Immunological investigation for the presence of lunasin, a chemopreventive soybean peptide, in the seeds of diverse plants

Authors: ALASWAD, ALAA - University Of Missouri; Krishnan, Hari

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2016
Publication Date: 3/25/2016
Publication URL: https://handle.nal.usda.gov/10113/5224318
Citation: Alaswad, A.A., Krishnan, H.B. 2016. Immunological investigation for the presence of lunasin, a chemopreventive soybean peptide, in the seeds of diverse plants. Journal of Agricultural and Food Chemistry. 64:2901-2909. doi: 10.1021/acs.jafc.6b00445.

Interpretive Summary: Soybean is a widely available, cost-effective source of quality protein. Soybean proteins provide adequate amounts of all essential amino acids with the exception of methionine. Research conducted during the last few decades has established that certain compounds in soybean seeds can positively influence human health. Among soybean seed proteins, lunasin has received particular attention because it has been demonstrated under experimental conditions to have anti-cancer and anti-inflammatory properties. In the last few years lunasin has been reported to be found in barley, wheat, rye, oat and triticale. However, recent studies have failed to detect lunasin-encoding genes in cereals. Thus, the reported occurrence of lunasin in cereals and other plant species remain inconclusive. To clarify this issue we have carried out an in-depth investigation to confirm the presence or absence of lunasin in cereals and other plant species. The results of our study demonstrate that lunasin is not present in cereals and seeds of several other plant seeds. Our finding demonstrates that soy is a rich source of lunasin and soy consumption may have human health benefits.

Technical Abstract: Lunasin, a 43-amino acid soybean bioactive peptide, exhibits anti-cancer and anti-inflammatory properties. All soybean varieties that have been examined contain lunasin. It has also been reported in a few other plant species including Amaranth, black nightshade, wheat, barley, rye and triticale. Interestingly, detailed searches of transcriptome and DNA sequence databases of cereals failed to identify lunasin-coding sequences raising questions about the authenticity of lunasin in cereals. In order to clarify the presence or absence of lunasin in cereals and other plant species, an immunological investigation was conducted utilizing polyclonal antibodies raised against the first 20 amino acid N-terminal peptide (SKWQHQQDSCRKQLQGVNLT) and a 15 amino acid C-terminal peptide (CEKHIMEKIQGRGDD) of lunasin. Protein blot analyses revealed the presence of proteins from several plants that reacted against the lunasin N-terminal peptide antibodies. However, the same proteins failed to react against the lunasin C-terminal peptide antibodies. Our results demonstrate that peptides identical to soybean lunasin are absent in seeds of diverse plants examined in our study.