5-Hydroxytrytophan inhibits tert-butylhydroperoxide (t-BHP)-induced oxidative damage via the suppression of reactive species (RS) and nuclear factor-kappaB (NF-kappaB) activation on human fibroblast.
5-Hydroxytryptophan (5HTP), an analogue of tryptophan, is a precursor of serotonin that also has effective antioxidative and anti-apoptotic properties (1) . However, the cellular mechanisms underlying these properties of 5HTP have not been explored. In this study, we tested the hypothesis that 5HTP exerts its antioxidative action against oxidative stress and inflammation by suppressing the activation of the key pro-inflammatory transcriptional pathways, p38 mitogen-activated protein kinase (p38MAPK) and nuclear factor-kappaB (NF-kappaB). The study was carried out using human fibroblast cells that were challenged by tert-butylhydroperoxide (t-BHP)-induced oxidative damage. Results show that 5HTP significantly reduced t-BHP-induced oxidative damage in human fibroblast cells, as determined by cell cytotoxicity, intracellular reactive species (RS) and peroxynitrite (ONOO(-)) generation, and inducible nitric oxide synthase expression. Moreover, 5HTP protected human fibroblast cells against t-BHP-induced oxidative DNA damage, as determined by 4,6-diamidino-2-phenlylindole (DAPI) staining. Pretreatment of human fibroblast cells with 5HTP also dose-dependently inhibited glutathione (GSH) depletion, indicating that it protects cells against t-BHP-induced oxidative damage. Western blot analysis revealed that 5HTP also markedly increased Bcl-2 expression and suppressed both p38MAPK and NF-kappaB activation in the t-BHP-treated human fibroblast cells. When these results are taken together, they strongly indicate that 5HTP has beneficial and protective effects against t-BHP-induced cell death in vitro, as demonstrated by its antioxidative and anti-inflammatory actions. Data further showed that the protective mechanisms underlying the actions of 5HTP against oxidative stress-induced damage are associated with RS/ONOO(-) scavenging and the inhibition of lipid peroxidation and GSH depletion.
Bae
Sung Jin
SJ
Department of Pharmacy, Pusan National University, Busan 609-735, Korea.
Lee
Jun Sik
JS
Kim
Ji Min
JM
Lee
Eun Kyeong
EK
Han
Yu Kyeong
YK
Kim
Hyun Jung
HJ
Choi
Jehun
J
Ha
Young Mi
YM
No
Jae-Kyung
JK
Kim
Yun Hee
YH
Yu
Byung Pal
BP
Chung
Hae Young
HY
D006916:5-Hydroxytryptophan / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects; D005347:Fibroblasts / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D005978:Glutathione / Q000032:analysis; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D016328:NF-kappa B / Q000032:analysis / Q000037:antagonists & inhibitors*; D052247:Nitric Oxide Synthase Type II / Q000032:analysis; D018384:Oxidative Stress / Q000187:drug effects*; D030421:Peroxynitrous Acid / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000032:analysis / Q000037:antagonists & inhibitors; D020122:tert-Butylhydroperoxide / Q000494:pharmacology*
D000975:Antioxidants; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D030421:Peroxynitrous Acid; D020122:tert-Butylhydroperoxide; D006916:5-Hydroxytryptophan; D052247:Nitric Oxide Synthase Type II; D048051:p38 Mitogen-Activated Protein Kinases; D005978:Glutathione