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Amaryllidaceae alkaloids (AAs), such as galanthamine and lycorine, are natural products of Lycoris radiata possessing various pharmacological activities including anti-acetylcholinesterase, anti-inflammatory, and antitumour activities. Elucidating the biosynthesis of these special AAs is crucial for understanding their production and potential modification for improved clinical application, of which cytochrome P450 enzymes catalyse the formation of key alkaloid skeletons and subsequent modification processes, with the NAPDH cytochrome P450 reductases (CPRs) serving as essential redox partners. This study identified three CPRs, LrCPR1, LrCPR2, and LrCPR3, encoding 700, 697 and 695 amino acids, respectively, which belong to Class II CPRs. The LrCPRs reduced cytochrome c and ferricyanide in an NADPH-dependent manner, and their activities all followed the typical Michaelis-Menten curve. In yeast, the co-expression of LrCPRs and CYP96T6 produced the galantamine-like alkaloid namely N-demethylnarwedine, suggesting that they support the catalytic activity of CYP96T6. Quantitative analysis of the transcriptional expression profiles showed that LrCPRs were expressed in all the examined tissues of L. radiata, and their gene expression patterns are consistent with other genes that may be involved in the biosynthetic pathway of AAs, including cinnamate 4-hydroxylase and phenylalanine ammonia-lyase. Our study firstly provides the functional characterization of LrCPRs in L. radiata, which will contribute to the discovery of biosynthetic pathways and heterologous production of AAs.Key message: • Three LrCPRs genes were identified and characterized, which were further co-expressed with CYP96T6 in yeast, producing N-demethylnarwedine significantly. [ABSTRACT FROM AUTHOR]

Plants of the subfamily Amaryllidoideae are a source of unique and bioactive alkaloids called Amaryllidaceae alkaloids. The study of their anticancer potential has intensified in recent years. This work aims to locate and characterize the profile of cytotoxic alkaloids biosynthesized and stored in different tissues of Phaedranassa lehmannii Regel using different histochemical methods and chromatographic analysis. The histochemical analysis in the bulbs revealed the presence of alkaloids at the basal edge of the scale-like leaves and bud apical zone. The GC-MS analysis indicated that the bulbs biosynthesize crinane- (9.80 µg/g DW), galanthamine- (8.04 µg/g DW), lycorine- (7.38 µg/g DW), and narciclasine-type (3.75 µg/g DW) alkaloids. The root biosynthesizes alkaloids that are mainly distributed mostly in lycorine- (225.29 µg/g DW) and galanthamine-type (72.35 µg/g DW) alkaloids. The total alkaloids biosynthesized by the root (324.93 µg/g DW) exceeded eleven times the abundance of the alkaloids identified in the bulbs (28.97 µg/g DW). In addition, the total alkaloid fractions exhibited a dose-dependent cytotoxic effect in the evaluated concentrations, with IC50 values of 11.76 ± 0.99 µg/mL and 2.59 ± 0.56 µg/mL against human lung (A549) cancer cells and 8.00 ± 1.35 µg/mL and 18.74 ± 1.99 µg/mL against gastric (AGS) cancer cells. The present study provided evidence to locate and characterize the alkaloids of P. lehmannii grown under nursery conditions as a species producing potential antiproliferative alkaloids. [ABSTRACT FROM AUTHOR]

Amaryllidaceae alkaloids (AAs) are complex plant secondary metabolites possessing a wide range of biological activities. 4′-O-methylnorbelladine (4OMN) is the branchpoint intermediate for the entire AAs, and was the last common intermediate before AA pathway branches diverge. The cyclization of 4OMN by C-C oxidative coupling, which can afford para-para ′, ortho-para ′, and para-ortho ′ scaffold, was catalyzed by cytochrome P450 96T (CYP96T) family enzymes. To clarify the mechanisms involved in this controversial step, four CYP96T homologs (LauCYP96T1, LauCYP96T1-like-1, LauCYP96T1-like-2 and LauCYP96T1-like-3) were cloned from the full-length transcriptome of Lycoris aurea. All the four LauCYP96T are localized to endoplasmic reticulum. Functional analysis reveals that LauCYP96T1 and LauCYP96T1-like proteins display inverted regioselectivity for oxidative coupling of 4OMN, in which LauCYP96T1 and LauCYP96T1-like-2 dominantly afford para-para ′ scaffold, and LauCYP96T1-like-1 and LauCYP96T1-like-3 are responsible for para-ortho ′ scaffold formation. Using molecular homology modeling and docking studies, we predicted models for the binding of 4OMN to LauCYP96T, and identified two amino acid residues that might be responsible for the dominant changes in generated products of para-ortho ′ and para-para ′ oxidative coupling. Our results highlight the functional diversity and promiscuity of LauCYP96T enzymes and might provide valuable information for Amaryllidaceae alkaloid production. [ABSTRACT FROM AUTHOR]

Amaryllidaceae alkaloids (AAs) are complex plant secondary metabolites possessing a wide range of biological activities. 4'-O-methylnorbelladine (4OMN) is the branchpoint intermediate for the entire AAs, and was the last common intermediate before AA pathway branches diverge. The cyclization of 4OMN by C-C oxidative coupling, which can afford para-para', ortho-para', and para-ortho' scaffold, was catalyzed by cytochrome P450 96T (CYP96T) family enzymes. To clarify the mechanisms involved in this controversial step, four CYP96T homologs (LauCYP96T1, LauCYP96T1-like-1, LauCYP96T1-like-2 and LauCYP96T1-like-3) were cloned from the full-length transcriptome of Lycoris aurea. All the four LauCYP96T are localized to endoplasmic reticulum. Functional analysis reveals that LauCYP96T1 and LauCYP96T1-like proteins display inverted regioselectivity for oxidative coupling of 4OMN, in which LauCYP96T1 and LauCYP96T1-like-2 dominantly afford para-para' scaffold, and LauCYP96T1-like-1 and LauCYP96T1-like-3 are responsible for para-ortho' scaffold formation. Using molecular homology modeling and docking studies, we predicted models for the binding of 4OMN to LauCYP96T, and identified two amino acid residues that might be responsible for the dominant changes in generated products of para-ortho' and para-para' oxidative coupling. Our results highlight the functional diversity and promiscuity of LauCYP96T enzymes and might provide valuable information for Amaryllidaceae alkaloid production. [ABSTRACT FROM AUTHOR]

