Abstract: ObjectiveTo study the effect of curcum in(Cur)on the imto chondria and some correlation facto rs in HaCaT cells irradiated with UVB and its protection effect on the cells damaged by UVB.MethodsAfter different doses of Cur were added into HaCaT cells irradiated with UVB,the cells were continually cultured.The mitochondria membrane potential(Δψ)and the free intracellular calcium(Ca²⁺i)concentration were measured with Rhodamine 123 and Fluo-3/AM fluo rescence,respectively.The prote in expressions of caspase-3 and cytochromc(Cytc)were examined by flowcy tometry.ResultsAs compared with tho sein the normal control group after UVB irradiation,all indices increased significantly(P<0.01).The cell population of olig-Δψ potential was 80.8±2.23%;theCa²⁺i concentra tion was 71.9±1.61% and the prote in expressions of caspase-3 and Cytc were 29.00±1.60% and 27.5±1.60%,respectively.As compared with tho sein the UVB group,a down-regulation dose-effects of Cur in the Δψ potential andCa²⁺i concentration and the prote in expressions of caspase-3 and Cytc were shown.ConclusionThe results suggest that Cur could inhibit HaCaT cell apoptosis caused by UVB irradiation through the increase of Δψ potential and the decreases of theCa²⁺i concentration and the cascade reaction of Cytc and caspase-3,and have protective effect on HaCaT cells damaged by UVB.