Isolated from the Chinese drug Ch'an Su which is prepd from Chinese toads (Bufo asiaticus = bufo gargarizans Cantor). Isoln: Kotake, Kuwada, C.A. 31, 70652 (1937); Ruckstubl, Meyer, Helv. Chim. Acta 40, 1270 (1957). Structure: Bernoulli et al., ibid. 45, 240 (1962).