Cancer poses a substantial global health challenge, driving the need for innovative therapeutic solutions that offer improved effectiveness and fewer side effects. Topoisomerase I (Topo I) has emerged as a validated molecular target in the pursuit of developing anticancer drugs due to its critical role in DNA replication and transcription. (+)-Pancratistatin (PST), a naturally occurring compound found in various Amaryllidaceae plants, exhibits promising anticancer properties by inhibiting Topo I activity. However, its clinical utility is hindered by issues related to limited chemical availability and aqueous solubility. To address these challenges, molecular modelling techniques, including virtual screening, molecular docking, molecular mechanics with generalised born and surface area solvation (MM-GBSA) calculations, and molecular dynamics simulations were utilised to evaluate the binding interactions and energetics of PST analogues with Topo I, comparing them with the well-known Topo I inhibitor, Camptothecin. Among the compounds screened for this study, nitrogenated analogues emerged as the most encouraging drug candidates, exhibiting improved binding affinities, favourable interactions with the active site of Topo I, and stability of the protein-ligand complex. Structural analysis pinpointed key molecular determinants responsible for the heightened potency of nitrogenated analogues, shedding light on essential structural modifications for increased activity. Moreover, in silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) predictions highlighted favourable drug-like properties and reduced toxicity profiles for the most prominent nitrogenated analogues, further supporting their potential as effective anticancer agents. In summary, this screening study underscores the significance of nitrogenation in augmenting the anticancer efficacy of PST analogues targeting Topo I. The identified lead compounds exhibit significant potential for subsequent experimental validation and optimisation, thus facilitating the development of novel and efficacious anticancer therapeutics with enhanced pharmacological profiles. [ABSTRACT FROM AUTHOR]

Norbelladine derivatives have garnered attention in recent years due to their diverse biological activities and pivotal role in the biosynthetic pathway of Amaryllidaceae alkaloids. This study reports the synthesis and biological evaluation of four O,N-methylated derivatives of norbelladine. These derivatives were synthesized through a three-step process: forming imine intermediates from benzaldehydes with tyramine, hydrogenating them to secondary amines, and N-methylating these amines. The products were purified and characterized by 1H and 13C NMR spectroscopy. Their biological activities were assessed by evaluating their ability to inhibit Alzheimer's disease-related enzymes acetylcholinesterase and butyrylcholinesterase. Additionally, the cytotoxic activity of the novel derivatives was tested against cancer cell lines derived from hepatocarcinoma (Huh7), adenocarcinoma (HCT-8), and acute myeloid leukemia (THP-1) cells, and their antiviral properties against a human coronavirus (HCoV-OC43), a flavivirus (dengue virus), and a lentivirus (pseudotyped HIV-1). Docking analysis was performed to understand the impact of the N-methylation on their pharmacological relevance. The results indicate that while N-methylation does not significantly affect antiviral activity, it enhances butyrylcholinesterase inhibition for N-methylnorbelladine and 4′-O,N-dimethylnorbelladine. Overall, this work enhances our understanding of norbelladine derivatives, provides new tools for Alzheimer's disease research, and lays the groundwork for future pharmaceutical developments. [ABSTRACT FROM AUTHOR]

Galanthamine is an immensely valuable alkaloid exhibiting anti-cancer and antiviral activity. The cultivation of plant tissues in in vitro conditions is a good source for the synthesis and enrichment of secondary metabolites of commercial interest. In this study, the Amaryllidaceae alkaloid galanthamine was quantified in three Zephyranthes species, such as Zephyranthes candida, Zephyranthes grandiflora, and Zephyranthes citrina, and the impact of the methyl jasmonate (MJ) signaling molecule on galanthamine accumulation was monitored in in vitro-derived plant tissues. This is the first ever study of the MJ-regulated accumulation of galanthamine in in vitro-grown Zephyranthes tissues. Shoot regeneration was obtained in all three Zephyranthes species on Murashige and Skoog (MS) medium containing 2.0 mgL−1 benzylaminopurine (BAP) + 0.5 mgL−1 naphthalene acetic acid (NAA). The regenerated shoots were rooted on a medium containing 2.0 mgL−1 indole butyric acid (IBA). A GC-MS study of Zephyranthes extracts revealed the presence of 34 phyto-compounds of varied levels with therapeutic activities against diseases. The galanthamine content was quantified in plant parts of the three Zephyranthes species using high-performance thin layer chromatography (HPTLC); the maximum was found in Z. candida bulb (2.41 µg g−1 dry wt.), followed by Z. grandiflora (2.13 µg g−1 dry wt.), and then Z. citrina (2.02 µg g−1 dry wt.). The galanthamine content showed bulb > leaf > root source order. The in vitro-generated plantlets were treated with different MJ concentrations, and the galanthamine yield was measured in bulb, leaf, and root tissues. The highest galanthamine content was recorded in bulbs of Z. candida (3.97 µg g−1 dry wt.) treated with 150 µM MJ, showing an increase of 64.73% compared to the control. This accumulation may be attributed to MJ-induced stress, highlighting the potential commercial synthesis of galanthamine in vitro. [ABSTRACT FROM AUTHOR]

