Chemical Composition and Antioxidant, Anti-Inflammatory and Neuroprotective Properties of Hexane Extracts from the Roots of Centaurea acaulis and Centaurea pullata

Background: In herbal medicine, Centaurea is used in the treatment of many diseases such as dizziness, headaches, etc. It also reduces inflammatory pain and is used to treat liver diseases. The roots of Centaurea acaulis and Centaurea pullata have not yet been studied for biological properties. Objective: The aim of this research was to evaluate the chemical composition and the antiinflammatory, antioxidant and neuroprotective properties of hexane extracts of Centaurea acaulis and Centaurea pullata roots, and their major component, aplotaxene. Methods: The hexane extract was prepared by the maceration process and identified by GC and GCMS. Aplotaxene was isolated by flash chromatography. The antioxidant activity was assessed using 2,2- diphenyl 1-picrylhydrazyle DPPH, the β-carotene bleaching, and Ferric Reducing Antioxidant Power (FRAP) methods. The anti-inflammatory effect was assessed by egg albumin denaturation assay and the neuroprotective activity was assessed against acetyl cholinesterase (AChE) and Butyrylcholinesterase (BChE). Results: The chemical composition of hexane extract of Centaurea pullata was mainly represented by non-terpenic compounds such as Aplotaxene (80.3%), while, hexane extract of Centaurea acaulis was characterized by high levels of Aplotaxene (56.9%), 9-oxabicyclo(6,1,0)nonane (9.2%), Caryophyllene oxide (8.3%) and Isocaryophyllene (6.0%). The hexane extracts of the two Centaurea showed very good antioxidant activities with all three methods. Aplotaxene has shown excellent antioxidant activity compared to Butylated hydroxytoluene (BHT) and ascorbic acid. Centaurea acaulis hexane extract showed very high anti-inflammatory activity with an IC50 of 0.76 mg/L in the egg albumin denaturation test compared to diclofenac (IC50 of 1.01 mg/L). The extract of Centaurea pullata and Aplotaxene showed an interesting anti-inflammatory activity with IC50s of 1.72 and 1.36 mg/L, but which remains lower than that of diclofenac sodium. The neuroprotective activity of Centurea pullata and Centaurea acaulis extracts, and Aplotaxene did not show inhibition against AChE, whereas they inhibited BChE with IC50 values of 92.3, 583, and 81.5 mg/L, respectively. Conclusion: Further analysis is still needed to further demonstrate the biological efficacy of Centaurea acaulis and Centaurea pullata extracts and Aplotaxene.