Objective: To study the protective effect of Eucommia ulmoides agains UV irradiation-induced damage in ESF-1 cells and its mechanism. Method: E. ulmoides was extracted by 70 ethanol

then the extract was eluted with gradient of ethanol by macroporous resin

ESF-1 cells were immediately treated with different concentrations of 50% ethanol eluate after UVA irradiation (40 J ·cm-2) or UVB irradiation (70 mJ ·cm-2). Twenty-four hours later

the proliferation of cells was detected by MTT

SOD

LDH and MDA content were assayed by colrorimetry and TBA methods respectively. Result: Compared with the UVA group

the concentration of 125

250 mg ·L-1 could increase the proliferation(P<0.05) and reduce the activity of LDH (P<0.05). The concentration of 250 mg ·L-1 could increase the activitiy of SOD (P<0.05) and decreased the content of MDA (P<0.05). Compared with the UVB group

the concentration of 125

250 and 500 mg ·L-1could increase the proliferation (P<0.05). The concentration of 125 mg ·L-1could increase the activity of SOD (P<0.05) and reduce the activity of LDH (P<0.05) and decreased the content of MDA (P<0.05). Conclusion: The ethanol eluate of 50% can inhibit UV irradiation-induced damage in ESF-1 cells. Its mechanism is due to its abilities of increasing SOD

scavenging oxygen free radicals

inhibiting lipid peroxidation

and protecting membrane structure.