title: Andrographolide protects liver cells from H2O2 induced cell death by upregulation of Nrf-2/HO-1 mediated via adenosine A2a receptor signalling.
abstract: Andrographolide, principle constituent of Andrographis paniculata Nees is used in traditional medicine in Southeast Asia and is known to exhibit various biological activities. Its antioxidant activity is due to its ability to activate one of the antioxidant enzymes, heme oxygenase-1 (HO-1) which is regulated transcriptionally through Nrf-2. However, molecular mechanism underlying activation of Nrf-2/HO-1 has not yet been clearly understood.
  
  
  
  Protective effect of andrographolide against H2O2 induced cell death, reactive oxygen species and lipid peroxidation was observed in HepG2 cells. Ability of andrographolide to modulate G-protein coupled receptor (GPCR) mediated signalling was determined using in silico docking and gene expression was analyzed by qRT-PCR, confocal microscopy and western blot analysis.
  
  
  
  We clearly show that andrographolide via adenosine A2A receptor signalling leads to activation of p38 MAP kinase, resulting in upregulation of Nrf-2, its translocation to nucleus and activation of HO-1. Additionally, it activates adenylate cyclase resulting in cAMP formation which in turn activates protein kinase A leading to inhibition of GSK-3β by phosphorylation. Inactivated GSK-3β leads to retention of Nrf-2 in the nucleus leading to sustained expression of HO-1 by binding to its antioxidant response element (ARE).
  
  
  
  Thus, andrographolide probably by binding to adenosine A2a receptor activates Nrf-2 transcription and also inhibits its exclusion from the nucleus by inactivating GSK-3β, together resulting in activation of HO-1.
  
  
  
  We speculate that andrographolide can be used as a therapeutic drug to combat oxidative stress implicated in pathogenesis of various diseases such as diabetes, osteoporosis, neurodegenerative diseases etc.
authors.affiliation: Department of Zoology, Savitribai Phule Pune University, Pune 411007, India.
authors.forename: Smriti P K
authors.initials: SPK
authors.lastname: Mittal
authors.affiliation: Department of Zoology, Savitribai Phule Pune University, Pune 411007, India.
authors.forename: Swati
authors.initials: S
authors.lastname: Khole
authors.affiliation: Strategic Science Group, Naturals and Traditional Medicine, Unilever R and D Bangalore 64, Main Road, Whitefield, Bangalore 560066, India.
authors.forename: Nidhi
authors.initials: N
authors.lastname: Jagadish
authors.affiliation: Strategic Science Group, Naturals and Traditional Medicine, Unilever R and D Bangalore 64, Main Road, Whitefield, Bangalore 560066, India.
authors.forename: Debjani
authors.initials: D
authors.lastname: Ghosh
authors.affiliation: Strategic Science Group, Naturals and Traditional Medicine, Unilever R and D Bangalore 64, Main Road, Whitefield, Bangalore 560066, India.
authors.forename: Vijay
authors.initials: V
authors.lastname: Gadgil
authors.affiliation: Strategic Science Group, Naturals and Traditional Medicine, Unilever R and D Bangalore 64, Main Road, Whitefield, Bangalore 560066, India.
authors.forename: Vilas
authors.initials: V
authors.lastname: Sinkar
authors.affiliation: Department of Zoology, Savitribai Phule Pune University, Pune 411007, India. Electronic address: ssg@unipune.ac.in.
authors.forename: Saroj S
authors.initials: SS
authors.lastname: Ghaskadbi
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D016923:Cell Death / Q000187:drug effects; D004224:Diterpenes / Q000494:pharmacology*; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism*; D056945:Hep G2 Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism*; D043705:Receptor, Adenosine A2A / Q000378:metabolism*; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: D000975:Antioxidants; D004224:Diterpenes; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D043705:Receptor, Adenosine A2A; C030419:andrographolide; D006861:Hydrogen Peroxide; D051547:Heme Oxygenase-1
keywords: GSK-3β; HepG2 cells; MAP kinase; Nrf-2; Oxidative stress; Protein kinase A