Bioscience Evidence 2024, Vol.14, No.3, 98-109 http://bioscipublisher.com/index.php/be 99 margin, and are covered with fine hairs. The flowers are tubular, typically purple or yellow, and are arranged in a raceme. The fruit is a capsule that contains numerous small seeds (Li et al., 2018; Xia et al., 2021a). 2.2 Geographical distribution and cultivation practices Rehmannia glutinosa is native to China and has been cultivated for centuries in various regions, including Henan, Shandong, and Hebei provinces. It is also grown in Korea, Japan, and northern Vietnam (Xia et al., 2021a; Qin et al., 2022). The plant thrives in well-drained, fertile soils with a pH range of 5.5 to 7.5 and requires a temperate climate with adequate rainfall. The cultivation of R. glutinosa involves both sexual reproduction through seeds and asexual reproduction through rootstock. However, the latter is more common due to its higher efficiency and reliability in producing uniform plants (Kim et al., 2020). In Henan Province, which is a major cultivation area, R. glutinosa is typically planted in spring and harvested in late autumn. The cultivation practices include soil preparation, planting, irrigation, fertilization, and pest management. The soil is usually plowed and enriched with organic matter before planting. The rootstocks are planted at a depth of 5~10 cm and spaced 20~30 cm apart. Regular irrigation is essential, especially during dry periods, to ensure optimal growth and development (Kim et al., 2020; Zhang et al., 2021). One of the significant challenges in the cultivation of R. glutinosa is the prevalence of viral diseases, which can severely affect the yield and quality of the roots. Studies have identified several viruses that infect R. glutinosa, including Rehmannia mosaic virus (ReMV), cucurbit chlorotic yellows virus (CCYV), and tobacco mild green mosaic virus (TMGMV) (Zhang et al., 2021; Qin et al., 2022). These viral infections are often exacerbated by the asexual reproduction method, which can facilitate the spread of viruses through the rootstock. To mitigate this issue, researchers have developed in vitro tissue culture methods to produce virus-free seedlings and rootstocks, which have shown promising results in improving the productivity and quality of R. glutinosa (Kim et al., 2020). In addition to traditional cultivation methods, modern biotechnological approaches are being employed to enhance the production and quality of R. glutinosa. For instance, the use of scanning electron microscopy (SEM) and quantitative taxonomy has enabled the identification and classification of different germplasms, which can be used for breeding superior cultivars (Li et al., 2018). Furthermore, the complete chloroplast genome sequencing of R. glutinosa cultivars has provided valuable insights into the genetic diversity and evolutionary history of the species, which can aid in conservation and breeding programs (Xia et al., 2021b). Overall, the cultivation of Rehmannia glutinosa involves a combination of traditional agricultural practices and modern biotechnological techniques to ensure the production of high-quality medicinal roots. The ongoing research and development efforts aim to address the challenges associated with viral diseases and improve the overall productivity and sustainability of R. glutinosa cultivation (Li et al., 2018; Kim et al., 2020; Xia et al., 2021b; Zhang et al., 2021; Qin et al., 2022). 3 Chemical Composition of Rehmannia glutinosa 3.1 Overview of phytochemical constituents Rehmannia glutinosa, a traditional Chinese medicinal herb, is known for its diverse array of bioactive compounds. The primary phytochemicals identified in R. glutinosa include iridoid glycosides, phenethyl alcohol glycosides, polysaccharides, and various minor constituents. These compounds contribute to the plant's therapeutic properties, such as anti-inflammatory, antioxidant, and hypoglycemic effects (Dai et al., 2018; Jeong et al., 2020; Piątczak et al., 2020). 3.2 Major bioactive components 3.2.1 Iridoid glycosides Iridoid glycosides are among the most significant bioactive components in R. glutinosa. Key iridoid glycosides include aucubin, catalpol, and geniposide. These compounds have been extensively studied for their pharmacokinetic properties and biological activities. For instance, a validated method for the simultaneous determination of aucubin, catalpol, and geniposide in rat biological samples has shown high precision and
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