Inhibitory effect of quercetin on tumor necrosis factor and interleukin 1β
AIM: To study the effects of quercetin on tumor necrosis 
factor (TNF) and interleukin 1β (IL 1β) pro osteoclastic 
activities. METHODS: TdR uptake by osteoblasts was used to measure 
cell proliferation, microspectrophotometer for cellular AlP activity 
using p nitrophenyl phosphate as enzyme substrate, and 
radioimmunoassay for prostaglandin E 2. RESULTS: Quercetin 5-40 μ 
mol·L -1 reduced the inhibition of cell proliferation and AlP 
activity induced by TNF or IL 1β in a concentration dependent 
manner. PGE 2 produc￣tion stimulated by either cytokines was also 
reduced by quercetin at 20 and 40 μmol·L -1 . CONCLUSION: 
quercetin exerted a marked inhibitory effect on TNF and IL 1 
activities, related to their pro osteoclastic function.