ABSTRACT
A scientifically operated charge-coupled device detector combined with fluorescence quenching high-performance thin-layer chromatographic plates was employed for the detection of organic compounds, The plates were excited with 254 nm light from a mercury lamp, and quantitative information was obtained from organic compounds that absorbed the optimum conditions for detection. The linear dynamic range, sensitivity, and reproducibility of the system were evaluated by quantitative analysis of famotidine, acetaminophen, caffeine, and acetylsalicylic acid. The detection limits of the system were found to be in the nanogram range.
Subject(s)
Chromatography, High Pressure Liquid/methods , Chromatography, Thin Layer/methods , Signal Processing, Computer-Assisted , Acetaminophen/analysis , Acetaminophen/chemistry , Aspirin/analysis , Aspirin/chemistry , Autoanalysis , Caffeine/analysis , Caffeine/chemistry , Chromatography, High Pressure Liquid/instrumentation , Chromatography, Thin Layer/instrumentation , Famotidine/analysis , Famotidine/chemistry , Sensitivity and SpecificityABSTRACT
Four new macrocyclic polypeptides were isolated and identified from an extract of the tropical tree Chassalia parvifolia. Circulins C-F are 29-30 amino acid cyclic peptides in which the entire primary amino acid chain is covalently cyclized via peptide bonds. Their structures were deduced from a combination of FABMS analyses, N-terminal Edman degradation, endoproteinase digestion, and amino acid analyses. All the peptides share a high degree of sequence homology and contain six cysteine residues forming three intramolecular disulfide bridges. Circulins C-F inhibited the cytopathic effects of in vitro HIV-1 infection with EC(50) values of 50-275 nM.
