This work relates the development of an analytical methodology to simultaneously determine three methylxanthines (caffeine, theobromine, and theophylline) in beverages and urine samples based on reversed-phase high-performance liquid chromatography. Separation is made with a Bondesil C18 column using methanol-water-acetic acid or ethanol-water-acetic acid (20:75:5, v/v/v) as the mobile phase at...

Communications to the Editor local vasodilator and reduces platelet aggregation in vitro; it is believed to mediate dipyridamole’s in moo antiplatelet and vasodilator effects. It is unclear how methylxanthines cause bronchodilation; almost all act to block adenosine receptors. Aminophylline has been shown to reduce cerebral blood flow, probably by antagonizing the vasodilator effects of adenosi...

Bronchial asthma is characterized by persistent airway inflammation and airway wall remodeling. Among many different cells and growth factors triggering changes in bronchi structure, transforming growth factor β1-induced fibroblast to myofibroblast transition is believed to be very important. The aim of this study was to evaluate whether theophylline (used in asthma therapy) and two other methy...

Chromatographic system for simultaneous determination of levodopa, biogenic amines, and methylxanthines in food has been developed. Chromatographic column and precolumn with octadecylsilane phase and simultaneously fluorescence and DAD detectors have been used. Gradient elution with acetate buffer (pH=4.66) with acetonitrile has been applied. Examination included levodopa, norepinephrine, dopam...

The objective of this study was to determine the urinary excretion of methylxanthines in horses following ingestion of chocolate over eight days. The study was performed in response to gas chromatography-mass spectrometry (GC-MS) confirmation of the presence of caffeine in a positive urine test in a racehorse. The trainer of the horse alleged that he often administered chocolate-coated peanuts ...