XDH and prostate carcinoma: Of these, three compounds inhibited the XO activity in a concentration-dependent manner with IC50 values of 90.2, 116.1, and 181.8 μM. The compound with the highest XO inhibition (3α-acetoxy-22-oxo-5α-lanosta-8,24-dien-21-oic acid) (Figure 23) is a mixed inhibitor with Ki of 0.6 μM. However, this compound also presented the most interesting result in human prostatic cancer cells, also enhancing the cytotoxicity induced by cisplatin [93].