A method of isolating biologically-active compounds which exhibit a coronary dilating effect from the venous blood of the pancreas comprising dialyzing the serum of the venous blood of the pancreas against a 2N solution of acetic acid at a temperature of 3-10.degree.C for from 24 to 28 hours, lyophilizing the dialyzate, gel filtering the lyophilizate on a column with packing having a pore size of 200-400 .mu., and separating said compounds from each other by down-flow paper chromatography using said butyl alcohol-acetic acid-water solvent system in a ration of 4:1:5 followed by high voltage paper electrophoresis in an electrophoretic field of 1,500 volts in a citrate buffer, at an ionic strength of 0.1 and a current density of 1.2 mA/cm.