Mistletonone, a novel antioxidative diarylheptanoid from the branches and leaves of Viscum coloratum

Traditional Uses, Phytochemical Constituents and Ethnopharmacological Properties of Mistletoe from Phoradendron and Viscum Species

Plants from the genus Phoradendron and Viscum, also known as American and European mistletoe, are a group of hemiparasitic plants traditionally used to treat many diseases. Mistletoes have a rich content of natural compounds like terpenes, alkaloids, proteins, and phenolic compounds associated with their potential medicinal properties. In this sense, mistletoes have shown antiproliferative, antioxidant, anti-inflammatory, and antimicrobial activity, which has been attributed to their phytochemical constituents. The mechanisms in which mistletoe plants act vary and depend on their phytochemical content and distribution, which in part will depend on the mistletoe species. In this sense, recent literature research is needed to visualize state of the art in the ethnopharmacological potential of mistletoe. Thus, this literature review aims to systematically report recent studies (2010-2023) on the phytochemical characterization and bioactive studies of mistletoe plants, mainly the Viscum and Phoradendron genera. We gather recent information of 140 references selected in our research. Here we report that although there are several bioactivity studies of mistletoe species, bioavailability studies are still scarce, and the precise mechanisms of action are not fully known. We encourage that further studies include a systematic strategy to cover these areas of opportunity.

Exploring the resources of the genus Viscum for potential therapeutic applications

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Viscum comprises approximately 100 species that are mainly distributed across Africa, Asia and Europe. The extracts and preparations of Viscum species are widely used as common complementary and alternative medicines in the treatment of rheumatism and cancer.

AIM OF THE REVIEW

This review aims to explore the medicinal properties of twelve species belonging to the genus Viscum for potential therapeutic applications.

MATERIALS AND METHODS

We collected online information (including PubMed, CNKI, Google Scholar, and Web of Science) from January 1915 to April 2021 and knowledge from classical books on Chinese herbal medicines available for 12 species of the genus Viscum, including Viscum coloratum (Kom.) Nakai, Viscum album L., Viscum articulatum Burm. f., Viscum liquidambaricola Hayata, Viscum ovalifolium DC., Viscum capitellatum Sm., Viscum cruciatum Sieber ex Boiss., Viscum nudum Danser, Viscum angulatum B.Heyne ex DC., Viscum tuberculatum A.Rich., Viscum multinerve Hayata, and Viscum diospyrosicola Hayata.

RESULTS

At least 250 different compounds have been reported across twelve Viscum species, including amino acid and peptides, alkaloids, phenolic acids, flavonoids, terpenoids, carbohydrates, fatty acids, lipids, and other types of compounds. In particular, for Viscum coloratum (Kom.) Nakai and Viscum album L., the plants, preparations, and bioactive components have been thoroughly reviewed. This has allowed to elucidate the role of active components, including lectins, viscotoxins, flavonoids, terpenoids, phenolic acids, and polysaccharides, in multiple bioactivities, such as anti-cancer, anti-rheumatism arthralgia, anti-inflammation, anti-cardiovascular diseases, enhancing immunity, and anti-chemotherapy side effects. We also evaluated quality control methods based on active compounds, in vivo exposure compounds, and discriminated chemical markers.

CONCLUSIONS

This is the first report to systematically review the pharmaceutical development history, chemical composition, clinical evidence, pharmacological activity, discriminated chemical markers, in vivo exposure, and quality control on twelve distinct species of Viscum plants with medicinal properties. The significant safety and efficacy, along with the minor side effects are constantly confirmed in clinics. The genus Viscum is thus an important medicinal resource that is worth exploring and developing in future pharmacological and chemical studies.

Chemical constituents of Viscum coloratum (Kom.) Nakai and their cytotoxic activities

A new diarylheptanoid, (1 R,2S,3S,5S)-2,3-dihydroxy-3',3''-dimethoxy-4'-de-O-methylcentrolobine (1) and a new bisabolane-type sesquiterpenoid, (1 R,7S)-1,12,13-trihydroxybisabola-3,10-diene (2), together with nineteen known compounds (3-21) were isolated from the EtOH extract of the stems and branches of Viscum coloratum (Kom.) Nakai. Their structures were elucidated by extensive analysis of 1 D and 2 D NMR spectra and from the HRESIMS. All the compounds were evaluated for their cytotoxic activity against eight human tumor cell lines.

Diarylheptanoids as nutraceutical: A review

Phenolic compounds are naturally occurring compounds present ubiquitously in plants. They have potential health benefits and substantiate evidence for their nutraceutical applications. Diarylheptanoids are part of the broad class of plant phenolics with structurally divergent compounds. They have been used in traditional medicines and homemade remedies to treat various ailments, as organoleptic additives in foods, and also for aesthetic purposes. With their potential therapeutic and organoleptic characteristics, diarylhepatanoids can be rightly termed as nutraceuticals. This review summarizes the wide range of pharmacological activities of diarylhepatanoids and nutraceutical formulations, with relevance to human health.

