Quantitative HPLC determination of methylxanthines in traditional Bulgarian herbal teas

Abstract

Introduction: The aim of present study is to determine the content of three methylxanthines in dif­ferent types of tea and coffee available on the Bulgarian market. The most important naturally oc­curring methylxanthines are caffeine, theophylline and theobromine (purine alkaloids), which are found in varying amounts in tea, coffee and other plants. Caffeine is the most widely used drug. Its main pharmaceutical applications are as a cardiac and respiratory stimulant. Theobromine is mild diuretic, stimulates and relaxes the smooth muscles of the bronchi. Theophylline has anti-inflamma­tory effects, stimulates the central nervous system, acting mainly on the medullary respiratory cen­tre. Materials and methods: Sample preparation procedure includes boiling water extraction, filtration and purification. High-Pressure Liquid Chromatography (HPLC) analysis was performed on column Synergi 4u Hydro-RP (250 x 4.6 um) with a mobile phase of acetonitrile: water = 90:10. Three meth­ylxanthines were monitored by ultraviolet (UV) detection at 274 nm. Results: Three purine alkaloids were quantified in almost all samples. The research shows a highest concentration of caffeine at about 35.0 mg/150 ml, whereas theophylline and theobromine values are around 5.0 mg/150 ml each. Conclusion: The statistical data observed that people from all over the world drink more than 2 bil­lion cups of coffee every day. Coffee is the second most traded product in the world after oil. In Bul­garia it is more consumed than tea. Worldwide, tea is the drink of choice from many people - over 3 billion cups per day. The HPLC method is appropriate for separation and quantification of caffeine, theobromine and theophylline. According to the European Food Safety Authority (EFSA) recom­mendation for caffeine daily intake (400 mg/day) three cups of analysed samples give the beneficial effects.