Bioassay-Guided Isolation and Active Compounds Identification of the AntiDiabetic Fractions of Centaurea calcitrapa Extract and the Predicted Interaction Mechanism

<i>Centaurea calcitrapa</i> is a well-known plant with antioxidant, anti-proliferative, and antimicrobial properties. The plant contains various phenolic compounds, flavonoids, and other bioactive molecules contributing to its medicinal properties. However, little is known about its antidiabetic activity. The study's purpose is the isolation and identification of active compounds of <i>C. calcitrapa</i> aerial parts in diabetic rats induced by streptozotocin. The ethyl acetate extract (E2) was separated into eight subfractions by column chromatography. The subfractions were evaluated for their antidiabetic activity using diabetic-induced rats. The most active subtraction was purified, and the active compounds were identified using UV spectrophotometry, Fourier Transform Infrared Spectroscopy, Mass spectrophotometry, and HPLC. Subfraction E2-VIII showed the most effective reduction in blood glucose levels, comparable to metformin. In HPLC analysis, subfraction E2-VIII showed three main compounds: nepetin, kaempferide, and Luteolin. The nepetin flavonoid was examined using molecular docking, and it showed a high affinity to α-amylase. In conclusion, the aerial parts of <i>C. calcitrapa</i> extract and isolated compounds especially nepetin present promising antidiabetic agents this is probably mediated by its strong antioxidants and α-amylase inhibitory effect.