Formosanin C (Polyphyllin B) is a compound isolated from Rhizoma Paridis, showed pro-apoptosis and immunoregulation with antitumor activity in cultured cells and animal systems.

Attenuation of formosanin C-induced change of Deltapsi(m) by caspase-2 inhibitor (Z-VDVAC) implies that caspase-2 acts upstream of the mitochondria. Blockage of formosanin C-induced apoptotic process by using either permeability transition pore inhibitor (cyclosporine A) or caspase-9 inhibitor (Z-LEHD) demonstrates the necessity of mitochondria and caspase-9 in formosanin C-induced apoptosis of HT-29 cells.

The enzyme activity and kinetics of the purified ROCK1(3-543) are determined using scintillation proximity assay. In this assay, purified ROCK1 is incubated with peptide substrate (Biotin-Ahx-AKRRLSSLRA-CONH2), and 33ATP and the subsequent incorporation of 33P into the peptide is quantified by streptavidin bead capture. For IC50 determination, test compounds are dissolved at 10 mM in 100% DMSO, with subsequent serial dilution in 100% DMSO. Compounds are typically assayed over an 11-point dilution range with a concentration in the assay of 10 μM to 0.2 nM in 3-fold dilutions. For dose-response curves, data are normalized and expressed as percentage inhibition using the formula 100×[(U-C1)/(C2-C1)], where U is the unknown value, C1 is the average of the high signal (0%) control wells, and C2 is the average of the low signal (100%) control wells. Curve fitting is performed The results for each compound are recorded as pIC50 values[1].