Spectrophotometric study of tannins in the herb Achillea millefolium L.

Abstract

Tannins are an important class of secondary metabolites with a wide range of pharmacological effects, due to which they are used in various fields of treatment. In plants of the genus Achillea L., tannins are the dominant class of compounds. This allows the use of plant raw materials and extracts of yarrow for the development of complex herbal and combined formulations of medicines. The search for new sources of natural tannin compounds for pharmaceutical and cosmetic purposes is of significant interest and encourages the improvement of phytochemical research methods of known species of medicinal plants. The aim of the work was to develop a spectrophotometric method for determining the quantitative composition of tannin compounds in terms of gallic acid in the herb of Achillea millefolium L. Materials and methods. The study utilized dried air-dried raw material of yarrow for analysis. The quantitative content of polyphenols in the plant material was determined using a modified UV spectrophotometric method, with calculations based on pyrogallol equivalents. The development of the spectrophotometric technique for determining tannins from the herb of Achillea millefolium L., expressed as gallic acid equivalents, considered the effects of extractant concentration and the degree of plant material grinding. Results. The water extract from the herb of Achillea millefolium L. exhibited a quantitative content of polyphenols, calculated as pyrogallol equivalents, at 2.9781 ± 0.0177 %. It was observed that the particle size of the raw material significantly influenced the yield of active substances. The optimal technological parameters for the developed method involved extracting plant material that was crushed to a size of 0.5–1.0 mm, using 70 % ethanol in a ratio of 1:10, resulting in a yield of 4.08 ± 0.01 %. Conclusions. Based on the obtained results, it is recommended to utilize the developed method, employing gallic acid equivalents, for the quantification of tannins in alcohol-water extracts of yarrow.