Chamaenerion angustifolium (L.) Scop. (fireweed) is a perennial herbaceous plant of the Onagraceae family widely used in folk and scientific medicine. It is a promising source of bioactive components. One of the modern trends in extraction is the use of natural deep eutectic solvents (NADESs) combined with ultrasound-assisted extraction (UAE). However, works devoted to the extraction of biologically active substances from C. angustifolium using NADESs are scarce. The aim of this work is a comprehensive study of UAE of bioactive components from C. angustifolium using NADESs based on choline chloride and malonic, malic, tartaric, and citric acids. The antioxidative properties, total phenols, and flavonoids content were estimated for NADES-based extracts. The reference solvents were water and 90% v/v ethanol. Volatile extracted components were identified using GC-MS. The kinetics of the UAE were studied at 45 °C for 20–180 min with water added to 30 wt% NADES. The power of the ultrasound was 120 W, and the frequency was 40 kHz. It was found that NADES choline chloride + citric acid is more effective for the extraction of bioactive components. For this, NADES UAE conditions were optimized following a Box–Behnken design of the experiment and a response surface methodology. The temperature ranged from 30 to 60 °C, the time of extraction ranged from 20 to 60, and the addition of water ranged from 30 to 70 wt%. We established the optimal extraction conditions: temperature 58 °C, time of extraction 35 min, and 70 wt% water. The obtained results expand the knowledge about the use of NADES for the extraction of biologically active compounds from cheap and available plant raw materials.

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Flavonoids represent a wide group of polyphenols involved in many key processes of plant growth and its can be successfully used in medical practice. In plants that are exposed to extreme factors of various nature, the flavonoids synthesis occurs more intensively compared with plants of the same species growing under more favorable conditions. Thus, it can be assumed that it is the Arctic plants that can be important sources of flavonoids. This paper presents the results of a search for flavonoid sources among herbaceous plants growing in the Arctic zone, in particular, the Murmansk region. The total flavonoid content in ethanol extracts of 24 plant species was estimated using the reaction of complexation with aluminum chloride. It was shown that Lathyrus pratensis L., Lupinus arcticus L., Hedysarum alpinum L., Chamaenerion angustifolium L., and Polygonum weyrichii species contain the highest amounts of flavonoids.

This work presents the results of the use of maceration and ultrasonic extraction for the isolation of antioxidant substances, particularly flavonoids, from the Polygonum Weyrichii Fr. Schmidt growing in the Murmansk region. This plant is characterized by a high content of flavonoids and other antioxidant substances, and therefore may be of interest as a potential source of natural antioxidants. The efficiency of extracting flavonoids from various parts of plants (inflorescences and leaves) by maceration for 24 hours in 70% ethanol and using ultrasonic extraction for 1-5 hours at a temperature of 50 °C is compared. Antioxidant activity was evaluated for all extracts using the phosphomolybdate method. It was found that the maximum extraction of flavonoids is achieved by using ultrasonic extraction for 2 to 4 hours.

Koenigia Weyrichii (F. Schmidt) T.M. Schust. et Reveal, which grows on the Kola Peninsula, contains a significant amount of flavonoids in the aerial parts of the plant, rapidly builds up biomass, and is resistant to various climatic conditions. This makes K. Weyrichii a promising source of biologically active substances (BAS) in the Arctic zone. A relatively new method for extracting biologically active substances from plants is the use of deep eutectic solvents (DES), for example, a mixture of choline chloride with glycerol, which has shown high efficiency in the extraction of flavonoids from other plants. Previously, DES was not used for the extraction of biologically active substances from K. Weyrichii. The aim of this work is to evaluate the efficiency of ultrasonic extraction using traditional solvents (water, ethanol) and DES choline chloride + glycerol and to optimize the extraction conditions. Comparison of the total content of polyphenols, flavonoids, antioxidative, and antiradical activity in various extracts is carried out. It was found that the most favorable conditions for extraction are: water content in DES – 17.5 wt%, temperature – 65 °C, and time – 3 hours. At the same time, under identical extraction conditions (temperature and time), more target substances can be extracted with 60% ethanol than with DES. However, DES can be seen as an alternative to using ethanol. The data obtained can be useful for the further development of innovative technologies of the extraction of biologically active substances from plant material. Also, K. Weyrichii may be considered as a source of biologically active substances in cosmetics and the food industry.