Antimicrobial, Anti-Inflammatory, General Toxicity and Antioxidant Activities of Ultrasound-Assisted Extracts from Prunella vulgaris L.

Background/Objectives: This study compared five ultrasound-assisted extracts of Prunella vulgaris L. prepared with water or aqueous ethanol (30%, 50%, 70%, and 96%) and evaluated their phytochemical composition and preliminary antimicrobial, anti-inflammatory, brine-shrimp lethality, and antioxidant properties. Methods: Gallic acid and rosmarinic acid were quantified in all five extracts by a validated HPLC-UV method, with LC-ESI-MS used to support compound identification. Antimicrobial activity was evaluated by broth serial dilution and minimum inhibitory concentration (MIC) determination. Anti-inflammatory activity was assessed in a carrageenan-induced rat paw edema model. General toxicity screening was performed using the Artemia salina lethality assay. Antioxidant activity was evaluated by a ferricyanide reducing-power assay and the DPPH radical-scavenging assay. Results: Rosmarinic acid was detected in all extracts and was most abundant in PV70 (7.6%). PV70 showed MIC values of 12.5 μg/mL against Staphylococcus aureus and Bacillus subtilis. In the carrageenan model, PV70 produced 76.8% inhibition of paw-weight gain at 25 mg/kg, whereas diclofenac produced 66.6% inhibition at 10 mg/kg; this numerical comparison was descriptive and was not interpreted as evidence of superiority. The tested extracts caused low mortality of Artemia salina under the experimental conditions. Conclusions: The findings identify PV70 as a chemically distinct extract with notable activity in the screening models used. Because the extracts are multicomponent mixtures and mechanistic biomarkers were not measured, the observed biological effects cannot be attributed to rosmarinic acid alone. Further work is required to confirm mechanisms, safety, standardization, and efficacy.