Tripleurospermum callosum (Boiss. & Heldr.) E. Hossain Extracts: Interaction with Ciprofloxacin and Cytotoxic Effects on Normal and Cancer Cell Lines

Background and Aims: Tripleurospermum callosum (Boiss. & Heldr.) E. Hossain is traditionally used in Türkiye for various ailments. This study aimed to evaluate the antibacterial potential and cytotoxic profiles of ethanol, infusion, and decoction extracts obtained from the aerial parts of the plant.Methods: The antibacterial activity and synergistic potential of the extracts in combination with ciprofloxacin (CIP) were evaluated against Pseudomonas aeruginosa ATCC 9027 using the checkerboard method. Cytotoxicity was determined via the MTT assay on mouse embryonic fibroblast (NIH/3T3), Human non-small-cell lung cancer (A549), and human colorectal adenocarcinoma (HT-29) cell lines. Half-maximal inhibitory concentration (IC50) values were calculated using GraphPad Prism (v9.2.0).Results: Antibacterial assays indicated that none of the extracts alone exhibited significant activity (MIC > 5000 μg/mL). However, combination studies revealed additive effects for the infusion Fractional Inhibitory Concentration Index (ΣFIC) = (0.51) and decoction (ΣFIC = 0.51), whereas the ethanol extract showed an indifferent interaction (ΣFIC = 1.031). In cytotoxicity assays, ethanol extract exhibited the most potent activity against A549 (IC₅₀ = 564.99±19.99 μg/mL) and HT-29 (IC₅₀ = 177.80±1.76 μg/mL) cancer cell lines, though it also displayed significant toxicity towards the normal NIH/3T3 (IC₅₀ = 62.98±2.82 μg/mL). In contrast, infusion and decoction extracts were not cytotoxic to cancer cells (IC50 >1000 μg/mL) and showed lower toxicity on the NIH/3T3 line (IC₅₀ > 300 μg/mL).Conclusion: This study is the first to evaluate the interaction of T. callosum extracts with CIP and their in vitro cytotoxic profiles. The results provide preliminary insights into the biological activities of these extracts, highlighting differential cytotoxic responses and potential additive antibacterial effects when combined with conventional antibiotics.