Article · Volume 13, Issue 51S · pp. S519–S524
Correlation Between Polyphenol Oxidase (PPO) Activity and Total Phenolic Contents in Crocus sativus L. Corms During Dormancy and Sprouting Stages
Nardana Esmaeili1, Hassan Ebrahimzadeh2, Khosrou Abdi3
- 1Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA.
- 2Department of Plant Biology, School of Biology, College of Science, University of Tehran, Tehran.
- 3Department of Radiopharmacy and Medicinal Chemistry, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran.
Abstract
Purification and characterization of polyphenol oxidase (PPO) enzyme and determination of total phenolic contents during dormancy and sprouting stages in Crocus sativus corms were performed. PPO enzyme was purified by ammonium sulfate precipitation and ion-exchange chromatography using DEAE-Sephadex A25 and two isoenzymes were obtained on the SDS- PAGE, which corresponded to molecular weights of 70 and 54 kDa. The Km values of the enzyme were 4.87 and 2.12 mM for l-DOPA in dormancy and waking stages, respectively. Also, enzyme showed higher Vmax values of 0.026 (ΔOD.min-1) in dormancy compared with the value of 0.019 (ΔOD. min-1) in waking corms. Results showed an inverse correlation between phenolic contents and PPO activity. Accordingly, it can be concluded that as plant progressed through sprouting stage, in contrast to polyphenol oxidase activity, there was a significant increase in total amount of phenolic compounds, as determined by Folin-Ciocalteu method and water and aqueous ethanol extractions.
Keywords: Crocus sativus; DEAE-Sephadex A25; phenolics; polyphenol oxidase
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