Quantitative determination of the content of flavonoids and tannins in pine needles of Pinus sylvestris and Picea abies

Conifers and their assimilation organs are a valuable source of polyphenolic compounds with pronounced antioxidant and anti-inflammatory properties, which leads to their growing demand in pharmaceuticals and cosmetology. The purpose of this study was a comprehensive analysis of the chemical composition of the woody greens of the common pine Pinus sylvestris and the common spruce Picea abies with an assessment of seasonal variability and optimization of extraction parameters. Quantitative determination of the amount of flavonoids and tannins was carried out by standardized analytical methods in terms of the mass of absolutely dry raw materials. Clear seasonal trends have been identified: in winter, the concentration of flavonoids decreases in both breeds, most significantly in pine, while the content of tannins increases, especially intensively in spruce. It was found that spruce needles accumulate 2-3 times more tannins than pine needles. It has been experimentally proven that during extraction by the Soxhlet method, a 60% aqueous-ethanol solution provides an optimal extraction profile, allowing for maximum yield of tannins without a significant decrease in the concentration of flavonoids. The use of 96% ethanol is justified mainly for a pine raw material with priority extraction of flavonoid fractions, however, it is accompanied by a noticeable decrease in the efficiency of tannin extraction. The higher efficiency of the extraction of biologically active substances from woody greens by the Soxhlet method, compared with maceration, has been confirmed. Thus, the content of flavonoids and tannins in Soxhlet extracts of spruce is 2 times higher than maceration by the pharmaceutical method. The results of the work create a scientific basis for the development of resource-saving technologies for the production of standardized plant extracts.