What Is the Benefits of Valerian Extract?

Valeriana L. belongs to the Valerianaceae family. Its medicinal use has a long history, with approximately 250 species worldwide, most of which are distributed in temperate regions, primarily in Europe and Asia [1]. This plant is rich in components such as monoterpenes, sesquiterpenes, and lignans, and has various effects, including sedation and calming. Clinically, it is primarily used to treat mental disorders (such as epilepsy and hysteria), severe coughing, constipation, and other conditions [2].

In Europe, Valeriana has a long history of research and is used for medicinal, aromatic, and ornamental purposes. As early as 1983, Valerian officinalis was included in the European Pharmacopoeia as a sedative, and its preparations are listed in the pharmacopoeias of over 20 countries, including the Netherlands, Germany, Japan, and the United Kingdom. Currently, Valerian extracts and their preparations are commercially available in the international market. Northern valerian (Valeriana fauriei) grows in the northeastern region of China and has a history of over a century in traditional Chinese medicine [3]. In recent years, domestic and international scholars have conducted extensive research on the chemical constituents, pharmacological activities, and mechanisms of action of Valeriana species, achieving significant progress. This paper reviews the relevant research on this genus, providing a reference for further studies on this plant.

1 Overview of domestic Valeriana resources

Valerian is widely used as a medicinal and aromatic plant. There are differing opinions among scholars regarding the number of species and distribution of Valerian. The Flora of China lists 17 species and 2 varieties, while the Dictionary of Chinese Seed Plant Families and Genera records 24 species. The Illustrated Flora of China suggests that there are approximately 10 species in China. Cheng Jingrong et al. conducted a taxonomic study on the similar species of Valeriana in China, concluding that the similar species differ from those in Europe and classified them into 6 species and 1 variety based on their distribution and morphological characteristics [4]. The specific sources and distribution of Valeriana plants are shown in Table 1.

2 Active Components of Valeriana Extracts

Approximately 150 chemical components have been isolated from Valeriana extracts, most of which exhibit biological activity. Extensive research has revealed that Valeriana extracts contain cycloaromatic terpenoids, sesquiterpenoids, lignans, alkaloids, and valerenic acid, which demonstrate strong sedative, cytotoxic, antitumor, antioxidant, and vasodilatory activities [5]. among which valerianin exhibits significant sedative and anxiolytic pharmacological activity.

2.1 Iridoids

Iridoids are aldol derivatives of iridoic aldehydes. Based on whether the cyclopentane ring is cleaved, they are classified into two major categories: cyclopentane-ring iridoids (iridoids) and cleaved-ring iridoids (secoiridoids). The hemiacetal C1-OH group is unstable and primarily exists in plants as glycosides. The glycosidic bond is easily hydrolyzed by acids, yielding aglycones [6]. Typical iridoids consist of one iridoid ring and one cyclopentane ring, where the C6, C7, and C8 positions of the cyclopentane ring can be substituted by substituents, which are commonly ester groups or hydroxyl groups; epoxy ether-type cycloaromatic terpenoids often form epoxy ether structures between C7-8 or C6-7, and all natural products are β-type [7]; In studies on the chemical composition of Valeriana sp., researchers isolated numerous ring-split cycloether terpenoids, which commonly feature a double bond at the C8–9 or C8–10 positions, with the C7 position often connected to a hydroxyl group or ester group, and the C10 position typically esterified to form an ester group or connected to a hydroxyl group [8]. In recent years, scholars have discovered oxygen-bridged cyclic enol-ether terpenoids, typically characterized by the cleavage of the C3 double bond followed by the formation of an oxygen bridge with the hydroxyl group at the C8 or C10 position [9]. The parent nucleus structure is shown in Figure 1, and the cyclic enol-ether terpenoids are listed in Table 2.

2.2   Lignans

In recent years, most lignans reported domestically and internationally have been of the bis-epoxy type or 7,9'-monoepoxy type lignans and their glycosides. The structures of lignans from the Valeriana genus are shown in Figure 2 and Table 3.

