Ultrasound-Treated Ethanolic Extracts of Endemic Mount Ida Plants (Sideritis trojana and Hypericum kazdaghensis) Show Antiviral and Antibacterial Potential Against Norovirus Surrogates and Foodborne Bacteria.

Human noroviruses and persistent bacterial pathogens remain major food-safety concerns. This screening study compared 40% (v/v) ethanolic extracts (EE) and ultrasound-treated ethanolic extracts (UTE) of the endemic Mount Ida plants Sideritis trojana Ehrend. and Hypericum kazdaghensis Gemici & Leblebici. Feline calicivirus (FCV) and murine norovirus (MNV) served as cultivable human-norovirus surrogates; four reference bacteria were examined by disc diffusion. Ultrasound treatment was associated with higher measured total phenolic content (approximately 2.2- to 3.8-fold) and antioxidant capacity (approximately 1.9- to 2.3-fold) than EE. The largest reduction was 4.71 log10 TCID50/mL for H. kazdaghensis-UTE against FCV after overnight exposure. For MNV, the largest reduction was 2.42 log10 TCID50/mL for S. trojana-EE after overnight exposure. Inhibition-zone diameters ranged from 6.25 to 11.75 mm, including the 6-mm disc. FRhK-4 viability ranged from approximately 56% to 100% across the tested conditions, precluding a general claim of low cytotoxicity. The results provide preliminary, surrogate- and assay-specific evidence of antiviral and antibacterial activity. Because solvent-only and positive controls were not included, causal attribution to plant constituents and comparison with established antimicrobials are not possible. Confirmatory controlled assays are required before practical food-safety use can be proposed.