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J Ethnopharmacol. 2016 May 13;183:1-8. doi: 10.1016/j.jep.2016.02.024. Epub 2016 Feb 21.

Kinetics of α-amylase and α-glucosidase inhibitory potential of Zea mays Linnaeus (Poaceae), Stigma maydis aqueous extract: An in vitro assessment.

Author information

1
Phytomedicine and Phytopharmacology Research Group, Department of Plant Sciences, University of the Free State, QwaQwa Campus, Phuthaditjhaba 9866, South Africa; Department of Microbial, Biochemical, and Food Biotechnology, University of the Free State, Bloemfontein, South Africa.
2
Department of Microbial, Biochemical, and Food Biotechnology, University of the Free State, Bloemfontein, South Africa.
3
Phytomedicine and Phytopharmacology Research Group, Department of Plant Sciences, University of the Free State, QwaQwa Campus, Phuthaditjhaba 9866, South Africa. Electronic address: ashafaaot@ufs.ac.za.

Abstract

ETHNOPHARMACOLOGICAL RELEVANCE:

Corn silk (Zea mays L., Stigma maydis) is an important herb used traditionally in many parts of the world to treat array of diseases including diabetes mellitus. Inhibitors of α-amylase and α-glucosidase offer an effective strategy to modulate levels of post prandial hyperglycaemia via control of starch metabolism.

AIM OF THE STUDY:

This study evaluated α-amylase and α-glucosidase inhibitory potentials of corn silk aqueous extract. Active principles and antioxidant attributes of the extract were also analysed.

MATERIALS AND METHODS:

The α-amylase inhibitory potential of the extract was investigated by reacting its different concentrations with α-amylase and starch solution, while α-glucosidase inhibition was determined by pre-incubating α-glucosidase with different concentrations of the extract followed by addition of p-nitrophenylglucopyranoside. The mode(s) of inhibition of the enzymes were determined using Lineweaver-Burke plot.

RESULTS:

In vitro analysis of the extract showed that it exhibited potent and moderate inhibitory potential against α-amylase and α-glucosidase, respectively. The inhibition was concentration-dependent with respective half-maximal inhibitory concentration (IC50) values of 5.89 and 0.93mg/mL. Phytochemical analyses revealed the presence of alkaloids, flavonoids, phenols, saponins, tannins and phytosterols as probable inhibitory constituents. Furthermore, the extract remarkably scavenges reactive oxygen species like DPPH and nitric oxide radicals, elicited good reducing power and a significant metal chelating attributes.

CONCLUSION:

Overall, the non-competitive and uncompetitive mechanism of action of corn silk extract is due to its inhibitory effects on α-amylase and α-glucosidase, respectively. Consequently, this will reduce the rate of starch hydrolysis, enhance palliated glucose levels, and thus, lending credence to hypoglycaemic candidature of corn silk.

KEYWORDS:

Acarbose; Active principles; Diabetics; Postprandial hyperglycaemia; Reactive oxygen species

PMID:
26902829
DOI:
10.1016/j.jep.2016.02.024
[Indexed for MEDLINE]

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