Table 3 Lignans from Valeriana

2.3 Essential oils

Valerian contains a wide variety of essential oil components, which vary depending on the ecological environment. To date, approximately 40 sesquiterpenoid compounds have been isolated from the essential oils of Valerian. The primary active components include valerian aldehyde, valerianic acid, and valerianone, among others. Their main compound types and major components are similar to those of other Valeriana species such as Valeriana latifolia and Valeriana officinalis.

2.4 Other chemical components

Water extracts of Valeriana contain some organic acids, alkaloids, flavonoids, and other compounds. Tang [37] isolated two new flavonoid glycosides, acacetin 7-O-β-sophoroside and acacetin 7-O-(6″-O-α-lrh-amnopyranosyl)-β-sophoroside, from spiderwort. Archana Pande et al. [38] extracted 4-methoxy-8-pentyl-1-naphthoic acid from Valeriana.

3 Pharmacological Effects

3.1 Effects on the Central Nervous System

3.1.1 Antiepileptic  

Wagner et al. found that valerenic acid and other cycloartenol triterpenoids significantly prolonged the seizure latency period, reduced seizure mortality, and alleviated smooth muscle cell contractions, exhibiting strong central nervous system inhibitory effects [39]. Valerian extracts can reduce neural network excitability and exert a protective effect on neurons when exposed to β-amyloid-induced toxicity, preventing neuronal volume reduction and associated neural degeneration [40]. Luo Guojun et al. [41] found that broad-leaved valerian alters the expression of GABA transporter mRNA, thereby influencing GABA concentration, thereby exerting an antiepileptic effect. They also explored the anticonvulsant effects of high, medium, and low doses of broad-leaved valerian against pentylenetetrazole (PTZ)-induced seizures, finding that all three doses exhibited certain anticonvulsant effects, with the high-dose group showing more pronounced effects. Additionally, the anticonvulsant effect of broad-leaved valerian against PTZ exhibited a dose-dependent relationship.

3.1.2 Sedative and Anxiolytic Effects

Schulz et al. conducted clinical trials on patients with sleep disorders using drugs containing valerian and root extracts, finding that the patients' slow-wave sleep time significantly increased, the density of K-shaped complex waves improved, but the effect on β waves was minimal, indicating that valerian can shorten the sleep latency period and significantly improve sleep quality [42]. Chen Jiasui et al. [43] investigated the effects of the petroleum ether fraction of black valerian on the levels of the neurotransmitters 5-hydroxytryptamine (5-HT) and γ-aminobutyric acid (GABA) in the brains of mice. The results showed that different doses of the extract significantly increased neurotransmitter levels and markedly prolonged sleep duration in mice. Tao Tao et al. [44] studied valerian alcohol extracts and found that they have a synergistic effect with pentobarbital sodium, inhibiting spontaneous activity in mice and prolonging their sleep time.

3.2 Effects on the circulatory system

Valerian can improve myocardial ischemia. Valerian trichloroethane extract not only inhibits the central nervous system but also improves myocardial circulation and prevents myocardial ischemia. Xue Cunkuan et al. found through animal experiments that valerian essential oil increases microcirculation in coronary blood flow, thereby reducing the infarct size of myocardial infarction, indicating that valerian essential oil has anti-myocardial ischemia effects [45]. Gong Zhanfeng [46] first used serum pharmacochemistry to study the active sites of valerian's antiarrhythmic activity.

The results indicated that valerian metabolites may be the active substances responsible for its antiarrhythmic effects, providing important reference for exploring the active substances of valerian's antiarrhythmic activity. Yang Qian et al. [47] conducted a study on the treatment of coronary heart disease patients with broad-leaved valerian essential oil, using Danshen injection as a control treatment. The results showed that in terms of rehabilitating ischemic myocardium and improving myocardial ischemia, the efficacy of broad-leaved valerian was significantly superior to that of Danshen injection. Additionally, in terms of reducing the frequency of angina attacks, alleviating angina symptoms, and shortening the duration of angina attacks, the efficacy of broad-leaved valerian was also significantly superior. This indicates that broad-leaved valerian has significant therapeutic effects in both improving myocardial ischemia and alleviating angina symptoms.

