(-)-Amarbellisine, a lycorine-type alkaloid from Amaryllis belladonna L. growing in Egypt

Benzoindolizidine Alkaloids Tylophorine and Lycorine and Their Analogues with Antiviral, Anti-Inflammatory, and Anticancer Properties: Promises and Challenges

Ongoing viral research, essential for public health due to evolving viruses, gains significance owing to emerging viral infections such as the SARS-CoV-2 pandemic. Marine and plant alkaloids show promise as novel potential pharmacological strategies. In this narrative review, we elucidated the potential of tylophorine and lycorine, two naturally occurring plant-derived alkaloids with a shared benzoindolizidine scaffold, as antiviral agents to be potentially harnessed against respiratory viral infections. Possible structure-activity relationships have also been highlighted. The substances and their derivatives were found to be endowed with powerful and broad-spectrum antiviral properties; moreover, they were able to counteract inflammation, which often underpins the complications of viral diseases. At last, their anticancer properties hold promise not only for advancing cancer research but also for mitigating the oncogenic effects of viruses. This evidence suggests that tylophorine and lycorine could effectively counteract the pathogenesis of respiratory viral disease and its harmful effects. Although common issues about the pharmacologic development of natural substances remain to be addressed, the collected evidence highlights a possible interest in tylophorine and lycorine as antiviral and/or adjuvant strategies and encourages future more in-depth pre-clinical and clinical investigations to overcome their drawbacks and harness their power for therapeutic purposes.

Lycorine Alkaloid and Crinum americanum L. (Amaryllidaceae) Extracts Display Antifungal Activity on Clinically Relevant Candida Species

Candida species are the main fungal agents causing infectious conditions in hospital patients. The development of new drugs with antifungal potential, increased efficacy, and reduced toxicity is essential to face the challenge of fungal resistance to standard treatments. The aim of this study is to evaluate the in vitro antifungal effects of two crude extracts of Crinum americanum L., a rich alkaloid fraction and lycorine alkaloid, on the Candida species. As such, we used a disk diffusion susceptibility test, determined the minimum inhibitory concentration (MIC), and characterized the components of the extracts using Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (ESI FT-ICR MS). The extracts were found to have antifungal activity against various Candida species. The chemical characterization of the extracts indicated the presence of alkaloids such as lycorine and crinine. The Amaryllidaceae family has a promising antifungal potential. Furthermore, it was found that the alkaloid lycorine directly contributes to the effects that were observed for the extracts and fraction of C. americanum.

Alkaloid Profiling, Anti-Enzymatic and Antiproliferative Activity of The Endemic Chilean Amaryllidaceae Phycella cyrtanthoides

This research aims to identify the alkaloid profile and to evaluate the enzyme inhibitory potential and antiproliferative effects of the Amaryllidaceae plant Phycella cyrtanthoides. The alkaloid extracts from bulbs and leaves were analyzed using ultrahigh performance liquid chromatography orbitrap mass spectrometry (UHPLC-Orbitrap-MS) analysis. A total of 70 alkaloids were detected in the P. cyrtanthoides’ extracts. The enzyme inhibition potential against cholinesterases (AChE: acetylcholinesterase, and BChE butyrylcholinesterase) and tyrosinase were studied. Bulbs displayed the best IC₅₀ values against AChE (4.29 ± 0.03 µg/mL) and BChE (18.32 ± 0.03 µg/mL). These results were consistent with docking experiments with selected major compounds in the active sites of enzymes, while no activity was observed against tyrosinase enzyme. Antiproliferative effects were investigated against human cervical (HeLa), lung (A549, SW1573), colon (WiDr), and breast (HBL-100, T-47D) tumor cell lines. Bulbs and leaves were active in all cell lines (GI₅₀ < 2.5 µg/mL). These findings suggest that the endemic Chilean plant P. cyrtanthoides contains diverse types of bioactive alkaloids with antiproliferative activities and inhibitory effects with potential therapeutic applications for neurodegenerative diseases

Cytotoxic Phenylpropanoid Derivatives and Alkaloids from the Flowers of Pancratium maritimum L

Regarding our growing interest in identifying biologically active leads from Amaryllidaceous plants, the flowers of Pancratium maritimum L. (Amaryllidaceae) were investigated. Purification of the cytotoxic fractions of the alcoholic extract of the flowers gave a new glycoside, 3-[4-(β-D-glucopyranosyloxy)phenyl]-2-(Z)-propenoic acid methyl ester (1), together with the previously reported compounds 3-methoxy-4-(β-D-glucopyranosyloxy)benzoic acid methyl ester (2), 3-(4-methoxyphenyl)propan-1-ol-1-O-β-D-glucopyranoside (3), (E)-3-(4-hydroxyphenyl)acrylic acid methyl ester (4), caffeic acid (5), dihydrocaffeic acid methyl ester (6), and pancratistatin (7). Interestingly, compounds 1 and 2 are phenolic-O-glycosides, while the glucose moiety in 3 is attached to the propanol side chain. This is the first report about the existence of 1-6 in the genus Pancratium. Further, glycosides 1-3 from the Amaryllidaceae family are reported on here for the first time. The structures of 1-7 were determined by analyses of their 1D (¹H and ¹³C) and 2D (COSY, HMQC, HMBC) NMR spectra, and by high-resolution mass spectral measurements. Pancratistatin displayed potent and selective growth inhibitory effects against MDA-MB-231, HeLa, and HCT 116 cells with an IC₅₀ value down to 0.058 µM, while it possessed lower selectivity towards the normal human dermal fibroblasts with IC₅₀ of 6.6 µM.

