Specific inhibitor of V-type (vacuolar) H+-ATPase that displays > 2000-fold selectivity over other H+-ATPases (IC50 values are 9.2, > 20000, > 20000 and > 20000 nM for yeast V-type, F-type, P-type H+-ATPases and porcine P-type Na+,K+-ATPase respectively). Blocks cell surface expression of virus envelope glycoproteins without affecting synthesis and exhibits cytotoxicity in several cell lines.