Hippeastrum papilio (Ravenna) Van Scheepen (Amaryllidaceae) is an endangered endemic species from the rainforests of Brazil. It is not only an attractive ornamental plant, but the species with the highest content of the valuable alkaloid galanthaminе used for treatment of Alzheimer's disease. The rapid propagation of the plants is crucial for biomass production as an alternative plant raw material for industrial galanthamine extraction. The aim of the present study was to accelerate the growth of H. papilio bulbs using two different hydroponic systems and to evaluate their effectiveness, as well as to determine the galanthamine content in the leaves. Differences in seedlings' growth on Flood & Drain hydroponic system, on Cutting board hydroponic system, and in soil substrate as a control were significant (P<0.001, Anova single factor). Best results were obtained on the Cutting board hydroponic system where plant weight increased an average of 59.1 ± 24.0 times while the lowest growth was in the control, with an average weight increase of 11.1 ± 4.7 times. One month after adaptation of plants to soil substrate they were analysed by GC-MS. Galanthamine was the main alkaloid in the leaves of plants from all variants, and its content varied between 0.66% and 0.86%, which was commensurable with that of the native plants. Feasibility of soilless cultivation of in vitro propagated H. papilio bulblets was also proven. [ABSTRACT FROM AUTHOR]

Plants of the subfamily Amaryllidoideae are a source of unique and bioactive alkaloids called Amaryllidaceae alkaloids. The study of their anticancer potential has intensified in recent years. This work aims to locate and characterize the profile of cytotoxic alkaloids biosynthesized and stored in different tissues of Phaedranassa lehmannii Regel using different histochemical methods and chromatographic analysis. The histochemical analysis in the bulbs revealed the presence of alkaloids at the basal edge of the scale-like leaves and bud apical zone. The GC-MS analysis indicated that the bulbs biosynthesize crinane- (9.80 µg/g DW), galanthamine- (8.04 µg/g DW), lycorine- (7.38 µg/g DW), and narciclasine-type (3.75 µg/g DW) alkaloids. The root biosynthesizes alkaloids that are mainly distributed mostly in lycorine- (225.29 µg/g DW) and galanthamine-type (72.35 µg/g DW) alkaloids. The total alkaloids biosynthesized by the root (324.93 µg/g DW) exceeded eleven times the abundance of the alkaloids identified in the bulbs (28.97 µg/g DW). In addition, the total alkaloid fractions exhibited a dose-dependent cytotoxic effect in the evaluated concentrations, with IC50 values of 11.76 ± 0.99 µg/mL and 2.59 ± 0.56 µg/mL against human lung (A549) cancer cells and 8.00 ± 1.35 µg/mL and 18.74 ± 1.99 µg/mL against gastric (AGS) cancer cells. The present study provided evidence to locate and characterize the alkaloids of P. lehmannii grown under nursery conditions as a species producing potential antiproliferative alkaloids.

Summary: Alkaloids are a large group of plant secondary metabolites with various structures and activities. It is important to understand their functions in the interplay between plants and the beneficial and pathogenic microbiota.Amaryllidaceae alkaloids (AAs) are unique secondary metabolites in Amaryllidaceae plants. Here, we studied the interplay between AAs and the bacteriome in Lycoris radiata, a traditional Chinese medicinal plant containing high amounts of AAs.The relationship between AAs and bacterial composition in different tissues of L. radiata was studied. In vitro experiments revealed that AAs have varying levels of antimicrobial activity against endophytic bacteria and pathogenic fungi, indicating the importance of AA synthesis in maintaining a balance between plants and beneficial/pathogenic microbiota. Using bacterial synthetic communities with different compositions, we observed a positive feedback loop between bacteria insensitive to AAs and their ability to increase accumulation of AAs in L. radiata, especially in leaves. This may allow insensitive bacteria to outcompete sensitive ones for plant resources. Moreover, the accumulation of AAs enhanced by insensitive bacteria could benefit plants when challenged with fungal pathogens.This study highlights the functions of alkaloids in plant–microbe interactions, opening new avenues for designing plant microbiomes that could contribute to sustainable agriculture. [ABSTRACT FROM AUTHOR]

Fresh bulbs of Stenomesson miniatum, a plant belonging to the Amaryllidaceae family with a poorly investigated phytochemical profile, were traditionally employed by Andean healers to treat tumors and abscesses. The aims of this study were to characterize the extract from the bulbs of S. miniatum and to test its cytotoxic and antibacterial potential. A previous structural study of the major extract constituents was extended to include the minor components by means of 13C-NMR-based dereplication. Cytotoxic activities were evaluated on A431 human epidermoid carcinoma cells through a metabolic assay and on Jurkat human acute T-leukemia cells through a cell-impermeant fluorescent nuclear probe. Antibacterial assays were carried out against Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes by using a standardized broth microdilution method. Eleven known Amaryllidaceae alkaloids were identified together with another compound determined as being an extraction artefact. The alkaloid-enriched extract showed good cytotoxic activity against both tumor cell lines, reaching an IC50 of 3.3 µg/mL against A431 cells and of 10.9 µg/mL against Jurkat cells. Biological assays carried out on single fractions showed that activity can be attributed to the presence of pretazettine and haemanthamine. Conversely, no antibacterial activities were recorded for any of the samples. [ABSTRACT FROM AUTHOR]

Norbelladine derivatives have garnered attention in recent years due to their diverse biological activities and pivotal role in the biosynthetic pathway of Amaryllidaceae alkaloids. This study reports the synthesis and biological evaluation of four O,N-methylated derivatives of norbelladine. These derivatives were synthesized through a three-step process: forming imine intermediates from benzaldehydes with tyramine, hydrogenating them to secondary amines, and N-methylating these amines. The products were purified and characterized by 1H and 13C NMR spectroscopy. Their biological activities were assessed by evaluating their ability to inhibit Alzheimer’s disease-related enzymes acetylcholinesterase and butyrylcholinesterase. Additionally, the cytotoxic activity of the novel derivatives was tested against cancer cell lines derived from hepatocarcinoma (Huh7), adenocarcinoma (HCT-8), and acute myeloid leukemia (THP-1) cells, and their antiviral properties against a human coronavirus (HCoV-OC43), a flavivirus (dengue virus), and a lentivirus (pseudotyped HIV-1). Docking analysis was performed to understand the impact of the N-methylation on their pharmacological relevance. The results indicate that while N-methylation does not significantly affect antiviral activity, it enhances butyrylcholinesterase inhibition for N-methylnorbelladine and 4′-O,N-dimethylnorbelladine. Overall, this work enhances our understanding of norbelladine derivatives, provides new tools for Alzheimer’s disease research, and lays the groundwork for future pharmaceutical developments.

