Where to find compounds IC50 on an enzyme?

Question

[db4]

I am looking for compounds IC50 values on a enzyme. I already searched through ChemBL, PubChem and BindingDB. The three seems to give consistent result. However looking in the literature, there more compounds which are not in these databases. These later may provide higher level of curation. I am still interested in the data available in literature. Any other available repository or text mining approach will be great.