3.3 Antitumor

The cycloartenol terpenoids in Valeriana officinalis exhibit strong antitumor activity, with cycloartenol esters showing the most pronounced effect [48]. Bounthanh et al. found through in vitro experiments that Valeriana officinalis extract inhibits liver cancer cells, bone marrow hematopoietic progenitor cells, Kreb2 ascites cancer cells, and T2 lymphocytes [49]. The (+)-9'-isovaleroxy lariciresinol (a lignan monomer component) in Valeriana sp. exhibited inhibitory effects on PC-3M (prostate metastatic cancer cells) and HCT-8 (colon cancer cells) in vitro [50]. Yan Zhiyong et al. [51] conducted relevant studies using liver cancer H22 mice. In addition to proposing that the total flavonoids in spider incense exert an antitumor effect on experimental mice, they further suggested that the mechanism of action may involve inhibiting the JAK/STAT signaling pathway.

3.4 Antimicrobial and antiviral

Yang et al. [24] compared the antibacterial activity of Valeriana officinalis in vitro using the cup-plate method. The results showed that Valeriana officinalis exhibited inhibitory effects against Bacillus subtilis, Escherichia coli, and Staphylococcus aureus, with the ring-containing triterpenoids being the primary active components responsible for the antibacterial activity. The total alkaloids of Valeriana officinalis exhibit good inhibitory effects on Gram-positive bacteria and can be used for the treatment of respiratory diseases. Murakmi N et al. found that Valeriana officinalis extract inhibits the transport of the cellular regulatory protein Rev from the cell nucleus to the cytoplasm, thereby inhibiting HIV replication and exhibiting anti-AIDS activity [52].

3.5 Other

Parvaneh Mirabi et al. [53] conducted a double-blind study on women to investigate whether Valerian has phytoestrogenic effects, and the results indicated that Valerian can treat menopausal hot flashes in women. Jéssie Haigert Sudati et al. [54] used black-bellied fruit flies as test subjects to study the effects of Valerian on the toxicity induced by rotenone, and the results showed a certain inhibitory effect, thereby suggesting that Valerian extract may have good therapeutic effects on neurodegenerative diseases. The pharmacological effects of specific individual compounds in the Valerian genus are shown in Table 5.

3.6 Drug Safety

Jiang Zhongren et al. [55] administered valerian extract orally to SD rats via gastric lavage for 90 consecutive days and observed its effects on biochemical indicators, hematological indicators, and histopathological indicators in animals. After the experiment, the animals were euthanized, and no toxic damage changes were observed in the high-dose group.

4 Conclusion

Traditional Chinese medicine considers Valerian plants to primarily have sedative and anxiolytic effects, primarily used to treat insomnia and depression. Recent studies have identified that the cycloartenol terpenoids in Valeriana contain neuroprotective effects, while lignans exhibit promising therapeutic effects for degenerative diseases such as Alzheimer's disease. As summarized in this review, the chemical constituents of Valeriana are relatively concentrated, with specific active components and mild pharmacological effects. However, most pharmacological studies to date have been limited to crude extracts, and the specific active sites or the mechanisms of action of these chemical components remain to be further investigated. To date, due to the limited research on the material basis of Valeriana, not only are the anti-tumor or cardiovascular pharmacological active components yet to be clearly identified, but it is also difficult to evaluate their quality, making it challenging to ensure the safety and efficacy of clinical use. Therefore, it is necessary to identify the active sites and specific active components under the guidance of bioactivity screening, and further elucidate the material basis and mechanisms of action based on these active components. Among these, cycloaromatic terpenoids and lignans exhibit significant bioactive potential and hold promise for the development of new drugs with good therapeutic effects, thereby further expanding the application prospects of Valerian.

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