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Title: Kunitz trypsin inhibitor in addition to Bowman-Birk inhibitor influence stability of lunasin against pepsin-pancreatin hydrolysis

Author
item PRICE, SAMUEL - University Of Tennessee
item PANGLOLI, PHILIPUS - University Of Tennessee
item Krishnan, Hari
item DIA, VERMONT - University Of Tennessee

Submitted to: Food Research International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2016
Publication Date: 11/4/2016
Publication URL: https://handle.nal.usda.gov/10113/5598792
Citation: Price, S.J., Pangloli, P., Krishnan, H.B., Dia, V.P. 2016. Kunitz trypsin inhibitor in addition to Bowman-Birk inhibitor influence stability of lunasin against pepsin-pancreatin hydrolysis. Food Research International. 90:205-215. Available: http://dx.doi.org/10.1016/j.foodres.2016.10.051.

Interpretive Summary: Soybean is the most widely used legume throughout the world producing more biologically available protein compared to other crops. It contains biologically active components with reported health benefits including many biologically active peptides such as the protease inhbitors Bowman-Birk inhibitor (BBI), Kunitz trypsin inhibitor (KTI) and a small peptide called lunasin. Lunasin has been reported to possess therapeutic propertis, including anti-cancer properties, anti-inflammatory activities and immunomodulating properties. One potential issue for the use of lunasin as a therapeutic agent is its susceptibility to protease digestion (breakdown in the gut). In this study we have examined the effect of adding the protease inhibitors, BBI and KTI to the stability of lunasin against protease digestion. Our results showed that both KTI and BBI improved the stability of lunasin against proteases. Our finding demonstrates that the effectiveness of lunasin as a cancer therapeutic agent can be improved by the inclusion of Bowman-Birk inhibitor and Kunitz trypsin inhibitors. Information obtained from this study will aid scientists to increase the effectiveness of lunasin as a therapeutic agent.

Technical Abstract: Soybean contains several biologically active components and one of this belongs to the bioactive peptide group. The objectives of this study were to produce different lunasin-enriched preparations (LEP) and determine the effect of Bowman-Birk inhibitor and Kunitz trypsin concentrations on the stability of lunasin against pepsin-pancreatin hydrolysis (PPH). In addition, the effect of KTI mutation on lunasin stability against PPH was determined. LEP were produced by calcium and pH precipitation methods of 30% aqueous ethanol extract from defatted soybean flour. LEP, lunasin-enriched commercially available products and KTI control and mutant flours underwent PPH and samples were taken after pepsin and pepsin-pancreatin hydrolysis. The concentrations of BBI, KTI, and lunasin all decreased after hydrolysis, but they had varying results. BBI concentration ranged from 167.5 to 655.8 µg/g pre-hydrolysis and 171.5 to 250.1 µg/g after hydrolysis. KTI concentrations ranged from 0.3 to 122.3 µg/g pre-hydrolysis and 9.0 to 18.7 µg/g after hydrolysis. Lunasin concentrations ranged from 8.5 to 71.0 µg/g pre-hydrolysis and 4.0 to 13.2 µg/g after hydrolysis. In all products tested, lunasin concentration after PPH significantly correlated with BBI and KTI concentrations. Mutation in two KTI isoforms led to a lower concentration of lunasin after PPH. This is the first report on the potential role of KTI in lunasin stability against PPH and must be considered in designing lunasin-enriched products that could potentially survive digestion after oral ingestion.