Extraction of antibacterial peptides against Helicobacter pylori from bovine milk casein

Introduction: More than half of the world's population is infected with Helicobacter pylori, which may cause gastritis, peptic ulcer and even gastric cancer. The World Health Organization (WHO) has announced that H. pylori infection is a class I carcinogen and hence eradication of it is highly important. Bovine milk contains caseins, which can be digested by various enzymes in the human stomach to produce antibacterial peptides. Material and methods: This study used in vitro methods to extract anti-H. pylori peptides from caseins by the gastric protease pepsin under environments with similar pH values to those found in the human stomach. The molecular weights and sequences of the peptides were identified by MALDI-TOF mass spectrometry and MS/MS Ion Search, respectively. Antibacterial activity tests were performed to calculate the minimum inhibitory concentration (MIC90) of the extracts. Results: The findings of this study revealed that the major products of bovine milk casein digestion by pepsin are casecidin 17 and beta-casein 207-224. The extracts produced promising anti-H. pylori effects with the lowest MIC90 found at pH values of 1.5 and 2.0. Conclusions: This study identified the anti-H. pylori effects of casecidin 17 and beta-casein 207-224, which may help in developing therapeutic agents to modulate the effect of antibiotics on H. pylori infections.