Pepsin-catalyzed plastein reaction with tryptophan increases the in vitro activity of lactoferrin hydrolysates with BGC-823 cells

Lactoferrin hydrolysates (LF-H) were digested using pepsin and modified using a pepsin-catalyzed plastein reaction with tryptophan (Trp) to obtain a target product. LF-H, the target product, plastein reaction-modified LF-H alone, and a mixture of LF-H and Trp were evaluated for their activities with human gastric cancer BGC-823 cells at 24 and 48 h. Assay results indicated that the target product had decreased free amino groups and had incorporated Trp. LF-H and the plastein reaction-modified LF-H alone did not show detectable growth inhibition on BGC-823 cells at 1–3 mg/mL; however, the target product at the same dose levels inhibited cell growth, and showed higher activity than the mixture (P