Ameliorating effect of Yokukansan on the development of atopic dermatitis-like lesions and scratching behavior in socially isolated NC/Nga mice

Traditional uses, chemical compounds, pharmacological activities and clinical studies on the traditional Chinese prescription Yi-Gan San

ETHNOPHARMACOLOGICAL RELEVANCE

A widely used traditional prescription, Yi-Gan San (YGS) is a remedy for neurodegenerative disorders. The formulation consists of seven Chinese medicinal materials in specific proportions, namely Uncariae Ramulus cum Uncis (Uncaria rhynchophylla (Miq.) Miq. ex Havil.), Bupleuri Radix (Bupleurum chinense DC.), Angelicae Sinensis Radix (Angelica sinensis (Oliv.) Diels), Chuanxiong Rhizoma (Ligusticum wallichii Franch.), Poria (Poria cocos (Schw.) Wolf), Atractylodis Macrocephalae Rhizoma (Atractylodes macrocephala Koidz.) and Glycyrrhizae Radix et Rhizoma (Glycyrrhiza uralensis Fisch.). Using YGS has been shown to alleviate various behavioural and psychological symptoms of dementia (BPSD).

AIM OF THIS REVIEW

The goal of this review is to give up-to-date information about the traditional uses, chemistry, pharmacology and clinical efficacy of YGS based on the scientific literature and to learn the current focus and provide references in the next step.

MATERIALS AND METHODS

The database search room was accessed using the search terms "Yi-Gan San" and "Yokukansan" to obtain results from resources such as Web of Science, PubMed, Google Scholar and Sci Finder Scholar. We not only consulted the literature of fellow authors for this review but also explored classical medical books.

RESULTS

YGS has been used to cure neurosis, sleeplessness, night weeping and restlessness in infants. Its chemical components primarily consist of triterpenes, flavonoids, phenolics, lactones, alkaloids and other types of compounds. These active ingredients displayed diverse pharmacological activities to ameliorate BPSD by regulating serotonergic, glutamatergic, cholinergic, dopaminergic, adrenergic, and GABAergic neurotransmission. In addition, YGS showed neuroprotective, antistress, and anti-inflammatory effects. The majority of cases of neurodegenerative disorders are treated with YGS, including Alzheimer's disease and dementia with Lewy bodies.

CONCLUSIONS

Based on previous studies, YGS has been used as a traditional prescription in East Asia, such as Japan, Korea and China, and it has diverse chemical compounds and multiple pharmacological activities. Nevertheless, few experimental studies have focused on chemical and quantitative YGS studies, suggesting that further comprehensive research on its chemicals and quality assessments is critical for future evaluations of drug efficacy.

Study on the Molecular Basis of Huanglian Jiedu Decoction Against Atopic Dermatitis Integrating Chemistry, Biochemistry, and Metabolomics Strategies

Atopic dermatitis (AD) is a common chronic relapsing skin inflammation, which severely affect the quality of life of patients. Inhibiting itching and enhancing immunity to mitigate scratching are key elements in the fight against AD. Huanglian Jiedu decoction (HLJDD) has multiple pharmacological effects in the treatment of AD. However, the effective ingredients and underlying molecular mechanisms have not yet been fully explored. Thus, this study integrates chemistry, biochemistry, and metabolomics strategies to evaluate the active substance basis of HLJDD against AD. First, HLJDD was split to five fractions (CPF, 40AEF, 90AEF, PEF and WEF) and 72 chemical components were identified. NSD (Non-similarity degree) among the different fractions showed significant chemical differences (>81%). Interleukin IL-13, IL-17A, IL-3, IL-31, IL-33, IL4, IL-5, TSLP, IgE, and histamine in the serum, and IL-4Rα, JAK1, and HRH4 levels in skin, participating in inhibiting itching and regulating immunity signaling, were found to be restored to varying degrees in AD treating with HLJDD and its fractions, especially 40AEF and CPF. Untargeted metabolomics analysis demonstrated that forty metabolites were differential metabolites in plasma between the HLJDD-treated group and the AD group, involving in histidine metabolism, arginine biosynthesis, pyrimidine metabolism, and so on. Further, targeted metabolomics analysis revealed that eleven differential metabolites, associating with physiological and biochemical indices, were significant improved in the HLJDD and its fractions groups. In conclusion, HLJDD exhibited anti-AD effects by inhibiting itching and enhancing immunity, which in turn regulating the levels of relative metabolites, and CPF and 40AEF were considered the most important components of HLJDD.

