title: Different curcuminoids inhibit T-lymphocyte proliferation independently of their radical scavenging activities.
abstract: OBJECTIVE
  We investigated the inhibitory effects of curcumin, curcumin derivatives and degradation products on OKT3-induced human peripheral blood mononuclear cell (PBMC) proliferation and the role of their radical scavenging activity.
  
  
  METHODS
  OKT3-induced human PBMC proliferation was determined by measuring 3H-thymidine incorporation. Radical scavenging activity was evaluated by using an in vitro DPPH assay.
  
  
  RESULTS
  OKT3-induced PBMC proliferation was inhibited by curcumin, isocurcumin, bisdesmethoxy-, diacetyl-, tetrahydro-, hexahydro-, and octahydrocurcumin as well as by vanillin, ferulic acid, and dihydroferulic acid with IC50-values of 2.8, 2.8, 6.4, 1.0, 25, 38, 82, 729, 457, and >1,000 microM, respectively. The investigated substances with the strongest effect on radical scavenging were tetrahydro-, hexahydro-, and octahydrocurcumin with IC50 values of 10.0, 11.7, and 12.3 microM, respectively. IC50-values of dihydroferulic acid, ferulic acid, and curcumin were 19.5, 37, and 40 microM. The substances with the lowest radical scavenging activities were vanillin, isocurcumin, diacetylcurcumin, and bisdesmethoxycurcumin with IC50 values higher than 100 microM each.
  
  
  CONCLUSIONS
  Curcuminoid-induced inhibition of OKT3-induced PBMC proliferation depends on the number of carbon atoms and double bonds of the 1,6-heptadiene-3,5-dione structure as well as on the phenolic ring substitutes of the curcuminoids but is not correlated to their respective radical scavenging activity.
authors.affiliation: Institute of Pharmacology, Hannover Medical School, 30623, Hannover, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Deters
authors.forename: Heiko
authors.initials: H
authors.lastname: Knochenwefel
authors.forename: Daniel
authors.initials: D
authors.lastname: Lindhorst
authors.forename: Therese
authors.initials: T
authors.lastname: Koal
authors.forename: Hartmut H
authors.initials: HH
authors.lastname: Meyer
authors.forename: Wolfram
authors.initials: W
authors.lastname: Hänsel
authors.forename: Klaus
authors.initials: K
authors.lastname: Resch
authors.forename: Volkhard
authors.initials: V
authors.lastname: Kaever
mesh_terms: D000328:Adult; D001713:Biphenyl Compounds; D017252:CD3 Complex / Q000276:immunology; D049109:Cell Proliferation / Q000187:drug effects; D003474:Curcumin / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D010851:Picrates / Q000494:pharmacology; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013601:T-Lymphocytes / Q000187:drug effects*
chemical_list: D001713:Biphenyl Compounds; D017252:CD3 Complex; D016166:Free Radical Scavengers; D010851:Picrates; C004931:1,1-diphenyl-2-picrylhydrazyl; D003474:Curcumin