpagophytum procumbens DC. IV. Effects on some isolated muscle preparations.

Occhiuto F, Circosta C, Ragusa S, Ficarra P, Costa De Pasquale R.

Effects of the crude methanolic extract of Harpagophytum procumbens secondary roots and two of its active principles, harpagoside and harpagide, on some smooth muscle in vitro have been studied. The results obtained show how the action of H. procumbens is due to a complex interaction between the various active principles contained in the drug and suggest that they, especially harpagoside, interfere with the mechanisms that regulate the influx of calcium in the cells.