Biological Investigation of Amaryllidaceae Alkaloid Extracts from the Bulbs of Pancratium trianthum Collected in the Senegalese Flora

Amaryllidaceae plants are rich in alkaloids with biological properties. Pancratium trianthum is an Amaryllidaceae species widely used in African folk medicine to treat several diseases such as central nervous system disorders, tumors, and microbial infections, and it is used to heal wounds. The current investigation explored the biological properties of alkaloid extracts from bulbs of P. trianthum collected in the Senegalese flora. Alkaloid extracts were analyzed and identified by chromatography and mass spectrometry. Alkaloid extracts from P. trianthum displayed pleiotropic biological properties. Cytotoxic activity of the extracts was determined on hepatocarcinoma Huh7 cells and on acute monocytic leukemia THP-1 cells, while agar diffusion and microdilution assays were used to evaluate antibacterial activity. Antiviral activity was measured by infection of extract-treated cells with dengue virus (DENV_GFP) and human immunodeficiency virus-1 (HIV-1_GFP) reporter vectors. Cytotoxicity and viral inhibition were the most striking of P. trianthum’s extract activities. Importantly, non-cytotoxic concentrations were highly effective in completely preventing DENV_GFP replication and in reducing pseudotyped HIV-1_GFP infection levels. Our results show that P. trianthum is a rich source of molecules for the potential discovery of new treatments against various diseases. Herein, we provide scientific evidence to rationalize the traditional uses of P. trianthum for wound treatment as an anti-dermatosis and antiseptic agent.

Pancracine, a Montanine-Type Amaryllidaceae Alkaloid, Inhibits Proliferation of A549 Lung Adenocarcinoma Cells and Induces Apoptotic Cell Death in MOLT-4 Leukemic Cells

Pancracine, a montanine-type Amaryllidaceae alkaloid (AA), is one of the most potent compounds among natural isoquinolines. In previous studies, pancracine exhibited cytotoxic activity against diverse human cancer cell lines in vitro. However, further insight into the molecular mechanisms that underlie the cytotoxic effect of pancracine have not been reported and remain unknown. To fill this void, the cell proliferation and viability of cancer cells was explored using the Trypan Blue assay or by using the xCELLigence system. The impact on the cell cycle was determined by flow cytometry. Apoptosis was evaluated by Annexin V/PI and by quantifying the activity of caspases (-3/7, -8, and -9). Proteins triggering growth arrest or apoptosis were detected by Western blotting. Pancracine has strong antiproliferative activity on A549 cells, lasting up to 96 h, and antiproliferative and cytotoxic effects on MOLT-4 cells. The apoptosis-inducing activity of pancracine in MOLT-4 cells was evidenced by the significantly higher activity of caspases. This was transmitted through the upregulation of p53 phosphorylated on Ser392, p38 MAPK phosphorylated on Thr180/Tyr182, and upregulation of p27. The pancracine treatment negatively altered the proliferation of A549 cells as a consequence of an increase in G1-phase accumulation, associated with the downregulation of Rb phosphorylated on Ser807/811 and with the concomitant upregulation of p27 and downregulation of Akt phosphorylated on Thr308. This was the first study to glean a deeper mechanistic understanding of pancracine activity in vitro. Perturbation of the cell cycle and induction of apoptotic cell death were considered key mechanisms of pancracine action.

Plant Metabolites as Antiviral Preparations Against Coronaviruses

In 2019-2020, the Coronavirus (CoV) disease 2019 pandemic created a serious challenge for health care systems in several countries worldwide. A cure has not been developed yet and currently used treatment protocols are aimed at relieving clinical symptoms of the disease. This article presents a retrospective review of biologically active compounds of plant origin that can inhibit the reproduction of CoVs, which makes them potential candidates for creating medicinal antiviral preparations against severe acute respiratory syndrome CoV-2 infections. A literature review of articles from highly rated journals was performed using public databases. The search was carried out using keywords related to CoVs, targets for therapy, and plant as antiviral agents. Although inhibition of viral replication is often considered the common mechanism of antiviral activity exerted by most natural products, several plant-derived compounds show specific activity for particular target viruses. In this context, certain classes of plant preparations can serve as a basis for designing modern antiviral agents. In addition, a large number of plant compounds that are potentially active against CoVs are the main components of certain common dietary supplements that can be used to improve the resistance of a population against certain respiratory infections. In this review, we have attempted to characterize the main groups of biologically active plant compounds that have the potential to disrupt the key stages of CoV replication. It has been shown that the use of certain herbal preparations can change the course of infection.

Amaryllidaceae alkaloids with anti-Trypanosoma cruzi activity

Background

Chagas disease, caused by the protozoan Trypanosoma cruzi, is a neglected disease that affects ~7 million people worldwide. Development of new drugs to treat the infection remains a priority since those currently available have frequent side effects and limited efficacy at the chronic stage. Natural products provide a pool of diversity structures to lead the chemical synthesis of novel molecules for this purpose. Herein we analyzed the anti-T. cruzi activity of nine alkaloids derived from plants of the family Amaryllidaceae.

Methods

The activity of each alkaloid was assessed by means of an anti-T. cruzi phenotypic assay. We further evaluated the compounds that inhibited parasite growth on two distinct cytotoxicity assays to discard those that were toxic to host cells and assure parasite selectivity.

Results

We identified a single compound (hippeastrine) that was selectively active against the parasite yielding selectivity indexes of 12.7 and 35.2 against Vero and HepG2 cells, respectively. Moreover, it showed specific activity against the amastigote stage (IC₅₀ = 3.31 μM).

Conclusions

Results reported here suggest that natural products are an interesting source of new compounds for the development of drugs against Chagas disease.

