Lectin-Carbohydrate Interactions: Implications for the Development of New Anticancer Agents.

Lectins are a large group of proteins found in animals, plants, fungi, and bacteria that recognize specific carbohydrate targets and play an important role in cell recognition and communication, host-pathogen interactions, embryogenesis, and tissue development. Recently, lectins have emerged as important biomedical tools that have been used in the development of immunomodulatory, antipathogenic, and anticancer agents. Several lectins have been shown to have the ability to discriminate between normal cells and tumor cells as a result of their different glycosylation patterns. Furthermore, the specific binding of lectins to cancer cells has been shown to trigger mechanisms that can promote the death of these abnormal cells. Here, we review the importance of lectins-carbohydrates interactions in cancer therapy and diagnosis. We examine the use of lectins in the modification of nanoparticles (liposomes, solid lipid nanoparticles and other polymers) for anticancer drug delivery. The development of drug delivery systems (liposomes, alginate/chitosan microcapsules, alginate beads) carrying some antitumor lectins is also discussed. In these cases, the processes of cell death induced by these antitumor lectins were also showed (if available). In both cases (lectin-conjugated polymers or encapsulated lectins), these new pharmaceutical preparations showed improved intracellular delivery, bioavailability and targetability leading to enhanced therapeutic index and significantly less side effects.

Healing activity evaluation of the galactomannan film obtained from Cassia grandis seeds with immobilized Cratylia mollis seed lectin.

Galactomannan films from Cassia grandis seeds, associated or not with Cramoll 1,4, were used on topical wounds of rats for the evaluation of the healing process during 14days. All of the films were evaluated by cytotoxic assay, FTIR and lectin hemagglutinating activity (HA). Forty-five male rats were submitted to aseptic dermal wounds (Ø=0.8cm) and divided in groups (n=15): control, test 1, and test 2, treated respectively with saline, galactomannan film and film with immobilized Cramoll 1,4. Macroscopic evaluations were performed by clinical observations and area measurements, and microscopic analysis by histological criteria. Epithelial cell proliferation and differentiation was immunohistochemically assessed using CK14 and PCNA. The presence of CO peaks in the FTIR spectrum confirmed the immobilization of Cramoll 1,4 in the film, while the residual HA confirmed the stability of the lectin after immobilization with 90.94% of the initial HA. The films presented non-cytotoxicity and cell viability exceeding 80%. All of the animals presented re-epithelization around 10days, furthermore test 2 group showed a diffuse response at the stromal tissue and the basal layer associated with wounds completely closed with 11days of experiment. The results suggest a promising use of the films as topical wound curatives.

Immobilization of bioactive compounds in Cassia grandis galactomannan-based films: Influence on physicochemical properties.

Galactomannan extracted from Cassia grandis seeds was used for the production of films containing different concentrations of the bioactive compounds lactoferrin (LF), bioactive peptides (BAPs), and phytosterols. SEM, FTIR, mechanical and thermal properties, colour, moisture content (MC), solubility, water vapour permeability (WVP), and contact angle (CA) were performed evaluating the effect of increasing concentrations of bioactive compounds on the films' physicochemical properties. The immobilization of bioactive compounds leads to films with roughness on their surface, as observed by SEM. The thermal events demonstrated that bioactive compounds avoided the establishment of more hydrogen bonds when compared to galactomannan control film; this behaviour was also confirmed by FTIR. All the studied films had a strong whiteness tendency as well as a yellowish appearance. The addition of Lf reduced MC and solubility values and leads to an increase of WVP and CA values, while the addition of BAPs and phytosterols did not changed the films solubility. The mechanical properties were affected by the addition of bioactive compounds, which improved the stiffness of the films. Galactomannan-based films from C. grandis showed to be a promising structure for the immobilization of biomolecules, pointing at a significant number of possible applications in food and pharmaceutical industries.