What Is the Health Benefit of Dandelion?

Dandelion is derived from the dried whole grass of various dandelions in the Asteraceae family. It is commonly known as yellow daylily, mother-in-law's cap, yellow Sanqi, etc., and is a perennial herb [1]. Dandelion was first recorded in the New Revised Materia Medica. It is bitter and sweet in taste, cold in nature, and enters the liver and stomach meridians. It has the effects of clearing away heat and toxins, inducing diuresis and resolving lumps. It is mainly used to treat red eyes, sore throat, hepatitis, gastritis, acute mastitis, lymphadenitis, cholecystitis, urinary tract infections, etc. [2].

Dandelion is also a medicinal herb with edible properties. As its use in medical treatment and healthcare increases, the market's demand for high-quality dandelion is also becoming more stringent. There is an urgent need to identify the active ingredients in dandelion and improve its quality standards. This paper integrates and sorts out research on the active ingredients and pharmacological effects of dandelion root. Based on the idea of quality markers, it predicts and analyzes the quality markers of dandelion medicinal materials, providing a reference for determining the quality markers of dandelion medicinal materials, establishing a quality control system, and product development and utilization.

1 Active ingredients

At present, research on the active ingredients of dandelion extracts has been quite thorough. Dandelion contains a variety of active ingredients, mainly flavonoids, phenolic acids, polysaccharides, terpenes, sterols, essential oils, alkaloids, etc., among which flavonoids, phenolic acids, and terpenes are the main active ingredients of dandelion.

1.1 Flavonoids

Dandelion extract contains about 1.35% total flavonoids, of which luteolin is the most abundant [2]. The main flavonoids that have been isolated and identified so far are luteolin and its glycosides, apigenin and its glycosides, quercetin and its glycosides, genistein and its glycosides, kaempferol, rutin, etc. [3-10]. For the names and molecular formulas of the reported flavonoids, see Table 1.

1.2 Phenolic acids and their derivatives

The total phenolic acid content in dandelion extract is about 120.5 mg/g [11], mainly including caffeic acid, monocaffeoyl tartaric acid, chlorogenic acid, ferulic acid, chicoric acid, phenylacetic acid, protocatechuic acid, p-coumaric acid, etc. [12-18]. For the names and molecular formulas of the reported phenolic acid compounds, see Table 2.

1.3 Terpenoids

The terpenoids contained in dandelion roots mainly include pentacyclic triterpenoids and sesquiterpenoids [19-22]. The names and molecular formulas of the reported terpenoids are detailed in Table 3.

1.4 Sterols

Sterol compounds have been isolated and identified in the pollen, roots and whole grass of dandelions, with the pollen containing more. Among the identified monomer sterols, sitosterol is the most abundant, followed by stigmasterol and campesterol [23]. The sterols in dandelion also include carotene, pollen sterols, isofucosterol and cyclomarin.

1.5 Other components

Dandelion is rich in polysaccharides, as well as pigments, alkaloids, fatty acids, essential oils and other chemical components [24-25]. Some scholars have also isolated and identified from dandelion Mongolian dandelionin A, Mongolian dandelionin B, eugenol, phenylethanol, vanillin, taraxacin and other compounds [26].

2 Pharmacological effects

2.1 Anti-inflammatory

Dandelion contains a variety of components with strong anti-inflammatory activity, which work through different mechanisms. Dandelion polysaccharides have good anti-inflammatory activity in vitro and can inhibit the mRNA expression of inflammatory factors tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) [27]. The triterpenoids taraxerol and taraxasterol are also the main active ingredients in anti-inflammation. They can not only inhibit the production of inflammatory-related inducible enzymes and inflammatory mediators such as TNF-α and IL-6, but also exert anti-inflammatory effects by affecting the MAPK and NF-κB signal pathways [28-29]. Dandelion essential oil can treat tissue inflammation and injury and inhibit the release of the inflammatory factor NO [24]. The dandelion phenolic acid components chicoric acid, caffeic acid, and chlorogenic acid can all reduce the level of inflammatory factors in bronchial epithelial cells induced by lipopolysaccharides, with chicoric acid being the most active [30]. Network pharmacology research shows that the main active ingredients of dandelion that are used to treat parotitis, tonsillitis and pharyngitis in Dandelion Anti-inflammatory Oral Liquid, in addition to monocaffeoyl tartaric acid, chlorogenic acid and chicoric acid, also include the flavonoid luteolin and its glycoside [31].

