Expression of Bioactive Lunasin Peptide in Transgenic Rice Grains for the Application in Functional Food

Abstract

Lunasin, a bioactive peptide initially isolated from soybean, has anticancer, anti-inflammatory, and antioxidant activity. Due its great application value, lunasin seems to be a candidate gene in improving the nutritional value of crops. In this study, lunasin was inserted into the rice genome to evaluate whether it was feasible to express lunasin using the rice expression system and improve the bioactivity of protein in rice for our needs. We generatedlunasin-overexpressing rice lines, and chose three independent transgenic rice lines for further study. The lunasin content in trans-lunasin rice detected by UPLC-MS/MS was 1.01 × 10−3 g·kg−1 dry rice flour with grease removal in the lunasin extracts. The antioxidant efficacy of LET (lunasin-enriched fraction from trans-lunasin rice) and PEW (peptide-enriched fraction from wild type rice) was compared. Due to the presence of lunasin, LET showed higher (p < 0.05) antioxidant activity than PEW. LET exhibited high DPPH radical scavenging activity (IC50 value, 8 g·L−1), strong ABTS+ radical scavenging activity (IC50 value, 1.18 g·L−1), and great oxygen radical scavenging activity (170 μmol·L−1 Trolox equivalents when the concentration reached 4 g·L−1). Moreover, LET presented significantly higher (p < 0.05) anti-inflammatory activity on macrophage cells, and the NO production and the release of pro-inflammatory cytokines (IL-6, MCP1, and TNF-α) were significantly inhibited by LET. However, because of the low purity, LET showed weaker antioxidant and anti-inflammatory activity when compared to the Lunasin standard. These results suggested that it is feasible to use the rice expression system to express the exogenous lunasin in rice, and lunasin-overexpressing rice seems to be a candidate resource for application in functional food. Rice rich in lunasin is beneficial for human health, and could be used as a functional food in the diets of cancer and obese patients in the future.

Effects of Salt Stimulation on Lunasin Accumulation and Activity during Soybean Germination

“…The mass spectrum acquired from the peak at 3.66 min. generated [ Figure 2B), which was consistent with a previous report [22].…”

Optimization and Identification of Antioxidant Peptide from Underutilized Dunaliella salina Protein: Extraction, In Vitro Gastrointestinal Digestion, and Fractionation

“…According to Olagunju et al [25] and Ren et al [26], enrichment of bioactive peptide from protein hydrolysates could be carried out using ultrafiltration method, which was employed and modified as ultrafiltration-centrifugation technique in present study. The digested peptide was fractionated into three groups according to molecular weight, i.e., 100-500, 500-1000, and 1000-3000 Da.…”

“…Recently, centrifugal ultrafiltration, combined with dialysis, has been regarded as an efficient approach to purify and fractionate the bioactive proteins or peptide in very small volume, which will be verified in this work [24–26]. Ultrasound assisted extraction has been considered as an efficient and green/ecofriendly technology to disrupt the matrices and subsequently release the target component by bubble cavitation at mild condition in short time [27, 28].…”

Overexpression of Soybean-Derived Lunasin in Wheat and Assessment of Its Anti-Proliferative Activity in Colorectal Cancer HT-29 Cells

“…Moreover, the lunasin extracted from transgenic soybean possessed anti-proliferative activity in MDA-MB-231 human breast cancer cells [ 25 ]. Liu et al and Zhu et al efficiently overexpressed lunasin in Escherichia coli and Pichia pastoris , respectively [ 21 , 23 ]. Therefore, we proposed a new strategy to produce lunasin in wheat, and the soybean-derived lunasin overexpressed in wheat was able to exert anti-colon cancer activity.…”

“…Due to the low expression or absence of lunasin in different cereals, soybean-derived lunasin has been introduced into Escherichia coli , Pichia pastoris , rice, and soybean [ 20 , 21 , 22 , 23 , 24 ]. However, lunasin has not been transferred into wheat yet, partially because of its much lower transformation efficiency [ 25 ].…”