Abstract: The present invention relates to a process for obtaining Physalis angulata extracts, particularly to isolate ergostane-type steroidal derivatives, such as physalins, which are useful in the treatment of infections caused by protozoans. The physalins of the invention have also prophylactic and therapeutic properties for treating auto-immune diseases in mammals. The isolation process to obtain physalins comprises the steps of: (a) grinding roots, leaves or stem-bark of Physalis ssp; (b) extracting the material obtained in step (a) with solvents selected from the group consisting of water and alcohols, such as methanol, ethanol, 1-propanol, 2-propanol, isobutanol; (c) evaporating the extract obtained in step (b) and washing the syrup material with a suitable solvent; (d) rapid filtering of the extract of step (c) and fractionating the components of the extract according to a polarity gradient of organic solvents; and (e) separating the steroidal components contained in the fractions by chromatography.