For the three Gram-negative bacteria, Pseudomonas fluorescens, Escherichia coli, and Erwinia amylovora, p-benzoquinone was the principal bactericidal agent formed in vitro during the oxidation of hydroquinone by horseradish peroxidase, whereas no toxicity could be associated with either phenolic or oxygen-free radicals. Even the continuous generation of p-benzosemiquinone during the simultaneou...

Past efforts to employ a structure-based approach to design an inhibitor of the fusion-inducing conformational change in the influenza virus hemagglutinin (HA) yielded a family of small benzoquinones and hydroquinones. The most potent of these, tert-butyl hydroquinone (TBHQ), inhibits both the conformational change in HA from strain X:31 influenza virus and viral infectivity in tissue culture c...

The mechanism by which reducing power is transferred from the biological quinols, ubiqninol and plastoquinol, to their respective acceptors, presumably cytochrome cl in mitochondria and cytochrome f of chloroplasts, is obscure. The difficulty arises from the fact that, at around neutral pH, the quinols are primarily two-equivalent hydrogen atom donors, whereas their acceptors are primarily one-...

Polychlorinated biphenyls (PCBs) comprise a group of persistent organic pollutants that differ significantly in their physicochemical properties, their persistence, and their biological activities. They can be metabolized via hydroxylated and dihydroxylated metabolites to PCB quinone intermediates. We have recently demonstrated that both dihydroxy PCBs and PCB quinones can form semiquinone radi...

We have compared the steady-state kinetics of wild-type nitrate reductase A and two mutant forms with altered beta subunits. To mimic conditions in vivo as closely as possible, we used analogues of the physiological quinols as electron donors and membranes with overexpressed nitrate reductase A in preference to a purified alpha beta gamma complex. With the wild-type enzyme both menadiol and dur...

Dimethyl-celecoxib is a celecoxib analog that lacks the capacity as cyclo-oxygenase-2 inhibitor and therefore the life-threatening effects but retains the antineoplastic properties. The action mechanism at the molecular level is unclear. Our in vitro assays using a sarcoplasmic reticulum preparation from rabbit skeletal muscle demonstrate that dimethyl-celecoxib inhibits Ca2+-ATPase activity an...

BACKGROUND Endangered plant species are an important resource for new chemistry. Lindera melissifolia is native to the Southeastern U.S. and scarcely populates the edges of lakes and ponds. Quantum mechanics (QM) used in combination with NMR/ECD is a powerful tool for the assignment of absolute configuration in lieu of X-ray crystallography. METHODS The EtOAc extract of L. melissifolia was su...