The condensation of 3-hydroximino-2-butanone (1) with 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione (2) yields 6,7-dimethyl-8-ribityllumazine (3). At slightly alkaline pH, the carbonyl group of 1 reacts preferentially with the 5-amino group of 2 (regioselectivity, 4:1). Under acidic conditions, the reaction occurs with higher yield and marginal regioselectivity of opposite direction (1:1.4)...

The complexes of divalent Cobalt with bis(2,6-diacetyl pyridine monoxime)1,2-diiminobenzene have been prepared separately in presence of respective salts. The general molecular formula of the complexes have been found to be [Co(L)]X2 where L=Bis(2,6-diacetyl pyridine monoxime)1,2-di-iminobenzene, X=chloride, bromide, sulphate, perchlorate, nitrate, acetate ions, On the characterisation of the c...

BACKGROUND Bronchiolitis obliterans, an irreversible lung disease, was first associated with inhalation of butter flavorings (diacetyl) in workers at a microwave popcorn company. Excess rates of lung-function abnormalities were related to cumulative diacetyl exposure. Because information on potential excess mortality would support development of permissible exposure limits for diacetyl, we inve...

We report the engineering of Lactococcus lactis for the efficient conversion of sugar into diacetyl by combining NADH-oxidase overproduction and alpha-acetolactate decarboxylase inactivation. Eighty percent of the carbon flux was found to be rerouted via alpha-acetolactate to the production of diacetyl by preloading the cells with NADH-oxidase before their use as a cell factory.

Diacetyl is a by-product of pyruvate metabolism in Lactococcus lactis, where pyruvate is first converted to alpha-acetolactate, which is slowly decarboxylated to diacetyl in the presence of oxygen. L. lactis usually converts alpha-acetolactate to acetoin enzymatically, by alpha-acetolactate decarboxylase encoded by the aldB gene. We took advantage of the fact that this enzyme also has a central...

Both diacetyl and acetoin were produced by cell-free extracts and cultures of Pseudomonas fluorescens, Aerobacter aerogenes, Lactobacillus brevis, and Saccharomyces cerevisiae 299, whereas only acetoin was produced by cell-free extracts and cultures of Streptococcus lactis, Serratia marcescens, Escherichia coli, and S. cerevisiae strains 513 and 522. Cell-free extracts that produced diacetyl di...

The free-living spirochete Spirochaeta aurantia was nearly as susceptible to diacetyl chloramphenicol, the product of chloramphenicol acetyltransferase, as it was to chloramphenicol itself. This unexpected susceptibility to diacetyl chloramphenicol was wholly or partly the consequence of intrinsic carboxylesterase activity, as indicated by high-performance liquid chromatography, thin-layer chro...

The target site for inhaled vapor-induced injury often differs in mouth-breathing humans compared with nose-breathing rats, thus complicating the use of rat inhalation toxicity data for assessment of human risk. We sought to examine sensitivity of respiratory/transitional nasal (RTM) and tracheobronchial (TBM) mucosa to two electrophilic irritant vapors: diacetyl and acrolein. Computational flu...

BACKGROUND There are > 7,000 e-cigarette flavors currently marketed. Flavoring chemicals gained notoriety in the early 2000s when inhalation exposure of the flavoring chemical diacetyl was found to be associated with a disease that became known as "popcorn lung." There has been limited research on flavoring chemicals in e-cigarettes. OBJECTIVE We aimed to determine if the flavoring chemical d...