Tokaramide A (1) was isolated by Fusetani et al. from the marine sponge Theonella aff. mirabilis and was shown to highly inhibit cathepsin B with an IC 50 value of 29 ng/mL. 1 Cathepsin B, the most extensively studied enzyme of the group, is not only a lysosomal cysteine protease that plays a role in a large number of physiological processes, but is also known to be involved in various disease stages, such as inflammation, trauma, muscular dystrophy, and tumors. ...