This study aimed to comparatively evaluate the phytochemical composition, biological activities, and metal-binding properties of phenolic-rich extracts obtained from Teucrium polium (TPE), Teucrium orientale (TOE), and Teucrium turcicum (TTE). Total phenolic content, antioxidant activity, α-glucosidase inhibitory effect, antibacterial activity, and in vitro cytotoxicity were determined using spectrophotometric and bioanalytical techniques. In addition, FTIR, UV–Vis spectroscopy, fluorescence quenching, and Job’s plot analyses were performed to investigate metal–extract interactions and complex formation behavior. Among the investigated extracts, TPE exhibited the highest total phenolic content (39.43 mg GAE/L) together with the strongest antioxidant activity (DPPH EC₅₀ = 2.70 mg/mL). TPE also demonstrated notable α-glucosidase inhibitory activity with an IC₅₀ value of 6.88 mg/mL. In antibacterial analyses, TOE showed the strongest inhibitory effect, particularly against Streptococcus mutans and Escherichia coli. Spectroscopic analyses revealed selective interactions of TTE and TPE with Hg²⁺ ions and TOE with Cu²⁺ ions. Fluorescence quenching and Job’s plot analyses confirmed selective 1:1 complex formation between the extracts and target metal ions. Cytotoxicity assays demonstrated concentration-dependent effects against HT-29 and CaCo-2 colorectal cancer cell lines. The IC₅₀ values for HT-29 cells were determined as 178.4 µg/mL for TPE, 192.6 µg/mL for TTE, and 261.3 µg/mL for TOE, whereas the corresponding IC₅₀ values for CaCo-2 cells were 134.8 µg/mL, 148.5 µg/mL, and 207.4 µg/mL, respectively. In contrast, L929 fibroblast cells exhibited comparatively higher viability under the tested conditions. FTIR analyses suggested that hydroxyl and aromatic oxygen-containing functional groups play a major role in metal coordination and complex stabilization. Overall, the findings indicate that phenolic-rich Teucrium extracts possess multifunctional biological activities together with selective metal-binding properties, highlighting their potential for future studies involving natural bioactive compounds and sensing-related applications. Bioactive potential, antibacterial efficacy, anticancer activity, and metal-binding properties of three Teucrium species (T. polium, T. orientale, and T. turcicum). T. polium exhibit the highest phenolic content, remarkable antioxidant capacity, strong α-glucosidase inhibition, and superior antibacterial activity. These extracts play a central role in metal coordination, conferring high selectivity toward Hg²⁺ (T. polium, T. turcicum) and Cu²⁺ (T. orientale).
Arslan et al. (Mon,) studied this question.