Structure Elucidation and Biomimetic Synthesis of Hostasinine A, a New Benzylphenethylamine Alkaloid from Hosta plantaginea

Potential active constituents responsible for treating acute pharyngitis in the flowers of Hosta plantaginea (Lam.) Aschers and their pharmacokinetics

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...

Cytotoxic steroidal glycosides from the underground parts of Hosta ventricosa

A phytochemical study on the underground parts of Hosta ventricosa yielded one new spirostanol saponin (1), two new furostanol saponins (2 and 3), and one new pregnane glycoside (4), along with three known compounds (5‒7). Their structures were elucidated on the basis of chemical and spectroscopic analysis. All isolated compounds were evaluated for their cytotoxic effects against five human cancer cell lines (HL-60, A-549, SMMC-7721, MCF-7, and SW-480). Compounds 1, 2, and 5‒7 showed cytotoxic activities with IC₅₀ values of 3.21-17.06 μM.

Traditional uses, phytochemistry, pharmacology and toxicological aspects of the genus Hosta (Liliaceae): A comprehensive review

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.

Natural product sciences: an integrative approach to the innovations of plant natural products

The study on plant natural products not only helps us understand that their structural diversity is the inevitable result of plant species diversity, but also helps us understand certain rules and unity of the inevitable connection between the two. The diversity and complexity of chemical structures of many natural products are beyond imagination before we elucidated their structures. The question that follows is what is the biological significance of these natural products. Intrigued by the relationship between plant resources, natural products and biological functions, the Hao laboratory has taken an integrative approach that employs tools and knowledge from multi-disciplines, including natural product chemistry, chemical ecology and chemical biology, to unveil the effects of plant natural products on plant resistance to diseases, and environmental acclimations. Collaborating with cell biologists, the research has resulted in discovery of new mechanisms of cellular signaling and lead compounds.

Chemodiversity, chemotaxonomy and chemoecology of Amaryllidaceae alkaloids

The Amaryllidaceae alkaloids are a distinctive chemotaxonomic feature of the subfamily Amaryllidoideae of the family Amaryllidaceae, which consists of 59 genera and >800 species distributed primarily in tropical and subtropical areas. Since the first isolation, ca. 140 ago, >600 structurally diverse Amaryllidaceae alkaloids have been reported from ca. 350 species (44% of all species in the subfamily). A few have been found in other plant families, but the majority are unique to the Amaryllidoideae. These alkaloids have attracted considerable research interest due to their wide range of biological and pharmacological activities, which have been extensively reviewed. In this chapter we provide a review of the 636 structures of isolated or tentatively identified alkaloids from plants of the Amaryllidoideae and their classification into 42 skeleton types, as well as a discussion on their distribution, and chemotaxonomical and chemoecological aspects.

Steroidal glycosides from the underground parts of Hosta ventricosa and their anti-inflammatory activities in mice

Two new pregnane glycosides, 2α, 3β-dihydroxy-5α-pregn-16-en-20-one-3-O-{α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→4)]-β-D-galactopyranoside} (1) and 2α, 3β-dihydroxy-5α-pregn-16-en-20-one-3-O-{β-D-glucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside}(2), have been isolated along with two known spirostanol saponins from the underground parts of Hosta ventricosa. Their structures were elucidated on the basis of chemical and spectral evidence. The anti-inflammatory activities of these steroidal glycosides were evaluated using a xylene-induced ear edema model. Our results indicated that the compounds exhibited promising anti-inflammatory activities.

Application of Electrocyclic Ring-Opening and Desymmetrizing Nucleophilic Trappings of meso-6,6-Dibromobicyclo[3.1.0]hexanes to Total Syntheses of Crinine and Haemanthamine Alkaloids

The thermally induced electrocyclic ring-opening of C₂-symmetric ( meso) 6,6-dibromobicyclo[3.1.0]hexanes such as 10 in the presence of the chiral, nonracemic 1°-amine 28 afforded a ca. 1:1 mixture of the diastereoisomeric and chromatographically separable 1-amino-2-bromo-2-cyclohexenes 37 (42%) and 38 (45%). Each of these was elaborated over 13 steps, including Suzuki-Miyaura cross-coupling, radical cyclization, and Pictet-Spengler reactions, into (-)- or (+)-crinane (1 or ent-1, respectively). Variations on these protocols were applied to the total syntheses of (+)- and (-)-11-hydroxyvattitine [(+)- and (-)-3], (+)- and (-)-bulbispermine [(+)- and (-)-4], (+)- and (-)-haemanthamine [(+)- and (-)-5], (+)- and (-)-pretazettine [(+)- and (-)-6], and (+)- and (-)-tazettine [(+)- and (-)-7] as well as (±)-hamayne [(±)-8] and (±)-apohaemanthamine [(±)-9]. A number of these alkaloids were synthesized for the first time.

Hosta plantaginea (Lam.) Aschers (Yuzan): an overview on its botany, traditional use, phytochemistry, quality control and pharmacology

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.

A comprehensive overview on the botany, traditional use, phytochemistry, quality control and pharmacology of H. plantaginea is reported, providing evidence for its further research and clinical applications.

