Functional Evaluation of Five Sideritis Species Traditionally Consumed as Herbal Teas: Enzyme Inhibitory Activities Relevant to Neurodegenerative and Metabolic Disorders

The growing interest in plant-based medicines has increased attention toward medicinal plants as therapeutic agents. This study evaluated the antidiabetic and anticholinesterase potentials of five Sideritis species through α-amylase, α-glucosidase, AChE, and BChE inhibition assays, followed by LC–MS/MS profiling of the most active extracts. Sideritis montana subsp. montana dichloromethane extract exhibited the strongest α-amylase inhibition (82.38% ± 0.09%), while no extract showed notable α-glucosidase activity. Moderate AChE inhibition was observed in Sideritis lanata (18.78 ± 0.91%), whereas BChE inhibition was more pronounced in Sideritis argyrea (44.96% ± 0.15%) and S. lanata (38.23% ± 0.08%) dichloromethane extracts. LC–MS/MS analysis revealed chlorogenic acid, rosmarinic acid, and quinic acid as major constituents, especially abundant in butanol and water extracts of Sideritis hololeuca, S. lanata, and Sideritis libanotica. Dichloromethane fractions were richer in mid-polarity phenolics such as 4-OH-benzoic, syringic and vanillic acids. Overall, the results highlight species- and solvent-dependent bioactivity, suggesting Sideritis taxa as promising sources of natural enzyme inhibitors.