Antitrypanosomial Activity of Some Saponins from Calendula arvensis, Hedera helix, and Sapindus mukurossi - Tedlaouti, F; Gasquet, M; Delmas, F; Timon-David, P; Elias, R; Vidal-Ollivier, E; Crespin, F; Balansard, G (Planta Medica, 1991)