ABSTRACT
In the present study it has been shown that the reactive nitrogen species, peroxynitrite, can cause at least a 7.1-fold increase in the frequency of occurrence of drug-resistant mutants of Helicobacter pylori at a pathophysiological concentration (e.g. 1.0 microM) and in the presence of CLR. Furthermore, the CLR MIC of these resistant H. pylori strains increased by at least 250 times or higher in CLR susceptibility. In the 45 resistant strains, the modification of 23S rRNA A2142G was the predominant mutation (22/45), followed by A2143G (17/45) within the sequences of 23S rRNA. The other mutants were one each (1/45) in A2142T, and T2269G, and two each (2/45) in C2695G and T1944C, respectively. These results show that the inflammatory host reaction involving induction of reactive oxygen species (e.g. O(.-)2), and the inducible form of nitric oxide synthase, is a significant cause of mutation via peroxynitrite formation, particularly in drug-resistant bacterial strains.
Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial , Helicobacter pylori/drug effects , Helicobacter pylori/genetics , Mutation/drug effects , Nitric Oxide/pharmacology , Peroxynitrous Acid/pharmacology , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , DNA, Bacterial/genetics , Helicobacter Infections/drug therapy , Helicobacter Infections/microbiology , Helicobacter pylori/enzymology , Humans , Microbial Sensitivity Tests , Nitric Oxide/analogs & derivatives , Nitric Oxide Synthase/genetics , Nitric Oxide Synthase/metabolism , RNA, Ribosomal, 23S/geneticsABSTRACT
A potent antioxidative compound in crude canola oil, canolol, was recently identified, and reported herein are studies of its scavenging capacity against the endogenous mutagen peroxynitrite (ONOO(-)). ONOO(-) is generated by the reaction between superoxide anion radical and nitric oxide, both of which are produced by inflammatory leukocytes. Among various antioxidative substances of natural or synthetic origin, canolol was one of the most potent antimutagenic compounds when Salmonella typhimurium TA102 was used in the modified Ames test. Its potency was higher than that of flavonoids (e.g., rutin) and alpha-tocopherol and was equivalent to that of ebselen. Canolol suppressed ONOO(-)-induced bactericidal action. It also reduced intracellular oxidative stress and apoptosis in human cancer SW480 cells when used at a concentration below 20 microM under H(2)O(2)-induced oxidative stress. In addition, canolol suppressed plasmid DNA (pUC19) strand breakage induced by ONOO(-), as revealed by agarose gel electrophoresis.
