Targeting Metabolic and Neurodegenerative Enzymes With Cousinia cirsioides Boiss. and Bal. Extracts and Major Compounds: LC-HRMS-Based Phytochemistry and Bioactivity Assessment.

This study investigated the antioxidant properties and enzyme-inhibitory activities of Cousinia cirsioides extracts and sub-extracts, along with their phytochemical composition. In this study, the aerial parts of C. cirsioides were extracted with 70% methanol and fractionated into n-hexane, ethyl acetate (CSE), n-butanol, and water sub-extracts. Enzyme inhibition activities were tested against α-amylase, α-glucosidase, acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and tyrosinase. Antioxidant capacities were evaluated using DPPH, ABTS, FRAP, and CUPRAC assays. TPC, TFC and LC-HRMS analyses were used to identify the phytochemical profile of the extracts. Additionally, the antimicrobial activity was investigated using the microdilution method. As a result, the CSE sub-extract exhibited the most potent antioxidant and enzyme inhibitory activities among the extracts. It showed significant inhibition of α-amylase (IC50 = 167.967 µg/mL), AChE (IC50 = 134.165 µg/mL), and tyrosinase (IC50 = 122.354 µg/mL), among others. Moreover, a moderate antimicrobial effect was found in n-hexane sub-extract. LC-HRMS analysis revealed high levels of isoquercitrin, caffeic acid, chlorogenic acid, and protocatechuic acid in the active sub-extract. These compounds were also subjected to the same bioactivity tests. It is revealed that these compounds demonstrated individual bioactivities, although less potent than the extract, suggesting synergistic effects.