Apigenin 4′-O-β-d-glucoside 7-O-β-d)- glucuronide: The copigment in the blue pigment of Centaurea cyanus

The copigment present in the crystalline blue pigment isolated from Blue Boy cornflowers (Centaurea cyanus L.) was identified as apigenin 4′-O-β-glucoside 7-O-β-d-glucuronide. The NMR spectra of aryl glucuronides are discussed.     

Presence of prostaglandins E2 and A2 in canine gastric secretions

The presence of prostaglandins (PGs) was determined in gastric juice obtained from 3 conscious dogs, provided with a chronic gastric fistula. Outputs of acid (mequiv min^?1) and PGs (pg min^?1) were measured in gastric secretions stimulated by pentagastrin (100 or 200 ng kg^?1min^?1). Prostaglandin activity was estimated, after extraction and thin layer chromatography, by radioimmuno-assay of the PGB formed by treatment with alkali. Tritiated PGs were added to gastric juice for the purpose of correcting for PGs recovery. Using this method, the minimum mass of PGB which could be satisfactorily distinguished from zero was 25 pg. Prostaglandins A₂ and E₂ were present in pentagastrin-activated gastric secretions and averaged (mean ± SE, n = 8) 200.7 ± 18.1 and 260.1 ± 18.0 pg min^?1 respectively. The identity of PGA₂ and PGE₂ was confirmed by gas liquid chromatography combined with mass spectrometry. The amount of PGE₂ converted to PGA₂ during extraction, separation and conversion procedures was estimated from the amount of [³H] PGA₂ found when only [³H] PGE₂ had been added to a sample of gastric juice and averaged 14.5% ± 2.0. Our preliminary results support the possibility that PGE₂ and PGA₂ may be of physiological importance in the regulation of canine gastric secretions.     

Stimulation of choline acetyltransferase activity by ethanol in in vitro preparations of rat cerebrum

Choline acetyltransferase activity in homogenates, or in partially purified extracts of rat brain cerebra, was increased by 11–37% in the presence of ethanol when incubated at 38°C with [¹⁴C] acetyl-CoA, choline chloride and alcohol concentrations of 0.17M to 1.02M. In preincubation experiments with enzyme preparations and ethanol, inactivation of the enzyme by the alcohol, which occurs at incubation times longer than 20 minutes, could be at least partially prevented by the addition of certain components of the incubation mixture to the preincubation mixture.