Active soybean lectin in foods: quantitative determination by ELISA using immobilised asialofetuin

Development of a Phage-Displayed Nanobody-Based Competitive Immunoassay for the Sensitive Detection of Soybean Agglutinin

Soybean agglutinin (SBA) is a primary antinutritional factor in soybeans that can inhibit the growth of humans and mammals, disrupt the intestinal environment, and cause pathological changes. Therefore, detecting and monitoring SBA in foods is essential for safeguarding human health. In this paper, M13 phage-displayed nanobodies against SBA were isolated from a naive nanobody library. An M13 phage-displayed nanobody-based competitive enzyme-linked immunosorbent assay (P-cELISA) was then established for SBA analysis using biotinylated anti-M13 phage antibody (biotin-anti-M13) and streptavidin poly-HRP conjugate (SA-poly-HRP). The biotin-anti-M13@SA-poly-HRP probe can easily amplify the detection signal without the chemical modifications of phage-displayed nanobodies. The established P-cELISA presented a linear detection range of 0.56-250.23 ng/mL and a limit of detection (LOD) of 0.20 ng/mL, which was 12.6-fold more sensitive than the traditional phage-ELISA. Moreover, the developed method showed good specificity for SBA and acceptable recoveries (78.21-121.11%) in spiked wheat flour, albumen powder, and whole milk powder. This study proposes that P-cELISA based on biotin-anti-M13@SA-poly-HRP may provide a convenient and effective strategy for the sensitive detection of SBA.

Application of the Bromocresol Purple Index (BCPI) to Evaluate the Effectiveness of Heating Soybeans and Their Products

In this study, a number of the most common methods used in assessing the efficiency of soybean heat treatment were compared. All the methods proved to be useful in assessing the efficiency of heating soybean seeds and soybean products. However, considering the sensitivity, precision, time consumed, and the effectiveness of determination of the characteristics of the samples, the use of the bromocresol purple index (BCPI) appears to be justified. The BCPI method turned out to be universal, allowing distinguishing unheated (BCPIBSM < 70 mg·g−1), under-heated (70 mg·g−1 < BCPI BSM < 130 mg·g−1), properly heated (BCPI BSM = 130–140 mg·g−1), and over-heated samples (BCPI BSM > 140 mg·g−1).

Lectin Activity in Commonly Consumed Plant-Based Foods: Calling for Method Harmonization and Risk Assessment

Lectins are ubiquitous proteins characterized through their ability to bind different types of carbohydrates. It is well known that active lectins from insufficiently prepared legumes can cause adverse human health effects. The objective of this study was to determine the activity of lectins in samples across plant families representing commercially available edible plants, and the feasibility of inactivating lectins through soaking and boiling. Lectins were extracted from the plant families Adoxaceae, Amaranthaceae, Cannabaceae, Fabaceae, Gramineae, Lamiaceae, Linaceae, Pedaliaceae, and Solanaceae. A hemagglutination assay based on non-treated or trypsin treated rabbit erythrocytes was used to measure the lectin activity. The results showed the highest lectin activity in species from the Fabaceae family and demonstrated that soaking and boiling have an effect on the levels of active lectins. This is the first large study that combines lectin activity obtained from two different assays with raw and processed edible plants. In addition, we examined the current risk assessment, and regulations necessary for an adequate official reporting of results. We encourage the scientific community to further explore this field and agree on harmonized methods for analysis and interpretation, and hope that our methodology can initiate this development.

Selection, Identification, and Application of Aptamers against Agaricus bisporus Lectin to Establish an Aptamer-AuNPs Colorimetric Method for Detection of ABL

Agaricus bisporus lectin (ABL), which is one of the antinutritional factors in A. bisporus, is an important allergen and harmful to human health. Due to the shortcomings of the current detection methods, it is extremely urgent to establish a rapid and sensitive detection method for ABL in foods. To isolate the ssDNA aptamer of ABL, 13 rounds of subtractive systematic evolution of ligands by exponential enrichment (SELEX) selection were carried out. As a result, six candidate aptamers were selected and further examined for their binding affinity and specificity by enzyme-linked aptamer method. One aptamer (seq-41) against ABL with a high affinity and specificity was isolated and demonstrated to be the optimal aptamer whose dissociation constant reaches the nanomolar level, Kd = 31.17 ± 0.1070 nM. Based on seq-41, an aptamer-AuNPs colorimetric method was established to detect ABL with a linear range of 0.08∼1.70 μg/mL and the detection limit is 0.062 μg/mL. This study provides a novel aptamer-AuNPs colorimetric method with high sensitivity and specificity for detection of ABL and a novel strategy for development of detection method of fungal or plant allergens.

