The protective role of the Bowman-Birk protease inhibitor in soybean lunasin digestion: the effect of released peptides on colon cancer growth

Food Funct. 2015 Aug;6(8):2626-35. doi: 10.1039/c5fo00454c. Epub 2015 Jul 1.


Lunasin is a naturally-occurring peptide demonstrating chemopreventive, antioxidant and anti-inflammatory properties. To exhibit these activities, orally ingested lunasin needs to survive proteolytic attack of digestive enzymes to reach target tissues in active form/s. Preliminary studies suggested the protective role of protease inhibitors, such as the Bowman-Birk inhibitor and Kunitz-trypsin inhibitor, against lunasin's digestion by both pepsin and pancreatin. This work describes in depth the behaviour of lunasin under conditions simulating the transit through the gastrointestinal tract in the absence or presence of soybean Bowman-Birk isoinhibitor 1 (IBB1) in both active and inactive states. By liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS), the remaining lunasin at the end of gastric and gastro-duodenal phases was quantified. Protection against the action of pepsin was independent of the amount of IBB1 present in the analyzed samples, whereas an IBB1 dose-dependent protective effect against trypsin and chymotrypsin was observed. Peptides released from lunasin and inactive IBB1 were identified by MS/MS. The remaining lunasin and IBB1 as well as their derived peptides could be responsible for the anti-proliferative activity against colon cancer cells observed for the digests obtained at the end of simulated gastrointestinal digestion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cell Line
  • Cell Proliferation*
  • Colonic Neoplasms / diet therapy
  • Colonic Neoplasms / metabolism
  • Colonic Neoplasms / physiopathology*
  • Digestion
  • Gastrointestinal Tract / chemistry
  • Gastrointestinal Tract / metabolism*
  • Glycine max / chemistry
  • Glycine max / metabolism*
  • Humans
  • Models, Biological
  • Molecular Sequence Data
  • Peptides / chemistry*
  • Peptides / metabolism
  • Seeds / chemistry
  • Seeds / metabolism
  • Sequence Alignment
  • Soybean Proteins / chemistry
  • Soybean Proteins / metabolism*
  • Trypsin Inhibitor, Bowman-Birk Soybean / chemistry
  • Trypsin Inhibitor, Bowman-Birk Soybean / metabolism*


  • GM2S-1 protein, soybean
  • Peptides
  • Soybean Proteins
  • Trypsin Inhibitor, Bowman-Birk Soybean