Ana Paula Passos de Paiva1,2, Amanda Rodrigues de Souza2,3, Juliana Barbosa Coitinho1,2, Renato Graciano de Paula 1,2
The Non-Conventional Food Plant (PANC) Xanthosoma sagittifolium (L.) Schott (taioba) is a monocotyledon of the Araceae family and Xanthosoma genus. Its leaves exhibit notable nutritional properties, containing a satisfactory amount of total fiber and a protein content comparable to that of the PANC Ora-pro-nóbis. Additionally, it is a rich source of iron, calcium, magnesium, vitamin C, and phenolic compounds. Extracts obtained from both leaves and roots have also demonstrated significant antiproliferative, anti-inflammatory, and antimicrobial potential. Given these attributes, taioba is an interesting target for proteomic and metabolomic studies to identify the molecules present in its leaves (and roots) and associate them with biologically relevant activities of biotechnological interest. In this context, the present study aims to purify and characterize lectins found in taioba leaves, as these proteins, due to their specific and reversible carbohydrate-binding capacity, are associated with the described biological activities. The purification process was monitored through hemagglutination assays and SDS-PAGE, revealing bands with a molecular mass ranging between 12–14 kDa, corresponding to the monomeric unit of lectins. Hemagglutinating fractions were obtained through sequential saline precipitation ((NH4 )2 SO4at 15% and 35%) from the protein extract of leaves and roots. The 15% precipitated fraction from the leaf extract was selected for further purification using size exclusion chromatography in an HPLC system, yielding two partially purified hemagglutinating fractions. The protein profile of these fractions displayed bands corresponding to the monomeric unit and its multiples, suggesting the formation of supramolecular arrangements, a common characteristic of lectins. These fractions were further analyzed by mass spectrometry (data not yet available). It was demonstrated that the fractions obtained after saline precipitation of the leaf extract (P15F and P35F) exhibited hemagglutination activity with specificity for mannose, without distinguishing ABO blood types. The hemagglutination activity of P15F was more effective at an optimal pH between 7.5 and 7.9 and a
temperature of 37°C, showing dependence on magnesium ions. Using a resazurin-based cell viability assay, the hemagglutinating fractions – obtained from size-exclusion chromatography – exhibited dose-dependent cytotoxicity (~0.1 µg to 53 µg) against rat glioma (C6), human colon carcinoma (RKO), and human primary ovarian malignant adenocarcinoma (TOV-21G) cell lines, except for the human glioblastoma cell line (U373), reducing viability by up to 78%. Thus, in this study, two hemagglutinating fractions with cytotoxic potential were partially purified, representing the first steps toward their full biochemical and functional characterization, as well as the exploration of taioba’s biotechnological
potential.
Agradecimentos: Funding agencies - Fapes, Capes, CNPq, Laboratório Multiusuário de Análises Biomoleculares (Labiom/UFES), Fundação Ezequiel Dias (FUNED/MG), Dra. Alessandra Cristine de Souza Matavel, Laboratório de Química de Proteínas (LQP/UFES), Laboratório de Bioquímica e Biofísica Molecular de Proteínas (LB2MP/UFES)