Reserpine attenuates biofilm formation and virulence of Staphylococcus aureus

This study investigated the effects of reserpine, the main bioactive compound of Rauwolfia serpentina, on biofilm formation and biofilm-associated virulence factors production in a Gram-positive pathogen, Staphylococcus aureus. Crystal violet assay, MTT assay, Congo red binding, CLSM studies were performed to assess the anti-biofilm activity. Molecular docking was performed to explain the possible mode of action, catheter model was used to evaluate its application potential and the combinatorial study was performed in search of an improved therapeutic formulation. Reserpine affected biofilm formation, EPS production, biofilm cell viability and virulence factor production. It could eradicate 72.7% biofilm at 1/2 x MIC dose and could also stop the metabolic activity of 50.6% bacterial cells in a biofilm. Staphylococcus aureus biofilm- and virulence-regulatory proteins like AgrA, AtlE, Bap, IcaA, SarA and SasG were found to interact with reserpine which might lead to the attenuation of its pathogenicity. Reserpine along with other commercial antibiotics could generate a hightened antibiofilm response, and also eradicated a good percentage of bacterial biofilm from a urinary catheter model. These findings suggested reserpine as a good alternative entity to generate new improved therapeutic formulations.