Activity of Luetzelburgia auriculata Lectin Against Leishmania major Promastigote Via Carbohydrate Recognition Domain

Leishmaniasis, an infectious disease, significantly impacts patients' quality of life. Current treatments primarily involve glucantime and amphotericin B. Although these drugs are effective, their limitations necessitate the exploration of alternative therapies. Lectins show promise in this context due to their established ability to interact with membrane glycans of various pathogens.

Luetzelburgia auriculata agglutinin (LAA) exhibits binding affinity for galactose and lactose carbohydrates.

Based on these properties, this study evaluated the in vitro anti-promastigote potential of LAA in L. major strains. Promastigotes were incubated with different concentrations of LAA (5- 320 μg/mL), and cell viability was determined using Neubauer chamber counting. After determining the 24-hour IC₅₀ of LAA, we examined the contribution of the carbohydrate recognition domain (CRD) to the lectin's activity. To explore possible mechanisms underlying its effects, fluorescence assays were performed using 2',7'-dichlorodihydrofluorescein diacetate (DCFH₂-DA) and propidium iodide (PI). Scanning electron microscopy was used to evaluate the morphological changes induced by LAA in promastigotes. Additionally, the effects of combining LAA with amphotericin B and glucantime on promastigote forms were assessed.

LAA inhibited the growth of promastigote forms of Leishmania major in a time- and concentration- dependent manner, with IC₅₀ values of 82 μg/mL at 24 h, 25 μg/mL at 48 h, and 20 μg/mL at 72 h. Fluorescence assays indicated that the lectin stimulates reactive oxygen species production and compromises parasite membrane integrity.

This effect is likely associated with LAA's ability to interact with glycans from L. major. Furthermore, evidence suggests that LAA exerts a modulatory effect when co-administered with amphotericin B, enhancing the drug's activity.

Overall, our results indicate that LAA is a promising alternative for the treatment of cutaneous Leishmaniasis caused by L. major. However, further in vivo studies are required to elucidate its mechanisms of action in a biological system.