2.2 Bacteriostatic

Dandelion extracts, decoctions, and leachates all have antibacterial activity, and the various active ingredients they contain have a significant inhibitory effect on cocci and bacilli [32]. Sun Jimei et al. [33] screened the antibacterial activity of dandelion decoction liquid externally by the micro broth dilution method, and confirmed that dandelion decoction liquid has an inhibitory effect on a variety of clinically common infectious bacteria, especially gram-positive cocci. The fat-soluble components of dandelion play a bacteriostatic role by destroying the cell membrane of Salmonella bacteria and causing their contents to leak out [34]. The phenolic acid component chlorogenic acid has a strong antibacterial effect as a metabolite of dihydrocaffeic acid after oral administration [35].

2.3 Antioxidant

The antioxidant mechanism of dandelion is mainly reflected in the removal of free radicals and reactive oxygen species. Chlorogenic acid, chicoric acid, caffeic acid and mono-caffeoyl-tartaric acid have multiple pharmacological activities, with outstanding anti-inflammatory and antioxidant effects [34-36]. Cichoric acid has strong antioxidant capacity, can remove free radicals, increase superoxide dismutase activity, and inhibit apoptosis and damage [37-39]. The phenolic acids contained in dandelion and chicory stems are similar in type. Meng Chuangge et al. [40] analyzed the antioxidant activity of five phenolic acids contained in chicory stems and found that the scavenging effects on DPPH and ·OH radicals were: chicoric acid > luteolin > chlorogenic acid > caffeic acid > mono-caffeoyl-L-tartaric acid; the optimal ratio of chlorogenic acid or luteolin to chicoric acid for synergistic antioxidant action was 1.5:1, and the synergistic effect of chlorogenic acid was weaker than that of luteolin. Luteolin can accelerate the removal efficiency of reactive oxygen species by affecting the autophagy process, reduce the production of reactive oxygen species, and exert a protective effect against oxidative stress damage after cerebral ischemia-reperfusion [41].

2.4 Antitumor

Polysaccharides and flavonoids in dandelion root have antitumor activity [42]. Dandelion water extract can inhibit tumor cell proliferation in tumor-bearing nude mice by down-regulating Survivin expression [43]; it can regulate transforming growth factor-β (TGF-β), mammalian target of rapamycin (mTOR), MMP-2 and gastric cancer model mice tumor tissue transforming growth factor-β (TGF-β), mammalian target of rapamycin (mTOR), MMP-2 and MMP-9 expression, inhibit tumor cell invasion and metastasis, exerting anti-tumor activity [44]. Dandelion medicinal serum can significantly inhibit the proliferation and movement of SMMC-7721 liver cancer cells [45]. Fifteen components identified from the phenolic acids or flavonoids of Taraxacum officinale can specifically bind to the target cell membrane of Hela or MK-1 or enter the target cells, and are potential active ingredients that exert anticancer effects [46]. Studies on dandelion metabolites have found that luteolin can block the cell cycle of breast cancer cells [47], and has varying degrees of therapeutic effect on a variety of malignant tumors [48-49].

2.5 Other effects

Existing studies have shown that dandelion root also has significant effects in lowering blood sugar [50-52], lowering blood lipids [53], anti-thrombosis, protecting the liver and gallbladder [54], and diuresis.