Chemical and Biological Aspects of Montanine-Type Alkaloids Isolated from Plants of the Amaryllidaceae Family

Plants of the Amaryllidaceae family are promising therapeutic tools for human diseases and have been used as alternative medicines. The specific secondary metabolites of this plant family, called Amaryllidaceae alkaloids (AA), have attracted considerable attention due to their interesting pharmacological activities. One of them, galantamine, is already used in the therapy of Alzheimer’s disease as a long acting, selective, reversible inhibitor of acetylcholinesterase. One group of AA is the montanine-type, such as montanine, pancracine and others, which share a 5,11-methanomorphanthridine core. So far, only 14 montanine-type alkaloids have been isolated. Compared with other structural-types of AA, montanine-type alkaloids are predominantly present in plants in low concentrations, but some of them display promising biological properties, especially in vitro cytotoxic activity against different cancerous cell lines. The present review aims to summarize comprehensively the research that has been published on the Amaryllidaceae alkaloids of montanine-type.

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.

Antibacterial Isoquinoline Alkaloids from the Fungus Penicillium Spathulatum Em19

In the search for new microbial antibacterial secondary metabolites, two new compounds (1 and 2) were isolated from culture broths of Penicillium spathulatum Em19. Structure determination by nuclear magnetic resonance and mass spectrometry identified the compounds as 6,7-dihydroxy-5,10-dihydropyrrolo[1,2-b]isoquinoline-3-carboxylic acid (1, spathullin A) and 5,10-dihydropyrrolo[1,2-b]isoquinoline-6,7-diol (2, spathullin B). The two compounds displayed activity against both Gram-negative and -positive bacteria, including Escherichia coli, Acinetobacter baumannii, Enterobacter cloacae, Klebsiella pneumonia, Pseudomonas aeruginosa, and Staphylococcus aureus. Compound 2 was more potent than 1 against all tested pathogens, with minimal inhibitory concentrations down to 1 µg/mL (5 µM) against S. aureus, but 2 was also more cytotoxic than 1 (50% inhibitory concentrations 112 and 11 µM for compounds 1 and 2, respectively, towards Huh7 cells). Based on stable isotope labelling experiments and a literature comparison, the biosynthesis of 1 was suggested to proceed from cysteine, tyrosine and methionine via a non-ribosomal peptides synthase like enzyme complex, whereas compound 2 was formed spontaneously from 1 by decarboxylation. Compound 1 was also easily oxidized to the 1,2-benzoquinone 3. Due to the instability of compound 1 and the toxicity of 2, the compounds are of low interest as possible future antibacterial drugs.

Antimicrobial Activity of Polyphenols and Alkaloids in Middle Eastern Plants

Antibiotic-resistant microorganisms have been an ever-growing concern over the past years. This has led researchers to direct their attention onto plants to be able to discover new possible antimicrobial compounds. The Middle East encompasses a wide spectrum of plant diversity with over 20,000 different species in habitats ranging from deserts to snow-capped mountains. Several plant secondary metabolites and their derivatives have been identified as possible antimicrobial agents. Among the secondary metabolites studied, alkaloids and polyphenols have shown strong antimicrobial activity. Polyphenols are one of the most numerous and diverse group of secondary metabolites; their antioxidant properties provide the basis for antimicrobial effects. Alkaloids provided the underlying structure for the development of several antibiotics with a diverse range of action. The ability of some plant secondary metabolites to act as resistance-modifying agents is a promising field in mitigating the spread of bacterial resistance.

Discovery and characterisation of lycorine-type alkaloids in Lycoris spp. (Amaryllidaceae) using UHPLC-QTOF-MS

INTRODUCTION

Lycorine, one of the most common alkaloids in Lycoris spp., is believed to possess pharmacological activity.

OBJECTIVE

To discover and identify lycorine-type alkaloids in the crude extracts of bulbs from six Lycoris spp. by ultra-high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) detection.

METHODOLOGY

A qualitative analytical method with a data mining strategy was utilised. Based on the fragmentation patterns of standards investigated in positive tandem mass spectrometry (MS/MS) mode, the fragmentation rules of lycorine-type alkaloids were summarised. These types of alkaloids were additionally classified as different subtypes based on structural features and MS/MS fragmentation patterns, and the diagnostic ions for characterisation of different subtypes of alkaloids were designated.

RESULTS

Thirty-seven lycorine type alkaloids, including 16 previously undescribed compounds, were efficiently screened out and tentatively identified from the crude extracts of six Lycoris spp. Lycoris sprengri may be a preferable species for studying or extracting lycorine-type alkaloids because of elevated relative concentrations and highest diversity of alkaloids.

CONCLUSION

The UHPLC-QTOF-MS and MS/MS data-mining strategy proved useful for the detection and tentative identification of lycorine-type alkaloids in bulbs of Lycoris spp. and could be extended to other Amaryllidaceae genera. The consequent profiling of the lycorine-type alkaloids will be useful in the quality control of raw materials of Lycoris species and the exploration of superior species.

Toxoflavin Produced by Burkholderia gladioli from Lycoris aurea Is a New Broad-Spectrum Fungicide

