N-oxide alkaloids from Crinum amabile (Amaryllidaceae)

Mitragyna parvifolia as apotential therapeutic agent for lymphatic filariasis

This study investigates the medicinal potential of Mitragyna parvifolia (M. parvifolia) leaves for the management of Lymphatic filariasis (LF). Phytochemical screening of the methanolic leaf extract revealed the presence of alkaloids, terpenoids, phenols, tannins, and flavonoids. The GC-MS analysis identified 24 phytoconstituents, including the major alkaloid "mitraphylline." Infrared spectroscopy confirmed the presence of various functional groups corresponding to the identified compounds. The extract exhibited significant antibacterial activity against Staphylococcus epidermidis, Bacillus cereus, and Salmonella typhi. In vitro macrofilaricidal screening demonstrated dose-dependent inhibition of worm motility and MTT reduction, indicating its potential as a macrofilaricidal agent. The larvicidal bioassay showed notable effectiveness against Culex quinquifasciatus larvae, with 1% concentration displaying the highest larvicidal activity. Concentration-dependent antioxidant activity was observed using the DPPH assay, with 100 µg/ml showing the highest antioxidant potential. The findings suggest the potential of M. parvifolia leaves for LF management, supporting further research to identify active compounds and elucidate their mechanisms of action. The study highlights the plant's diverse bioactive compounds, antibacterial and macrofilaricidal activities, larvicidal efficacy, and significant antioxidant properties. Future investigations, including in vivo experiments and clinical trials, are warranted to validate the safety and efficacy of M. parvifolia as a potential therapeutic agent for LF.

Auxin and light-mediated regulation of growth, morphogenesis, and alkaloid biosynthesis in Crinum x powellii 'Album' callus

Crinum x powellii 'Album' belongs to the Amaryllidaceae medicinal plant family that produces a range of structurally diverse alkaloids with potential therapeutic properties. The optimal conditions for in vitro tissue growth, morphogenesis, and alkaloid biosynthesis remain unclear. Auxin and light play critical roles in regulating plant growth, development, and alkaloid biosynthesis in several Amaryllidaceae plants. Here, we have succeeded in showing, for the first time, that the combination of auxin and light significantly influence C. x powellii "Album" in vitro tissue growth, survival, and morphogenesis compared to individual treatments. Furthermore, this combination also upregulates the expression of alkaloid biosynthetic genes and led to an increase in the content of certain alkaloids, suggesting a positive impact on the defense and therapeutic potential of the calli. Our findings provide insights into the regulation of genes involved in alkaloid biosynthesis in C. x powellii "Album" callus and underline the potential of auxin and light as tools for enhancing their production in plants. This study provides a foundation for further exploration of C. x powellii "Album" calli as a sustainable source of bioactive alkaloids for pharmaceutical and agricultural applications. Furthermore, this study paves the way to the discovery of the biosynthetic pathway of specialized metabolites from C. x powellii "Album", such as cherylline and lycorine.

A New Hypoglycemic Prenylated Indole Alkaloid N-Oxide from Endophytic Fungus Pallidocercospora crystalline

A new prenylated indole alkaloid-Penicimutamide C N-oxide (1), a new alkaloid penicimutamine A (2), along with six known alkaloids were isolated from an endophytic fungus Pallidocercospora crystallina. A simple and accurate method was used to determine the N-O bond in the N-oxide group of 1. By using a β-cell ablation diabetic zebrafish model, compounds 1, 3, 5, 6 and 8 showed significantly hypoglycemic activities under the concentration of 10 μM. Further studies revealed that compounds 1 and 8 lowered the glucose level through promoting glucose uptake in zebrafish. In addition, all eight compounds showed no acute toxicity, teratogenicity, nor vascular toxicity in zebrafish under the concentrations range from 2.5 μΜ to 40 μM. Importantly, these results provide new lead compounds for the development of antidiabetes strategies.

