Superoxide-producing lipoprotein fraction from Stevia leaves: definition of specific activity

BMC Complement Altern Med. 2019 Apr 25;19(1):88. doi: 10.1186/s12906-019-2500-1.

Abstract

Background: Stevia rebaudiana Bertoni has various pharmacological actions, which includes antidiabetic, antioxidant, anti-inflammatory activities. The superoxide and consequently NADPH oxidase (Nox) are relevant targets involved in biological effects of Stevia. The presence of NADPH-containing superoxide-producing lipoprotein (suprol) in Stevia leaves has not yet been tested. The mechanism of producing superoxide radicals (O2-) by suprol was determined in vitro, which is associated with the electron transfer from NADPH in the composition of suprol by traces of transition metal ions (Fe3+ or Cu2+) to molecular oxygen, turning it into O2-. It is expected that the therapeutic efficacy of Stevia leaves is caused by specific activity of superoxide-producing lipoprotein fraction.

Methods: For the first time, from the dry leaves of Stevia the NADPH-containing superoxide-producing lipoprotein was isolated and purified. The specific content of suprol (milligrams in 1 g of Stevia leaves- mg/g) was determined after desalination of suprol and lyophilization.

Results: According to the method provided, the specific content of the isolated suprol from Stevia's leaves was up to 4.5 ± 0.2 mg / g (yields up to 68.5 ± 4.7%, p < 0.05, n = 6). Nox forms a stable complex with suprol. The optical absorption spectrum of the Nox-suprol complex represents the overlapping suprol and Nox spectra, with a certain background increase and characteristic features of optical absorption for Nox. Due to O2- producing capacity suprol-Nox complex discolors KMnO4 solutions, Coomassie brilliant blue, restores nitrotetrazolium blue to formazan and oxidizes epinephrine to adrenochrome. The oxidation activity of adrenaline is 50.3 ± 5.1 U / mg / ml (p < 0.05, n = 6).

Conclusion: Superoxide-producing lipoprotein fraction-Nox complex from Stevia leaves (membranes) can modulate redox regulated signaling pathways and may play a positive role in type-2 diabetes by means of adrenaline oxidation mechanism.

Keywords: NADPH-containing superoxide-producing lipoprotein (suprol); Stevia leaves.

MeSH terms

  • Lipoproteins* / chemistry
  • Lipoproteins* / metabolism
  • NADP* / chemistry
  • NADP* / metabolism
  • NADPH Oxidases / chemistry
  • NADPH Oxidases / metabolism
  • Oxidation-Reduction
  • Plant Extracts / chemistry
  • Plant Extracts / metabolism
  • Plant Leaves / chemistry
  • Plant Proteins* / chemistry
  • Plant Proteins* / metabolism
  • Stevia / chemistry*
  • Superoxides* / chemistry
  • Superoxides* / metabolism

Substances

  • Lipoproteins
  • Plant Extracts
  • Plant Proteins
  • Superoxides
  • NADP
  • NADPH Oxidases