Therapeutic potential of mistletoe in CNS-related neurological disorders and the chemical composition of Viscum species

ETHNOPHARMACOLOGICAL RELEVANCE

Viscum album L., commonly known as mistletoe, has been used for centuries in traditional medicine to treat various neurological diseases, including epilepsy, hysteria, nervousness, hysterical psychosis, dizziness and headaches.

AIM OF THE STUDY

The aim of this review is to summarize existing evidence confirming the influence of mistletoe on the central nervous system and to investigate the compounds that may be responsible for this activity.

MATERIALS AND METHODS

Available information from studies of various species of the Viscum L. genus was collected from scientific journals, books, and reports via a library and an electronic data search (Elsevier, Google Scholar, PubMed, Springer, Science Direct, ResearchGate, and ACS).

RESULTS

The main chemical constituents of Viscum L. species are viscotoxins, lectins, flavonoids, phenolic acids, terpenoids, sterols, phenylpropanoids, and alkaloids. Various extracts of Viscum album L. showed central nervous system activity, including antiepileptic, sedative, antipsychotic, anxiolytic, antidepressant and antinociceptive effects in mice and rats. Additionally, the extracts increased the level of brain-derived neurotrophic factor, prevented apoptotic neuronal death induced by amyloid β and weakly inhibited cholinesterase activity.

CONCLUSIONS

Numerous historical references describe the use of mistletoe for the treatment of central nervous system disorders. In recent years, studies have started to confirm the antiepileptic, antipsychotic, sedative and antinociceptive effects of mistletoe. Additionally, mistletoe can be used as a complementary treatment for Alzheimer's disease. The therapeutic effect of mistletoe might be a result of the synergistic interactions of various secondary metabolites, including mistletoe-specific lectins. Further studies of the chemical composition and CNS activity of mistletoe are required. The mechanisms of action, target sites, pharmacokinetics, metabolic mechanisms, adverse effects and interactions of mistletoe with other drugs must also be investigated, as well.

From common to rare Zingiberaceae plants - A metabolomics study using GC-MS

Zingiberaceae plants, commonly known as gingers, have been popular for their medicinal and culinary uses since time immemorial. In spite of their numerous health-promoting applications, many Zingiberaceae plants still receive no scientific attention. Moreover, existing reports mostly focused only on the Zingiberaceae rhizomes. Here, untargeted metabolite profiling using Gas Chromatography - Mass Spectrometry (GC-MS) was used to compare the metabolic composition of leaves and rhizomes of the more common gingers, Zingiber officinale Rosc. (ZO), Curcuma longa L. (CL), and Etlingera elatior (Jack) R.M. Smith (EE), and the rare gingers, Amomum muricarpum Elmer (AM), Etlingera philippinensis (Ridl.) R.M. Smith (EP), and Hornstedtia conoidea Ridl. (HC). Principal component analysis (PCA) demonstrated that different species show substantial chemical differentiation and revealed potential markers among the different Zingiberaceae plants. Interestingly, the leaves of AM, CL, EE, EP, and HC had significantly higher levels of chlorogenic acid than ZO. Moreover, rhizomes of EP and HC were found to contain significantly higher levels of amino acids than ZO. Sugars and organic acids were generally less abundant in ZO leaves and rhizomes than in the other gingers. The leaves of EP and rhizomes of AM were found most similar to the leaves and rhizomes of common gingers, respectively. Results of this study provide significant baseline information on assessing the possible usage of the leaves of common gingers and further propagation and exploration of EP and AM. This study, being the first metabolomics report on rare plants such as AM, EP and HC, affirms the usefulness of untargeted metabolite profiling in exploring under-investigated plants.

Mistletoe alkaloid fractions alleviates carbon tetrachloride-induced liver fibrosis through inhibition of hepatic stellate cell activation via TGF-β/Smad interference

ETHNOPHARMACOLOGICAL RELEVANCE

Mistletoe (Viscum coloratum (Kom.) Nakai) has long been categorized as a traditional herbal medicine in Asia. In addition to its application in cancer therapy, mistletoe has also been used in the treatment of chronic hepatic disorders in China. In the present study, we investigated the antifibrotic effect and mechanisms of action of mistletoe extracts in a rat model of carbon tetrachloride (CCl4)-induced hepatotoxicity.

MATERIALS AND METHODS

An experimental model of hepatic fibrosis was established by intraperitoneal injection of rats with CCl4 for 8 weeks. Rats were subsequently treated with a mistletoe alkaloid fraction preparation via oral administration (120mg/kg daily for 8 weeks) or with distilled water as a control. Histopathological changes were observed by hematoxylin and eosin staining and Masson׳s trichrome staining. The expression of markers relevant to hepatic stellate cell (HSC) activation in the liver was assessed by real-time reverse transcription-polymerase chain reaction, immunohistochemistry and western blotting. The anti-fibrosis activity and mechanisms of action of mistletoe alkaloid fractions were further investigated in the HSC-T6 HSC line, following treatment with mistletoe alkaloid fractions (12mg/ml) for 48h.

