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Abstract
In East Asia, herbs are not only used by traditional medical practitioners but also commonly eaten by public. Compositae and Rhus are well-known antigens that can cause allergic contact dermatitis, but the other herbs are not well studied for antigenicity. Hosta plantaginea (also known as 'August lily' or 'Plantain lily') is originated from China and usually grown for ornamental purposes (Fig. 1a~c). In traditional medicine, flowers are used as oral medicines for sore throat or dysuria and sometimes topically applied for burn. This article is protected by copyright. All rights reserved.
In Asia, the flower of Hosta plantaginea (Lam.) Aschers (hosta flower) is both an edible food and medicine. The hosta flower is often used as a material for cooking porridge and scented tea and in combination with other plants for alleviating pharyngitis. To clarify the anti-pharyngitis effect of the hosta flower and evaluate its potential active ingredients, an ethanol extract of the hosta flower was prepared and partially purified via chromatography on a column packed with D101 macroporous resin, which was eluted with different concentrations of ethanol. The anti-pharyngitis effect of the crude extract and the various partially purified fractions was examined in an ammonia-induced acute pharyngitis rat model. The 30% ethanol-eluted fraction significantly alleviated the severity of pharyngitis in the rat, as evaluated by changes in the levels of cytokines (IL-1β, IL-6, and TNF-α) and histological changes in the pharynx tissues. Subsequent HPLC-QTOF/MS (high-performance liquid chromatography coupled with quadrupole-time of flight tandem mass spectrometry) analysis of this fraction revealed kaempferol and its glycosides as the main components. Three of the main components were isolated and identified by 1D NMR. Their pharmacokinetics were studied for the first time by UHPLC-QQQ/MS (ultrahigh-performance liquid chromatography coupled with mass spectrometry). The findings suggested that the 30% ethanol-eluted fraction of the hosta flower extract may be a potential functional food for treating pharyngitis.
Ethnopharmacological relevance
The genus Hosta (Liliaceae family) represents an interesting source of natural bio-constituents, and the 50 species of this genus are widespread in the world. Five species have been used as traditional East Asian medicines for treating inflammation and pain-related diseases. However, the available data for this genus have not been comprehensively reviewed regarding their extracts and secondary metabolites.
Aim of the study
The present review aims to provide a deeper insight, better awareness and detailed knowledge of traditional uses, phytochemistry, pharmacology along with toxicological aspects of the genus Hosta in the past decades (February 1964 to August 2020). In addition, the relevance among traditional uses, pharmacology and phytochemistry in folk medicines were extensively discussed.
Materials and methods
The relevant information of Hosta species was obtained from several databases. Moreover, the medical books, PhD and MSc dissertations in Chinese were also used to perform this work.
Results
Comprehensive analysis of the afore-mentioned databases, medical books and dissertations confirmed that ethnomedical uses of Hosta genus plants had been recorded in China, Japan, Korea and other countries. To date, only eight species have been studied for chemical constituents, and a total of 200 secondary metabolites (not include essential oil constituents), including steroids, flavonoids, alkaloids, furan derivatives, phenylpropanoids, phenethyl derivatives, terpenoids, aliphatics, and others. The crude extracts and isolated chemical constituents exhibited anti-inflammatory and analgesic, antioxidant, anti-tumor, anti-viral, acetylcholinesterase inhibitory, antimicrobial, anti-chronic prostatitis, and other effects. Moreover, only the n-butanol fraction of H. ventricosa (Salisb.) Stearn roots showed moderate acute toxicity in mice. In addition, the relevance among traditional uses, pharmacology and phytochemistry in folk medicines were extensively discussed.
Conclusions
Hosta spp. are plants rich in steroids and flavonoids with valuable medicinal properties; though, there are several gaps in understanding the traditional uses in the current available data. More high scientific quality preclinical studies with new methodology are necessary to assess the safety, efficacy and mechanism of these plants.