Fungal infections not only cause extensive agricultural damage but also result in serious diseases in the immunodeficient populations of human beings. Moreover, the increasing emergence of drug resistance has led to a decrease in the efficacy of current antifungals. Thus, screening of new antifungal agents is imperative in the fight against antifungal drug resistance. In this study, we show that an endophytic bacterium, Burkholderia gladioli HDXY-02, isolated from the medicinal plant Lycoris aurea, showed broad-spectrum antifungal activity against plant and human fungal pathogens. An antifungal ability assay indicated that the bioactive component was produced from strain HDXY-02 having an extracellular secreted component with a molecular weight lower than 1,000 Da. In addition, we found that this new antifungal could be produced effectively by liquid fermentation of HDXY-02. Furthermore, the purified component contributing to the antifungal activity was identified to be toxoflavin, a yellow compound possessing a pyrimido[5,4-e][1,2,4]triazine ring. In vitro bioactivity studies demonstrated that purified toxoflavin from B. gladioli HDXY-02 cultures had a significant antifungal activity against the human fungal pathogen Aspergillus fumigatus, resulting in abolished germination of conidia. More importantly, the growth inhibition by toxoflavin was observed in both wild-type and drug-resistant mutants (cyp51A and non-cyp51A) of A. fumigatus Finally, an optimized protocol for the large-scale production of toxoflavin (1,533 mg/liter) has been developed. Taken together, our findings provide a promising biosynthetic resource for producing a new antifungal reagent, toxoflavin, from isolates of the endophytic bacterium B. gladioli IMPORTANCE Human fungal infections are a growing problem associated with increased morbidity and mortality. Moreover, a growing number of antifungal-resistant fungal isolates have been reported over the past decade. Thus, the need for novel antifungal agents is imperative. In this study, we show that an endophytic bacterium, Burkholderia gladioli, isolated from the medicinal plant Lycoris aurea, is able to abundantly secrete a compound, toxoflavin, which has a strong fungicidal activity not only against plant fungal pathogens but also against human fungal pathogens Aspergillus fumigatus and Candida albicans, Cryptococcus neoformans, and the model filamentous fungus Aspergillus nidulans More importantly, toxoflavin also displays an efficacious inhibitory effect against azole antifungal-resistant mutants of A. fumigatus Consequently, our findings provide a promising approach to abundantly produce toxoflavin, which has novel broad-spectrum antifungal activity, especially against those currently problematic drug-resistant isolates.

Antifungal constituents of the plant family Amaryllidaceae

Globalization, the modern lifestyle, immuno-suppressive agents, invasive surgical procedures, the loss of efficacies of existing drugs, and multidrug resistance are some of the factors used to explain the rise in fungal infections in recent years. Significant advances have been made in attempts to replace existing antifungal schedules, especially with synthetic targets. The identification of other platforms for drug discovery is now entrenched in research programs across the globe. Plants offer significant benefits owing to their numerical superiority, exceedingly broad chemical basis and appealing sustainability characteristics. Furthermore, plants have a long and rich historical association with traditional approaches towards fungal diseases. These have in numerous instances served as markers in the bioassay-guided identification of the active constituents. Although the plant family Amaryllidaceae is conventionally associated with cancer and motor-neuron disease chemotherapies, around 30 of its species have been examined for antifungal activities with microgram per millilitre inhibitory activities detected in several instances. This review focuses on the nearly 40 constituents from the family, mainly isoquinoline alkaloids, which have been screened against around 50 fungal pathogens. Encouragingly, microgram per millilitre growth inhibitory activities were applicable for several of the compounds with a minimum inhibitory concentration of 4 μg/ml seen to be the lowest.

Antiplasmodial alkaloids from bulbs of Amaryllis belladonna Steud

A bioassay-guided fractionation and chemical investigation of Amaryllis belladonna Steud. bulbs resulted in the isolation and identification of the new crinane alkaloid 1,4-dihydroxy-3-methoxy powellan (1), along with the 3 known crinane alkaloids 2-4 and the two lycorane alkaloids 5-6. The structures were elucidated by interpretation of combined HR-ESIMS, CD and 2D NMR spectroscopic data. Among these isolated compounds the lycorane-type alkaloid acetylcaranine (5) exhibited strong antiplasmodial activity, while compounds 3 and 4 were moderately active, and compounds 1 and 6 were inactive.

Lycorine possesses notable anticancer potentials in on-small cell lung carcinoma cells via blocking Wnt/β-catenin signaling and epithelial-mesenchymal transition (EMT)

Lycorine, an natural isoquinoline alkaloid has reportedly that possesses multi-anticancer activity. However, to date, the anticancer feature of lycorine in non-small cell lung carcinoma (NSCLC) has still not fully been spelled out. The present study mainly focused on the molecular mechanism of lycorine against NSCLC in vitro and vivo. The results showed that lycorine evidently inhibited proliferation of A549 and H460 with IC₅₀ values were 10.83 ± 1.14 μM and 12.35 ± 1.13 μM, while caused slight cytotoxicity in normal pulmonary epithelial Beas-2B cells, and arrested cell cycle in G0/G1 phase. Hoechst DNA-binding staining showed that typical characteristics of nuclear morphology apoptosis, AnnexinV-FITC/PI staining revealed the early-period apoptosis and the dissipation of mitochondrial membrane potential (Δψm) were also captured after lycorine treatment. Moreover, lycorine effectively repressed the Wnt/β-catenin signaling and reversed epithelial-mesenchymal transition (EMT). In addition, lycorine also intervened the caspase-mediated mitochondrial apoptosis pathway. Furthermore, A549/Luc tumor xenograft model was also corroborated that lycorine significantly suppressed the growth and metastasis of the lung tumor. These data highlight the significance of lycorine as potential anti-neoplastic agents to combat NSCLC.

Alkaloid Constituents of the Amaryllidaceae Plant Amaryllis belladonna L

The plant family Amaryllidaceae is well-known for its unique alkaloid constituents, which exhibit a wide range of biological activities. Its representative, Amaryllis belladonna, has a geographical distribution covering mainly southern Africa, where it has significant usage in the traditional medicine of the native people. In this study, A. belladonna samples collected in Brazil were examined for alkaloid content. Alkaloid profiles of A. belladonna bulbs were generated by a combination of chromatographic, spectroscopic and spectrometric methods, including GC–MS and 2D NMR. In vitro screening against four different parasitic protozoa (Trypanosoma cruzi, T. brucei rhodesiense, Leishmania donovani and Plasmodium falciparum) was carried out using the A. belladonna crude methanol extract, as well as three of its alkaloid isolates. Twenty-six different Amaryllidaceae alkaloids were identified in the A. belladonna bulb samples, and three of them were isolated. Evidence for their respective biosynthetic pathways was afforded via their mass-spectral fragmentation data. Improved data for 1-O-acetylcaranine was provided by 2D NMR experiments, together with new ¹H-NMR data for buphanamine. The crude extract and 3-O-acetylhamayne exhibited good antiprotozoal activity in vitro, although both with a high cytotoxic index.