Galanthamine is an immensely valuable alkaloid exhibiting anti-cancer and antiviral activity. The cultivation of plant tissues in in vitro conditions is a good source for the synthesis and enrichment of secondary metabolites of commercial interest. In this study, the Amaryllidaceae alkaloid galanthamine was quantified in three Zephyranthes species, such as Zephyranthes candida, Zephyranthes grandiflora, and Zephyranthes citrina, and the impact of the methyl jasmonate (MJ) signaling molecule on galanthamine accumulation was monitored in in vitro-derived plant tissues. This is the first ever study of the MJ-regulated accumulation of galanthamine in in vitro-grown Zephyranthes tissues. Shoot regeneration was obtained in all three Zephyranthes species on Murashige and Skoog (MS) medium containing 2.0 mgL−1 benzylaminopurine (BAP) + 0.5 mgL−1 naphthalene acetic acid (NAA). The regenerated shoots were rooted on a medium containing 2.0 mgL−1 indole butyric acid (IBA). A GC-MS study of Zephyranthes extracts revealed the presence of 34 phyto-compounds of varied levels with therapeutic activities against diseases. The galanthamine content was quantified in plant parts of the three Zephyranthes species using high-performance thin layer chromatography (HPTLC); the maximum was found in Z. candida bulb (2.41 µg g−1 dry wt.), followed by Z. grandiflora (2.13 µg g−1 dry wt.), and then Z. citrina (2.02 µg g−1 dry wt.). The galanthamine content showed bulb > leaf > root source order. The in vitro-generated plantlets were treated with different MJ concentrations, and the galanthamine yield was measured in bulb, leaf, and root tissues. The highest galanthamine content was recorded in bulbs of Z. candida (3.97 µg g−1 dry wt.) treated with 150 µM MJ, showing an increase of 64.73% compared to the control. This accumulation may be attributed to MJ-induced stress, highlighting the potential commercial synthesis of galanthamine in vitro.

Scadoxus multiflorus (Martyn) Raf. (Amaryllidaceae) is traditionally used for the treatment of many respiratory problems (bronchitis, asthma, pneumonia, etc.). However, the alkaloidal composition of S. multiflorus has rarely been explored. In the present study, a full investigation of bulbs of S. multiflorus was carried out using HPLC-PDA-SPE-NMR, followed by structure elucidation using extensive spectroscopic techniques coupled with DFT calculation. With respect to the indigenous usage of this species for treating respiratory-related problems, antiviral activity against the severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) was assessed for all isolated compounds. As a result, a previously undescribed alkaloid, 9- O -demethyl-11-hydroxylgalanthine (or 2- O -methyl-11-hydroxypseudolycorine), together with fourteen known ones were identified. Nine alkaloids, i.e. 2- O -methylpseudolycorine, ungiminorine, ungiminorine N -oxide, 9-de- O -methyl-11β-hydroxygalanthamine, 2-hydroxy- O,N -dimethylnorbelladine, O -demethylmaritidine, 8- O -demethyloxomaritidine, narcissidine, and sanguinine, were reported for the first time in this species. In addition, also lycorine, narciclasine, lycoricidine, montanine and 3- O -acetylsanguinine were obtained. Results showed that 9- O -demethyl-11-hydroxylgalanthine, 8- O -demethyloxomaritidine, 3- O -acetylsanguinine and 9-de- O -methyl-11β-hydroxygalanthamine exhibited weak antiviral activity at non-cytotoxic concentrations (EC 50 of 53, 70, 49, 62 µM, respectively). S. multiflorus appears to be a promising source of anti-SARS-CoV-2 Amaryllidaceae alkaloid scaffolds. [Display omitted] • A new alkaloid was described: 9- O -demethyl-11-hydroxylgalanthine. • Nine alkaloids were reported for the first time in S. multiflorus. • Four alkaloids exhibited weak in vitro anti-SARS-CoV-2 activity (EC50 = 49–70 μM). • Four alkaloids displayed cytotoxicity (CC50 = < 10 μM). [ABSTRACT FROM AUTHOR]

Amaryllidaceae alkaloids (AAs) are a large group of plant specialized metabolites with diverse pharmacological properties. Norbelladine is the entry compound in AAs biosynthesis and is produced from the condensation of tyramine and 3,4-dihydroxybenzaldehyde (3,4-DHBA). There are two reported enzymes capable of catalyzing this reaction in-vitro, both with low yield. The first one, norbelladine synthase (NBS), was shown to condense tyramine and 3,4-DHBA, while noroxomaritidine/norcraugsodine reductase (NR), catalyzes a reduction reaction to produce norbelladine. To clarify the mechanisms involved in this controversial step, both NBS and NR homologs were identified from the transcriptome of Narcissus papyraceus and Leucojum aestivum, cloned and expressed in Escherichia coli. Enzymatic assays performed with tyramine and 3,4-DHBA with each enzyme separately or combined, suggested that NBS and NR function together for the condensation of tyramine and 3,4-DHBA into norcraugsodine and further reduction into norbelladine. Using molecular homology modeling and docking studies, we predicted models for the binding of tyramine and 3,4-DHBA to NBS, and of the intermediate norcraugsodine to NR. Moreover, we show that NBS and NR physically interact in yeast and in-planta, that both localize to the cytoplasm and nucleus and are expressed at high levels in bulbs, confirming their colocalization and co-expression thus their ability to work together in the same catalytic route. Finally, their co-expression in yeast led to the production of norbelladine. In all, our study establishes that both NBS and NR participate in the biosynthesis of norbelladine by catalyzing the first key steps associated in the biosynthesis of the Alzheimer's drug galanthamine. [ABSTRACT FROM AUTHOR]

