The Biochemical and Functional Food Properties of the Bowman-Birk Inhibitor

Abstract

The Bowman-Birk inhibitor (BBI) is a small water-soluble protein present in soybean and almost all monocotyledonous and dicotyledonous seeds. The molecular size of BBI ranges from 1,513 Da to about 20,000 Da. BBI is to seeds what α ₁ -antitrypsin is to humans. Soy-based food products rich in BBI include soybean grits, soymilk, oilcake, soybean isolate, and soybean protein concentrate. BBI is stable within the pH range encountered in most foods, can withstand boiling water temperature for 10 min, resistant to the pH range and proteolytic enzymes of the gastrointestinal tract, bioavailable, and not allergenic. BBI reduces the proteolytic activities of trypsin, chymotrypsin, elastase, cathepsin G, and chymase, serine protease-dependent matrix metalloproteinases, urokinase protein activator, mitogen activated protein kinase, and PI3 kinase, and upregulates connexin 43 (Cx43) expression. Several studies have demonstrated the efficacy of BBI against tumor cells in vitro, animal models, and human phase IIa clinical trials. FDA considers BBI as a drug. FDA also approves labels claiming that consumption of at least 3 to 4 oz of tofu or 8 oz of soymilk or soy protein may reduce the risk of coronary heart disease and breast cancer. This review highlights the biochemical and functional food properties of the Bowman-Birk inhibitor.

Keywords:

• Bowman-Birk inhibitor
• soybean (Glycine max)
• functional foods
• cancer
• angiogenesis
• tryptase and/or chymase inhibitor

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Erratum

ACKNOWLEDGEMENTS

The technical assistance of Drs. Mendel Friedman (USDA-WRRC, Albany, CA), Shuryo Nakai (The University of British Columbia, Vancouver, Canada), Natalia I. Larionova (University of Moscow), Grover Waldrop and J. Sam Godber (Louisiana State University, Baton Rouge, LA), Masahiro Ogawa (Kagawa University, Japan) and David Sessa (USDA-NRRC, Peoria, IL) is greatly appreciated.