title: Effects of phenolic constituents of daylily flowers on corticosterone- and glutamate-treated PC12 cells.
abstract: BACKGROUND
  Daylily flowers, the flower and bud parts of Hemerocallis citrina or H. fulva, are well known as Wang-You-Cao in Chinese, meaning forget-one's sadness plant. However, the major types of active constituents responsible for the neurological effects remain unclear. This study was to examine the protective effects of hydroalcoholic extract and fractions and to identify the active fractions.
  
  
  METHODS
  The extract of daylily flowers was separated with AB-8 resin into different fractions containing non-phenolic compounds, phenolic acid derivatives and flavonoids as determined using UPLC-DAD chromatograms. The neuroprotective activity was measured by evaluating the cell viability and lactate dehydrogenase release using PC12 cell damage models induced by corticosterone and glutamate. The neurological mechanisms were explored by determining their effect on the levels of dopamine (DA), 5-hydroxy tryptamine (5-HT), γ-aminobutyric acid (GABA), noradrenaline (NE) and acetylcholine (ACh) in the cell culture medium measured using an LC-MS/MS method.
  
  
  RESULTS
  Pretreatment of PC12 cells with the extract and phenolic fractions of daylily flowers at concentrations ranging from 0.63 to 5 mg raw material/mL significantly reversed corticosterone- and glutamate-induced neurotoxicity in a dose-dependent manner. The fractions containing phenolic acid derivatives (0.59% w/w in the flowers) and/or flavonoids (0.60% w/w) exerted similar dose-dependent neuroprotective effect whereas the fractions with non-phenolic compounds exhibited no activity. The presence of phenolic acid derivatives in the corticosterone- and glutamate-treated PC12 cells elevated the DA level in the cell culture medium whereas flavonoids resulted in increased ACH and 5-HT levels.
  
  
  CONCLUSIONS
  Phenolic acid derivatives and flavonoids were likely the active constituents of daylily flowers and they conferred a similar extent of neuroprotection, but affected the release of neurotransmitters in a different manner.
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, 151 Malianwa North Road, Haidian District, Beijing, 100193, People's Republic of China.|Key Laboratory of Food Nutrition and Safety, Ministry of Education, College of Food Engineering and Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, People's Republic of China.
authors.forename: Huan
authors.initials: H
authors.lastname: Tian
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, 151 Malianwa North Road, Haidian District, Beijing, 100193, People's Republic of China.
authors.forename: Fei-Fei
authors.initials: FF
authors.lastname: Yang
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, 151 Malianwa North Road, Haidian District, Beijing, 100193, People's Republic of China.
authors.forename: Chun-Yu
authors.initials: CY
authors.lastname: Liu
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, 151 Malianwa North Road, Haidian District, Beijing, 100193, People's Republic of China.|National Key Laboratory of Human Factors Engineering, China Astronaut Research and Training Centre, Beijing, 100094, People's Republic of China.
authors.forename: Xin-Min
authors.initials: XM
authors.lastname: Liu
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, 151 Malianwa North Road, Haidian District, Beijing, 100193, People's Republic of China.
authors.forename: Rui-Le
authors.initials: RL
authors.lastname: Pan
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, 151 Malianwa North Road, Haidian District, Beijing, 100193, People's Republic of China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Chang
authors.affiliation: Key Laboratory of Food Nutrition and Safety, Ministry of Education, College of Food Engineering and Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, People's Republic of China.
authors.forename: Ze-Sheng
authors.initials: ZS
authors.lastname: Zhang
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, 151 Malianwa North Road, Haidian District, Beijing, 100193, People's Republic of China. yhliao@implad.ac.cn.
authors.forename: Yong-Hong
authors.initials: YH
authors.lastname: Liao
mesh_terms: D000818:Animals; D002681:China; D002853:Chromatography, Liquid; D003345:Corticosterone / Q000494:pharmacology; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000494:pharmacology*; D035264:Flowers / Q000737:chemistry; D018698:Glutamic Acid / Q000494:pharmacology; D031421:Hemerocallis / Q000737:chemistry*; D018696:Neuroprotective Agents / Q000302:isolation & purification / Q000494:pharmacology*; D016716:PC12 Cells; D019800:Phenol; D051381:Rats
chemical_list: D004365:Drugs, Chinese Herbal; D018696:Neuroprotective Agents; D019800:Phenol; D018698:Glutamic Acid; D003345:Corticosterone
keywords: Flavonoids; Hemerocallis citrina; Neuroprotection; Neurotransmitters; PC12 cells; Phenolic acid derivatives