Table 1. Identification of pH-Selective Marine Natural Product Modulators of Cathepsin B^a.

^aA collection of pure marine natural products (purified) were assessed for the modulation of human cathepsin B activity (with preincubation) by screening them at pH 4.6 and pH 7.2 using pH-selective substrates of Z-E-K-AMC and Z-R-K-AMC, respectively. the asterisk indicates compounds that resulted in a significant inhibition of <50% (blue) or activation of >200% (green) with *p < 0.05.