Chemical composition, antioxidant and anticholinesterase activities of Algerian Inula conyza DC

Abstract

The phytochemical study of the chloroform and ethyl acetate extracts of Inula conyza DC. identified key constituents such as graveolide, illicic acid, axillarine, axillaroside and 1,5-di-O-caffeoylquinic acid via NMR analysis. The total polyphenol and flavonoid contents were quantified, with the ethyl acetate extract showing the highest polyphenolic (693.29 ± 5.00 mg GAE/g extract) and flavonoid content (280.17 ± 3.18 mg QE/g extract). The antioxidant capacity of chloroform, ethyl acetate and n-butanol extracts was evaluated using five complementary methods (DPPH, ABTS, β-Carotene, CUPRAC and reducing power) and compared to four standards (BHT, BHA, α-tocopherol and ascorbic acid). Additionally, the anticholinesterase activity was assessed against AChE and BChE enzymes. The ethyl acetate extract demonstrated excellent antioxidant activity in DPPH (IC50: 19.74 ± 0.39 μg/mL), ABTS (IC50: 5.94 ± 0.03 μg/mL), β-Carotene assays (IC₅₀: 1.17 ± 0.01 μg/mL), and excellent reducing capacities in CUPRAC (8.59 ± 0.17 μg/mL) and reducing power assays (11.20 ± 0.69 μg/mL). Additionally, moderate anticholinesterase activity was observed in the chloroform extract, which inhibited BChE with an IC50 of 140.20 ± 1.11 μg/mL. This study highlights the therapeutic potential of Inula conyza as a source of natural antioxidants and neuroprotective agents.

Keywords: Algeria; Inula conyza; anticholinesterase activity; antioxidant activity; flavonoids; phenolic compounds.