Abstract: Objective To explore the antioxidant effect and mechanism of kaempferol(KP), a component of Vernonia anthelmintica (L.) Willd., in human immortalized keratinocytes (HaCaT). Methods Using selective reaction/multiple response monitoring technique for quantitative analysis of the flavonoids in the seeds of Vernonia anthelmintica (L.) Willd.. HaCaT cells were divided into control group, model group(HaCaT cells were treated with AAPH to establish the oxidative stress model), low-, middle- and high-dose KP intervention groups.CCK-8 assay for proliferation, RT-qPCR was used for checking the expression of Nrf2, HO-1, NQO1, GCLC and GCLM mRNA, Western blot was used for checking the expression of Nrf2 protein. Results 1)The content of total flavonoids of Vernonia anthelmintica (L.) Willd.. was 0.97 g/100 g, and a total of 36 flavonoid compounds were quantified, the content of KP was 62.96 ng/100 g. 2)The optimum concentration of AAPH for constructing oxidative stress model was 25 mmol/L, and when the concentration of KP was 0-40 μmol/L, no obvious cytotoxicity was found. 3)Low-dose KP increased the expression of Nrf2, HO-1 and GCLC mRNA. Among them, the expression of HO-1 changed most significantly. 4)KP increased the expression of Nrf2 protein in a concentration-dependent manner. Conclusions A component of Vernonia anthelmintica (L.) Willd., reduces the oxidative stress injury of human keratinocytes, the mechanism might be related to the up-regulation of Nrf2 expression.

Key words: Vernonia anthelmintica (L.) Willd., kaempferol, vitiligo, oxidative stress, keratinocytes