Interaction of Pelargonium sidoides Compounds with Lactoferrin and SARS-CoV-2: Insights from Molecular Simulations.

(1) Background: Pelargonium sidoides extracts and lactoferrin are two important natural, anti-inflammatory, and antiviral agents, which can interfere with the early stages of SARS-CoV-2 infection. Molecular docking and molecular dynamics simulation approaches have been applied to check for the occurrence of interactions of the Pelargonium sidoides compounds with lactoferrin and with SARS-CoV-2 components. (2) Methods: Computational methods have been applied to confirm the hypothesis of a direct interaction between PEL compounds and the lactoferrin protein and between Pelargonium sidoides compounds and SARS-CoV-2 Spike, 3CLPro, RdRp proteins, and membrane. Selected high-score complexes were structurally investigated through classical molecular dynamics simulation, while the interaction energies were evaluated using the molecular mechanics energies combined with generalized Born and surface area continuum solvation method. (3) Results: Computational analyses suggested that Pelargonium sidoides extracts can interact with lactoferrin without altering its structural and dynamical properties. Furthermore, Pelargonium sidoides compounds should have the ability to interfere with the Spike glycoprotein, the 3CLPro, and the lipid membrane, probably affecting the functional properties of the proteins inserted in the double layer. (4) Conclusion: Our findings suggest that Pelargonium sidoides may interfere with the mechanism of infection of SARS-CoV-2, especially in the early stages.

Antioxidant and antimicrobial properties of Pelargonium sidoides DC and lactoferrin combination.

Lactoferrin (LAT), a multifunctional protein involved in numerous physiological functions, and the medicinal plant Pelargonium sidoides DC (PEL) have been described for their anti-inflammatory properties. Because the main advantage of natural products consists in administering them in combination rather than as single compound, we aimed to understand whether the combination of PEL and LAT, herein PELIRGOSTIM, could still prove beneficial or additive/synergistic activities during inflammatory conditions. To pursue this goal, we used macrophagic cells (J774.1) and treated them with PEL and LAT in a concentration-dependent manner. We found that PELIRGOSTIM was able to reduce the levels of reactive oxygen species (ROS) and nitrite, effects that were correlated to the release of lower levels of IL-1ß after LPS treatment. In addition, the combination of PEL and LAT showed bacteriostatic activities against Staphylococcus aureus and Escherichia coli which had limited growth starting from 5 hours up to 20 hours. This effect was stronger than that observed for penicillin/streptomycin. Our results provide PELIRGOSTIM as an innovative combination of natural products capable to prevent inflammation-, oxidative stress- and microbial-related disorders.