3 Analysis of quality markers

Traditional Chinese medicine (TCM) is an important means of treating diseases in traditional Chinese medicine, and the quality of TCM has been a focus of attention in the industry for many years. In recent years, with the gradual implementation of the national strategy to revitalize the cause of traditional Chinese medicine, the development of traditional Chinese medicine in China has entered a golden age. At the same time, the issue of internationally recognized quality control standards for traditional Chinese medicine has arisen. In 2016, Academician Liu Changxiao proposed a new concept of “quality markers” for traditional Chinese medicine, advocating a closer correlation between the effectiveness of traditional Chinese medicine, its material basis, and the quality control of signature components, to construct a quality control thinking model for traditional Chinese medicine [55], which has attracted the attention of many scholars in the industry and is widely used and promoted in the fields of traditional Chinese medicine and Chinese patent medicine. This paper selects quality markers for dandelion based on this concept.

3.1 Predictive analysis of quality markers based on the source plant

Dandelion is derived from the genus Taraxacum F.H. Wigg. of the Asteraceae family. There are about 2,000 species of Taraxacum plants worldwide, concentrated in the subtropical to temperate regions of the northern hemisphere. There are about 71 species in China, mainly distributed in the eastern, northwestern and southwestern provinces. The genus Taraxacum is divided into 16 groups, each of which is found in China. Among the various components identified in Taraxacum plants, flavonoids, phenolic acids, and terpene compounds are recognized as the main active ingredients [6, 56]. These types of components can be used as reference substances for screening quality markers for dandelions.

3.2 Quality marker prediction analysis based on traditional medicinal properties and traditional efficacy

Flavor and meridian are the basic attributes of traditional Chinese medicine. Traditional efficacy is a generalization of the effectiveness of traditional Chinese medicine, and both are important bases for clinical medication and prescription. Dandelion is bitter, sweet, cold in nature, and enters the liver and stomach meridians. Chang Xuehui et al. [57] believe that sweet-tasting medicines mostly contain components such as glycosides and sugars, which correspond to the polysaccharides and flavonoid glycosides in dandelion.

Yan Yongqing et al. [58] studied the chemical composition of 460 commonly used bitter Chinese herbs and found that bitter herbs mostly contain alkaloids, terpenoids, etc., which correspond to the alkaloids, triterpenoids, and other components in dandelion. In the 2020 edition of the Chinese Pharmacopoeia, dandelion is included for its efficacy in clearing away heat and toxins, reducing swelling and dispersing lumps, diuresis and treating strangury, and is used to treat diseases such as carbuncle, breast abscess, intestinal abscess, damp-heat jaundice, and painful strangury due to heat [59]. The phenolic acids, flavonoids and terpenoids in dandelion root have anti-inflammatory, antibacterial, antioxidant and anti-tumor effects, which are consistent with its traditional efficacy. Therefore, phenolic acids, flavonoids and terpenoids can be used as important references for screening quality markers in dandelion.

3.3 Predictive analysis of quality markers based on clinical efficacy and the effectiveness of ingredients

Dandelion has a diverse chemical composition and significant pharmacological effects. Modern medicine, modern chemistry, pharmacology and other research fields have elucidated the relationship between chemical composition and clinical treatment. Studies have shown that chlorogenic acid, chicoric acid, caffeic acid, monocaffeoyl tartaric acid, luteolin, and luteolin have multiple pharmacological activities, with prominent anti-inflammatory and antioxidant effects [34-37, 60]. Phenolic acid components chlorogenic acid and caffeic acid and some of their metabolites in the body have antibacterial activity [61]. Luteolin, dandelion sterol acetate, dandelion terpene alcohol, lupin alcohol, and caffeic acid have certain anticancer activities [43-44]. Dandelion polysaccharides, phenolic acids, and triterpenoids have anti-inflammatory, antibacterial, and antioxidant activities, while flavonoids have anti-tumor activities. They are often used in clinical practice to treat diseases such as acute mastitis, tonsillitis, gastritis, and alopecia due to spleen deficiency and damp-heat [62-63]. In summary, chlorogenic acid, monocaffeoyl tartaric acid, caffeic acid, chicoric acid, luteolin, and oleanolic acid can be used as reference indicators for the screening of dandelion quality markers.

