naphthoquinones and catechol

Topics: Biodegradation, Environmental; Catechols; Chromans; Industrial Microbiology; Naphthoquinones; Pseudomonas; Salicylic Acid

Plumbagin, a naphtoquinone present in the roots of Plumbago zeylanica, has been reported to have many beneficial effects such as antibacterial, antifungal, anticancer, antimutagenic and antioxidant effects, but this compound has also been reported to have many side effects. Given the wide use of P. zeylanica in traditional medicine and the various potential therapeutic uses of plumbagin, the present study was carried out to further elucidate the potential genotoxicity and antigenotoxicity of plumbagin in mouse lymphoma L5178Y cells, using the comet assay. Without affecting the cell viability, plumbagin itself was found to induce significant DNA damage at concentrations as low as 0.25 ng/ml. When the cells were exposed to non-DNA damaging concentrations of plumbagin, together with NQNO (known to interact with DNA in many different ways) or catechol (known to induce oxidative DNA damage), plumbagin was found to significantly reduce the catechol-induced DNA damage, but to be without protective effect against the NQNO-induced damage. The fact that non-DNA damaging concentrations of plumbagin diminished the DNA damage induced by catechol, provides further support for the idea that plumbagin may act as an antioxidative agent at low concentrations.

Topics: Animals; Antimutagenic Agents; Antineoplastic Agents, Phytogenic; Catechols; Cell Line, Tumor; Cell Survival; Comet Assay; DNA Damage; Dose-Response Relationship, Drug; Drug Combinations; Drug Interactions; Drug Screening Assays, Antitumor; Hydroxyquinolines; Lymphoma; Mice; Naphthoquinones

Macrophage-like defense cells (hemocytes) of the pond snail Lymnaea stagnalis generate reactive oxygen intermediates (ROIs) upon contact with non-self, following kinetics similar to those of ROI production by mammalian leukocytes during respiratory burst. In this study, several inhibitors of NADPH-oxidase, the key enzyme of the respiratory burst in mammalian phagocytes, were tested for their effect on oxidative activities [as demonstrated by nitroblue tetrazolium (NBT) reduction and luminol-dependent chemiluminescence (LDCL)] of phagocytosing snail hemocytes. In the presence of diphenylene iodonium, zymosan-stimulated hemocytes of L. stagnalis failed to reduce NBT and showed a markedly reduced LDCL response. Also, compounds that prevent assembly of functional NADPH-oxidase complexes in activated mammalian cells were effective; preincubation of hemocytes with 1,4-naphthoquinone inhibited the LDCL response and NBT reduction upon phagocytic stimulation. Furthermore, coincubation but not preincubation with five different catechol-like phenols inhibited oxidative activities of zymosan-stimulated hemocytes. These results imply similarities in composition and regulation of the ROI-generating mechanisms of both mammalian and snail defense cells. It is postulated that in L. stagnalis hemocytes, (1) NADPH-oxidase activity is responsible for ROI production, (2) an active NADPH-oxidase enzyme complex has to be assembled from putative cytosolic and membrane-associated components, and (3) continuous replacement of active NADPH-oxidase enzyme complexes is necessary to sustain respiratory burst-like oxidative activities during interactions with non-self.

Topics: Animals; Anti-Infective Agents; Catechols; Hemocytes; Luminescent Measurements; Luminol; Lymnaea; NADH, NADPH Oxidoreductases; NADPH Oxidases; Naphthoquinones; Nitroblue Tetrazolium; Onium Compounds; Reactive Oxygen Species; Respiratory Burst; Zymosan

Topics: Aldehydes; Benzoates; Carbon Isotopes; Catechols; Chromatography; Escherichia coli; Metabolism; Naphthoquinones; Pharmacology; Research; Shikimic Acid; Spectrophotometry; Ubiquinone; Vitamin K