Medicinal Plant Research 2025, Vol.15, No.2, 88-98 http://hortherbpublisher.com/index.php/mpr 90 to use, making it the most widely used method in traditional medicine and food processing. However, it also has limitations. Flavonoids are not very soluble in water, often resulting in suboptimal extraction concentrations. In contrast, extraction with ethanol, especially mixed water-alcohol solvents, is significantly more effective. Extraction efficiency is higher, and the flavonoid and polyphenol content is significantly higher than with water (Zhang et al., 2020). For example, when chrysanthemum leaves are extracted with water-alcohol, the polyphenol content is almost double that of water extraction, and the antimicrobial activity is also stronger. Figure 1 Content of total flavonoids and anthocyanins in different stages of “Hangju”. (A) Morphological characteristics of “Hangju” capitula in different growth stages: flower bud differentiation stage (BDS), bud stage (BS) and flower bloom stage (FBS); (B) Content of total flavonoids and (C) anthocyanin in different stages after flooding stress. Data represent mean values ± SD of three independent measurements. ** indicates a significant difference at p< 0.01 (Adopted from Wang et al., 2019) Reflux extraction, is also an old method. It relies on continuous heating and condensation to keep the solvent temperature and volume constant, thereby improving the extraction efficiency. This method can indeed enhance the release of active ingredients, but it also has many "side effects" - it takes a long time, consumes a lot of energy, and uses a large amount of solvent, which is not very environmentally friendly. What is more troublesome is that high-temperature and long-term processing may cause the degradation of some heat-sensitive flavonoids, which instead affects the quality and activity of the extract (Zhang et al., 2020; Liu et al., 2022). So, although reflux extraction technology is mature, it is more suitable for small-scale laboratory operations and less suitable for the demands of industrial or green production. 3.2 Modern green extraction technologies Although traditional extraction methods are classic, their efficiency and environmental burden have always been a difficult problem. To address these issues, many green extraction technologies have emerged in recent years. Ultrasound-assisted extraction (UAE) is one of them. It "shatters" the plant cell walls through ultrasonic waves, accelerating solvent penetration and component release, which not only increases the extraction rate but also saves a lot of time (Chaves et al., 2020; Liu et al., 2022).
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