In vitro antioxidant and, α-glucosidase inhibitory activities and comprehensive metabolite profiling of methanol extract and its fractions from Clinacanthus nutans

Abstract

Background: This study was aimed to evaluate antioxidant and α-glucosidase inhibitory activity, with a subsequent analysis of total phenolic and total flavonoid content of methanol extract and its derived fractions from Clinacanthus nutans accompanied by comprehensive phytochemical profiling.

Methods: Liquid-liquid partition chromatography was used to separate methanolic extract to get hexane, ethyl acetate, butanol and residual aqueous fractions. The total antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazy (DPPH) radical scavenging and ferric reducing antioxidant power assay (FRAP). The antidiabetic activity of methanol extract and its consequent fractions were examined by α-glucosidase inhibitory bioassay. The chemical profiling was carried out by gas chromatography coupled with quadrupole time-of-flight mass spectrometry (GC Q-TOF MS).

Results: The total yield for methanol extraction was (12.63 ± 0.98) % (w/w) and highest fractionated value found for residual aqueous (52.25 ± 1.01) % (w/w) as compared to the other fractions. Significant DPPH free radical scavenging activity was found for methanolic extract (63.07 ± 0.11) % and (79.98 ± 0.31) % for ethyl acetate fraction among all the fractions evaluated. Methanol extract was the most prominent in case of FRAP (141.89 ± 0.87 μg AAE/g) whereas most effective reducing power observed in ethyl acetate fraction (133.6 ± 0.2987 μg AAE/g). The results also indicated a substantial α-glucosidase inhibitory activity for butanol fraction (72.16 ± 1.0) % and ethyl acetate fraction (70.76 ± 0.49) %. The statistical analysis revealed that total phenolic and total flavonoid content of the samples had the significant (p < 0.05) impact on DPPH free radical scavenging and α-glucosidase inhibitory activity.

Conclusion: Current results proposed the therapeutic potential of Clinacanthus nutans, especially ethyl acetate and butanol fraction as chemotherapeutic agent against oxidative related cellular damages and control the postprandial hyperglycemia. The phytochemical investigation showed the existence of active constituents in Clinacanthus nutans extract and fractions.

Keywords: Activity phytochemical profiling; Antioxidant activity; Clinacanthus nutans; Reducing power; Total flavonoid; Total phenolic; α-glucosidase inhibitory activity.

Fig. 1

DPPH Free Radical Scavenging Activity at Different Concentration of Methanol Extract and its Fractions. The IC₅₀ values of Methanol Extract and its Hexane, EoAC, BuOH, R. aqueous Fractions are 0.3302 mg/ml, 0.1527 mg/ml, 0.2691 mg/ml, 0.2517 mg/ml, 0.585 mg/ml and 0.1927 mg/ml, respectively. Legends: MeOH, Hexane, EoAC, BuOH, R. Aqueous, Quercitin

Fig. 2

α-Glucosidase Inhibitory Activity at Different Concentration of Methanol Extract and its Fractions. The IC₅₀ values of Methanol Extract and its Hexane, EoAC, BuOH, R. aqueous Fractions are 0.06139 mg/ml, 0.04457 mg/ml, 0.05369 mg/ml, 0.3747 mg/ml, 0.0635 mg/ml and 0.03854 mg/ml, Respectively. Legends: MeOH, Hexane, EoAC, BuOH, R. Aqueous, Quercitin

Fig. 3

Effect of TPC and TFC on DPPH Free Radical Scavenging Activity. Bars with **P < 0.01, *P < 0.05 are Significantly Correlated whereas ^ns P > 0.05 Denotes Non significant Correlation According to Bonferroni Posttests (The Numerator on Bar Represent the Correlation with TPC and Denominator with TFC)

Fig. 4

Effect of TPC and TFC on α-Glucosidase Inhibitory Activity. Bars with ***P < 0.01, **P < 0.01, *P < 0.05 are Significantly Correlated whereas ^ns P > 0.05 Denotes Non significant Correlation According to Bonferroni Posttests (The Numerator on Bar Represent the Correlation with TPC and Denominator with TFC)