Amaryllidaceae alkaloids: Absolute configuration and biological activity

Plants belonging to the Amaryllidaceae family are well known for their ornamental and medicinal use. Plant members of this group are distributed through both tropical and subtropical regions of the world and are dominant in Andean South America, the Mediterranean basin, and southern Africa. Amaryllidaceae plants have been demonstrated to be a good source of alkaloids with a large spectrum of biological activities, the latter being strictly related to the absolute stereochemistry of the alkaloid scaffold. Among them, great importance for practical applications in medicine has galanthamine, which has already spawned an Alzheimer's prescription drug as a potent and selective inhibitor of the enzyme acetylcholinesterase. Furthermore, lycorine as well as its related isocarbostyryl analogs narciclasine and pancratistatine have shown a strong anticancer activity in vitro against different solid tumors with malignant prognosis. This review addresses the assignment of the absolute configuration of several Amaryllidaceae alkaloids and its relationship with their biological activities.

Phytochemical and biological investigations of Amaryllidaceae alkaloids: a review

Amaryllidaceae is a family that includes 75 genera and about 1100 species, which have a long history of medicinal use. Many plants have been proven to possess efficacy for neurological injury and inflammatory conditions. This article summarizes 357 Amaryllidaceae alkaloids, and cites 166 174 references over the last three decades. These alkaloids are classified into 14 skeleton types, and their abundant sources are also included. Modern pharmacology studies demonstrate that alkaloids that exclusively occur in Amaryllidaceae plant possess wide-ranging pharmacological actions, especially effects on the central nervous system, as well as antitumor, antimicrobial, and anti-inflammatory activities. Effective monomeric compounds from Amaryllidaceae screened for pharmacological activity in vivo and in vitro are also summarized.

A review of ethnoboatany, therapeutic value, phytochemistry and pharmacology of Crinum macowanii Baker: A highly traded bulbous plant in Southern Africa

ETHNOPHARMACOLOGICAL RELEVANCE

Crinum macowanii is a deciduous bulbous plant which grows in east, central and southern Africa. Crinum macowanii has been used as herbal medicine by the indigenous people of east and southern Africa has for several centuries. The bulb, leaves and roots of C. macowanii are reported to possess diverse medicinal properties and used to treat or manage various human and animal diseases and ailments throughout its distributional range. Crinum macowanii is used traditionally as a remedy for boils, diarrhoea, fever, inflammation, respiratory system problems, skin rashes, tuberculosis, wounds and urinary tract problems.

AIM OF THE REVIEW

The present review aims to summarize comprehensively the research that has been done on the ethnomedicinal uses, botany, phytochemistry and pharmacology of C. macowanii in different locations throughout its geographical range in east, central and southern African region so as to highlight research gaps and provide a foundation for further investigations on the plant species.

MATERIALS AND METHODS

A review of the literature was undertaken and an in-depth analysis of previous research on ethnobotany, therapeutic value, phytochemistry and pharmacology of C. macowanii throughout its distributional range in east, central and southern Africa. Literature sources included papers published in international journals, reports from international, regional and national organizations, conference papers, books, theses, websites and other grey literature. Electronic search engines such as Google, Google scholar, publishing sites such as Elsevier, scienceDirect, BMC, PubMed and other scientific database sites such as ChemSpider, PubChem were used as well as searching the library collections of the National Herbarium and Botanic Gardens (SRGH), Harare, Zimbabwe and the University of Fort Hare, South Africa.

RESULTS

A total of 32 ethnomedicinal uses of C. macowanii are documented in literature, which can be grouped into seven major ethnomedicinal general purpose usages, namely "fever", "wounds, sores and skin rashes", "boils and inflammation", "respiratory system problems", "blood cleansing", "urinary tract problem" and "veterinary uses". The chemical composition of C. macowanii is dominated by various isoquinoline alkaloids, which have been isolated from the bulbs, flowering stalks, leaves and roots. Major biological activities demonstrated by C. macowanii include antifungal, antiviral and antiplasmodial activities, cardiovascular effects as well as effects on the central nervous system. The population of C. macowanii is declining in the wild as the bulbs are over-collected for sale in medicinal (muthi) markets in southern Africa.

CONCLUSION

A literature search revealed that C. macowanii has a lot of potential as a possible source of pharmaceutical products for the treatment of a wide range of human and animal diseases and ailments. Some of the alkaloids isolated from C. macowanii have demonstrated various biological activities when investigated in in vitro assays. However, some of the ethnomedicinal uses of C. macowanii still require pharmacological investigations. Therefore, further studies are required to improve our knowledge about the mechanisms of action, efficacy, toxicity and clinical relevance of the plant species as well as its bioactive compounds.