Antileishmanial Activity of Clinanthus milagroanthus S. Leiva & Meerow (Amaryllidaceae) Collected in Peru

Leishmaniasis is a worldwide infectious parasitic disease caused by different species of protozoa of the genus Leishmania, which are transmitted to animals and humans through the bite of insects of the Psychodidae family. In the present work, the antileishmanial activity of an alkaloid extract of the bulbs of Clinanthus milagroanthus S. Leiva & Meerow (Amaryllidaceae) was evaluated in vitro, in vivo, and in silico against the parasite Leishmania braziliensis, and the chemical profile of the sample was determined by GC-MS analysis. At concentrations of 1, 10, and 100 µg·mL−1, the alkaloid extract presented inhibition percentages of 8.7%, 23.1%, and 98.8%, respectively, against L. braziliensis with a p < 0.05, and IC50 values of 18.5 ± 0.3 µg·mL−1. Furthermore, at a dose of 1.0 mg·kg−1, a greater decrease in lesion size was observed (90%) for in vivo assays, as well as a decrease in infection (96%), finding no significant differences (p > 0.05) in comparison with amphotericin B (92% and 98%, respectively). Eleven alkaloids were identified in C. milagroanthus bulbs: galanthamine, vittatine/crinine, 8-O-demethylmaritidine, anhydrolycorine, 11,12-dehydroanhydrolycorine, hippamine, lycorine, 2-hydroxyanhydrolycorine, 7-hydroxyclivonine, 2α-hydroxyhomolycorine, and 7-hydroxyclivonine isomer. A molecular model of Leishmania braziliensis trypanothione reductase (TRLb) was built using computational experiments to evaluate in silico the potential of the Amaryllidaceae alkaloid identified in C. milagroanthus toward this enzyme. The structures galanthamine, 7-hydroxyclivonine isomer, and crinine showed better estimated free energy of binding than the reference compound, amphotericin B. In conclusion, this is the first in vitro, in vivo, and in silico report about the antileishmanial potential and alkaloid profiling of the extract of C. milagroanthus bulbs, which could become an interesting source of bioactive molecules.

Alkaloids with cholinesterase inhibitory activities from the bulbs of Crinum × amabile Donn ex Ker Gawl

Seven previously undescribed alkaloids, crinamabilines A-G, two non-alkaloidal compounds, crinamabidiene and 6-phenylpiperonyl alcohol, two first naturally occurring alkaloids, 3-epibuphanisine and (+)-1β,2β-epoxy-epicrinine, together with nineteen known alkaloids, were isolated from the bulbs of Crinum × amabile Donn ex Ker Gawl. Their structures and absolute configurations were elucidated by NMR, MS and ECD spectroscopic techniques. Ungeremine displayed the most potent inhibitory activity against acetylcholinesterase (IC₅₀ 0.21 μM), which was about 6-fold more active than the reference drug, galanthamine (IC₅₀ 1.23 μM). Ungeremine also exhibited the strongest inhibitory activity against butyrylcholinesterase (IC₅₀ 3.57 μM), which was comparable to galanthamine (IC₅₀ 3.11 μM). The molecular docking studies were performed and were well in agreement with the experimental results.

The Phytochemistry and Pharmacology of Tulbaghia, Allium, Crinum and Cyrtanthus: ‘Talented’ Taxa from the Amaryllidaceae

Amaryllidaceae is a significant source of bioactive phytochemicals with a strong propensity to develop new drugs. The genera Allium, Tulbaghia, Cyrtanthus and Crinum biosynthesize novel alkaloids and other phytochemicals with traditional and pharmacological uses. Amaryllidaceae biomolecules exhibit multiple pharmacological activities such as antioxidant, antimicrobial, and immunomodulatory effects. Traditionally, natural products from Amaryllidaceae are utilized to treat non-communicable and infectious human diseases. Galanthamine, a drug from this family, is clinically relevant in treating the neurocognitive disorder, Alzheimer’s disease, which underscores the importance of the Amaryllidaceae alkaloids. Although Amaryllidaceae provide a plethora of biologically active compounds, there is tardiness in their development into clinically pliable medicines. Other genera, including Cyrtanthus and Tulbaghia, have received little attention as potential sources of promising drug candidates. Given the reciprocal relationship of the increasing burden of human diseases and limited availability of medicinal therapies, more rapid drug discovery and development are desirable. To expedite clinically relevant drug development, we present here evidence on bioactive compounds from the genera Allium, Tulgbaghia, Cyrtanthus and Crinum and describe their traditional and pharmacological applications.

