Plants have been used for medicinal purposes both intuitively and based on traditional knowledge for centuries. Recently, however, there has been a significant increase in research focused on medicinal plants to meet the growing demands of the pharmaceutical industry. As a result, it has become essential to evaluate the safety of natural products for human use. This review examines in vitro and in vivo toxicity studies of lectins, a class of plant proteins with pharmacological applications. The reviewed data indicate that many of these proteins do not appear to be toxic to human and animal cells, nor when administered to rodents through oral, intraperitoneal, or intravenous routes. However, some lectins have shown toxicity under certain conditions, such as depending on the administration route, dose, and treatment duration. These adverse effects may include behavioral changes, antinutritional effects, hepatotoxicity, nephrotoxicity, pancreatic hypertrophy, allergic reactions, and even death. Therefore, it is crucial to prioritize toxicological studies to ensure the safety of these plant proteins as potential drug candidates in the future.

Acute lung injury (ALI) is a severe inflammatory condition associated with high morbidity and mortality, and there are currently no specific pharmacological treatments available. In this context, plants and natural products have emerged as promising therapeutic alternatives. SteLL (Schinus terebinthifolia Raddi leaf lectin) has demonstrated several biological activities, including anti-inflammatory and immunomodulatory effects. This study evaluated the anti-inflammatory effects of SteLL in a murine model of lipopolysaccharide (LPS)-induced ALI. Female BALB/c mice received intraperitoneal (i.p.) administration of SteLL (1, 5, or 10 mg/kg), dexamethasone (2 mg/kg), or vehicle (PBS). Sixty minutes later, ALI was induced by intranasal instillation of 25 µL of LPS (1 μg/μL). After 24 h, the animals were euthanized. Bronchoalveolar lavage fluid (BALF) was obtained to evaluate inflammatory parameters and lungs were collected for histopathological analysis. The tested doses of SteLL resulted in a 45–66% lower leukocyte infiltration. The group treated with 5 mg/kg exhibited a lower proportion of neutrophils and a higher proportion of mononucleated cells. Pre-treatment with SteLL also minimized plasma leakage and myeloperoxidase (MPO) activity. Furthermore, SteLL attenuated the release of pro-inflammatory cytokines at all tested doses as well as prevented nitric oxide (NO) production at the highest dose (10 mg/kg). Histopathological analysis showed that SteLL (5 and 10 mg/kg) attenuated LPS-induced lung injury. Overall, SteLL demonstrated significant anti-inflammatory effects, showing its potential as a plant-derived compound for modulating pulmonary inflammation.

Moringa oleifera Lam. seeds contain lectins that exhibit interesting bioactive properties, but their effects on metabolic syndrome (MetS) remain poorly understood. This work evaluated the effects of the water-soluble lectin from M. oleifera seeds (WSMoL) on metabolic, inflammatory, and histopathological alterations in a mouse model of MetS-like features. Male Swiss mice were fed a high-fat diet plus condensed milk solution for 11 weeks. Animals then received phosphate-buffered saline (negative control), orlistat (40 mg/kg), or WSMoL (1, 2, or 4 mg/kg, i.p.) for 14 days. A healthy group (Sham) received standard chow. The MetS-like protocol induced obesity, hyperglycemia, dyslipidemia, visceral adiposity, and systemic inflammation. WSMoL improved metabolic parameters at all doses, reducing visceral fat, attenuating hyperglycemia, and improving the lipid profile. It also decreased pro-inflammatory cytokines (IL-2, IFN-γ, TNF-α, and IL-6) while increasing IL-10 levels. WSMoL prevented hepatic steatosis and renal lipid accumulation, although inflammatory and degenerative tissue changes persisted. The 4 mg/kg dose showed efficacy but was associated with elevated AST and more frequent inflammatory alterations. In conclusion, WSMoL mitigated key features of MetS-like condition, although incomplete tissue recovery and signs of organ stress at the highest dose warrant caution regarding its potential therapeutic use.