The Biological Activity of Alkaloids from the Amaryllidaceae: From Cholinesterases Inhibition to Anticancer Activity

Modern research has shown that Amaryllidaceae alkaloids represent a rich reservoir of potential small chemical molecules exhibiting several medicinal properties through various mechanisms. Among the many Amaryllidaceae compounds, galanthamine has been given a great amount of attention due to the fact that it possesses potent acetylcholinesterase inhibitory activity. In spite of the amount of evidence indicating the potential usefulness of Amaryllidaceae alkaloids in therapy, research groups have focused their attention on the other alkaloids present in this plant family. New investigations have shed light on many aspects of the structure of Amaryllidaceae alkaloids and on their semisynthetic modification, function, and mechanisms underlying in vitro and in vivo activity. In addition, Amaryllidaceae alkaloids have frequently been identified as having promising cytotoxic properties against cancer cell lines. While follow-up studies have repeatedly shown that Amaryllidaceae alkaloids and their derivatives demonstrate antiproliferative, cytotoxic and apoptosis-inducing activity, the mechanisms remain unclear. This review addresses the most important Amaryllidaceae alkaloids with anticancer potential, particularly those that have been studied for the purpose of gaining a better understanding of the basis of the activity at the cellular and molecular level.

Antiproliferative and Structure Activity Relationships of Amaryllidaceae Alkaloids

The antiproliferative activity of a set of seven natural Amaryllidaceae alkaloids and 32 derivatives against four cancer cell lines (A2780, SW1573, T47-D and WiDr) was determined. The best antiproliferative activities were achieved with alkaloids derived from pancracine (2), haemanthamine (6) and haemantidine (7). For each skeleton, some structure-activity relationships were outlined.

Relevant and selective activity of Pancratium illyricum L. against Candida albicans clinical isolates: a combined effect on yeast growth and virulence

Background

Alkaloids present in plants of the Amaryllidaceae family are secondary metabolites of high biological interest, possessing a wide range of pharmacological activities. In the search for new plant-derived compounds with antimicrobial activities, two alkaloid extracts obtained from bulbs and leaves of Pancratium illyricum L., a plant of the Amarillydaceae family, were tested for their effect on bacterial and yeast growth.

Methods

The broth microdilution susceptibility test was applied to study the effect of plant extracts on the growth of reference bacterial strains and Candida albicans reference and clinical isolates strains. Extracts obtained from the different parts of the plant were tested and compared with the pure components identified in the extracts. Since matrix metalloproteinase enzymes play a role in the dissemination process of Candida albicans, the effect of the bulb extract and pure alkaloids on in vitro collagenase activity was tested. Cell viability test was carried out on human embryo lung fibroblasts (HEL 299).

Results

Whilst both extracts did not show any inhibitory activity against neither Gram positive nor Gram negative bacteria, a strong antifungal activity was detected, in particular for the bulb extract. All clinical isolates were susceptible to the growth inhibitory activity of the bulb extract, with endpoint IC₅₀ values ranging from 1.22 to 78 μg/mL. The pure alkaloids lycorine and vittatine, identified as components of the extract, were also assayed for their capacity of inhibiting the yeast growth, and lycorine turned very active, with endpoint IC₅₀ values ranging from 0.89 to 28.5 μg/mL. A potent inhibition of the in vitro collagenase activity was found in the presence of the bulb extract, and this effect was much higher than that exerted by the pure alkaloids. Viability of cell lines tested was not affected by the extract.

Conclusions

Taken together, results suggest that the extract of Pancratium illyricum may act as antifungal agent both directly on the yeast growth and by altering the tissue invasion process.

Electronic supplementary material

The online version of this article (doi:10.1186/1472-6882-14-409) contains supplementary material, which is available to authorized users.

Chemical composition, and in vitro antibacterial and antifungal activity of an alkaloid extract from Crinum angustum Steud

In the search for novel antibacterial agents against multidrug-resistant bacteria, an alkaloid extract obtained from whole plants of Crinum angustum Steud., containing six different groups of alkaloids, was analysed by using gas chromatography/mass spectrometry, and its in vitro activity against American Type Culture Collection bacterial strains and clinical isolates was evaluated. The antimicrobial activity of the extract was tested against nine standard strains of microorganisms and two drug-resistant clinical isolates, methicillin-resistant Staphylococcus aureus and carbapenemase-producing Klebsiella pneumoniae. The extract exhibited a significant activity against six of the examined strains of microorganisms. Antibacterial activity was more pronounced on Gram-positive bacteria than on Gram-negative bacteria, and IC50 values ranged from 156 to 625 μg/mL. Mycostatic activity against Candida albicans was also found, with an IC50 of 78 μg/mL after 48 h of incubation . Promising results were also obtained from tests carried out on both clinical isolates investigated.

Traditional usage, phytochemistry and pharmacology of the South African medicinal plant Boophone disticha (L.f.) Herb. (Amaryllidaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Boophone disticha is the most common member of the South African Amaryllidaceae used extensively in traditional medicine of the various indigenous population groups, including the Sotho, Xhosa and Zulu as well as the San. This survey was carried out to identify and highlight areas relevant to the traditional usage of Boophone disticha. Pharmacological aspects were examined with the purpose of reconciling these with the traditional usage of the plant. In relation to phytochemical make-up, particular attention was paid on how its alkaloid constitution might corroborate the various biological effects manifested by the plant.

MATERIALS AND METHODS

Information gathering involved the use of four different database platforms, including Google Scholar, ScienceDirect, SciFinder(®) and Scopus. Arrangement and detailing of this information is as reflected in the various sections of the paper.

RESULTS

Sixteen categories were identified under which Boophone disticha finds use in traditional medicine. These were shown to include general usage purposes, such as 'cultural and dietary', 'well-being', 'personal injury', 'divinatory purposes', 'psychoactive properties' and 'veterinary uses'. Furthermore, traditional usage was seen to involve six body systems, including functions pertaining to the circulatory, gastrointestinal, muscular, neurological, respiratory and urinary systems. The four remaining categories relate to use for inflammatory conditions, cancer, malaria and tuberculosis. Overall, three areas were discernible in which Boophone disticha finds most usage, which are (i) ailments pertaining to the CNS, (ii) wounds and infections, and (iii) inflammatory conditions. In addition, several aspects pertaining to the toxic properties of the plant are discussed, including genotoxicity, mutagenicity and neurotoxicity.

