Inhibitory effect of quercetin on tumor necrosis factor and interleukin-1 beta pro-osteoclastic activities.

AIM: To study the effects of quercetin on tumor necrosis factor (TNF) and interleukin-1 beta (IL-1 beta) pro-osteoclastic activities. METHODS: [3H] TdR uptake by osteoblasts was used to measure cell proliferation, microspectrophotometer for cellular AIP activity using p-nitrophenyl phosphate as enzyme substrate, and radioimmunoassay for prostaglandin E2. RESULTS: Quercetin 5-40 mumol.L-1 reduced the inhibition of cell proliferation and AIP activity induced by TNF or IL-1 beta in a concentration-dependent manner. PGE2 production stimulated by either cytokines was also reduced by quercetin at 20 and 40 mumol.L-1. CONCLUSION: quercetin exerted a marked inhibitory effect on TNF and IL-1 activities, related to their pro-osteoclastic function.