Methods for the synthesis of crinane alkaloids of isoquinoline series of Amaryllidaceae that possess various biological activities are reviewed. [ABSTRACT FROM AUTHOR]

The genus Clinanthus Herb. is found in the Andes Region (South America), mainly in Peru, Ecuador, and Bolivia. These plants belong to the Amaryllidaceae family, specifically the Amaryllidoideae subfamily, which presents an exclusive group of alkaloids known as Amaryllidaceae alkaloids that show important structural diversity and pharmacological properties. It is possible to find some publications in the literature regarding the botanical aspects of Clinanthus species, although there is little information available about their chemical and biological activities. The aim of this work was to obtain the alkaloid profile and the anti-cholinesterase activity of four different samples of Clinanthus collected in South America: Clinanthus sp., Clinanthus incarnatus, and Clinanthus variegatus. The alkaloid extract of each sample was analyzed by gas chromatography coupled with mass spectrometry (GC-MS), and their potential against the enzymes acetyl- and butyrylcholinesterase were evaluated. Thirteen alkaloids have been identified among these species, while six unidentified structures have also been detected in these plants. The alkaloid extract of the C. variegatus samples showed the highest structural diversity as well as the best activity against AChE, which was likely due to the presence of the alkaloid sanguinine. The results suggest this genus as a possible interesting new source of Amaryllidaceae alkaloids, which could contribute to the development of new medicines. [ABSTRACT FROM AUTHOR]

A concise catalytic asymmetric approach to naturally occurring Amaryllidaceae alkaloids sharing a 5,10 b -ethanophenanthridine skeleton [(–)-oxomaritidine, (–)-dihydromaritidine, (–)-maritidine, and (–)- epi -maritidine] has been envisioned. The key intermediate in this strategy was obtained by a Pd(0)-catalyzed decarboxylative allylation of a 2-arylcyclohexan-1-one-derived allylenol carbonate (87%, 96% ee). [ABSTRACT FROM AUTHOR]

The Amaryllidaceae species are well-known as a rich source of bioactive compounds in nature. Although Hymenocallis littoralis has been studied for decades, its polar components were rarely explored. The current phytochemical investigation of Amaryllidaceae alkaloids from H. littoralis led to the identification of three previously undescribed compounds: O-demethyl-norlycoramine (1), (−)-2-epi-pseudolycorine (2) and (+)-2-epi-pseudolycorine (3), together with eight known compounds: 6α-hydroxyhippeastidine (4), 6β-hydroxyhippeastidine (5), lycorine (6), 2-epi-lycorine (7), zephyranthine (8), ungeremine (9), pancratistatin (10) and 9-O-demethyl-7-O-methyllycorenine (11). Among the eight previously reported compounds, five were isolated from H. littoralis for the first time (compounds 4, 5, 7, 8, and 9). Compounds 1, 4, 5, 7, 8, and 11 exhibited weak anti-SARS-CoV-2 activity (EC50 = 40–77 µM) at non-cytotoxic concentrations. Assessment of cytotoxicity on the Vero-E6 cell line revealed lycorine and pancratistatin as cytotoxic substances with CC50 values of 1.2 µM and 0.13 µM, respectively. The preliminary structure-activity relationship for the lycorine-type alkaloids in this study was further investigated, and as a result ring C appears to play a crucial role in their anti-SARS-CoV-2 activity. [ABSTRACT FROM AUTHOR]

Amaryllidaceae alkaloids (AAs) are a large group of plant specialized metabolites with diverse pharmacological properties. Norbelladine is the entry compound in AAs biosynthesis and is produced from the condensation of tyramine and 3,4-dihydroxybenzaldehyde (3,4-DHBA). There are two reported enzymes capable of catalyzing this reaction in-vitro, both with low yield. The first one, norbelladine synthase (NBS), was shown to condense tyramine and 3,4-DHBA, while noroxomaritidine/norcraugsodine reductase (NR), catalyzes a reduction reaction to produce norbelladine. To clarify the mechanisms involved in this controversial step, both NBS and NR homologs were identified from the transcriptome of Narcissus papyraceus and Leucojum aestivum, cloned and expressed in Escherichia coli. Enzymatic assays performed with tyramine and 3,4-DHBA with each enzyme separately or combined, suggested that NBS and NR function together for the condensation of tyramine and 3,4-DHBA into norcraugsodine and further reduction into norbelladine. Using molecular homology modeling and docking studies, we predicted models for the binding of tyramine and 3,4-DHBA to NBS, and of the intermediate norcraugsodine to NR. Moreover, we show that NBS and NR physically interact in yeast and in-planta, that both localize to the cytoplasm and nucleus and are expressed at high levels in bulbs, confirming their colocalization and co-expression thus their ability to work together in the same catalytic route. Finally, their co-expression in yeast led to the production of norbelladine. In all, our study establishes that both NBS and NR participate in the biosynthesis of norbelladine by catalyzing the first key steps associated in the biosynthesis of the Alzheimer’s drug galanthamine.

