Hepatoprotective efficacy of Nigella sativa seeds dietary supplementation against lead acetate-induced oxidative damage in rabbit - Purification and characterization of glutathione peroxidase

Biomed Pharmacother. 2017 May;89:711-718. doi: 10.1016/j.biopha.2017.02.044. Epub 2017 Mar 24.

Abstract

Lead (Pb) is a toxic ubiquitous environmental pollutant that induces hepatotoxicity in both animals and humans. The ability of Nigella saliva seeds (NSS) in ameliorating lead acetate (PbAc)-induced hepatic oxidative damage was investigated using a rabbit model. Forty New Zealand rabbits were given feed and water ad libitum. They were allocated randomly into four groups: control; PbAc (5g/L drinking water); NSS (20g/kg diet) and NSS+PbAc groups. After two months, liver samples were collected and analyzed for malondialdehyde (MDA), glutathione (GSH), glutathione S-transferase (GST) and glutathione peroxidase (GPx) contents. Purification and characterization of GPx were also evaluated. PbAc exposure significantly (p<0.05) increased MDA (lipid peroxidation biomarker) and reduced the GSH levels and the GST and GPx activities. Concurrently supplemented NSS significantly (p<0.05) decreased MDA levels and restored the GSH, GST, and GPx contents successfully. Electrophoretically, the homogeneous GPx preparation from the liver had a specific activity of 30.44 U/mg protein and a yield of 1.31%. The Km values for cumene hydroperoxide were 4.76μM in control, PbAc and NSS+PbAc groups, and 4.09μM in NSS group. The GPx reaction had a temperature optimum 40°C, pH optimum 8 and molecular weight 21 kDa. The obtained data indicated the potent efficacy of NSS against PbAc-induced oxidative stress; that was mediated through induction and activation of antioxidants, particularly GPx and scavenging free radicals. Moreover, the purified hepatic GPx is characterized as a selenoprotein (Se-GPx).

Keywords: Antioxidants; Enzyme purification; Lead toxicity; Nigella sativa; Oxidative stress; Protein expression.

MeSH terms

  • Animals
  • Antioxidants / pharmacology
  • Chemical and Drug Induced Liver Injury / prevention & control*
  • Diet
  • Dietary Supplements
  • Free Radical Scavengers / pharmacology
  • Glutathione / metabolism
  • Glutathione Peroxidase / chemistry
  • Glutathione Peroxidase / metabolism*
  • Male
  • Malondialdehyde / metabolism
  • Nigella sativa / chemistry*
  • Organometallic Compounds / toxicity*
  • Oxidative Stress / drug effects*
  • Plant Extracts / pharmacology*
  • Protective Agents / pharmacology*
  • Rabbits
  • Seeds / chemistry

Substances

  • Antioxidants
  • Free Radical Scavengers
  • Organometallic Compounds
  • Plant Extracts
  • Protective Agents
  • Malondialdehyde
  • Glutathione Peroxidase
  • Glutathione
  • lead acetate