Effects of resveratrol and curcumin on IL-1β-induced apoptosis as demonstrated by poly(ADP-Ribose) polymerase cleavage in primary chondrocytes. As IL-1β-mediated, caspase-induced cleavage of the DNA repair enzyme poly(ADP-Ribose) polymerase (PARP) is a sign of apoptosis, primary chondrocyte cultures were treated with 10 ng/ml IL-1β, 50 μM resveratrol, 50 μM curcumin, 50 μM resveratrol and 50 μM curcumin, or pre-treated with 50 μM resveratrol, 50 μM curcumin, 50 μM resveratrol and 50 μM curcumin for 4 hours and then co-treated with 10 ng/ml IL-1β, or left untreated for 24 hours. Equal amounts (500 ng protein per lane) of total protein were separated by 7.5% SDS-PAGE and analysed by immunoblotting with anti-PARP antibody. Stimulation of chondrocytes with IL-1β alone induced PARP cleavage. Pre-treatment with either resveratrol, curcumin or a combination of both inhibited IL-1β-induced PARP cleavage, however, and levels seen were similar to control cultures. Synthesis of the housekeeping protein β-actin remained unaffected.