Investigation of Algerian Crataegus monogyna Jacq Phenolic Compounds (Using LC-ESI-MS/MS Analysis, Antioxidant Activity, and Enzyme Inhibition) and Their Potential Implications for Food and Nutraceutical Applications

Investigations into the phenolic constituents of the butanolic fraction of <i>Crataegus monogyna</i> were optimized using LC-ESI-MS/MS analysis, identifying and quantifying at least 23 fingerprint phytochemical compounds. The major phenolic compounds were epicatechin (99.916 ± 2.208 mg/g), isoquercetrin (53.31 ± 1.172 mg/g), chlorogenic acid (47.457 ± 1.010 mg/g), quinic acid (37.819 ± 1.406 mg/g), rutin (29.98 ± 0.740 mg/g), hesperidin (5.296 ± 0.177 mg/g, detected for the first time in the <i>C. monogyna</i> species), astragalin (1.774 ± 0.020 mg/g), and nicotiflorin (1.482 ± 0.016 mg/g). The antioxidant properties of the lyophilized butanolic fraction were evaluated using DPPH, GOR, ABTS, CUPRAC, and reducing power assays, all of which demonstrated that there was strong activity. Additionally, the neuroprotective effect was evaluated in vitro, showing a potent inhibitory effect on acetylcholinesterase (AChE) with an IC50 of 43.65 ± 2.10 µg/mL. The antidiabetic effect was investigated through <i>α</i>-amylase inhibition (IC50 = 91.19 ± 0.10 µg/mL), showing high inhibitory activity. In addition, the butanolic extract exhibited significant urease inhibition with an IC50 of 26.36 ± 0.05 µg/mL. These results suggest that Algerian <i>C. monogyna</i> has potential as a therapeutic agent for managing diabetes complications and as a natural source of AChE inhibitors, making it a promising subject for the treatment of urease-related conditions. Its high concentrations of natural antioxidants, such as epicatechin, isoquercetrin, chlorogenic acid, quinic acid, rutin, hesperidin, and astragalin, make it suitable for integration into medicine, pharmaceuticals, cosmetics, and the food sector.