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: [H-3]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 E(2). RESULTS: Quercetin 5 - 40 mu mol . L(-1) reduced the inhibition of cell proliferation and AIP activity induced by TNF or IL-1 beta in a concentration-dependent manner. PGE(2) production stimulated by either cytokines was also reduced by quercetin at 20 and 40 mu mol . L(-1) CONCLUSION: quercetin exerted a marked inhibitory effect on TNF and IL-1 activities, related to their pro-osteoclastic function.