The effects of peptide-precipitating lignosulphonic acids on the proteolytic activity of pepsin in vitro and on the response of pigs to an ulcer inducing diet.

The inhibitory effect of peptide-precipitating lignosulphonic acids on the proteolytic activity of pepsin in vitro has been studied. When an unfractionated lignosulphonic acid preparation was used, total inhibition of the activity of 5 µ crystalline pepsin was obtained by addition of about 15 mg of lignosulphonic acids. The greatest inhibitory effect was seen with the high-molecular weight lignosulphonic acids, but an effect was also seen with middle-and low-molecular weight lignosulphonic acids. A reduction in the inhibitory effect was seen when the experiments were performed in the presence of arginine. The inhibition mechanism is discussed in relation to the peptide-precipitating ability of the lignosulphonic acids. No obvious protection against the appearance of stomach ulcers in four pigs receiving an ulcerogenic diet was seen.