Evaluation of Acute and Subacute Toxicity and LC-MS/MS Compositional Alkaloid Determination of the Hydroethanolic Extract of Dysphania ambrosioides (L.) Mosyakin and Clemants Flowers

Dysphania ambrosioides (L.) Mosyakin and Clemants is a medicinal plant that has traditionally been used to cure a range of diseases. There has been no thorough investigation of the potential toxicity of this plant. The objective of this study is to assess the acute and subacute toxicity of D. ambrosioides hydroethanolic extract (DAHE), as well as it alkaloids composition, utilizing LC-MS/MS analysis. An in silico approach was applied to determine pharmacokinetic parameters and to predict the toxicity of D. ambrosioides identified alkaloids. A 14-day treatment with a single oral dose of 1–7 g/kg was carried out to investigate acute toxicity. DAHE was given orally at dosages of 5, 50, and 500 mg/kg for 15 days in the subacute toxicity investigation, and body weight and biochemical parameters were evaluated. Livers, kidneys, lungs, and heart were examined histologically. Chromatographic investigation revealed the existence of nine alkaloids, with N-formylnorgalanthamine being the most prevalent. The oral LD₅₀ value of DAHE was found to be 5000 mg/kg in an acute toxicity study. No variations were observed with respect to food intake, water consumption, mortality, or body and organ weight in the subacute toxicity study. On the other hand, DAHE (500 mg/kg) significantly enhanced alanineaminotransferase, aspartate aminotransferase, and urea. Liver and kidney histological examinations revealed modest infiltration of hepatocyte trabeculae by inflammatory cells in the liver and slight alteration in the kidney histoarchitecture. According to our findings, DAHE exhibits low to moderate toxicity.

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 and Cholinesterase Inhibitory Potential of Crinum × amabile Donn. (Amaryllidaceae) Collected in Ecuador

Natural products are one of the main sources for developing new drugs. The alkaloids obtained from the plant family Amaryllidaceae have interesting structures and biological activities, such as acetylcholinesterase inhibition potential, which is one of the mechanisms used for the palliative treatment of Alzheimer's disease symptoms. Herein we report the alkaloidal profile of bulbs and leaves extracts of Crinum × amabile collected in Ecuador and their in vitro inhibitory activity on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. Using Gas Chromatography coupled to Mass Spectrometry (GC-MS), we identified 12 Amaryllidaceae alkaloids out of 19 compounds detected in this species. The extracts from bulbs and leaves showed great inhibitory activity against AChE and BuChE, highlighting the potential of Amaryllidaceae family in the search of bioactive molecules.

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.

Cytotoxic Agents in the Minor Alkaloid Groups of the Amaryllidaceae

Over 600 alkaloids have to date been identified in the plant family Amaryllidaceae. These have been arranged into as many as 15 different groups based on their characteristic structural features. The vast majority of studies on the biological properties of Amaryllidaceae alkaloids have probed their anticancer potential. While most efforts have focused on the major alkaloid groups, the volume and diversity afforded by the minor alkaloid groups have promoted their usefulness as targets for cancer cell line screening purposes. This survey is an in-depth review of such activities described for around 90 representatives from 10 minor alkaloid groups of the Amaryllidaceae. These have been evaluated against over 60 cell lines categorized into 18 different types of cancer. The montanine and cripowellin groups were identified as the most potent, with some in the latter demonstrating low nanomolar level antiproliferative activities. Despite their challenging molecular architectures, the minor alkaloid groups have allowed for facile adjustments to be made to their structures, thereby altering the size, geometry, and electronics of the targets available for structure-activity relationship studies. Nevertheless, it was seen with a regular frequency that the parent alkaloids were better cytotoxic agents than the corresponding semisynthetic derivatives. There has also been significant interest in how the minor alkaloid groups manifest their effects in cancer cells. Among the various targets and pathways in which they were seen to mediate, their ability to induce apoptosis in cancer cells is most appealing.