Topical creams of piperine loaded lipid nanocarriers for management of atopic dermatitis: development, characterization, and in vivo investigation using BALB/c mice model

The aim of the research work was to investigate the efficacy of cream loaded with lipid nanocarriers (ethosomes) of piperine for the management of atopic dermatitis (AD) in comparison to conventional cream. Ethosomes of piperine were formulated with varying concentration of phosphatidylcholine and ethanol; and evaluated for entrapment efficiency (EE), sedimentation behaviour, vesicle size, zeta potential, in vitro drug release, and shape. Creams loaded with optimized ethosomal dispersion of piperine were formulated and evaluated for physicochemical parameters, ex vivo permeation and drug retention in skin layers. Similarly, conventional creams of piperine in the same concentrations were formulated and evaluated. The optimized ethosomal a conventional cream was evaluated for cytotoxicity using HaCat cell lines and in vivo on BALB/c mice model. The EE (%) and vesicle size was 74.30 ± 3.88% and 318.1 nm, respectively, for optimized ethosomal dispersion. The zeta potential was -32.6 mV and vesicles were spherical in shape. The ethosomal cream showed higher deposition in the epidermis and dermis. The creams were non-cytotoxic to HaCat cell lines. In comparison to the negative control, the ethosomal (0.1%) and conventional (0.125%) cream, both significantly decreased the ear and skin thickness, skin severity; and WBC, granulocytes, and IgE antibodies level in the BALB/c mice model. The efficacy of ethosomal cream was significantly higher than conventional cream as compared to tacrolimus (0.1%). Ethosomal cream of piperine showed good potential for the management of AD in comparison to conventional cream.

Assessment of non-invasive techniques and herbal-based products on dermatological physiology and intercellular lipid properties

Skin is the largest external organ of the human body. It acts as a barrier to protect the human body from environmental pollution, mechanical stress, and excessive water loss. The defensive function resides primarily on top of the epidermis layer commonly known as stratum corneum (SC). Human SC consists of three major lipids, namely ceramide, free fatty acid, and cholesterol that comprise approximately 50%, 25%, and 25% of the total lipid mass, respectively. The optimal composition of SC lipids is the vital epidermal barrier function of the skin. On the other hand, skin barrier serves to limit passive water loss from the body, reduces chemical absorption from the environment, and prevents microbial infection. In contrast, epidermal lipids are important to maintain the cell structure, growth and differentiation, cohesion and desquamation as well as formation of a permeability barrier. Multiple non-invasive in vivo approaches were implemented on a regular basis to monitor skin physiological and intercellular lipid properties. The measurement of different parameters such as transepidermal water loss (TEWL), hydration level, skin elasticity, collagen intensity, melanin content, sebum, pH, and tape stripping is essential to evaluate the epidermal barrier function. Novel non-invasive techniques such as tape stripping, ultrasound imaging, and laser confocal microscopy offer higher possibility of accurate and detailed characterisation of skin barrier. To date, these techniques have also been widely used to determine the effects of herbal plants in dermatology. Herbal plants have been traditionally used for ages to treat a variety of skin diseases, as reported by the World Health Organisation (WHO). Their availability, lower cost, and minimal or no side effects have created awareness among society, thus increase the demand for natural sources as the remedy to treat various skin diseases. This paper reviews several non-invasive techniques and evaluations of herbal-based product in dermatology.

The formulae and biologically active ingredients of Chinese herbal medicines for the treatment of atopic dermatitis

Atopic dermatitis (AD) is a common relapsing inflammatory skin disease characterized by severe pruritus that seriously affects the quality of patients' life. There is an increasingly large amount of research demonstrating that traditional Chinese medicine (TCM) including herbal formulae and bioactive ingredients exerts pharmacological effects on atopic dermatitis. It has been a long history of TCM being used to treat atopic dermatitis, especially in preventing disease recurrence, maintaining long-term remission, and reducing disease burden. Nowadays, both of TCM monomer preparations and traditional formulae are still widely used. This review focuses on TCM as well as its bioactive ingredients for the treatment of AD, from the perspectives of animal model construction, pharmacodynamic mechanisms and clinical studies of formulae. To be more specific, the regulation and molecular mechanisms of the herbal formulae and bioactive ingredients of TCM are investigated, and the latest clinical research on TCM formulae is discussed. Furthermore, it provides a summary of the strengths and utilities of TCM, and will be useful for doctors who use Chinese medicine for treatment or researchers who select candidates for clinical treatments or further high-quality clinical studies.

