Abstract:

The aim of the work. Study of hydroxycinnamic acids profile of the dry bilberry shoot extract by high performance liquid chromatography. Materials and Methods. The dried extracts of bilberry shoots, obtained by the fractional maceration method from the crushed domestic origin bilberries shoots using alcohol-aqueous extractant with different ethanol content were used as material for the study. The hydroxycinnamic acid standard samples (Sigma-Aldrich, Fluka) were used to identify the hydroxycinnamic acids. HPLC studies were performed with the liquid chromatograph with a diode array detector (“Waters 2960»,”, USA). The XTerra C18 (“Waters”, USA) chromatographic column with a size of 250x4,6 mm (5 μm) at a temperature of (25±1) ° C was used. Results and Discussion. HPLC profiles of the bilberry shoots dry extract contained chromatographic peaks corresponding to the retention times of chlorogenic, caffeic, ferulic, trans-p-coumaric and 3-hydroxycinnamic acids. By analyzing their electronic absorption spectra, the presence only of the chlorogenic and caffeic acids was confirmed. A substance with a relative retention time of 4.2 (relative to chlorogenic acid) is characterized by an absorption spectrum identical to the spectrum of chlorogenic acid, that is indicating that this substance is a hydroxycinnamic acid. The HPLC profile of the extract contains chromatographic peaks of three substances whose absorption spectra are similar to those of trans-p-coumaric acid. They may probably belong to isomers or derivatives of this acid. HPLC studies of the hydroxycinnamic acid profiles of dry extracts obtained with the different ethanol content extractants were performed. It has been found that the content of caffeic acid in the dry extract increases but the content of chlorogenic acid decreases with decreasing ethanol content in the extractant. This is probably due with the intensification of the hydrolysis processes of chlorogenic acid to caffeic acid. This leads to a deeper study of this process in order to optimize the technology and to study the stability and storage conditions of the finished extract. Conclusions. The chromatographic "fingerprinting" method is advisable to use to identify the bilberry shoots dry extract by detecting the chlorogenic, caffeic, unknown hydroxycinnamic (relative retention time and 4.2 relative the chlorogenic acid) and derivatives of the trans-p-coumaric acids in its HPLC profiles, obtained at a detection wavelength of 270 and 330 nm. The comparison of the absorption spectra of the substances with the corresponding retention times is necessary simultaneously with the HPLC profiles studies. Due to the high content of individual hydroxycinnamic acids (chlorogenic, caffeic), the content of a single acid or of the hydroxycinnamic acids amount, in terms of chlorogenic acid, should be selected as one of the quantitative criteria for the quality of the dry extract.

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