Label-free cytosensing of cancer cells based on the interaction between protein and an electron-transfer carbohydrate-mimetic peptide

We used an electron-transfer carbohydrate-mimetic peptide (YYYYC) to construct an electrochemical cytosensing system. Magnetic beads were modified with either asialofetuin (ASF) or soybean agglutinin (SBA) to evaluate the effect on cell sensing. Because SBA binds to the galactose residue that exists at the terminals of the carbohydrate chains in ASF, the target protein was accumulated on the protein magnetic beads. SBA is an example of N-acetylgalactosamine- and galactose-binding proteins that readily combine with YYYYC. When the peptides and protein-immobilized beads competed for a target protein, the peak current of the peptides changed according to the concentration of the protein at the 10^-12 M level. Next, human myeloid leukemia cells (K562 cell) were measured using the peptide and the carbohydrate chains on the cell surface that recognize SBA. The electrode response was linear to the number of K562 cells and ranged from 1.0 × 10² to 5.0 × 10³ cells mL^-1. In addition, detection of a human liver cancer cell (HepG2 cell) was carried out using interactions with the peptide, the ASF receptors in HepG2 cells, and the carbohydrate chains of ASF. The peak currents were proportional and ranged between 5.0 × 10¹ and 1.5 × 10³ cells mL^-1. When the values estimated from an electrochemical process were compared with those obtained by ELISA, the results were within the acceptable range of measurement error.

Characterization of chickpea (Cicer arietinum L.) lectin for biological activity

Lectins are proteins that are subject of intense investigations. Information on lectin from chickpea (Cicer arietinum L.) with respect to its biological activities are very limited. In this study, we purified lectin from the seeds of chickpea employing DEAE-cellulose and SP-Sephadex ion exchange chromatography and identified its molecular subunit mass as 35 kDa. The free radical scavenging activity of lectin measured by the DPPH assay has IC₅₀ of 0.88 µg/mL. Lectin exerted antifungal activity against Candida krusei, Fusarium oxysporium oxysporium, Saccharomyces cerevisiae and Candida albicans, while antibacterial activity against E. coli, B. subtilis, S. marcescens and P. aeruginosa. The minimum inhibitory concentrations were 200, 240, 160 and 140 µg for C. krusei, F. oxysporium, S. cerevisiae and C. albicans respectively. Lectin was further examined for its antiproliferative potential against cancerous cell line. The cell viability assay indicated a high inhibition activity on Ishikawa, HepG2, MCF-7 and MDA-MB-231 with IC₅₀ value of 46.67, 44.20, 53.58 and 37.46 µg/mL respectively. These results can provide a background for future research into the benefits of chickpea lectin to pharmacological perspective.

Scientific opinion on an application by Dow AgroSciences LLC (EFSA-GMO-NL-2012-106) for the placing on the market of genetically modified herbicide-tolerant soybean DAS-44406-6 for food and feed uses, import and processing under Regulation (EC) No 1829/2003

Soybean DAS-44406-6 expresses 5-enolpyruvyl-shikimate-3-phosphate synthase (2mEPSPS), conferring tolerance to glyphosate-based herbicides, aryloxyalkanoate dioxygenase (AAD-12), conferring tolerance to 2,4-dichlorophenoxyacetic acid (2,4-D) and other related phenoxy herbicides, and phosphinothricin acetyl transferase (PAT), conferring tolerance to glufosinate ammonium-based herbicides. The molecular characterisation data and bioinformatics analyses did not identify issues requiring assessment for food/feed safety. The agronomic and phenotypic characteristics revealed no relevant differences between soybean DAS-44406-6 and its conventional counterpart, except for pod count, seed count and yield. The compositional analysis identified no differences requiring further assessment, except for an increase (up to 31%) in lectin activity in soybean DAS-44406-6. Such increase is unlikely to raise additional concerns for food/feed safety and nutrition of soybean DAS-44406-6 as compared to its conventional counterpart and non-GM reference varieties. There were no concerns regarding the potential toxicity and allergenicity of the three newly expressed proteins, and no evidence that the genetic modification might significantly change the overall allergenicity of soybean DAS-44406-6. Soybean DAS-44406-6 is as nutritious as its conventional counterpart and the non-GM soybean reference varieties tested. There are no indications of an increased likelihood of establishment and spread of occasional feral soybean DAS-44406-6 plants, unless exposed to the intended herbicides. The likelihood of environmental effects from the accidental release of viable seeds from soybean DAS-44406-6 into the environment is therefore very low. The post-market environmental monitoring plan and reporting intervals are in line with the intended uses of soybean DAS-44406-6. In conclusion, the GMO Panel considers that the information available for soybean DAS-44406-6 addresses the scientific comments raised by Member States and that soybean DAS-44406-6, as described in this application, is as safe as its conventional counterpart and non-GM soybean reference varieties with respect to potential effects on human and animal health and the environment in the context of the scope of this application.

