Domínguez X. A., Barragán V. A., León J. O., Krause L., Bravo G. A., Morales J., The constituents of Thelocactus bicolor. Part I. The isolation of itesmol, a new steroid and eisacol a new pentacyclic triterpenoid, Planta Medica, 1968, 16(4):458-461, doi: 10.1055/s-0028-1099935
Isolation of itesmol and eisacol from the unsaponifiable fraction of an extract of whole Thelocactus bicolor plants. Spectroscopic analyses and reactions of derivatives were used to characterise a steroid and a pentacyclic triterpenoid.