An Explorer of Chemical Biology of Plant Natural Products in Southwest China, Xiaojiang Hao

Xiaojiang Hao, who obtained Master Degree from Kunming Institute of Botany (KIB), Chinese Academy of Sciences (CAS) in 1985, and Doctor in Pharmacy degree in Pharmacy from Institute for Chemical Research, Kyoto University, in 1990, was born in Chongqing in July, 1951. In 1991, he returned to KIB, CAS, as an Associate professor and served as the chair of the Department of Phytochemistry. In 1994, he was promoted to a full professor at the current institute. He served as the Deputy Director of KIB and the Director of Open Laboratory of Phytochemistry from 1995 to 1997, and the Director of KIB from 1997 to 2005. Professor Hao has published more than 450 peer-reviewed SCI papers, which have been cited over 6000 times. He has obtained one PCT patent and 23 patents in China. Due to his tremendous efforts, one candidate drug, phenchlobenpyrrone, has entered the Phase II clinical trail for the treatment of Alzheimer's disease. Moreover, he won the First Prize of Natural Sciences in Yunnan Province for three times, and Ho Leung Ho Lee Fund Science and Technology Innovation Award in 2017.

Anti-TMV Effects of Amaryllidaceae Alkaloids Isolated from the Bulbs of Lycoris radiata and Lycoricidine Derivatives

Fifteen known amaryllidaceae alkaloids were isolated from the bulbs of Lycoris radiata. Some of the compounds and lycoricidine derivatives had been screened for the activities against tobacco mosaic virus (TMV) by the conventional half-leaf method. Lycoricidine derivatives were also carried out the assay of effect on systemic infection of TMV by western-blot and RT-PCR analysis. The tested compounds showed moderate inactivation effect, whereas the lycoricidine derivatives showed good protective effect. The protective inhibitory activity of compounds L1 (N-methyl-2,3,4-trimethoxylycoricidine) (60.8%) and L3 (N-methyl-2-methoxy-3,4-acetonidelycoricidine) (62.0%) was almost similar to the positive control, Ningnanmycin (66.4%). RT-PCR and Western-blot analysis displayed that compounds L1, L3, L5 (N-allyl-2,3,4-triallyloxylycoricidine) exhibited antiviral activity, which was evidenced by reducing TMV-CP gene replication and TMV-CP protein expression. Additionally, defensive enzyme activities confirmed that compound L1 could increase the activity of PAL, POD, SOD to improve disease resistance of tobacco.

The bioassay-guided isolation of antifungal saponins from Hosta plantaginea leaves

Four new steroidal saponins hostaside Ⅰ (1), hostaside Ⅱ (2), hostaside Ⅲ (3), and hostaside Ⅳ (4), together with five known steroidal saponins (5-9), were isolated by the bioassay-guided fractionation from the leaves of Hosta plantaginea (Lam.) Aschers, a worldwide well-known ornamental plant. Hostasides Ⅰ and Ⅱ showed significant antifungal activities, and they could inhibit the growth of Candida albicans and Fusarium oxysporium with MIC values as low as 4 μg/ml.

New steroidal glycosides from Hosta plantaginea (Lam.) Aschers

Four new furostanol glycosides were isolated from the flowers of Hosta plantaginea (Lam.) Aschers. On the basis of spectroscopic methods including 1D and 2D NMR experiments, their structures were elucidated as 26-O-β-d-glucopyranosyl-(25R)-22-O-methyl-5α-furostan-2α,3β,22ξ,26-tetrol 3-O-α-l-rhamnopyranosyl-(1 → 4)-O-β-d-xylopyranosyl-(1 → 3)-[O-β-d-glucopyranosyl-(1 → 2)]-O-β-d-glucopyranosyl-(1 → 4)-β-d-galactopyranoside (hostaplantagineoside A, 1), 26-O-β-d-glucopyranosyl-(25R)-5α-furostan-20(22)-ene-2α,3β,26-triol-3-O-β-d-glucopyranosyl-(1 → 2)-[O-β-d-xylopyranosyl-(1 → 3)]-O-β-d-glucopyranosyl-(1 → 4)-β-d-galactopyranoside (hostaplantagineoside B, 2), 26-O-β-d-glucopyranosyl-(25R)-5α-furostan-22(23)-ene-2α,3β,20α,26-tetraol-3-O-β-d-glucopyranosyl-(1 → 2)-[O-β-d-xylopyranosyl-(1 → 3)]-O-β-d-glucopyranosyl-(1 → 4)-O-β-d-galactopyranoside (hostaplantagineoside C, 3), 26-O-β-d-glucopyranosyl-(25R)-5α-furostan-20(22)-ene-2α,3β,26-triol-3-O-α-l-rhamnopyranosyl-(1 → 4)-O-β-d-xylopyranosyl-(1 → 3)-[O-β-d-glucopyranosyl-(1 → 2)]-O-β-d-glucopyranosyl-(1 → 4)-β-d-galactopyranoside (hostaplantagineoside D, 4).

A new Amaryllidaceae alkaloid from the bulbs of Lycoris radiata

Aim

To study the Amaryllidaceae alkaloids of the bulbs of Lycoris radiata.

