Kinase experiment:

Inhibitor (including Dimethylfraxetin) and enzyme solutions are preincubated together for 6 h at room temperature prior to assay, in order to allow for the formation of the enzyme-inhibitor complex[1].

Dimethylfraxetin is a Carbonic anhydrase inhibitor, with a Ki value of 0.0097 μM.

At CA I there is one stand out compound being Dimethylfraxetin (compound 17), a nanomolar CA I inhibitor. This trimethoxy coumarin is the most potent of any of the NP coumarins across the six CA isozymes of the present study[1].

References:
[1]. Davis RA, et al. Natural product coumarins that inhibit human carbonic anhydrases. Bioorg Med Chem. 2013 Mar 15;21(6):1539-43.