title: The Establishment of an Assay to Measure DNA Polymerase-Catalyzed Repair of UVB-Induced DNA Damage in Skin Cells and Screening of DNA Polymerase Enhancers from Medicinal Plants.
abstract: An in vitro assay method was established to measure the activity of cellular DNA polymerases (Pols) in cultured normal human epidermal keratinocytes (NHEKs) by modifying Pol inhibitor activity. Ultraviolet (UV) irradiation enhanced the activity of Pols, especially DNA repair-related Pols, in the cell extracts of NHEKs. The optimal ultraviolet B (UVB) exposure dose and culture time to upregulate Pols activity was 100 mJ/cm² and 4-h incubation, respectively. We screened eight extracts of medicinal plants for enhancement of UVB-exposed cellular Pols activity using NHEKs, and found that rose myrtle was the strongest Pols enhancer. A Pols' enhancement compound was purified from an 80% ethanol extract of rose myrtle, and piceatannol was isolated by spectroscopic analysis. Induction of Pol activity involved synergy between UVB irradiation and rose myrtle extract and/or piceatannol. Both the extract and piceatannol reduced UVB-induced cyclobutane pyrimidine dimer production, and prevented UVB-induced cytotoxicity. These results indicate that rose myrtle extract and piceatannol, its component, are potential photo-protective candidates for UV-induced skin damage.
authors.affiliation: Research Center, Maruzen Pharmaceuticals Co., Ltd., Onomichi, Hiroshima 722-0062, Japan. s-ikeoka@maruzenpcy.co.jp.
authors.forename: Sawako
authors.initials: S
authors.lastname: Ikeoka
authors.affiliation: Research Center, Maruzen Pharmaceuticals Co., Ltd., Onomichi, Hiroshima 722-0062, Japan. t-nakahara@maruzenpcy.co.jp.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Nakahara
authors.affiliation: Research Center, Maruzen Pharmaceuticals Co., Ltd., Onomichi, Hiroshima 722-0062, Japan. h-iwahashi@maruzenpcy.co.jp.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Iwahashi
authors.affiliation: Graduate School of Agriculture, Shinshu University, Minamiminowa-mura, Kamiina-gun, Nagano 399-4598, Japan. mizushina0101@gmai.com.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Mizushina
mesh_terms: D002460:Cell Line; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D010936:Plant Extracts / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry*; D014466:Ultraviolet Rays / Q000009:adverse effects
chemical_list: D010936:Plant Extracts; D004259:DNA-Directed DNA Polymerase
keywords: DNA polymerases; enzyme enhancer; normal human epidermal keratinocytes (NHEK); piceatannol; rose myrtle; ultraviolet B (UVB)