G 1728 (OTTO) 4-Guanidinobenzoic acid hydrochloride, 99% Cas 42823-46-1 - used in ELISA inhibition assay of mouse antiserum. G 1728 (OTTO) 4-Guanidinobenzoic acid hydrochloride, 99% Cas 42823-46-1 - used in the synthesis of human acrosin inhibitor 4′-acetaminophenyl 4-guanidinobenzoate hydrochloride.