Hosta plantaginea (Lam.) Aschers, as a traditional folk medicine, has been widely used both as a single herb and in prescriptions in Asia mainly due to its anti-inflammatory and analgesic effects. A total of 101 compounds including steroids, flavonoids, alkaloids and others have been isolated from H. plantaginea. Modern pharmacology has revealed that H. plantaginea possesses various therapeutic effects such as anti-inflammatory, analgesic and antibacterial effects both in vitro and in vivo. Although a number of reports on the chemical constituents and pharmacological activities of this plant are available, there is limited research on the bioactive constituents and the mechanism of the biological activities of H. plantaginea. Thus, it is essential to strengthen the research on bioactive constituents and their mechanisms as well as their structure–function relationships in H. plantaginea. Up to now, only three compounds have been established for the quality control of H. plantaginea. However, a comprehensive review on the botany, traditional use, phytochemistry, quality control and pharmacology information about this plant has not been reported so far; thus, a systematic and comprehensive review is very necessary. Therefore, this paper provided a comprehensive overview on the botany, traditional use, phytochemistry, quality control and pharmacology of H. plantaginea and also provided evidence for its further research and clinical applications.
Systemic contact dermatitis is usually seen as flare-up of previous dermatitis or de novo dermatitis similar to allergic contact dermatitis. Although systemic contact dermatitis from medicaments is a well-established entity, the existence of clinically relevant systemic reactions to oral nickel exposure, in particular systemic reactions to nickel in the daily diet, remains controversial. Several studies have shown that oral exposure to nickel can induce systemic contact dermatitis in nickel-sensitive individuals. In most of these studies, however, the exposure dose of nickel used has been considerably higher than the nickel content in the normal daily diet. The aim of the current investigation was to study dose-response dependency of oral exposure to nickel. In a double-blind, placebo-controlled oral exposure trial, 40 nickel-sensitive persons and 20 healthy (non-nickel-sensitive) controls were given nickel sulfate hexahydrate in doses similar to and greater than the amount of nickel ingested in the normal Danish daily diet. The nickel content in urine and serum before and after oral exposure was measured to determine nickel uptake and excretion. The influence of the amount of nickel ingested on the clinical reactions to oral exposure and on nickel concentrations in serum and urine was evaluated. Among nickel-sensitive individuals, a definite dose-response dependency was seen, following oral exposure to nickel. 7 of 10 nickel-sensitive individuals had cutaneous reactions to oral exposure to 4.0 mg nickel, an amount approximately 10 times greater than the estimated normal daily dietary intake of nickel. 4 of 10 nickel-sensitive individuals had cutaneous reactions to 1.0 mg nickel, a dose which is close to the estimated maximum amount of nickel contained in the daily diet. 4 of 10 nickel-sensitive individuals reacted to 0.3 mg nickel or to the amount equivalent to that contained in a normal daily diet, and 1 of 10 reacted to a placebo. None of the 20 healthy controls had cutaneous reactions to 4.0 mg nickel or to a placebo. Prior to oral exposure, there was no measurable difference in the amount of nickel in the urine or serum of nickel-sensitive persons and healthy controls. Following the oral challenge, the nickel content in the urine and serum of both nickel-sensitive and healthy control individuals was directly related to the dose of nickel ingested.
In Korea, Rhus has been used as a folk medicine to cure gastrointestinal diseases and as a health food. We review the clinicopathological and laboratory findings in patients with systemic contact dermatitis caused by intake of Rhus. We reviewed medical records and histopathological sections from 31 patients during a 10-year period. The male/female ratio was 1.4: 1 and the average age was 43.8 years (range 22-70). Ten patients (32%) had a known history of allergy to lacquer. Rhus was ingested to treat gastrointestinal problems including indigestion and gastritis (45%), and as a health food (39%), in cooked meat, in herbal medicine, or taken by inhalation. The patients developed skin lesions such as a maculopapular eruption (65%), erythema multiforme (EM, 32%), erythroderma (19%), pustules, purpura, weals and blisters. Erythroderma was very frequent in patients with a known history of allergy to lacquer, but maculopapular and EM-type eruptions were more frequently observed in those without a history of allergy. All patients experienced generalized or localized pruritus. Other symptoms included gastrointestinal problems (32%), fever (26%), chills and headache; many developed leucocytosis (70%) with neutrophilia (88%), while some showed toxic effects on liver and kidney. Fifty-nine per cent of patients observed cutaneous or general symptoms within a day after ingestion of Rhus. There was no difference in the time lag for symptoms to develop between patients allergic and not allergic to Rhus. All patients responded well to treatment with systemic steroids and antihistamines. Common histopathological findings were vascular dilatation, perivascular lymphohistiocytic infiltration, and extravasation of red blood cells in the upper dermis. Rhus lacquer should not be ingested in view of its highly allergic and toxic effects.