CONCLUSION

The widespread ethnic usage of Boophone disticha has justified its standing as a flagship for the Amaryllidaceae and its relevance to South African traditional medicine. Furthermore, its promising pharmacological and phytochemical profiles have stimulated significant interest in the clinical realm, especially in the areas of cancer and motor neuron disease chemotherapy. These collective properties should prove useful in steering the progress of the plant towards a wider audience.

Total synthesis of lycorine-type alkaloids by cyclopropyl ring-opening rearrangement

Anhydrocaranine, γ-lycorane and putative amarbellisine were synthesized based on a series reactions including a novel cyclopropyl ring-opening rearrangement.

Pharmacological and toxicological insights to the South African Amaryllidaceae

The plant family Amaryllidaceae is of provenance in the South African region which is known to harbor about a third of the global complement of around 1000 species. It has widespread usage in the traditional medicinal practices of the indigenous peoples of the region. As a consequence and given its unique alkaloid principles, its members have provided a viable platform for phytochemical based drug discovery. The medicinal potential of the family has been realized through the commercialization of galanthamine as an Alzheimer's drug due to its potent and selective inhibitory activity against the enzyme acetylcholinesterase. Further promising chemotherapeutic candidates of the family reside with the phenanthridone class of alkaloids such as pancratistatin which exhibit potent and cell line specific antiproliferative properties with significant potential for clinical development. Despite these interesting medicinal attributes, plants of the Amaryllidaceae are known to be poisonous and several of them have been classified as such. This survey taking into consideration Amaryllidaceae plants native to South Africa aims to strike a balance between the medicinal potential of the family on one hand and its adverse and toxic effects on the other.

Preparation and antimalarial activity of semisynthetic lycorenine derivatives

A set of twenty one lycorenine derivatives has been prepared from the alkaloid hippeastrine (1). The modifications performed on hippeastrine included some functional group transformations, structural simplification and preparation of dimers. All alkaloids were tested as potential antimalarial agents, being the hippeastrine dimers the most active compounds.

Amaryllidaceae alkaloids inhibit nuclear-to-cytoplasmic export of ribonucleoprotein (RNP) complex of highly pathogenic avian influenza virus H5N1

Please cite this paper as: He et al. (2013) Amaryllidaceae alkaloids inhibit nuclear‐to‐cytoplasmic export of ribonucleoprotein (RNP) complex of highly pathogenic avian influenza virus H5N1. Influenza and Other Respiratory Viruses 7(6), 922–931.

Background  Few drugs are currently licensed to treat influenza A infection, and new therapies are needed, especially for highly pathogenic strains. Traditional medicinal plants, such as Lycoris radiata, are a potential source of new antiviral agents.

Objective  To test 15 Amaryllidaceae alkaloids isolated from the bulbs of L. radiata in vitro for antiviral activities against influenza virus type A, A/Chicken/GuangDong/178/2004 (H5N1, 178).

Methods  Antiviral activities of the compounds were tested in time‐of‐addition assays, hemagglutination inhibition (HI) assays, neuraminidase (NA) activity assays, and viral entry inhibition assays using H5N1‐HIV pseudoviruses. Effects of the compounds on localization and activity of the viral ribonucleoprotein (RNP) were determined by immunofluorescence and an RNP minigenome assay, respectively.

Results  Among the alkaloids, lycorine (AA1), hippeastrine (AA2), hemanthamine (AA3) and 11‐hydroxy vittatine (AA4) exhibited antiviral activities, with EC₉₀ values of 0·52, 82·07, 4·15, and 13·45 μm, respectively. These compounds did not affect the function of the outer membrane proteins or the viral entry process and viral RNP activity. As AA1 and AA3 exhibited stronger antiviral activities, they were further analyzed. Intracellular nucleoprotein (NP) localization showed that AA1 and AA3 inhibited the RNP complex in the nucleus at an early stage of a single‐round and multi‐round of replication.

Conclusion  Four Amaryllidaceae alkaloids were first determined that could exert anti‐influenza activities after virus entry into cells. Furthermore, AA1 and AA3 could inhibit nuclear‐to‐cytoplasmic export of the RNP complex of virus replication. Thus, these compounds may be developed further as anti‐influenza drug candidates.

Alkaloid patterns in Leucojum aestivum shoot culture cultivated at temporary immersion conditions

The alkaloid patterns in Leucojum aestivum L. shoot culture cultivated at temporary immersion conditions were investigated using gas chromatography-mass spectrometry. 18 alkaloids were identified, and galanthamine, hamayne and lycorine were dominant. The L. aestivum 80 shoot culture, cultivated at temporary immersion conditions, is a prospective biological matrix for obtaining wide range Amaryllidaceae alkaloids, showing valuable biological and pharmacological activities. The temperature of cultivation influenced enzyme activities, catalyzing phenol oxidative coupling of 4'-O-methylnorbelladine and formation of the different groups Amaryllidaceae alkaloids. Decreasing the temperature of cultivation of L. aestivum 80 shoot culture led to activation of para-ortho' phenol oxidative coupling (formation of galanthamine type alkaloids) and inhibited ortho-para' and para-para' phenol oxidative coupling (formation of lycorine and haemanthamine types alkaloids).

Ungeremine effectively targets mammalian as well as bacterial type I and type II topoisomerases

From the methanol extract of the bulbs of Pancratium illyricum L., three phenanthridine type alkaloids, ungeremine (1), (-)-lycorine (2) and (+)-vittatine (3) were isolated. For the evaluation of their anticancer and antibacterial potential, compounds 1-3 were tested against human (I, IIα) and bacterial (IA, IV) topoisomerases. Our data demonstrated that ungeremine impairs the activity of both, human and bacterial topoisomerases. Remarkably, ungeremine was found to largely increments the DNA cleavage promoted by bacterial topoisomerase IA, a new target in antimicrobial chemotherapy.