Pharmacokinetic Study of Bioactive Flavonoids in the Traditional Japanese Medicine Keigairengyoto Exerting Antibacterial Effects against Staphylococcus aureus

Recent studies have demonstrated that flavonoid glucuronides can be deconjugated to the active form aglycone by β-glucuronidase-expressing macrophages. Keigairengyoto (KRT) is a flavonoid-rich traditional Japanese medicine reported to enhance bacterial clearance through immune modulation. Our aims are to examine the pharmacokinetics of KRT flavonoids and to identify active flavonoids contributing to the adjuvant effects of KRT. KRT was evaluated at pharmacokinetic analysis to quantify absorbed flavonoids, and cutaneous infection assay induced in mice by inoculation of Staphylococcus aureus. Preventive or therapeutic KRT administration reduced the number of bacteria in the infection site as well as macroscopic and microscopic lesion scores with efficacies similar to antibiotics. Pharmacokinetic study revealed low plasma levels of flavonoid aglycones after KRT administration; however, plasma concentrations were enhanced markedly by β-glucuronidase treatment, with baicalein the most abundant (C_max, 1.32 µg/mL). In random screening assays, flavonoids such as bacalein, genistein, and apigenin enhanced bacteria phagocytosis by macrophages. Glucuronide bacalin was converted to aglycone baicalein by incubation with living macrophages, macrophage lysate, or skin homogenate. Taken together, the adjuvant effect of KRT may be due to some blood-absorbed flavonoids which enhance macrophage functions in host defense. Flavonoid-rich KRT may be a beneficial treatment for infectious skin inflammation.

Multiple Psychopharmacological Effects of the Traditional Japanese Kampo Medicine Yokukansan, and the Brain Regions it Affects

Yokukansan (YKS), a traditional Japanese Kampo medicine, has indications for use in night crying and irritability in children, as well as neurosis and insomnia. It is currently also used for the remedy of the behavioral and psychological symptoms of dementia (BPSD), such as aggressiveness, agitation, and hallucinations. In parallel with clinical evidence, a significant amount of fundamental researches have been undertaken to clarify the neuropsychopharmacological efficacies of YKS, with approximately 70 articles, including our own, being published to date. Recently, we reviewed the neuropharmacological mechanisms of YKS, including its effects on glutamatergic, serotonergic, and dopaminergic neurotransmission, and pharmacokinetics of the ingredients responsible for the effects. This review is aimed to integrate the information regarding the psychopharmacological effects of YKS with the brain regions known to be affected, to facilitate our understanding of the clinical efficacy of YKS. In this review, we first show that YKS has several effects that act to improve symptoms that are similar to BPSDs, like aggressiveness, hallucinations, anxiety, and sleep disturbance, as well as symptoms like tardive dyskinesia and cognitive deficits. We next provide the evidence showing that YKS can interact with various brain regions, including the cerebral cortex, hippocampus, striatum, and spinal cord, dysfunctions of which are related to psychiatric symptoms, cognitive deficits, abnormal behaviors, and dysesthesia. In addition, the major active ingredients of YKS, geissoschizine methyl ether and 18β-glycyrrhetinic acid, are shown to predominantly bind to the frontal cortex and hippocampus, respectively. Our findings suggest that YKS has multiple psychopharmacological effects, and that these are probably mediated by interactions among several brain regions. In this review, we summarize the available information about the valuable effects of a multicomponent medicine YKS on complex neural networks.

Antistress effects of Kampo medicine "Yokukansan" via regulation of orexin secretion

OBJECTIVE

Various stressors induce stress responses through the hypothalamic-pituitary-adrenal and the sympathetic-adrenal-medullary axes, which are regulated, in part, by orexin. For example, secretion of orexin in the hypothalamus is increased in rats exposed to the stress of social isolation for 1 week. In this study, the antistress effects of Kampo medicine Yokukansan (YKS) via the regulation of orexin secretion were investigated using a rat model.

METHODS AND RESULTS

The administration of 300 mg/kg per day of YKS to rats for 1 week significantly decreased the plasma orexin levels compared with non-treated rats, whereas the administration of 1,000 mg/kg of YKS had no effect on orexin levels. Therefore, 300 mg/kg of YKS was an effective dose for controlling orexin secretion. Subsequently, rats were divided into group-housed control (Con), individually housed stress (Stress), and individually housed YKS (300 mg/kg)-treated stress (Stress + YKS) groups. After 1 week, a resident-intruder aggression test was performed, and the plasma levels of orexin and corticosterone were measured. In the Stress group, aggressive behavior and the levels of corticosterone and orexin significantly increased compared with the Con group; however, these effects were inhibited in the Stress + YKS group. Further, an orexin receptor antagonist (TCS 1102; 10 mg/kg) was intraperitoneally administered to rats exposed to isolation stress to determine whether orexin was involved in stress responses. Under these conditions, aggressive behavior and the level of corticosterone significantly decreased compared with the Stress group.

CONCLUSION

These results suggest that orexin is involved in the control of stress response and that YKS exerts an antistress effect via the regulation of orexin secretion.

