Oxidative DNA damage negatively affects humans and the research is currently ongoing to find ways to reduce oxidative stress. Oxidative stress has been identified as a key factor in triggering various diseases. Thus, its alleviation is important for human health. Broussonetia kazinoki (B. kazinoki) has been used in traditional Korean medicine as a dermatological therapy to treat burns, pruritus, and acne. B. kazinoki is generally segregated into peeled root (PR), root bark (RB), peeled stem (PS), and stem bark (SB). To assess these components for their antioxidant activity and protection against DNA damage, their ethyl acetate fractions were examined by 1,1-diphenyl-2-picryl hydrazyl (DPPH) and 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging assay. As a result of confirming the expression of factors involved in attenuating DNA damage, the protective effect of SB on oxidative stress suppressed the expression of p-p53 and γ-H2AX. Additionally, the levels of p53 and H2AX mRNA were significantly downregulated. In conclusion, these results indicated that the SB component of B. kazinoki had the potential to be used as an effective natural antioxidant compared to the other parts of the plant.

Abstract
Introduction
Materials and Methods
    Experimental materials
    DPPH radical scavenging activity
    ABTS radical scavenging activity
    Analysis of total phenolic compounds
    Cell culture
    Cell viability
    Immunoblotting
    Reverse transcription-Polymerase chain reaction (RT-PCR)
    Quantitative PCR Analysis
    Statistical analysis
Results and Discussion
References

• Tae-Won Jang(Department of Medicinal Plant Resources, Andong National University)
• Ji-Soo Choi(Department of Medicinal Plant Science, Jungwon University)
• Hoi-Ki Kim(Fanipinkorea Co., Ltd,)
• Eun-Ja Lee(Fanipinkorea Co., Ltd,)
• Ki-Beom Lee(Incheon Business Information Technopark. Biotechnology & Business Center)
• Tae-Hyung Kwon(Department of Research and Development, Chuncheon Bioindustry Foundation)
• Do-Wan Kim(Department of Food Science and Industry, Jungwon University)
• Jeong-Jwa Ahn(Department of Food Science and Industry, Jungwon University)
• Jae-Ho Park(Department of Pharmaceutical Science, Jungwon University) Corresponding author