Ambelline, an alkaloid from the Amaryllidaceae family with a crinane-type skeleton, has not yet demonstrated any outstanding biological activity. However, its analogues prepared by derivatization of the C-11 hydroxyl group show different interesting effects. Continuing our earlier work, twelve novel aromatic esters were developed (10, 14, 16, 17, 22–25, 30–33) and studied, together with previously synthesized derivatives (2–9, 11–13, 15, 18–21, 26–29) in terms of their cytotoxic activity. The cytotoxic potential was determined on a panel of nine human cancer cell lines and one noncancerous cell line to characterize their biological activity spectrum. To describe and foresee the structure–activity relationship for further research, substances synthesized and described in our previous work were also included in this cytotoxicity study. The most significant activity was associated with analogues having methyl (10), methoxy (14–17), or ethoxy (18) substitution on the phenyl condensed to ambelline. However, the 4-chloro-3-nitrobenzoyl derivative (32) showed the most promising IC50 values, ranging from 0.6 ± 0.1 µM to 9.9 ± 0.2 µM. In vitro cytotoxicity studies indicated the most potent antiproliferative activity of 32 in a dose-dependent and time-dependent manner. Besides, 32 was found to be effective in decreasing viability and triggering apoptosis of MOLT-4 T-lymphoblastic leukemia cells.

Cancer is a major cause of death and an impediment to increasing life expectancy worldwide. With the aim of finding new molecules for chemotherapeutic treatment of epidemiological relevance, ten alkaloid fractions from Amaryllidaceae species were tested against six cancer cell lines (AGS, BT-549, HEC-1B, MCF-7, MDA-MB 231, and PC3) with HaCat as a control cell line. Some species determined as critically endangered with minimal availability were propagated using in vitro plant tissue culture techniques. Molecular docking studies were carried out to illustrate binding orientations of the 30 Amaryllidaceae alkaloids identified in the active site of some molecular targets involved with anti-cancer activity for potential anti-cancer drugs. In gastric cancer cell line AGS, the best results (lower cell viability percentages) were obtained for Crinum jagus (48.06 ± 3.35%) and Eucharis bonplandii (45.79 ± 3.05%) at 30 µg/mL. The research focused on evaluating the identified alkaloids on the Bcl-2 protein family (Mcl-1 and Bcl-xL) and HK2, where the in vitro, in silico and statistical results suggest that powelline and buphanidrine alkaloids could present cytotoxic activity. Finally, combining experimental and theoretical assays allowed us to identify and characterize potentially useful alkaloids for cancer treatment. [ABSTRACT FROM AUTHOR]

The medicinal properties of the Narcissus genus are due to the presence of alkaloids known as Amaryllidaceae Alkaloids (AA). The presence of nanoparticles causes oxidative stress and stimulates production of secondary metabolites. Useing specific precursors in AA biosynthetic pathways can be effective on cumulative production of these compounds. In this study, the effect of iron oxide nanoparticles (Fe3O4-NPs), trans-cinnamic acid (tCA), and L-phenylalanine (L-Phe) as precursors has been investigated on changes in some biochemical parameters of Narcissus tazetta L. callus, especially alkaloid content. Treatment of calli generated from bulb explants in Morashig-Skoog (MS) media containing 2,4-D and BAP and Fe3O4-NPs, increased alkaloids, flavonoids, and phenolic compounds. Also, the activity of antioxidant enzymes (SOD, CAT and POD), and activity of phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) increased under Fe3O4-NPs treatments alone and in combination with tCA or L-Phe precursors. The evaluation of the studied parameter changes showed that both tCA and L-Phe treatment can change the plant's metabolism to improve the production of secondary metabolites. This was especially evident with the simultaneous application of Fe3O4-NPs and these precursors. Application of precursors in the culture medium increased H2O2 content under tCA treatment and decreased it under L-Phe treatment. Increased activity of the antioxidant enzymes caused by nanoparticle treatments along with the nutritional effect of tCA and L-Phe precursors, progressed signaling pathway of antioxidant responses by affecting the activity of biosynthetic enzymes and increases production of some secondary metabolites including alkaloids and phenolic compounds. Considering various properties of Amaryllidaceaea alkaloids, optimizing, and increasing the production of these alkaloids is important from a commercial and medical point of view. [ABSTRACT FROM AUTHOR]

Amaryllidaceae alkaloids are secondary metabolites with interesting medicinal properties. Almost every Narcissus species can synthesize them and constitute an excellent source for their isolation and study. Several Amaryllidaceae alkaloids have shown acetylcholinesterase inhibitory activities and are a promising tool for treating cholinergic disorders such as Alzheimer's disease (AD). Indeed, three of the four palliative treatments approved for AD are acetylcholinesterase (AChE) inhibitors and one of them, galanthamine, is an Amaryllidaceae alkaloid itself. This molecule is currently isolated from natural sources. However, its production is insufficient to supply the increasing demand for the active principle. Our main aim is to discover tools to improve galanthamine production and to prospect for potential new and more efficient drugs for AD treatment. Furthermore, we seek to broaden the knowledge of plants of the genus Narcissus from a chemotaxonomic perspective. Hence, in this study, we evaluate the alkaloid content through GC–MS and the AChE inhibitory activity of ten autumn-flowering Narcissus, which have been less studied than their spring-flowering counterparts. A total of thirty Amaryllidaceae alkaloids have been found, twenty-eight properly identified. Two Narcissus contained galanthamine, and seven were able to inhibit AChE. [ABSTRACT FROM AUTHOR]

We represented herein a two-step synthesis of 1-methyl-6 H -indol-6-one which is an N -containing 6/5 fused bicyclic building blocks in Amaryllidaceae alkaloids. The key step featured is a 'one-pot' ozonolysis/reductive amination/cyclization of allylated cyclohexa-1,3-dione to give bicyclic compounds. Moreover, the formal total synthesis of natural product γ-lycorane could be achieved through a photo-promoted cyclization/oxidation cascade reaction from the resulting bicyclic intermediate. [ABSTRACT FROM AUTHOR]