Amaryllidaceae Alkaloid Cherylline Inhibits the Replication of Dengue and Zika Viruses

Dengue fever, caused by dengue virus (DENV), is the most prevalent arthropod-borne viral disease and is endemic in many tropical and subtropical parts of the world, with an increasing incidence in temperate regions. The closely related flavivirus Zika virus (ZIKV) can be transmitted vertically in utero and causes congenital Zika syndrome and other birth defects. In adults, ZIKV is associated with Guillain-Barré syndrome. There are no approved antiviral therapies against either virus. Effective antiviral compounds are urgently needed. Amaryllidaceae alkaloids (AAs) are a specific class of nitrogen-containing compounds produced by plants of the Amaryllidaceae family with numerous biological activities. Recently, the AA lycorine was shown to present strong antiflaviviral properties. Previously, we demonstrated that Crinum jagus contained lycorine and several alkaloids of the cherylline, crinine, and galanthamine types with unknown antiviral potential. In this study, we explored their biological activities. We show that C. jagus crude alkaloid extract inhibited DENV infection. Among the purified AAs, cherylline efficiently inhibited both DENV (50% effective concentration [EC₅₀], 8.8 μM) and ZIKV replication (EC₅₀, 20.3 μM) but had no effect on HIV-1 infection. Time-of-drug-addition and -removal experiments identified a postentry step as the one targeted by cherylline. Consistently, using subgenomic replicons and replication-defective genomes, we demonstrate that cherylline specifically hinders the viral RNA synthesis step but not viral translation. In conclusion, AAs are an underestimated source of antiflavivirus compounds, including the effective inhibitor cherylline, which could be optimized for new therapeutic approaches.

Amaryllidaceae plants: a potential natural resource for the treatment of Chagas disease

Background

Chagas disease is a neglected zoonosis caused by the parasite Trypanosoma cruzi. It affects over six million people, mostly in Latin America. Drugs available to treat T. cruzi infection have associated toxicity and questionable efficacy at the chronic stage. Hence, the discovery of more effective and safer drugs is an unmet medical need. For this, natural products represent a pool of unique chemical diversity that can serve as excellent templates for the synthesis of active molecules.

Methods

A collection of 79 extracts of Amaryllidaceae plants were screened against T. cruzi. Active extracts against the parasite were progressed through two cell toxicity assays based on Vero and HepG2 cells to determine their selectivity profile and discard those toxic to host cells. Anti-T. cruzi-specific extracts were further qualified by an anti-amastigote stage assay.

Results

Two extracts, respectively from Crinum erubescens and Rhodophiala andicola, were identified as highly active and specific against T. cruzi and its mammalian replicative form.

Conclusions

The results retrieved in this study encourage further exploration of the chemical content of these extracts in search of new anti-T. cruzi drug development starting points.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04837-9.

Biosynthesis and Biological Activities of Newly Discovered Amaryllidaceae Alkaloids

Alkaloids are an important group of specialized nitrogen metabolites with a wide range of biochemical and pharmacological effects. Since the first publication on lycorine in 1877, more than 650 alkaloids have been extracted from Amaryllidaceae bulbous plants and clustered together as the Amaryllidaceae alkaloids (AAs) family. AAs are specifically remarkable for their diverse pharmaceutical properties, as exemplified by the success of galantamine used to treat the symptoms of Alzheimer's disease. This review addresses the isolation, biological, and structure activity of AAs discovered from January 2015 to August 2020, supporting their therapeutic interest.

The Bioassay-Guided Fractionation and Identification of Potent Acetylcholinesterase Inhibitors from Narcissus c.v. 'Hawera' Using Optimized Vacuum Liquid Chromatography, High Resolution Mass Spectrometry and Bioautography

Bioassay-guided isolation of bioactive compound is a modern and efficient technique in metabolites screening. It may shorten the total time of the entire process and reduce some costs of it. The aim of this paper was to fractionate and isolate alkaloids by developing an innovative vacuum liquid chromatography method for a species of Narcissus c.v. ‘Hawera’ rarely investigated so far and establishing the inhibitory activity of acetylcholinesterase (AChE). The studies consisted of the extraction of plant material by modern pressurized liquid extraction (PLE), followed by the isolation of alkaloidal fractions. For this purpose, the pioneering gradient vacuum liquid chromatography (gVLC) technique was employed by using two sorbents in various proportions packed in polypropylene cartridges for the first time. This step was performed in order to pre-clean the samples but also to establish the best combination of sorbents which permits obtaining potentially strong AChE inhibitors. The collected fractions were examined by HPLC/ESI-QTOF-MS in order to compare which combination of sorbents would allow us to obtain the highest concentration of alkaloids. The combination of these techniques confirmed the presence of the alkaloids and enabled the development of a modern method for the fractionation and isolation of the compounds with strong anti-AChE activity.

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.

