title: Trimer procyanidin oligomers contribute to the protective effects of cinnamon extracts on pancreatic β-cells in vitro.
abstract: OBJECTIVE
  Cinnamon extracts rich in procyanidin oligomers have shown to improve pancreatic β-cell function in diabetic db/db mice. The aim of this study was to identify the active compounds in extracts from two species of cinnamon responsible for the pancreatic β-cell protection in vitro.
  
  
  METHODS
  Cinnamon extracts were prepared from Cinnamomum tamala (CT-E) and Cinnamomum cassia (CC-E). Six compounds procyanidin B2 (cpd1), (-)-epicatechin (cpd2), cinnamtannin B1 (cpd3), procyanidin C1 (cpd4), parameritannin A1 (cpd5) and cinnamtannin D1 (cpd6) were isolated from the extracts. INS-1 pancreatic β-cells were exposed to palmitic acid (PA) or H2O2 to induce lipotoxicity and oxidative stress. Cell viability and apoptosis as well as ROS levels were assessed. Glucose-stimulated insulin secretion was examined in PA-treated β-cells and murine islets.
  
  
  RESULTS
  CT-E, CC-E as well as the compounds, except cpd5, did not cause cytotoxicity in the β-cells up to the maximum dosage using in this experiment. CT-E and CC-E (12.5-50 μg/mL) dose-dependently increased cell viability in both PA- and H2O2-treated β-cells, and decreased ROS accumulation in H2O2-treated β-cells. CT-E caused more prominent β-cell protection than CC-E. Furthermore, CT-E (25 and 50 μg/mL) dose-dependently increased glucose-stimulated insulin secretion in PA-treated β-cells and murine islets, but CC-E had little effect. Among the 6 compounds, trimer procyanidins cpd3, cpd4 and cpd6 (12.5-50 μmol/L) dose-dependently increased the cell viability and decreased ROS accumulation in H2O2-treated β-cells. The trimer procyanidins also increased glucose-stimulated insulin secretion in PA-treated β-cells.
  
  
  CONCLUSIONS
  Trimer procyanidins in the cinnamon extracts contribute to the pancreatic β-cell protection, thus to the anti-diabetic activity.
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.|School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Sun
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Wang
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Chen
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Bang-Wei
authors.initials: BW
authors.lastname: Yu
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Jia
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.|School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Kai-Xian
authors.initials: KX
authors.lastname: Chen
authors.affiliation: Department of Cardiovascular and Thoracic Surgery, Shanghai Heart Failure Research Center, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200123, China.
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Fan
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Li
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: He-Yao
authors.initials: HY
authors.lastname: Wang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002935:Cinnamomum zeylanicum / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D006861:Hydrogen Peroxide; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D007515:Islets of Langerhans / Q000378:metabolism; D015394:Molecular Structure; D018384:Oxidative Stress / Q000187:drug effects; D019308:Palmitic Acid; D010936:Plant Extracts / Q000737:chemistry; D044945:Proanthocyanidins / Q000302:isolation & purification / Q000494:pharmacology*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D007328:Insulin; D010936:Plant Extracts; D044945:Proanthocyanidins; D017382:Reactive Oxygen Species; D019308:Palmitic Acid; D006861:Hydrogen Peroxide