XDH and prostate cancer: The compound with the best activity (3-oxo-5α-lanosta-8-en-21-oic acid) (Figure 23), prepared by semisynthesis, was as a mixed inhibitor of XO, with a Ki value of 3.2 μM. The authors also reported the cytotoxicity of this compound against prostatic cancer cells, with an IC50 value of 23.9 μM being determined [92].