Enzyme Inhibitory Function and Phytochemical Profile of <i>Inula Discoidea</i> Plant Species with <i>in Vitro</i> Spectrophotometric Methods and <i>in Silico</i> Molecular Docking Analysis

Abstract

Inula plant species have a large diversity of secondary metabolites with different biological activities. This study aims to assess the determination of phenolic constituent, enzyme inhibitory, and antioxidant activities of Inula discoidea (I. discoidea) aqueous and methanol extracts. The enzyme assays showed that the methanol extract of I. discoidea had effective inhibitions against AChE, BChE, GST, and α-glycosidase enzymes. The IC50 values for AChE, BChE, GST, and α-Gly were found as 38.5 mg/mL, 34.65 mg/mL, 77.0 mg/mL, and 40.76 mg/mL, respectively. Antioxidant properties of the aqueous and methanol extracts of I. discoidea were determined by four well-known in vitro techniques (ABTS, CUPRAC, DPPH, and FRAP methods). The antioxidant capacities of both water and methanol extracts were found to be very high like the standard antioxidants (BHA, BHT, ascorbic acid, and α-tocopherol) in ABTS and CUPRAC methods. According to an updated LC-MS/MS technique analysis, quinic acid (21.08 mg/g), protocatechuic acid (4.49 mg/g), and gallic acid (0.48 mg/g) were found as major phenolic compounds of the plant extract. The interactions of major phenolic compounds of I. discoidea with the AChE, BChE, GST, and α-Gly enzymes were calculated using molecular docking studies.