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.

In this study, we evaluated the whitening activity of prethanol A and water extracts from Abeliophyllum distichum Nakai. The extracts were prepared using 0, 50, 70, and 100% prethanol A at 121℃, 1.2 atm for 15 minutes. To confirm effective extraction, the acteoside content of each extract was analyzed with the HPLC-PDA method. The antioxidant activity was evaluated using DPPH and ABTS scavenging activity assays, and the whitening activity was evaluated based on inhibitory activities on the protein and mRNA expression of tyrosinase, tyrosinase-related protein 1 (TRP-1), tyrosinase-related protein 2 (TRP-2), and microphthalmia-associated transcription factor (MITF) in B16 F10 cells. Each extract showed strong antioxidant and whitening activity. IC50 values of antioxidant activity from each extract were in order of 100%, 70%, 50%, and 0%. In addition, whitening activity inhibited the protein and mRNA expression of melanin synthesis factor, following the same pattern as antioxidant activity. In conclusion, water and prethanol A extracts of A. distichum showed effective antioxidant and whitening activity and are thus considered to be valuable materials for whitening cosmetics. The results of this study will also provide basic data for the safe and efficient production of A. distichum as a cosmetic material.