Brudzynski Katrina, Abubaker Kamal, Miotto Danielle
Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario, Canada L2S 3A1.
Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario, Canada L2S 3A1.
Food Chem. 2012 Jul 15;133(2):329-36. doi: 10.1016/j.foodchem.2012.01.035. Epub 2012 Jan 24.
Several compounds with antibacterial activities were identified in honey however, a mechanism by which they lead to bacterial growth inhibition and bacterial death remains still unknown. We recently found that honeys possess DNA degrading activity mediated by honey hydrogen peroxide and an unknown honey component(s). Here we provide evidence that active honeys (MIC90 of 6.25-12.5% v/v) possessed significantly higher levels of phenolics (p<0.02) of higher radical scavenging activities (p<0.005) than honeys of average activity. Removal of H2O2 by catalase eliminated bacteriostatic activities caused by both phenolics and H2O2 suggesting that the growth inhibition resulted from the coupling chemistry between these compounds. Both phenolics and H2O2 were involved in DNA degradation by honeys. Treatment of plasmid DNA with H2O2 alone did not affect the DNA integrity but H2O2 removal from honey by catalase prevented DNA degradation. Polyphenols extracted from honeys degraded plasmid DNA in the presence of H2O2 and Cu(II) in the Fenton-type reaction. The extent of DNA degradation was inversely related to the polyphenol concentration in this system as well as in honeys. At low content, honey polyphenols exerted pro-oxidant activity damaging to DNA. In conclusion, honey phenolics with pro-oxidant activities were necessary intermediates that conferred oxidative action of H2O2. Phenolic/H2O2-induced oxidative stress constituted the mechanism of honey bacteriostatic and DNA damaging activities.
然而，在蜂蜜中已鉴定出几种具有抗菌活性的化合物，但其导致细菌生长抑制和细菌死亡的机制仍然未知。我们最近发现，蜂蜜具有由蜂蜜过氧化氢和一种未知蜂蜜成分介导的DNA降解活性。在此，我们提供证据表明，活性蜂蜜（MIC90为6.25 - 12.5% v/v）的酚类物质含量显著更高（p<0.02），自由基清除活性也更高（p<0.005），高于平均活性的蜂蜜。用过氧化氢酶去除H2O2消除了由酚类物质和H2O2引起的抑菌活性，这表明生长抑制是由这些化合物之间的偶联化学反应导致的。酚类物质和H2O2都参与了蜂蜜对DNA的降解。单独用H2O2处理质粒DNA不会影响DNA完整性，但用过氧化氢酶从蜂蜜中去除H2O2可防止DNA降解。从蜂蜜中提取的多酚在Fenton型反应中，在H2O2和Cu(II)存在的情况下可降解质粒DNA。在该系统以及蜂蜜中，DNA降解程度与多酚浓度呈负相关。在低含量时，蜂蜜多酚发挥促氧化活性，对DNA造成损害。总之，具有促氧化活性的蜂蜜酚类物质是赋予H2O2氧化作用的必要中间体。酚类物质/H2O2诱导的氧化应激构成了蜂蜜抑菌和DNA损伤活性的机制。
