Plant lectin from Dioclea altissima as a potential SARS-CoV-2 inhibitor: insights from molecular docking studies

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains a relevant target for the identification of novel antiviral compounds. In this study, we investigated the molecular interactions between a plant-derived lectin from Dioclea altissima (DAL) and two key viral targets: the main protease (Mpro) and the spike glycoprotein. Molecular docking simulations were performed using HEX 8.0.0 to explore protein–protein interactions between the lectin and SARS-CoV-2 targets. The results revealed a markedly higher docking score of DAL toward Mpro (−83.73) compared to the spike protein (−40.71). Structural analysis of the top-ranked docking poses indicated that DAL interacts with amino acid residues in regions proximal to the catalytic site of Mpro, suggesting a potential influence on substrate accessibility or local conformational dynamics. In contrast, interactions with the spike protein were observed within the S2 subunit, outside the canonical receptor-binding domain, involving regions associated with conformational rearrangements required for membrane fusion. Visualization and interaction analyses were conducted using PyMOL, enabling the identification of key contact residues and interaction patterns contributing to complex stabilization. The comparative binding profile suggests preferential interaction of DAL with Mpro, supporting its potential as a scaffold for the development of antiviral agents against SARS-CoV-2. These findings provide preliminary in silico evidence of selective interaction between D. altissima lectin and a key viral enzyme, warranting further biochemical and pharmacological investigations.