RESULTS

Hepatic fibrosis decreased markedly in CCl4-treated animals following treatment with mistletoe alkaloid fractions, compared to controls. The mRNA levels of transforming growth factor-β1 (TGF-β1), procollagen I and tissue inhibitors of metalloproteinases (TIMPs) were significantly downregulated, by about 40%, 40% and 45%, respectively, in liver tissues from rats treated with mistletoe alkaloid fractions. Furthermore, significant downregulation of TGF-β1, TGF-β1 receptor, phosphorylated Smad 2 and alpha smooth muscle actin (α-SMA) proteins, by about 45%, 30% and 40%, respectively, was also observed in liver tissues from mistletoe alkaloid fractions-treated rats. In contrast, Smad 7 levels were significantly increased by about 30% in mistletoe alkaloid fractions-treated rats. Treatment of HSC-T6 cells with mistletoe alkaloid fractions significantly induced Smad 7 expression and inhibited the expression of α-SMA, TGFβ1, TGF-β1 receptor, Smad 2 and TIMP-1, in vitro.

CONCLUSION

We demonstrate that mistletoe alkaloid fractions decrease extracellular matrix accumulation by inhibiting HSC activation. Mechanistically, this may occur via inhibition of TGF-β1/Smad 2 and Smad 7 signal transduction, thereby blocking the synthesis of procollagen I and TIMP-1. These findings suggest that mistletoe alkaloid fractions may be a potential therapeutic agent for the treatment of hepatic fibrosis.

Flavanone and diphenylpropane glycosides and glycosidic acyl esters from Viscum articulatum

Seven new compounds including three flavanone glycosides, visartisides A-C (1-3), three glycoside acyl esters, visartisides D-F (4-6), and one diphenylpropane glycoside, (4'-hydroxy-2',3',6',3''-tetramethoxy-1,3-diphenylpropane)-4''-O-beta-d-glucopyranoside (7), along with four known flavanone glycosides (8-11) were isolated from the leaves and stems of Viscum articulatum. The structure elucidation of 1-7 was based on spectroscopic data analysis. Biological evaluation showed that 1, 2, and 10 exhibited antioxidant activity using a DPPH method and that compounds 1, 3, and 11 were active in a lipopolysaccharide-induced nitric oxide assay.

Diarylheptanoid phytoestrogens isolated from the medicinal plant Curcuma comosa: biologic actions in vitro and in vivo indicate estrogen receptor-dependent mechanisms

BACKGROUND

Diarylheptanoids isolated from Curcuma comosa Roxb. have been recently identified as phyto estrogens. However, the mechanism underlying their actions has not yet been identified.

OBJECTIVES

We characterized the estrogenic activity of three active naturally occurring diarylheptanoids both in vitro and in vivo.

METHODS

We characterized mechanisms of estrogenic action of the diarylheptanoids (3S)-1,7-diphenyl-(6E)-6-hepten-3-ol (D1), 1,7-diphenyl-(6E)-6-hepten-3-one (D2), and (3R)-1,7-diphenyl-(4E,6E)-4,6-heptadien-3-ol (D3) by using a real-time polymerase chain reaction assay, a mammalian transfection model, and a uterotrophic assay in mice.

RESULTS

All diarylheptanoids up-regulated estrogen-responsive genes in estrogen-responsive breast cancer cells (MCF-7). In HepG2 cells transfected with estrogen receptor (ER) beta or different ERalpha functional receptor mutants and the Vit-ERE-TATA-Luc reporter gene, all diarylheptanoids induced transcription through a ligand-dependent human ERalpha-ERE-driven pathway, which was abolished with ICI 182,780 (ER antagonist), whereas only D2 was active with ERbeta. An ERalpha mutant lacking the functional AF2 (activation function 2) region was not responsive to 17beta-estradiol (E(2)) or to any of the diarylheptanoids, whereas ERalpha lacking the AF1 domain exhibited wild-type-like activity. D3 markedly increased uterine weight and proliferation of the uterine epithelium in ovariectomized mice, whereas D1 and D2 were inactive. D3, like E(2), up-regulated lactoferrin (Ltf) gene expression. The responses to D3 in the uterus were inhibited by ICI 182,780. In addition, D3 stimulated both classical (Aqp5) and nonclassical (Cdkn1a) ER-mediated gene regulation.

CONCLUSIONS

The results suggest that the D3 diarylheptanoid is an agonist for ER both in vitro and in vivo, and its biological action is ERalpha selective, specifically requiring AF2 function, and involves direct binding via ER as well as ERE-independent gene regulation.