OBJECTIVETo investigate the oxidative damage of ultraviolet A (UVA) to human immortalized keratinocytes line HaCaT and the protective effects of total flavonoids of Broussonetia papyrifera (TFBP) gotten from the leaves of broussonetia papyifera.

METHODSBased on the culture of the human keratinocytes, the experiment group added with different dosages of TFBP before exposure to the radiation, received the UVA radiation together with the treatment group. The levels of malondialdehyde (MDA) and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were determined in cultured HaCaT cells as well as the cell activity with MTT reduction assay. Human immortalized keratinocytes HaCaT cells received ultraviolet A with the different dosages between 0.46 and 2.76 J/cm(2) respectively. The protective effects of TFBP at different concentrations were also evaluated.

RESULTSThe cell activity decreased gradually from 96.3% to 37.5% with the increase of UVA dosage from 0.46 J/cm(2) to 2.76 J/cm(2). After 10 mg/L up to 200 mg/L of TFBP were added the cell activity increased, the levels of MDA decreased from (5.14 +/- 0.58) nmol/mg pro to (2.98 +/- 0.14) nmol/mg pro, the levels of SOD increased from (23.09 +/- 3.91) U/mg pro to (34.50 +/- 1.59) U/mg pro and the activity of GSH-Px increased somewhat.

CONCLUSIONUltraviolet A causes significant oxidative injury to HaCaT cells under the conditions of this study. TFBP gotten from the leaves of broussonetia papyrifera has certain protective effect on HaCaT epithelial cells.