title: Antioxidant and angiotensin converting enzyme (ACE) inhibitory activities of ethanol extract and pure flavonoids from Adinandra nitida leaves.
abstract: BACKGROUND
  Adinandra nitida Merr. ex. H.L. Li (Theaceae) is an indigenous plant in south China. Its leaves have been reported to have many curative effects such as reducing blood pressure, as well as antibacterial, antioxidant, and analgesic properties, which could be used in foods and medicines.
  
  
  OBJECTIVE
  The antioxidant and angiotensin converting enzyme (ACE) inhibitory activities of the main flavonoids and ethanol extract (EE) of A. nitida leaves were investigated for the first time.
  
  
  METHODS
  The main flavonoids of A. nitida leaves (camellianin A, camellianin B) were prepared and their contents in EE were determined by HPLC. The antioxidant activities of the samples were measured by DPPH radical scavenging assay and Rancimat test. The ACE inhibitory activities of the samples were carried out by using an assay kit with hippuryl-glycyl-glycine as substrate.
  
  
  RESULTS
  The contents of camellianin A, camellianin B and apigenin in EE were determined as 41.98, 2.67, and 1.73%, respectively. The antioxidant activities of the flavonoids were far lower than that of EE in DPPH radical scavenging and Rancimat assays. However, the ACE-inhibitory activities of camellianin A, camellianin B and apigenin were higher than that of EE.
  
  
  CONCLUSIONS
  The flavonoid content of EE was more than 45%. The high activities of EE in DPPH scavenging and Rancimat assay could be mainly attributed to compounds other than flavonoids. However, the ACE-inhibitory activity of EE could be mainly attributed to the presence of the flavonoids.
authors.affiliation: School of Food Science, Henan Institute of Science and Technology, Xinxiang 453003, China. zzgclbg@126.com
authors.forename: Benguo
authors.initials: B
authors.lastname: Liu
authors.forename: Jiguo
authors.initials: J
authors.lastname: Yang
authors.forename: Yuxiang
authors.initials: Y
authors.lastname: Ma
authors.forename: Erdong
authors.initials: E
authors.lastname: Yuan
authors.forename: Chungang
authors.initials: C
authors.lastname: Chen
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D000975:Antioxidants / Q000302:isolation & purification / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D000431:Ethanol / Q000737:chemistry; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology*; D006801:Humans; D010936:Plant Extracts / Q000494:pharmacology; D018515:Plant Leaves; D012997:Solvents / Q000737:chemistry; D028242:Theaceae / Q000737:chemistry*
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D000975:Antioxidants; D005419:Flavonoids; D010936:Plant Extracts; D012997:Solvents; C053580:camellianin B; C053579:camellianin A; D000431:Ethanol