3.4 Predictive analysis of pharmacokinetic-based quality markers

The biological activity of an active ingredient in the body largely depends on its absorption and metabolism. Dandelion contains phenolic acids such as chlorogenic acid, caffeic acid, and chicoric acid, which can be absorbed into the bloodstream in their original form. Chlorogenic acid is absorbed in the stomach, small intestine, and large intestine, and is absorbed into the bloodstream in its original form in the stomach and small intestine. The main metabolic pathway in the body is intestinal metabolism, and the metabolites are caffeic acid, quinic acid, etc. [34, 64]. Cichoric acid can quickly distribute to various tissues and organs after oral administration, and the main form of existence is mainly binding to tissue proteins. So far, a total of 7 metabolites, such as cichoric acid esterification and sulfation, have been detected [65-66].

The metabolic pathways of the flavonoid component luteolin in rats are oxidation, methylation, glucuronidation and sulfonation, while luteolin is hydrolyzed by intestinal bacterial hydrolytic enzymes and then undergoes further chemical reactions [67]. Zhang Xue [68] used high performance liquid chromatography to analyze the drug urine in the dandelion water extract, and found that there were 22 components and metabolites in dandelion that enter the blood. It was further determined that dandelion sterols and lupulinol are the active substances in dandelion extracts that inhibit the proliferation of MCF-7 breast cancer cells. In summary, it is predicted that chlorogenic acid, chicoric acid, luteolin, luteolin 7-O-glucoside, taraxerol and lupeol can be used as reference indicators for the screening of dandelion quality markers.

3.5 Predictive analysis of quality markers based on the detectability of components

The detectability of chemical components is also an important reference for the selection of quality markers. Liu Yan et al. [69] used HPLC to simultaneously determine the contents of monocaffeoyl tartaric acid, chlorogenic acid, caffeic acid and chicoric acid in dandelion, among which the contents of monocaffeoyl tartaric acid and chicoric acid were much higher than those of chlorogenic acid and caffeic acid. A study used ultra-high performance liquid chromatography tandem mass spectrometry to simultaneously determine the four index components of dandelion, namely, coumaric acid, caffeic acid, luteolin, and luteolin glucoside [70].

Liu Aipeng et al. [71] used high-performance liquid chromatography (HPLC) to determine the content of six components in dandelion, namely, monocaffeoyl tartaric acid, chlorogenic acid, caffeic acid, chicoric acid, isochlorogenic acid A, and luteolin. In the 2020 edition of the Chinese Pharmacopoeia, the index component under the assay of dandelion medicinal materials has been changed from caffeic acid in previous versions to chicoric acid, and the mass fraction must not be less than 0.45% [59]. Overall analysis shows that phenolic acid components are closely related to their medicinal effects, and that caffeoyl tartaric acid, chlorogenic acid, isochlorogenic acid A, chicoric acid, caffeic acid, quercetin, luteolin, and luteolin glucoside can all be quantitatively analyzed by chromatography and can be used as screening indicators for quality markers.

4 Conclusion

Dandelion root is one of China's traditional medicinal plants with a long history of use. It is a perennial herb with a wide variety of species and abundant natural resources, and has broad development prospects. In this paper, based on a summary of the chemical composition and pharmacological effects of dandelion, and guided by the theory of quality markers in traditional Chinese medicine, the quality markers of dandelion are predicted from the aspects of dandelion's affinity and component specificity, clinical efficacy and component effectiveness, the predictability of quality markers for dandelion, taking into account the predictability of quality markers for dandelion from the aspects of the kinship and component specificity of dandelion, clinical efficacy and component effectiveness,measurability of chemical components and pharmacokinetics. After comprehensive consideration, monocaffeoyl tartaric acid, chlorogenic acid, caffeic acid, chicoric acid, luteolin and luteolin glucoside were selected as the quality markers for dandelion medicinal materials, in order to facilitate the establishment of a reasonable quality control system for dandelion.

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