HPLC-DAD analysis, antioxidant potential and anti-urease activity of Asparagus gracilis collected from District Islamabad

Abstract

Background: Asparagus gracilis subspecie of Asparagus capitatus Baker, is described as food and medicine for various ailments. In this study we investigated, its phenolic constituents, in vitro antioxidant potential against various free radicals and anti-urease potential.

Methods: Asparagus gracilis aerial parts collected from District Islamabad, Pakistan were extracted with crude methanol which was further fractionated into n-hexane, ethyl acetate, n-butanol and aqueous fraction. Total phenolic and flavonoid contents were estimated for extract and all the derived fractions. Diverse in vitro antioxidants assays such as DPPH, H2O2, •OH, ABTS, β-carotene bleaching assay, superoxide radical, lipid peroxidation, reducing power, and total antioxidant capacity were studied to assess scavenging potential. Antiurease activity of methanol extract and its derived fractions was also investigated. HPLC-DAD analysis of crude methanol extract was performed by using different phenolic standards.

Results: Ethyl acetate fraction expressed maximum content of flavonoids (240.6 ± 6.1 mg RE/g dry sample), phenolics (615 ± 13 mg GAE/g dry sample) and best antioxidant potential among different fractions of crude methanol extract. Hydrogen peroxide assay and hydroxyl, supeoxide, nitric oxide free radicals antioxidant assays as well as beta carotene assay showed significant correlation with flavonoid content while hydrogen peroxide, ABTS and lipid peroxidation assay displayed significant correlation with phenolic content. HPLC analysis showed the presence of important phenolics i.e. catechin (4.04 ± 0.02 μg/mg sample), caffeic acid (0.89 ± 0.003 μg/mg sample), rutin (24.58 ± 0.1 μg/mg sample), myricetin (1.13 ± 0.07 μg/mg sample) and quercetin (14.91 ± 0.09 μg/mg sample). Ethyl acetate fraction expressed lowest IC50 in antiurease activity. Correlation analysis of antiurease activity expressed significant correlation with flavonoids (P < 0.004) and phenolics (P < 0.02) proposing multipotent activity of fractions.

Conclusion: These results revealed the presence of some bioactive compound in the ethyl acetate fraction having both antioxidant as well as antiurease potential.

Figure 1

DNA protection assay of crude methanol extract and various fractions of Asparagus gracilis {l: Control, 2: 2 mM FeSO ₄ , 3: 30% H ₂ O ₂ , 4: 2 mM FeSO ₄  + 30% H ₂ O ₂ ,5: AGME (100 μg/ml), 6: AGME (50 μg/ml), 7: AGME (25 μg/ml), 8: AGBE (100 μg/ml), 9:AGBE (50 μg/ml), 10: AGBE (25 μg/ml), 11: AGEE (100 μg/ml), 12: AGEE (50 μg/ml), 13: AGEE (25 μg/ml), 14: AGHE (100 μg/ml), 15: AGHE (50 μg/ml), 16: AGHE (25 μg/ml),17:AGAE (100 μg/ml),18:AGAE (50 μg/ml),19:AGAE (25 μg/ml)}. AGME; Asparagus gracilis crude methanol extract. AGEE; Asparagus gracilis ethyl acetate fraction. AGBE; Asparagus gracilis n-butanol fraction. AGAE; Asparagus gracilis aqueous fraction. AGHE;Asparagus gracilis n-hexane fraction.

Figure 2

IC ₅₀ values of anturease activity of Asparagus gracilis crude methanol extract and its derived various fractions. AGME; Asparagus gracilis crude methanol extract. AGEE; Asparagus gracilis ethyl acetate fraction. AGBE; Asparagus gracilis n-butanol fraction. AGAE; Asparagus gracilis aqueous fraction. AGHE; Asparagus gracilis n-hexane fraction.