Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 17, 2012
Publication Date: July 1, 2012
Repository URL: http://handle.nal.usda.gov/10113/54251
Citation: Krishnan, H.B., Jang, S., Baxter, I.R., Wiebold, W.J. 2012. Growing location has a pronounced effect on the accumulation of cancer chemopreventive agent Bowman-Birk inhibitor in soybean seeds. Crop Science. 52:1786-1794. Interpretive Summary: Soybeans contain several health promoting compounds including phytosterols, isoflavones, phytic acid, and protease inhibitors. Soybean contains two types of protease inhibitors; the Kunitz trypsin inhibitor and the Bowman-Birk protease inhibitor. These protease inhibitors have been traditionally treated as anti-nutritional components since they interfere with the efficient feed utilization. Recently, Bowman-Birk protease inhibitors have received greater attention since it has been demonstrated that this bioactive peptide possesses chemopreventive activity against different types of cancer. In spite of the important role of BBI in cancer prevention, very little is known on the effect of the environment on the accumulation of this bioactive peptide. In this study we report that growing location/environment has profound effect on the accumulation of BBI. Further, we demonstrate that geographical location also can significantly affect the nutritive quality of soybean seed. The information obtained from our study will be valuable for farmers to grow soybeans with enhanced amounts of this cancer chemopreventive agent.
Technical Abstract: Soybeans contain several health promoting compounds including phytosterols, isoflavones, phytic acid, and protease inhibitors. The two abundant protease inhibitors of soybean seeds are the Kunitz trypsin inhibitor and the Bowman-Birk inhibitor (BBI). BBI is a serine protease inhibitor that can inhibit both trypsin and chymotrypsin activities. This serine protease inhibitor has been touted as a potential cancer chemopreventive agent for humans. Little information is available on the effect of growing environment/location on the accumulation of this cancer chemopreventive agent. In this study we have examined the protein profile of eight soybean varieties that were grown in three Missouri locations in 2009 and 2010. SDS-polyacrylamide gel electrophoresis analysis demonstrated that soybean varieties that were grown in Grand Pass contained elevated levels of the ß-subunit of ß-conglycinin and reduced amounts of BBI in their seeds. This observation was confirmed by western blot analysis using BBI peptide antibodies and antibodies raised against purified the ß-subunit of ß-conglycinin. This difference in the levels of BBI was also reflected in the chymotrypsin inhibitor activity. Growing location also influenced the overall sulfur content of soybean seeds as evidenced by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis. Seeds grown in Grand Pass had lower amounts of total sulfur content than those that were grown in Annada and Columbia in both 2009 and 2010. Our results demonstrate that growing location has a profound effect on the accumulation of BBI and it is possible to modulate the concentration of this cancer chemopreventive agent by simple changes in agronomic practices.