NAVY BEAN EXTRACT AS A POTENTIAL SOURCE OF LECTIN

Lectins are glycoproteins found in many plants, such as peas, soybeans, wheat, lentils, and beans. This biopolymer is noteworthy due to its ability to specifically bind to glycoproteins, mono- and oligosaccharides. Therefore, since some of these compounds constitute the intestinal cell surface, lectin may be a suitable material for building delivery systems, as it would promote a cytoadhesive property to the carrier. Endocytosis mechanisms can also be activated by lectin, allowing the body to absorb the vehiculated bioactive. Navy beans have a high lectin content compared to other crops. However, the use of navy bean lectin is still unexplored. Therefore, in this study we aimed to obtain and characterize a navy bean extract (NBE). The extract, obtained under neutral conditions (pH 7.4), presented 40 % proteins, 20 % carbohydrates, and 20 % lipids after freeze-drying. Electrophoretic analysis showed that NBE proteins were mostly composed of lectin (~30 kDa), followed by smaller amounts of low molecular weight albumins (15-20 kDa). Furthermore, zeta potential screening showed that NBE had an isoelectric point (IP) around pH = 3.5 and was negatively charged above this pH. FTIR spectra of NBE presented peaks at 1039 cm^-1, typical of polysaccharides, as well as 1390 cm^-1 (amide III), 1535 cm^-1 (amide II), 1633 cm^-1 (amide I), 2922 cm^-1 (amide B), and 3267 cm^-1 (amide A). These results, combined with the low IP and high concentration of carbohydrates, indicate that NBE is mainly composed of glycoproteins (lectin). Therefore, extraction under neutral conditions is a suitable method for obtaining NBE with moderate amounts of lectin. We hope that this study can provide relevant data on this unexplored material (navy bean extract) and that it can contribute to its future application for building lectin-based delivery systems.