Dietary Lectins: Gastrointestinal and Immune Effects

Plant Toxic Proteins: Their Biological Activities, Mechanism of Action and Removal Strategies

Plants evolve to synthesize various natural metabolites to protect themselves against threats, such as insects, predators, microorganisms, and environmental conditions (such as temperature, pH, humidity, salt, and drought). Plant-derived toxic proteins are often secondary metabolites generated by plants. These proteins, including ribosome-inactivating proteins, lectins, protease inhibitors, α-amylase inhibitors, canatoxin-like proteins and ureases, arcelins, antimicrobial peptides, and pore-forming toxins, are found in different plant parts, such as the roots, tubers, stems, fruits, buds, and foliage. Several investigations have been conducted to explore the potential applications of these plant proteins by analyzing their toxic effects and modes of action. In biomedical applications, such as crop protection, drug development, cancer therapy, and genetic engineering, toxic plant proteins have been utilized as potentially useful instruments due to their biological activities. However, these noxious metabolites can be detrimental to human health and cause problems when consumed in high amounts. This review focuses on different plant toxic proteins, their biological activities, and their mechanisms of action. Furthermore, possible usage and removal strategies for these proteins are discussed.

Potential Application of Combined Therapy with Lectins as a Therapeutic Strategy for the Treatment of Bacterial Infections

Antibiotic monotherapy may become obsolete mainly due to the continuous emergence of resistance to available antimicrobials, which represents a major uncertainty to human health. Taking into account that natural products have been an inexhaustible source of new compounds with clinical application, lectins are certainly one of the most versatile groups of proteins used in biological processes, emerging as a promising alternative for therapy. The ability of lectins to recognize carbohydrates present on the cell surface allowed for the discovery of a wide range of activities. Currently the number of antimicrobials in research and development does not match the rate at which resistance mechanisms emerge to an effective antibiotic monotherapy. A promising therapeutic alternative is the combined therapy of antibiotics with lectins to enhance its spectrum of action, minimize adverse effects, and reduce resistance to treatments. Thus, this review provides an update on the experimental application of antibiotic therapies based on the synergic combination with lectins to treat infections specifically caused by multidrug-resistant and biofilm-producing Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. We also briefly discuss current strategies involving the modulation of the gut microbiota, its implications for antimicrobial resistance, and highlight the potential of lectins to modulate the host immune response against oxidative stress.

Protection of the intestinal epithelium of poultry against deleterious effects of dietary lectins by a multi-strain bacterial supplement

The intake of antinutritional factors produce impairment on the intestinal digestive function, impeding the efficient use of nutrients. Probiotics could be useful in poultry breeding to prevent negative effects of antinutritional factors, like the dietary lectins soybean agglutinin (SBA) and wheat germ agglutinin (WGA). Therefore, this investigation aimed to verify that SBA and wheat, which contains WGA, exert harmful effects on the intestinal mucosa and the digestive system of young poultry, and determine if the administration of probiotics able to capture lectins could counteract their effects. The trials performed demonstrated that a mixture of Bifidobacterium infantis CRL 1395, Enterococcus faecium LET 301, Lactobacillus salivarius LET 201, L. reuteri LET 210, and Propionibacterium acidipropionici LET 103, strains with ex vivo ability to interfere with the interaction of lectins and epithelial cells, has no negative effect on young chickens health. Middle levels of SBA, as well as wheat as a source of WGA, resulted in lower activities of intestinal and brush border enzymes and alterations in the integrity and morphological parameters of the chicks jejunal mucosa. The bacteria blend increased the activity of several digestive enzymes and the intestinal maturation marker alkaline phosphatase in birds fed with a conventional diet. Besides, it partially countered the deleterious effects of increased content of SBA, as well as the negative effect of a dietary source of WGA, on digestive enzymes activity and intestinal mucosa integrity. The results highlight the capability of multifunctional bacterial mixtures to protect the digestive system of avian against residual dietary lectins.