title: Beneficial effects of Glycyrrhizae radix extract in preventing oxidative damage and extending the lifespan of Caenorhabditis elegans.
abstract: BACKGROUND
  Glycyrrhizae radix (GR) is a medicinal herb extensively used in traditional Chinese medicine. This study aimed to evaluate the pharmacological effect of GR and the possible mechanisms of GR, to provide a pharmacological basis in traditional medicine.
  
  
  METHODS
  In the present study, C. elegans (L1-larvae to young adults) was exposed to 0.12-0.24 g/mL of GR in 12-well sterile tissue culture plates at 20°C in the presence of food. Lethality, growth, lifespan, reproduction, locomotion, metabolism, intestinal autofluorescence, and reactive oxygen species (ROS) production assays were performed to investigate the possible safety profile and beneficial effects of GR in these nematodes. We found that the lifespan of nematodes exposed to 0.18-0.24 g/mL of GR was extended. We then determined the mechanism of the longevity effect of GR using quantitative reverse transcription PCR and oxidative stress resistance assays induced by heat and paraquat.
  
  
  RESULTS
  Prolonged exposure to 0.12-0.24 g/mL of GR did not induce lethality, alter body length, morphology or metabolism, affect brood size, locomotion, the development of D-type GABAergic motor neurons, or induce significant induction of intestinal autofluorescence and intestinal ROS production. In C. elegans, pretreatment with GR suppressed the damage due to heat-stress or oxidative stress induced by paraquat, a ROS generator, on lifespan, and inhibited the induction of intestinal ROS production induced by paraquat. Moreover, prolonged exposure to GR extended lifespan, increased locomotion and decreased intestinal ROS production in adult day-12 nematodes. Furthermore, prolonged exposure to GR significantly altered the expression patterns of genes encoding the insulin-like signaling pathway which had a key role in longevity control. Mutation of daf-16 gene encoding the FOXO transcription factor significantly decreased lifespan, suppressed locomotion, and increased intestinal ROS production in GR exposed adult nematodes.
  
  
  CONCLUSIONS
  GR is relatively safe and has protective effects against the damage caused by both heat-stress and oxidative stress at the examined concentrations. Furthermore, GR is capable of extending the lifespan of nematodes, and the insulin-like signaling pathway may play a crucial role in regulating the lifespan-extending effects of GR.
authors.affiliation: Center for Drug Safety Evaluation and Research, Nanjing University of Chinese Medicine, Nanjing 210023, China; Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing University of Chinese Medicine, Nanjing 210023, China; Jiangsu Key Laboratory for High Technology Research of TCM Formulae, Nanjing University of Chinese Medicine, Nanjing 210023, China.
authors.forename: Qinli
authors.initials: Q
authors.lastname: Ruan
authors.affiliation: Center for Drug Safety Evaluation and Research, Nanjing University of Chinese Medicine, Nanjing 210023, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Qiao
authors.affiliation: Key Laboratory of Developmental Genes and Human Disease in Ministry of Education, Medical School of Southeast University, Nanjing 210009, China.
authors.forename: Yunli
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Center for Drug Safety Evaluation and Research, Nanjing University of Chinese Medicine, Nanjing 210023, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Center for Drug Safety Evaluation and Research, Nanjing University of Chinese Medicine, Nanjing 210023, China; Jiangsu Key Laboratory for High Technology Research of TCM Formulae, Nanjing University of Chinese Medicine, Nanjing 210023, China. Electronic address: mengwang.drug@hotmail.com.
authors.forename: Meng
authors.initials: M
authors.lastname: Wang
authors.affiliation: Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing University of Chinese Medicine, Nanjing 210023, China; Jiangsu Key Laboratory for High Technology Research of TCM Formulae, Nanjing University of Chinese Medicine, Nanjing 210023, China. Electronic address: dja@njutcm.edu.cn.
authors.forename: Jinao
authors.initials: J
authors.lastname: Duan
authors.affiliation: Key Laboratory of Developmental Genes and Human Disease in Ministry of Education, Medical School of Southeast University, Nanjing 210009, China. Electronic address: dayongw@seu.edu.cn.
authors.forename: Dayong
authors.initials: D
authors.lastname: Wang
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects; D006035:Glycyrrhiza / Q000737:chemistry*; D006358:Hot Temperature; D008136:Longevity / Q000187:drug effects*; D009154:Mutation; D018384:Oxidative Stress / Q000187:drug effects*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry*; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D010936:Plant Extracts; D011506:Proteins
keywords: Beneficial effect; Caenorhabditis elegans; Glycyrrhizae radix; Insulin-like signaling; Lifespan; Oxidative stress