Purification and characterization of lectin(s) from Xanthosoma sagittifolium (L.) Schott (Taioba): hemagglutinin(s) with potential cytotoxic effect
Name: ANA PAULA PASSOS DE PAIVA
Publication date: 19/03/2025
Examining board:
Name |
Role |
|---|---|
| JAIRO PINTO DE OLIVEIRA | Examinador Interno |
| JULIANA BARBOSA COITINHO GONCALVES | Presidente |
| MARIANA AMALIA FIGUEIREDO COSTA | Examinador Externo |
Summary: Lectins are carbohydrate-binding proteins that appear in all domains of life and, due to their ability to bind specifically and reversibly to carbohydrate glycoconjugates through specific sites/domains - being known as agglutinins - they play an essential role in various biological processes. The antimicrobial and antitumor potential of these proteins has been explored for the development of alternative drugs and/or adjuvants. The presence of lectins in the leaves and roots of various plant species has been described, which are associated with inflammatory responses, antioxidant capacity, antiproliferative and pro-apoptotic effects of these plants. This work aimed to purify and characterize – biochemically and functionally – hemagglutinating fractions - lectin(s) - from Xanthosoma sagittifolium (L.) – Taioba – an Unconventional Food Plant (UFP). The purification process was monitored by hemagglutination and SDS-PAGE assays (presence of bands with a molecular mass between 12-14 kDa - the monomeric unit of lectins). Hemagglutinating fractions were obtained by sequenced saline precipitation ((NH4)2SO4 15% and 35%) from the protein extract of leaves and roots. The fraction of the leaf extract precipitated at 15% was selected for the continuation of the purification process – molecular exclusion chromatography in an HPLC system – from which two partially purified hemagglutinating fractions were obtained. The protein profile of these fractions showed bands with the molecular mass of the monomeric unit and its multiples, suggesting the formation of supramolecular arrangements, a common characteristic of lectins. It was shown that the hemagglutinating fractions (P15 and P35 from leaves) have mannose binding specificity and do not differentiate between blood types (ABO). P15 from the taioba leaf also showed an optimum pH between 7,5 and 7,9 and an optimum temperature of 37°C, being dependent on the magnesium ion. Using the resazurin-based cell viability assay, it was shown that the hemagglutinating fractions - from molecular exclusion - were cytotoxic in a dose-dependent manner (~ 0. 1 g to 53 g), 1 g to 53 g) for the cancerous cell lines of rat glioma (C6), human colon carcinoma (RKO) and primary malignant human ovarian adenocarcinoma (TOV- 21G), except for the human glioblastoma tumor line (U373), reducing viability by up to 78%. Preliminary tests did not identify any antifungal activity for Trichoderma reesei. In this work, two hemagglutinating fractions with cytotoxic potential were partially purified, which represents the first steps towards their complete biochemical and functional characterization, as well as the exploration of their biotechnological potential.
