Study of Flavonoid Accumulation Patterns in Common Yarrow Herb of Synanthropic Flora in Rostov Oblast

Most of the exploited resources of wild medicinal plants are located in the human economic activity zone, the areas accessible by transport. The anthropogenic impact on medicinal plants is an important factor affecting the synthesis of secondary metabolites. The biochemical antioxidant-defense system containing a large number of components, including phenolic compounds, is an important activation mechanism of plant resistance under extreme and stressful factors. The objective of the study was to investigate the flavonoid accumulation patterns in the common yarrow herb of synanthropic flora in Rostov oblast. The common yarrow herb was harvested near broad highway M-21 (category IA), a slow-traffic nonhighway road (category IV), and the North Caucasus railway mainline. Samples were collected within 1–300 m distance from routes at 100-m increments. The choice of land areas for sampling the medicinal plant raw materials can be explained by the lack of reliable information on the accumulation of biologically active substances in plant raw materials, depending on the distance from highways and railways. The total flavonoid content converted to luteolin content in the common yarrow herb samples was determined in accordance with the standards provided by the state pharmacopoeia with the use of an SF-2000 spectophotometer. All the harvested medicinal herbal raw materials of the common yarrow herb meet the requirements of the State Pharmacopoeia of the Russian Federation (SP XIV) for the total flavonoid content converted to luteolin content, except for the sample prepared in the land area adjacent to the M-21 highway. The study-based outcomes provide the opportunity to conclude that an increase in the contents of phenolic compounds in plants is a response to a moderate impact of adverse factors caused by the released environmental toxicants. However, inhibition of the plant antioxidant system expressed as suppression of polyphenol production is possible under the factors causing toxic stress syndrome (near a heavy-traffic highway of category IA and a railway mainline). These findings correlate with the findings of investigations into the variation patterns for the common yarrow herb prepared under the same environmental conditions in Voronezh oblast, which can allow us to consider the revelation of the regularities in induction and inhibition of flavonoid compound biosynthesis in various plant ecotopes.