|Gonzalez de mejia, E|
Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/1/2004
Publication Date: 9/22/2004
Citation: Gonzalez De Mejia, E., Vasconez, M., De Lumen, Nelson, R.L. 2004. Lunasin content in different genotypes of soybean seeds and commercial products. Journal of Agriculture and Food Chemistry. 52(19):5882-5887. Interpretive Summary: Lunasin is a unique and novel cancer preventive peptide originally isolated from soybean seeds. We developed an analytical method for quantifying lunasin concentration in soybean seeds and extracted soy protein. Lunasin was found in all forms of processed soy protein analyzed. We evaluated commercial soybean varieties, ancestors of commercial soybean varieties and exotic soybean germplasm and found large differences among entries in all three categories. The range of lunasin was smallest in commercial varieties. These data indicate that it should be possible to develop soybean varieties with increased concentrations of lunasin. These results will be of interest to soybean breeders and geneticists as well as other scientists interested in bioactive compounds found in soybean seeds.
Technical Abstract: Lunasin is a unique and novel cancer preventive peptide originally isolated from soy. Information on lunasin concentration of soybean cultivars and commercial soy proteins would be useful in developing lunasin-enriched cultivars and soy products. We report the development of an ELISA method to identify lunasin and quantify the variations in concentration in 144 selected, diverse soybean accessions from the USDA Soybean Germplasm Collection and in several commercially available soy protein fractions. With synthetic lunasin and monoclonal antibody, ELISA shows a linear concentration range of 24-72 ng/ml, good reproducibility, a detection limit of 8 ng/ml and a recovery of 90% in spiked soy samples. Lunasin concentrations in the tested materials range from 0.10 to 1.33 g/100g flour. Differences that exceeded 100% are observed among accessions of similar maturity that were grown in the same environment, indicating genetic differences in soybeans exist for lunasin. The mean of 23 major ancestral lines of U.S. cultivars is similar to the mean of 16 modern cultivars selected to represent the current diversity of the crop, but the highest values where found within the ancestral and exotic accessions. Soy protein concentrate, isolate and hydrolyzate contain 2.81 +/- 0.30, 3.75 +/- 0.43 and 4.43 +/- 0.59 g lunasin/100g flour, respectively while soy flour and soy flakes contain 1.24 +/- 0.22 g lunasin/100g flour. The average molecular weight of lunasin in the samples is 5.45 +/- 0.25 kDa. The wide range of lunasin concentrations within the Glycine max species indicates that the levels of this important bioactive peptide can be genetically manipulated. Furthermore, soy isolates and hydrolyzed soy proteins contain the highest concentrations of lunasin.