Skin cancer has high rates of mortality and therapeutic failure. In this study, to develop a multi-agent strategy for skin cancer management, the selective cytotoxicity of several alkaloid fractions and pure alkaloids isolated from Amaryllidaceae species was evaluated in melanoma cells. In addition, UVB-stimulated keratinocytes (HaCaT) were exposed to seven alkaloid fractions characterized by GC-MS, and the production of intracellular reactive oxygen species (ROS) and IL-6, were measured to evaluate their photoprotection effects. The Eucharis caucana (bulb) alkaloid fraction (20 μg/ml) had a clear effect on the viability of melanoma cells, reducing it by 45.7% without affecting healthy keratinocytes. This alkaloid fraction and tazettine (both at 2.5 μg/ml) suppressed UVB-induced ROS production by 31.6% and 29.4%, respectively. The highest anti-inflammatory potential was shown by the Zephyranthes carinata (bulb) alkaloid fraction (10 μg/ml), which reduced IL-6 production by 90.8%. According to the chemometric analysis, lycoramine and tazettine had a photoprotective effect on the UVB-exposed HaCaT cells, attenuating the production of ROS and IL-6. These results suggest that Amaryllidaceae alkaloids have photoprotective and therapeutic potential in skin cancer management, especially at low concentrations. [ABSTRACT FROM AUTHOR]

Amaryllidaceae plants are well known for producing isoquinoline-type alkaloids which have important biological activities, however the production of these secondary metabolites in plants is very low, it's necessary to study mechanisms to increase the productivity of them. Our study shows the alkaloids composition on the wild bulbs and in vitro bulbs of four species Chilean Amaryllidaceae. Qualitative and semi-quantitative analysis of alkaloid extracts carried out by GC/MS–MS we found a total of 48 different alkaloids produced in wild plants and in vitro culture; 38 alkaloids were identified. These results suggest that different combinations of auxins and cytokinins can modulate plant biochemical pathways that regulate alkaloid biogenesis and show the high potential that plants of the Amaryllidaceae family have to produce lycorine type alkaloids. This study allowed knowing the content of alkaloids in wild and in vitro bulbs of the studied species. These results enable to establish the culture media with 4.44 µM BAP and 2.70 µM NAA and 2.20 µM BAP and 5.40 µM NAA increased the production of lycorine-type alkaloids for R. advena and R. pratensis respectively, therefore it is able to promote oxidative phenol coupling via ortho-para' and demonstrates how it is possible to direct the production of these molecules through the use of phytohormones in in vitro culture. Finally, we can say that the results confirm that micropropagation is a good tool to produce this type of alkaloids. Key message: Amaryllidaceae alkaloid biosynthesis by the plant in vitro systems and the effect of plant growth regulators on the biosynthetic route and its mode of action is reviewed to provide a starting point for scaling-up of the production of these valuable medicinal alkaloids. [ABSTRACT FROM AUTHOR]

The AChE inhibitory activity of alkaloid extracts and compounds has been in the focus of research on the plants of Amaryllidoideae subfamily since the approval of galanthamine in 2001 by FDA for treatment of mild to moderate Alzheimer's disease. A small fraction of the huge biodiversity of the plants producing Amaryllidaceae alkaloids has been studied as a source of AChE inhibitors. Less than 20% of the known Amaryllidaceae alkaloids have been tested in vitro for their ability to inhibit AChE. Galanthamine, lycorine and haemanthamine are scaffolds for semi-synthesis of potent AChE inhibitors. In the last years, galanthamine has been studied in silico for drug optimization and synthesis of potent dual-binding AChE inhibitors. In silico studies of other Amaryllidaceae alkaloids have also provoked the interest of researchers in the last years. The aim of this article is to provide a comprehensive review on studies of the AChE inhibitory activity of extracts and compounds from the plants of Amaryllidoideae subfamily covering the literature from the last two decades. [ABSTRACT FROM AUTHOR]

Abstract Free-living amoebae of the genus Acanthamoeba are the causative agents of granulomatous encephalitis and keratitis, severe human infections. Bioactive compounds from plants are recognized as an alternative source for the development of new drugs. The Amaryllidaceae is a botanical family able to synthesize a very specific and consistent group of biologically active isoquinoline-like alkaloids. The alkaloidal fractions from the Brazilian species Hippeastrum canastrense, H. diniz-cruziae, H. puniceum, and Crinum x amabile, along with the alkaloid lycorine, were investigated against Acanthamoeba castellanii. The in vitro assays were performed with distinct concentrations of lycorine and alkaloidal fractions, while the cell viability was evaluated by the MTT method upon MDCK cells. Chlorhexidine 0.02% was used as the positive control. The effect of alkaloid fractions was concentration dependent, and 2000 μg mL-1 of H. canastrense and H. diniz-cruziae provided a 100% inhibition. At concentrations of 250, 500, and 1000 μg mL-1, the H. diniz-cruziae alkaloidal fraction showed the lowest cytotoxic effect (5%-7%) and remarkable anti-amoebic activity, demonstrating values of IC50 285.61 μg mL-1, low cytotoxicity (5%-7%), and selectivity index (7.0). Taken together, the results are indicative of the great potential that the alkaloids from H. diniz-cruziae have as new candidates for anti-amoebicidal compounds.

The genus Clinanthus Herb. is found in the Andes Region (South America), mainly in Peru, Ecuador, and Bolivia. These plants belong to the Amaryllidaceae family, specifically the Amaryllidoideae subfamily, which presents an exclusive group of alkaloids known as Amaryllidaceae alkaloids that show important structural diversity and pharmacological properties. It is possible to find some publications in the literature regarding the botanical aspects of Clinanthus species, although there is little information available about their chemical and biological activities. The aim of this work was to obtain the alkaloid profile and the anti-cholinesterase activity of four different samples of Clinanthus collected in South America: Clinanthus sp., Clinanthus incarnatus, and Clinanthus variegatus. The alkaloid extract of each sample was analyzed by gas chromatography coupled with mass spectrometry (GC-MS), and their potential against the enzymes acetyl- and butyrylcholinesterase were evaluated. Thirteen alkaloids have been identified among these species, while six unidentified structures have also been detected in these plants. The alkaloid extract of the C. variegatus samples showed the highest structural diversity as well as the best activity against AChE, which was likely due to the presence of the alkaloid sanguinine. The results suggest this genus as a possible interesting new source of Amaryllidaceae alkaloids, which could contribute to the development of new medicines.

