A New Dimeric Dihydrochalcone and a New Prenylated Flavone from the Bud Covers of Artocarpus altilis: Potent Inhibitors of Cathepsin K

A MeOH/CH2Cl2 extract of the bud covers of Artocarpus altilis collected in Micronesia showed activity in a cathepsin K inhibition assay. In addition to the three known flavonoids isolated from the bud covers of this species, two new compounds have been identified whose structures were determined on the basis of spectral data. These compounds include a dimeric dihydrochalcone, cycloaltilisin 6 (2), and a new prenylated flavone, cycloaltilisin 7 (3). Novel compounds 2 and 3 have IC50 values of 98 and 840 nM, respectively, in cathepsin inhibition.