Journal of
Medicinal Plants Research

  • Abbreviation: J. Med. Plants Res.
  • Language: English
  • ISSN: 1996-0875
  • DOI: 10.5897/JMPR
  • Start Year: 2007
  • Published Articles: 3672

Full Length Research Paper

Antioxidant and α-amylase inhibition activities in vitro of various solvent extracts of Thymus schimperi Ronniger

Engeda Dessalegn
  • Engeda Dessalegn
  • Center for Food Science and Nutrition, College of Natural Science, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia.
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Geremew Bultosa
  • Geremew Bultosa
  • Department of Food Science and Postharvest Technology, Haramaya University, P.O. Box 138, Dire Dawa, Ethiopia.
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Gulelat Desse Haki
  • Gulelat Desse Haki
  • Center for Food Science and Nutrition, College of Natural Science, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia.
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H. P. Vasantha Rupasinghe*
  • H. P. Vasantha Rupasinghe*
  • Department of Environmental Sciences, Faculty of Agriculture, Dalhousie University P.O. Box 550, Truro, Nova Scotia B2N 5E3, Canada.
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  •  Received: 11 May 2015
  •  Published: 17 April 2015

Abstract

Thymus schimperi Ronniger is a wild endemic herb to Ethiopia, and is traditionally used as food flavoring, preservative as well as medicinal ingredient. This paper reports the total phenolic and flavonoid contents, antioxidant capacity and α-amylase inhibition activity of various solvent extracts of the dried leaves. The acetone extracts contained the highest total phenolic content (122.0±11.6 mg GAE/g). Total flavonoid content was the highest in methanol extract (45.1±2.9 mg QRE/g). The aqueous methanol extract showed the highest 2,2-diphenylpicrylhydrazyl (DPPH) radical scavenging ability (IC50 =11.0±1.0 µg/ml), iron reducing power (60.1±1.0 mg AAE/g), and total antioxidant capacity (1.1±0.1 mg BHTE/g). The water extract exhibited the highest iron chelating activity (IC50 = 65.4±1.1 µg/ml) while the methanol extract exhibited the highest percentage of α-amylase inhibition activity (IC50 = 335. 6±90.4 µg/ml). Except for iron chelating activity, all antioxidant activities were positively correlated with total phenolic and flavonoid contents. The study revealed that antioxidant and α-amylase inhibitory activities of the crude extract were variable when extracted by different solvents indicating a high potential to be used as natural antioxidants in food preservation as well as for preventing oxidative stress mediated human disorders.  

 

Key words: Antioxidant activity, α-amylase, BHT, phenolic, Thymus schimperi Ronniger, thyme.