Different curcuminoids inhibit T-lymphocyte proliferation independently of their radical scavenging activities.
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.
Deters
Michael
M
Institute of Pharmacology, Hannover Medical School, 30623, Hannover, Germany.
Knochenwefel
Heiko
H
Lindhorst
Daniel
D
Koal
Therese
T
Meyer
Hartmut H
HH
Hänsel
Wolfram
W
Resch
Klaus
K
Kaever
Volkhard
V
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*
D001713:Biphenyl Compounds; D017252:CD3 Complex; D016166:Free Radical Scavengers; D010851:Picrates; C004931:1,1-diphenyl-2-picrylhydrazyl; D003474:Curcumin