Background: Prunella vulgaris L., known as self-healing herb, is a widely spread species in the spontaneous flora with beneficial effects on human health, a fact proven in particular by Asian researchers. The aim of this study was to evaluate the antitumor activity and the antibacterial effect on different bacterial strains, including multidrug-resistant ones, depending on the type of solvent used (aqueous, hydroalcoholic), the plant product taken into consideration (spike inflorescence, leaf), its quantity and the concentration of active principles.
Material and method: For screening of antimicrobial susceptibility, both minimum inhibitory concentration and minimum bactericidal concentration were determined on Escherichia coli, Klebsiella pneumoniae, Providencia stuartii, Pseudomonas aeruginosai, and methicillin-resistant Staphylococcus aureus species, including reference strains and hospital strains. Leaves and flower extracts (aqueous and 70% methanolic) were first assessed, and the one with the best antibacterial potential was further tested as a concentrated extract. The antitumor activity was determined on MDA-MB-231 breast adenocarcinoma cells and on a non-tumor cell line, MCF-10A breast epithelial cells by means of Alamar blue technique and Scratch assay.
Results: Inflorescence extracts showed better bacteriostatic effects than leaf extracts on most bacteria, in both aqueous and hydroalcoholic extracts. The concentrated extract of spike inflorescence showed measurable activity with good effects on Gram-positive bacteria, but also on multidrug-resistant Gram-negative ones. The 70% methanolic extract of the species Prunella vulgaris L. (spike inflorescence) demonstrated a concentration-dependent cytotoxic and anti-migratory activity on MDA-MB-231 breast cancer cells, while affecting the non-tumor cell line less.
Conclusions: The results suggest that Prunella vulgaris extracts present antibacterial potential in the complementary treatment of multidrug-resistant infections. The extract from the spike inflorescence of Prunella vulgaris L. produced a dose and time-dependent reduction in cell viability and migration, eliciting a stronger effect on the breast adenocarcinoma cell line.
