The present invention relates to a composition containing extracts of Encelia canescens Lam and to aqueous or ethanolic extracts obtained therefrom, the procedure for the obtainment and crystallization thereof, and the uses thereof for the prevention and treatment of cancer, for example cancer of the pancreas, gastric tract, prostate, breast, kidney, colon, lung, vesicle, uterus, oral cavity, colorectal region, bladder, liver, brain tumors, and chronic and acute leukemia, in addition to metabolic diseases such as diabetes mellitus types I and II, viral and bacterial diseases, in particular related to E. coli, Kiebsiella, M. flavus, S. aureus and B. subtilis. Furthermore the use thereof is claimed in diseases related to oxidative stress and as a useful agent in the preparation of analgesics.