Scientific Opinion on an application by Dow AgroSciences LLC (EFSA-GMO-NL-2011-91) for the placing on the market of genetically modified herbicide-tolerant soybean DAS-68416-4 for food and feed uses, import and processing under Regulation (EC) No 1829/2003

Soybean DAS-68416-4 was developed by Agrobacterium tumefaciens-mediated transformation to express the aryloxyalkanoate dioxygenase-12 (AAD-12) protein, conferring tolerance to 2,4-dichlorophenoxyacetic acid (2,4-D) and other related phenoxy herbicides, and the phosphinothricin acetyltransferase (PAT) protein, conferring tolerance to glufosinate ammonium-based herbicides. The molecular characterisation data and bioinformatics analyses did not identify issues requiring further assessment for food/feed safety. The agronomic and phenotypic characteristics tested revealed no relevant differences between soybean DAS-68416-4 and its conventional counterpart, except for 'days to 50% flowering'. The compositional analysis identified no differences requiring further assessment, except for an increase (up to 36%) in lectin activity in soybean DAS-68416-4. Such increase is unlikely to raise additional concerns for food/feed safety and nutrition for soybean DAS-68416-4 as compared to its conventional counterpart and the non-GM reference varieties. There were no concerns regarding the potential toxicity and allergenicity of the two newly expressed proteins, and no evidence that the genetic modification might significantly change the overall allergenicity of soybean DAS-68416-4. Soybean DAS-68416-4 is as nutritious as its conventional counterpart and the non-GM reference varieties. There are no indications of an increased likelihood of establishment and spread of occasional feral soybean DAS-68416-4 plants, unless these are exposed to the intended herbicides. The likelihood of environmental effects resulting from the accidental release of viable seeds from soybean DAS-68416-4 into the environment is therefore very low. The post-market environmental monitoring plan and reporting intervals are in line with the intended uses of soybean DAS-68416-4. The GMO Panel concludes that the information available addresses the scientific comments of the Member States and that soybean DAS-68416-4, as described in this application, is as safe as its conventional counterpart and the tested non-GM reference varieties with respect to potential effects on human and animal health and the environment in the context of the scope of this application.

Detoxification and anti-nutrients reduction of Jatropha curcas seed cake by Bacillus fermentation

Jatropha curcas seed cake is a by-product generated from oil extraction of J. curcas seed. Although it contains a high amount of protein, it has phorbol esters and anti-nutritional factors such as phytate, trypsin inhibitor, lectin and saponin. It cannot be applied directly in the food or animal feed industries. This investigation was aimed at detoxifying the toxic and anti-nutritional compounds in J. curcas seed cake by fermentation with Bacillus spp. Two GRAS (generally recognized as safe) Bacillus strains used in the study were Bacillus subtilis and Bacillus licheniformis with solid-state and submerged fermentations. Solid-state fermentation was done on 10 g of seed cake with a moisture content of 70% for 7 days, while submerged fermentation was carried out on 10 g of seed cake in 100 ml distilled water for 5 days. The fermentations were incubated at the optimum condition of each strain. After fermentation, bacterial growth, pH, toxic and anti-nutritional compounds were determined. Results showed that B. licheniformis with submerged fermentation were the most effective method to degrade toxic and anti-nutritional compounds in the seed cake. After fermentation, phorbol esters, phytate and trypsin inhibitor were reduced by 62%, 42% and 75%, respectively, while lectin could not be eliminated. The reduction of phorbol esters, phytate and trypsin inhibitor was related to esterase, phytase and protease activities, respectively. J. curcas seed cake could be mainly detoxified by bacterial fermentation and the high-protein fermented seed cake could be potentially applied to animal feed.

Simultaneous and rapid determination of the anticarcinogenic proteins Bowman-Birk inhibitor and lectin in soybean crops by perfusion RP-HPLC

There are numerous studies demonstrating a direct association between the ingestion of soybean and low cancer incidence. This fact has been related to the presence of Bowman-Birk inhibitor (BBI) and lectin in soybean. The simultaneous and fast determination of BBI and lectin in soybean is proposed, for the first time, in this work. Two different strategies were designed for the extraction of BBI and lectin: extraction of soybean proteins using a Tris-HCl buffer followed by isolation of BBI and lectin by the isoelectric precipitation of other soybean proteins (method I) or by the direct extraction of BBI and lectin using an acetate buffer (method II). The effect of the previous soybean defating on the extraction of BBI and lectin was also studied. Moreover, the possibility of using a high-intensity focalized ultrasonic probe for accelerating the extraction was explored and an optimization of the extraction time and ultrasound amplitude was performed. The extracts obtained were analysed by RP-HPLC-ESI-MS for the correct identification of BBI and lectin in soybean. Moreover, a fast chromatographic methodology using a perfusion column and UV detection was optimized for the rapid determination of BBI and lectin in soybean. After evaluating its analytical characteristics (linearity, precision, and recovery), the method was applied to the quantitation of BBI and lectin in different soybean varieties.