After the oral administration of nicotinamide to human subjects, two ultraviolet-absorbing compounds have regularly been detected on chromatograms of plasma extracts. The less polar of these, named Compound Y, has been identified as N’-methyl2-pyridone-5-carboxamide (1). In the present communication, evidence is presented that the more polar metabolite, Compound X, is N’-methyl-4-pyridone-3-car...

Polar regions are remote and challenging areas on the earth. In view of the unique environment and the severe competition in polar regions, it's considered that the ecological system might be the producer of new compounds with diversity biological activities. This review is an attempt to consolidate the studies about 97 natural products isolated from Antarctic and Arctic organisms including mic...

Molecular polar surface (PS) descriptors are very useful parameters in prediction of drug transport properties. They could be also used to investigate the blood-brain barrier (BBB) permeation rate for various chemical compounds. In this study, a dataset of drugs (n = 19) from various pharmacological groups was studied to estimate their potential properties to permeate across the BBB. Experiment...

■ ■ 2.5 μm particle size provides the flexibility to operate on a variety of systems IN T RO DU C T IO N Hydrophilic-interaction chromatography (HILIC) is increasingly becoming a method of choice for the analysis of polar compounds [1-5]. One set of polar analytes that poses particular challenges are the monoamine neurotransmitters, dopamine (DA), serotonin (5-HT), epinephrine (EP), and norepin...

New Schiff bases derived from 2-aminopyridene and 2-aminopyrazine have been synthesized. The UV-Visible spectra of the compounds have been investigated in acetonitrile and toluene. The compounds were in tautomeric equilibrium (enol-imine O- H...N, keto-amine O...H-N forms) in polar and nonpolar solvents. For some derivatives the keto-amine form was observed in both toluene and acetonitrile. 1H-...