Multidimensional Studies of Pancratium parvum Dalzell Against Acetylcholinesterase: A Potential Enzyme for Alzheimer's Management

Objective: Pancratium L. (Amaryllidaceae J.St. Hil.) is a monocot genus with bulbous habitat and about 20 species worldwide have significant medicinal properties. The present envision aims to investigate the potential ability of Pancratium species for acetylcholinesterase (AChE) inhibition as a remedy for Alzheimer disease (AD). Different Pancratium species were screened for the inhibition of AChE enzyme from various localities across India. Prominent species was further studied for anti-inflammatory, antioxidant, metal chelating and UHPLC-QTOF-MS analysis.Methods: Nine different species collected across India were examined for AChE inhibition and for binding affinity studies using Surface Plasmon Resonance (SPR). Highest inhibition species was subjected to Response Surface Methodology (RSM) to accomplish the effective conditions for maximum extraction of phytomolecules in accordance with the inhibition of the AChE. Further, extract under optimized conditions were used to study anti-inflammatory, antioxidant, metal chelating and UHPLC-QTOF-MS analysis for tentative identification of phytomolecules.Results: Amongst different species collected, P. parvum Dalzell exhibited maximum inhibition 93.30 ± 1.71% with promising IC₅₀ 20 ± 0.22 µg/ml value. In addition, binding affinity toward AChE and β plaques using SPR technique showed a higher binding response toward the enzyme. RSM study resulted that water extracts at 50 °C and 5.46 hours heating executed maximum inhibition. Other studies showed prominent anti-inflammatory and metal chelating ability with low antioxidant property.Conclusion: By using UHPLC-QTOF-MS compounds were tentatively identified for the concerned activities mentioned above. This work reports for accounting the detailed study of P. parvum and which can be further entailed for the treatment of various neurological disorders.

Antiprotozoal alkaloid principles of the plant family Amaryllidaceae

Protozoan-borne diseases are prominent amongst diseases caused by parasites. Given their alarming morbidity and mortality statistics, there is ever growing interest in new therapies against these diseases. Whilst synthetic drugs such as benznidazole and melarsoprol have had a profound influence on the clinical setup, there has been significant interest in the phytochemical platform to also deliver such drug candidates. The plant family Amaryllidaceae is recognizable for its isoquinoline alkaloids, which exhibit attractive molecular architectures and interesting biological properties. This survey focuses on the antiprotozoal activities of 73 of such substances described in 18 different species of the Amaryllidaceae. Of these, 2-O-acetyllycorine was identified as the most potent (IC₅₀ 0.15 μg/mL against Trypansoma brucei brucei). Also considered are structure-activity relationships which have served to modulate activities, as well as the plausible mechanisms that underpin these effects and afford insight to the Amaryllidaceae alkaloid antiprotozoal pharmacophore.

The Amaryllidaceae as a source of antiplasmodial crinane alkaloid constituents

Malaria is prevalent in tropical and subtropical regions of the globe. With over 200 million cases reported annually, particularly in sub-Saharan Africa, it is an unnecessary burden to already overworked and ailing healthcare structures. Traditional medicine (TM) remains vibrant in most of these regions wherein plants often serve as the first line of defense against malaria. Given this fact as well as the successes elsewhere of therapies such as Artemisia annua emanating from evidence-based TM, interest in plants as a source of new antimalarial drugs has been rejuvenated. The bulbous plant family Amaryllidaceae is recognized for its structurally-diverse alkaloid constituents which exhibit interesting biological properties. This review focuses on the in vitro activities demonstrated by its crinane alkaloids against various strains of the malaria-causing parasite Plasmodium falciparum. The survey embraces the twelve genera of the Amaryllidaceae whose nineteen representative species have been examined for antiplasmodial crinane alkaloid principles. A total of seventy-two compounds were screened against nine strains of P. falciparum, with the α-crinanes reflecting better overall activities than their corresponding β-crinane subgroup congeners. In terms of potency, an ED₅₀ of 0.14 μg/mL (for augustine in the D-6 strain) and IC₅₀ of 0.35 μg/mL (for haemanthidine in the K1 strain) were the lowest activity indices observed. Structure-activity relationship studies afforded useful insight on the antiplasmodial pharmacophore and the features supporting its efficacy. Overall, crinane alkaloids have provided a useful platform for the study of antiplasmodial effects, not only in terms of potency but also in terms of structural diversity.