Methods

The chemical constituents were isolated and purified by various chromatographic techniques, and the chemical structures were elucidated on the basis of spectroscopic methods. In addition, the antiviral activities of alkaloids 1–10 were evaluated using flu virus A.

Results

One new homolycorine-type alkaloid 2α-methoxy-6-O-ethyloduline (1), together with nine known alkaloids 2α-methoxy-6-O-methyloduline (2), trispherine (3), 8-O-demethylhomolycorine (4), homolycorine (5), 9-O-demethylhomolycorine (6), oduline (7), lycorenine (8), 6α-O-methyllycorenine (9) and O-ethyllycorenine (10) were obtained.

Conclusion

Alkaloid 1 is a new compound, and 1–3 were major alkaloids in this plant. Alkaloids 1–3 showed weak antiviral activities against flu virus A with IC50 values of 2.06, 0.69, and 2.71 μg·mL-1 and CC50 values of 14.37, 4.79, and 80.12 μg·mL-1, respectively.

Towards a molecular understanding of the biosynthesis of amaryllidaceae alkaloids in support of their expanding medical use

The alkaloids characteristically produced by the subfamily Amaryllidoideae of the Amaryllidaceae, bulbous plant species that include well know genera such as Narcissus (daffodils) and Galanthus (snowdrops), are a source of new pharmaceutical compounds. Presently, only the Amaryllidaceae alkaloid galanthamine, an acetylcholinesterase inhibitor used to treat symptoms of Alzheimer's disease, is produced commercially as a drug from cultivated plants. However, several Amaryllidaceae alkaloids have shown great promise as anti-cancer drugs, but their further clinical development is restricted by their limited commercial availability. Amaryllidaceae species have a long history of cultivation and breeding as ornamental bulbs, and phytochemical research has focussed on the diversity in alkaloid content and composition. In contrast to the available pharmacological and phytochemical data, ecological, physiological and molecular aspects of the Amaryllidaceae and their alkaloids are much less explored and the identity of the alkaloid biosynthetic genes is presently unknown. An improved molecular understanding of Amaryllidaceae alkaloid biosynthesis would greatly benefit the rational design of breeding programs to produce cultivars optimised for the production of pharmaceutical compounds and enable biotechnology based approaches.

Synthesis and biological evaluation of lycorine derivatives as dual inhibitors of human acetylcholinesterase and butyrylcholinesterase

Background

Alzheimer’s disease (AD) is a neurologically degenerative disorder that affects more than 20 million people worldwide. The selective butyrylcholinesterase (BChE) inhibitors and bivalent cholinesterase (ChE) inhibitors represent new treatments for AD.

Findings

A series of lycorine derivatives (1–10) were synthesized and evaluated for anti-cholinesterase activity. Result showed that the novel compound 2-O-tert-butyldimethylsilyl-1-O-(methylthio)methyllycorine (7) was a dual inhibitor of human acetylcholinesterase (hAChE) and butyrylcholinesterase (hBChE) with IC₅₀ values of 11.40 ± 0.66 μM and 4.17 ± 0.29 μM, respectively. The structure-activity relationships indicated that (i) the 1-O-(methylthio)methyl substituent in lycorine was better than the 1-O-acetyl group for the inhibition of cholinesterase; (ii) the acylated or etherified derivatives of lycorine and lycorin-2-one were more potent against hBChE than hAChE; and (iii) the oxidation of lycorine at C-2 decreases the activity.

Conclusion

Acylated or etherified derivatives of lycorine are potential dual inhibitors of hBChE and hAChE. Hence, further study on the modification of lycorine for ChE inhibition is necessary.

Chemical Constituents of Lycoris albiflora and their Cytotoxic Activities

An alcoholic extract of Lycoris albiflora (Amaryllidaceae) showed potent cytotoxic activity against HL-60 cells with an IC50 value of 1.7 μg/mL. Phytochemical examination of the extract resulted in the isolation of 15 alkaloids, including two phenanthridine-type alkaloids (1, 2), one benzylphenethylamine-type alkaloid (3), two crinane-type alkaloids (4, 5), one pyrrolophenanthridine-type alkaloid (6), six lycorenan-type alkaloids (7–12), and three galanthamine-type alkaloids (13–15), together with three neolignans (16–18), two flavans (19, 20), and two acetophenone derivatives (21, 22). Compound 3 (hostasinine A) has not been isolated from Amaryllidaceae plants, and 1, 2, 4, 5, 7–9, 11, 12 and 14–22 are the first isolation and identification from L. albiflora. The phenanthridine-type alkaloids (1, 2), as well as the alkaloids (3–5), exhibited potent cytotoxic activities against not only HL-60 cells but also HSC-2 cells, thus leading to the conclusion that these alkaloids are mainly responsible for the cytotoxicity of the L. albiflora extract. Compound 1 (lycoricidinol), with the most potent cytotoxic activities, induced apoptosis in both HL-60 cells and HSC-2 cells. It is notable that 1 induced transient autophagy and morphological changes in mitochondria in the early stages of the apoptotic cell death process in HSC-2 cells.