Two new alkaloids from Narcissus serotinus L

The Amaryllidaceae family is well known for the presence of an exclusive group of alkaloids with a wide range of biological activities. Narcissus serotinus L. is a plant belonging to this family and its geographical distribution is mainly located along the Mediterranean coast. In the present work, specimens collected near Casablanca (Morocco) were used to study the alkaloid content of this species. Starting with 350 g of the whole plant we used standard extraction and purification procedures to obtain fractions and compounds for GC-MS and NMR analysis. As well as five known alkaloids, we isolated two new compounds: 1-O-(3´-acetoxybutanoyl)lycorine and narseronine. The latter has been previously published, but with an erroneous structure.

Effect of isoquinoline alkaloids from two Hippeastrum species on in vitro acetylcholinesterase activity

The treatment of neurological disorders and neurodegenerative diseases is related to the levels of acetylcholine (ACh) through the inhibition of acetylcholinesterase (AChE). Galanthamine, an important alkaloid isolated from the Amaryllidaceae family, is approved for the pharmacological treatment of Alzheimer's disease (AD) and acts by inhibiting the acetylcholinesterase (AChE) activity. In the present study, Ellman's method was used to verify the inhibition of AChE activity of some isoquinolines alkaloids such as galanthamine, montanine, hippeastrine and pretazettine. At the concentrations 1mM, 500 microm and 100 microm, galanthamine presented an AChE inhibition higher than 90%. Montanine inhibited, in a dose-dependent manner, more than 50% of the enzyme at 1mM concentration. With the concentrations 500 microm and 100 microm, 30-45% of AChE activity inhibition was detected. The alkaloids hippeastrine and pretazettine presented no significant inhibition of the AChE activity. The results demonstrate that montanine significantly inhibits AChE activity at the tested concentrations, suggesting the necessity of further investigations on this alkaloid use in treating neurological disorders.

Lycorine, the main phenanthridine Amaryllidaceae alkaloid, exhibits significant antitumor activity in cancer cells that display resistance to proapoptotic stimuli: an investigation of structure-activity relationship and mechanistic insight

Twenty-two lycorine-related compounds were investigated for in vitro antitumor activity using four cancer cell lines displaying different levels of resistance to proapoptotic stimuli and two cancer cell lines sensitive to proapoptotic stimuli. Lycorine and six of its congeners exhibited potency in the single-digit micromolar range, while no compound appeared more active than lycorine. Lycorine also displayed the highest potential (in vitro) therapeutic ratio, being at least 15 times more active against cancer than normal cells. Our studies also showed that lycorine exerts its in vitro antitumor activity through cytostatic rather than cytotoxic effects. Furthermore, lycorine provided significant therapeutic benefit in mice bearing brain grafts of the B16F10 melanoma model at nontoxic doses. Thus, the results of the current study make lycorine an excellent lead for the generation of compounds able to combat cancers, which are naturally resistant to proapoptotic stimuli, such as glioblastoma, melanoma, non-small-cell-lung cancers, and metastatic cancers, among others.

Pancratium canariense as an important source of amaryllidaceae alkaloids

Four new alkaloids (1-4) have been isolated from a methanolic extract of bulbs of Pancratium canariense, together with 12 known alkaloids (5-16). The structures of the new alkaloids were determined by extensive 1D and 2D NMR spectroscopic studies and X-ray diffraction.

Pressurized liquid extraction and anticholinesterase activity-based thin-layer chromatography with bioautography of Amaryllidaceae alkaloids

Modern extraction technique-pressurized liquid extraction (PLE) was optimised for extraction of lycorine and galanthamine (Amaryllidaceae alkaloids) from Narcissus jonquilla 'Pipit'. Crude extracts were purified on Oasis MCX cartridges, and the alkaloids eluted with 80-100% recoveries using methanol-10% ammonia solution (3:1, v/v). Quantitative results were obtained by both HPTLC-densitometry on silica gel plates and RP-HPLC with diode array (DAD) on XTerra C(18) stationary phase. Both methods were fully validated in terms of specificity, precision (including intra- and inter-day measurements), LOD and LOQ values, correlation of UV spectra and linearity of calibration curves. The methods were also well correlated each other with correlation coefficients (r) 0.98823 and 0.99081, respectively, for the mean values of galanthamine and lycorine. Among the investigated solvents methanol and 1% tartaric acid methanolic solution at default conditions (120 degrees C, p=60bar, time: 10min, one static cycle) permit the highest yields of the total sum of the alkaloids, whereas for toluene the lowest amounts were measured. Lycorine to galanthamine mean ratios were dependant on the type of solvent used, and in toluene galanthamine and related alkaloids were preferably extracted. In temperature experiments for galanthamine, the levels of this compound increased from the temperature of 20 till 150 degrees C in the investigated solvent systems, then decreased with slight increase from the temperature of 175 to 200 degrees C in 1% tartaric acid methanolic solution. When lycorine was analysed, similar trends were observed, however the maximum of the concentration was measured at a temperature about 125 degrees C. The ratios of the mean values of these two compounds differed in temperature-dependant experiments in both solvent systems. Further more, two TLC with bioautography approaches were used in screening for anticholinesterese properties of the extracts. No qualitative differences were found among the different solvent extracts, and AChE inhibition was correlated with galanthamine and related compounds. In conclusion, optimised PLE was much more effective than previously applied hot-solvent extraction, microwave-assisted extraction (MAE) or ultrasound-assisted extraction (USAE).