Recombinant production and initial characterization of a novel lectin-like protein from the red alga Kappaphycus alvarezii.

Marine macroalgae are essential sources of bioactive compounds, widely explored for their pharmacological and biotechnological properties. Kappaphycus alvarezii (Rhodophyta), a red macroalga widely cultivated worldwide as a major source of κ-carrageenan, is emerging as a rich source of lectins with high carbohydrate-binding specificity, offering promising applications in diagnostics and antitumor therapies. This study aimed to recombinantly produce, purify, and characterize the biological activities of a novel lectin-like protein from K. alvarezii, designated KAL-1 lectin-like, with emphasis on its anticancer potential against human osteosarcoma U2OS cells. The recombinant KAL-1 lectin-like protein was expressed in CHO cells, purified by affinity chromatography, and subsequently evaluated for cytotoxicity and cellular selectivity using the MTT viability assay in HaCaT and U2OS cell lines. KAL-1 significantly reduced the viability of U2OS cells at very low concentrations (0.025 μM), without inducing relevant inhibitory effects on the viability of normal epithelial cells (HaCaT). These results indicate a selective antitumor action of KAL-1, suggesting its potential as a promising candidate for the development of targeted anticancer agents.