engleski

Investigation of the Flavonoids in Croatian Propolis by Thin-Layer Chromatography

Flavonoids and phenolic acids, with various biological activities, are considered to be main compounds in propolis &#8211 ; a natural product produced by the honeybee. With increasing use of the propolis, a rapid analytical method for screening of pharmacologically active components is necessary. By using the numerical taxonomy methods (determination of information theory and discriminating power) we have tested the efficiency of 11 mobile phases appropriate for TLC of 19 standard solutions (flavonoids and phenolic acids) and 80 % ethanolic extracts of 14 propolis samples. For chromatographic analysis we used 20 x 20 cm glass-backed TLC plates coated with 0.25 mm layers of silica gel 60 F254 (Merck). 10 &#956 ; l of 80 % ethanolic standard solutions was applied to TLC plates. After establishing the most appropriate mobile phases for the separation of standards, the procedure was repeated for propolis samples. The plates were developed in glass chambers to the height of approximately 16 cm from the start. The average time of development was 1 hour and 45 minutes. Visualization was performed under UV lamp in three ways: 1. short wave UV light (254 nm) 2. long wave UV light (366 nm) after spraying with 1 % methanolic diphenylboryloxyethylamine and 5 % ethanolic polyethyleneglycole 4000 3. long wave UV light (366 nm) after spraying with 1 % ethanolic AlCl3. After the visualization, the difference in flavonoids´ composition of the propolis from different geografic regions of Croatia was found. TLC is shown to be highly suitable method for rapid analysis.

flavonoids; phenolic acids; propolis; TLC; numerical taxonomy

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