Phytochemical Investigation, Antiulcer, Cyclooxygenase-2, and 15-Lipoxygenase Inhibitory Activities of Echinops erinaceus Kit Tan

Abstract

Plants of the genus Echinop (Asteraceae) are traditional medicinal plants used to treat several GIT ailments, owing to their diverse bioactive secondary metabolites, including sesquiterpenoids, triterpenoids, phytosterols, phenolics, flavonoids, alkaloids, and essential oils. Echinops erinaceus Kit Tan is a wild perennial herb of the genus Echinops which is endemic to Oman, Saudi Arabia, and Yemen. Currently, there are no previous reports exploring its anti-ulcer and anti-inflammatory effects. Additionally, few reports have described the chemical profile of E. erinaceus Kit Tan. In the current study, the CHCl3 fraction of the aerial parts of the plant was subjected to chromatographic isolation and spectroscopic identification via 1D and 2D NMR, and MS. The plant afforded two new compounds, designated erinaceolic acid (E3) and erinaceoside (E5), in addition to five known compounds, namely taraxasterol acetate (E1), taraxasterol (E2), apigenin (E4), stigmasterol-3-O-β-D-glucoside (E6), and speranskoside (E7). The evaluation of the gastric ulcer protective activity of the total extract and successive fractions of E. erinaceus, using the in vivo ethanol-induced ulcer in rats model, revealed the significant effect of the tested extracts and fractions on the percentage of gastric ulcer protection and ulcer index (500 mg/kg) compared to antodine (20 mg/kg). The tested extracts and fractions also reduced the stomach contents of TNF-α and reduced IL-6 as compared to the untreated group. Histopathological examination of the gastric mucosal tissues of rats supportedprevious results. In addition, the main subfractions and their isolates were assessed for their in vitro anti-inflammatory activity against COX-2 and 15-LOX enzymes. The new compounds erinaceolic acid (E3) and speranskoside (E7) exhibited strong inhibition against COX-2 (3.41 and 2.62 µg/mL) and 15-LOX (10.05 and 5.51 µg/mL), respectively. A molecular docking study was performed to reveal the binding interaction modes of the most active compounds against the binding sites of COX-2 (PDB ID 3LN1) and 15-LOX (PDB ID 1LOX) proteins. Speranskoside (E7) showed a dual binding affinity better than that of the cocrystallized references, celecoxib and (2E)-3-(2-oct-1-yn-1-ylphenyl)acrylic acid (RS7) against both enzymes. This study shed a light on the potential use of E. erinaceus in the protection and treatment of gastric ulcers.