Understanding autoimmunity: The ion channel perspective

Ion channels are integral membrane proteins that orchestrate the passage of ions across the cell membrane and thus regulate various key physiological processes of the living system. The stringently regulated expression and function of these channels hold a pivotal role in the development and execution of various cellular functions. Malfunction of these channels results in debilitating diseases collectively termed channelopathies. In this review, we highlight the role of these proteins in the immune system with special emphasis on the development of autoimmunity. The role of ion channels in various autoimmune diseases is also listed out. This comprehensive review summarizes the ion channels that could be used as molecular targets in the development of new therapeutics against autoimmune disorders.

Herbal Medicines Prevent the Development of Atopic Dermatitis by Multiple Mechanisms

Atopic dermatitis (AD) is among the most common skin disorders in humans. Although a variety of regimens are available for the treatment of AD, preventive approaches are limited. Recent studies have demonstrated that certain naturally-occurring herbal medicines are effective in preventing the development of AD via divergent mechanisms, such as inhibiting cytokine and chemokine expression, IgE production, inflammatory cell infiltration, histamine release, and/or enhancement of epidermal permeability barrier function. Yet, they exhibit few adverse effects. Since herbal medicines are widely available, inexpensive and generally safe, they could represent an ideal approach for preventing the development of AD, in both highly developed and developing countries.

Yokukansan, a traditional Japanese medicine, adjusts glutamate signaling in cultured keratinocytes

Glutamate plays an important role in skin barrier signaling. In our previous study, Yokukansan (YKS) affected glutamate receptors in NC/Nga mice and was ameliorated in atopic dermatitis lesions. The aim of this study was to assess the effect of YKS on skin and cultured human keratinocytes. Glutamate concentrations in skin of YKS-treated and nontreated NC/Nga mice were measured. Then, glutamate release from cultured keratinocytes was measured, and extracellular glutamate concentrations in YKS-stimulated cultured human keratinocytes were determined. The mRNA expression levels of NMDA receptor 2D (NMDAR2D) and glutamate aspartate transporter (GLAST) were also determined in YKS-stimulated cultured keratinocytes. The glutamate concentrations and dermatitis scores increased in conventional mice, whereas they decreased in YKS-treated mice. Glutamate concentrations in cell supernatants of cultured keratinocytes increased proportionally to the cell density. However, they decreased dose-dependently with YKS. YKS stimulation increased NMDAR2D in a concentration-dependent manner. Conversely, GLAST decreased in response to YKS. Our findings indicate that YKS affects peripheral glutamate signaling in keratinocytes. Glutamine is essential as a transmitter, and dermatitis lesions might produce and release excess glutamate. This study suggests that, in keratinocytes, YKS controls extracellular glutamate concentrations, suppresses N-methyl-D-aspartate (NMDA) receptors, and activates glutamate transport.

Topical application of an ethanol extract prepared from Illicium verum suppresses atopic dermatitis in NC/Nga mice

ETHNOPHARMACOLOGICAL RELEVANCE

Illicium verum is a traditional herbal medicine with anti-inflammatory properties used in Asia. However, its usefulness in the treatment of allergic diseases remains unclear. This study evaluated the anti-inflammatory and antiallergic effects of I. verum extract (IVE) in a mouse model of atopic dermatitis.

MATERIALS AND METHODS

We investigated the effects of IVE on compound 48/80-induced histamine release, and phorbol 12-myristate13-acetate and calcium ionophore A23187-stimulated cytokines secretion in MC/9 mast cells. Atopic dermatitis was induced in NC/Nga mice by exposure to extract of house dust mite (Dermatophagoides farinae). After a topical application of IVE on ear and skin lesions, we evaluated the severity of skin symptoms, ear thickness, inflammatory cell infiltration, and serum levels of immunoglobulin E (IgE), histamine, interleukin (IL)-6, and intercellular adhesion molecule (ICAM)-1. In addition, we determined the expression of IL-4, IL-6, tumor necrosis factor (TNF)-α, interferon (IFN)-γ thymus- and activation-regulated chemokine (TARC), regulated on activation, normal T cell expressed and secreted (RANTES), ICAM-1, and vascular cell adhesion molecule (VCAM)-1 in ear tissues.

RESULTS

IVE inhibited secretion of histamine, IL-4, IL-6, and TNF-α from mast cells in a dose-dependent manner. Topical application of IVE significantly reduced dermatitis scores, ear thickness, and serum levels of IgE, histamine, IL-6, and ICAM-1. Histopathological analysis demonstrated decreased epidermal thickening and dermal infiltration by inflammatory cells. In the ear lesions, IVE treatment reduced expression of IL-4, IL-6, TNF-α, TARC, RANTES, ICAM-1, and VCAM-1, but not IFN-γ.

CONCLUSIONS

These results indicate that IVE inhibits atopic dermatitis-like skin lesions by suppressing the expression of cytokines, chemokines, and adhesion molecules. These results suggest that IVE may be a potential therapeutic candidate for atopic dermatitis.