Potent AChE enzyme inhibition activity of Zizyphus oxyphylla: A new source of antioxidant compounds.

The purpose of this study was to assess the antioxidant potential and enzyme inhibition of various fractions of Zizyphus oxyphylla. The plant metabolites were extracted in methanol and partitioned with n-hexane, chloroform, ethyl acetate and n-butanol successively. Phytochemical screening showed presence of alkaloids, terpenoids and flavonoids in ethyl acetate and n-butanol fractions. The antioxidant potential and acetylcholine esterase assay of all these fractions and remaining aqueous fraction was evaluated by using reported methods. The results revealed that chloroform soluble fraction exhibited highest percent inhibition of DPPH radical as compared to other fractions. It showed 95.01 ± 0.37% inhibition of DPPH radical at a concentration of 120 μg/mL. The IC₅₀ of this fraction was 13.20 ± 0.27 μg/mL, relative to butylated hydroxytoluene (BHT, a reference standard), having IC₅₀ of 12.10 ± 0.29 μg/mL. It also showed highest total antioxidant activity i.e. 1.723 ± 0.34 as well as highest FRAP value (339.5 ± 0.57 TE μm/mL) and highest total phenolic contents (142.65 ± 1.20 GAE mg/g) as compared to the other studied fractions. The fractions were also studied for Acetylcholine esterase enzyme (AChE) enzyme inhibition activity and n-butanol soluble fraction exhibited maximum inhibition (95.5 ± 0.13 mg/mL with IC50 =9.58 ± 0.08 mg/mL relative to galanthamine (13.26 ± 0.73 mg/mL), while n- hexane soluble fraction (165.15 ± 0.94 mg/mL) showed non-significant. We are still working to isolate pure compounds for active fractions targeting potent inhibition responsible for some activities.