4-Nitrophenyl 4-guanidinobenzoate (NPGB) hydrochloride is a potent sperm acrosin inhibitor, and also a trypsin substrate.
References:
[1]. J M Kaminski, et al. Synthesis and inhibition of human acrosin and trypsin and acute toxicity of aryl 4-guanidinobenzoates. J Med Chem. 1986 Apr;29(4):514-9.
















