Q-VD-OPh (quinolyl-valyl-O-methylaspartyl-[-2,6-difluorophenoxy]-methyl ketone) is a broad-spectrum caspase inhibitor, provides a cost-effective, non-toxic, and highly specific means of apoptotic inhibition and provides new insight into the design of new

It is significantly more effective in preventing apoptosis than the widely used inhibitors, ZVAD-fmk and Boc-D-fmk. Q-VD-OPh is also equally effective in preventing apoptosis mediated by the three major apoptotic pathways, caspase 9/3, caspase 8/10, and caspase 12. In addition to the increased effectiveness, Q-VD-OPh was not toxic to cells, even at high concentrations. Q-VD-OPh is equally effective at inhibiting the three major apoptotic pathways, it can inhibit recombinant caspases 1, 3, 8, and 9 with IC50 values ranging from 25 to 400 nM2. The effectiveness of Q-VD-OPh as an apoptotic inhibitor is evidenced by the complete suppression of an apoptotic inducer capable of inducing substantial cell death in less than 4 hours. Q-VD-OPh protected against the substantial apoptosis induced by actinomycin D. In addition, Q-VD-OPh alone exhibited little or no toxicity, even at extremely high concentrations [2].