2011 Volume 33 Issue 3 Pages 81-88
The anti-genotoxicity effect of aqueous extracts of Connarus ruber cortex was studied in cultured human cells and mice. Connarus extract decreased bi-nuclei cells with micronuclei (MNBNC) significantly in NER-proficient WTK1 cells that were exposed to MNU, MMC, or UVC and in NER-deficient XPL3KA cells (that is, in XP-C) that were exposed to MNU or MMC, but not UVC. The genotoxicity-suppressing effect was further studied by the comet assay. Connarus extract decreased DNA migration significantly in WTK1 cells that were exposed to MNU or UVC and in XPL3KA cells that were exposed to MNU but not UVC. In WTK1 cells, in contrast, DNA migration increased with the extract in the presence of DNA repair inhibitors (araC and HU), suggesting that the anti-genotoxic potential is due to an enhanced incision step of global genome repair (GGR) subpathways in NER. Chemical analysis revealed that the extract contains epicatechine, one of the anti-mutagenic components contained in green tea. Connarus extract fractions that decreased UVC-induced DNA migration were those not to contain epicatechine and they were different from those that decreased MNU-induced DNA migration, suggesting that some anti-mutagenic components other than epicatechine might be contained in Connarus extract and that a number of anti-genotoxic components with different modes of anti-genotoxicity are contained in Connarus extract. The anti-clastogenic effect of Connarus extracts was examined in mice using a micronucleus assay. When mice received ≦2000 mg/kg Connarus extract by oral gavage at the same time as intraperitoneal injection of MMC, a decrease in the frequency of micronucleated reticulocytes was observed. This decrease was not due to a delay in the maturation of micronucleated reticulocytes.