Aiming to find Amaryllidaceae alkaloids against breast cancer, including the highly aggressive triple-negative breast cancer, the phytochemical study of Pancratium maritimum was carried out. Several Amaryllidaceae-type alkaloids, bearing scaffolds of the haemanthamine-, homolycorine-, lycorine-, galanthamine-, and tazettine-type were isolated (3–11), along with one alkamide (2) and a phenolic compound (1). The antiproliferative effect of compounds (1–11) was evaluated by the sulforhodamine B assay against triple-negative breast cancer cell lines MDA-MB-231 and MDA-MB-468, breast cancer cells MCF-7, and the non-malignant fibroblast (HFF-1) and breast (MCF12A) cell lines. The alkaloids 3, 5, 7, and 11 showed significant growth inhibitory effects against all breast cancer cell lines, with IC50 (half-maximal inhibitory concentration) values ranging from 0.73 to 16.3 µM. The homolycorine-type alkaloid 7 was selected for further investigation in MDA-MB-231 cells. In the annexin-V assay, compound 7 increased cell death by apoptosis, which was substantiated, in western blot analyses, by the increased expression of the pro-apoptotic protein Bax, and the decreased expression of the anti-apoptotic protein Bcl-xL. Consistently, it further stimulated mitochondrial reactive oxygen species (ROS) generation. The antiproliferative effect of compound 7 was also associated with G2/M cell cycle arrest, which was supported by an increase in the p21 protein expression levels. In MDA-MB-231 cells, compound 7 also exhibited synergistic effects with conventional chemotherapeutic drugs such as etoposide. [ABSTRACT FROM AUTHOR]

The study aimed to evaluate the safety and pharmacological activity Amaryllidaceae, Lycopodiaceae alkaloids and coumarins obtained from Narcissus triandrus L., Lycopodium clavatum L., Lycopodium annotinum L., Huperzia selago L. and Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav. In the in vivo studies. The influence of the tested compounds on the central nervous system of rats was assessed in behavioral tests (locomotor activity, Y-maze, passive avoidance). In order to investigate the mechanisms of action, biochemical determinations were performed (AChE activity, BChE activity, IL-1β, IL-6 concentration). In order to assess safety, the concentrations of AST, ALT, GGT and urea and creatinine were determined. The results of the conducted studies indicate a high safety profile of the tested compounds. Behavioral tests showed that they significantly improved rodent memory in a passive avoidance test. The results of biochemical studies showed that by reducing the activity of AChE and BChE and lowering the concentration of IL-1β and IL-6, the coumarin-rich Angelica dahurica extract shows the most promising potential for future therapeutic AD strategies. [ABSTRACT FROM AUTHOR]

Amaryllidaceae alkaloids (AAs) are plant specialized metabolites with therapeutic properties exclusively produced by the Amaryllidaceae plant family. The two most studied representatives of the family are galanthamine, an acetylcholinesterase inhibitor used as a treatment of Alzheimer's disease, and lycorine, displaying potent in vitro and in vivo cytotoxic and antiviral properties. Unfortunately, the variable level of AAs' production in planta restricts most of the pharmaceutical applications. Several biotechnological alternatives, such as in vitro culture or synthetic biology, are being developed to enhance the production and fulfil the increasing demand for these AAs plant-derived drugs. In this review, current biotechnological approaches to produce different types of bioactive AAs are discussed. [ABSTRACT FROM AUTHOR]

During the search for a general, efficient route toward the synthesis of C-1 analogues of narciclasine, natural narciclasine was protected and converted to its C-1 enol derivative using a novel semi-synthetic route. Attempted conversion of this material to its triflate in order to conduct cross-coupling at C-1 resulted in a triflate at C-6 that was successfully coupled with several functionalities. Four novel compounds were fully deprotected after seven steps and subjected to evaluation for cytotoxic activity against three cancer cell lines. Only one derivative showed moderate activity compared to that of narciclasine. Spectral and physical data are provided for all new compounds. [ABSTRACT FROM AUTHOR]

Nature has perennially served as an infinite reservoir of diverse chemicals with numerous applications benefiting humankind. In recent years, due to the emerging COVID-19 pandemic, there has been a surge in studies on repurposing natural products as anti-SARS-CoV-2 agents, including plant-derived substances. Among all types of natural products, alkaloids remain one of the most important groups with various known medicinal values. The current investigation focuses on Amaryllidaceae alkaloids (AAs) since AAs have drawn significant scientific attention as anti-SARS-CoV-2 agents over the past few years. This study serves as a mini-review, summarizing recent advances in studying the anti-SARS-CoV-2 potency of AAs, covering two aspects: structure-activity relationship and mechanism of action (MOA). The study covers the period from 2019 to 2023. The information in this review were retrieved from common databases including Web of Science, ScienceDirect, PubMed and Google scholar. Reported anti-SARS-CoV-2 potency, cytotoxicity and possible biological targets of AAs were summarized and classified into different skeletal subclasses. Then, the structure-activity relationship (SAR) was explored, pinpointing the key pharmacophore-related structural moieties. To study the mechanism of action of anti-SARS-CoV-2 AAs, possible biological targets were discussed. In total, fourteen research articles about anti-SARS-CoV-2 was selected. From the SAR point of view, four skeletal subclasses of AAs (lycorine-, galanthamine-, crinine- and homolycorine-types) appear to be promising for further investigation as anti-SARS-CoV-2 agents despite experimental inconsistencies in determining in vitro half maximal inhibitory effective concentration (EC 50). Narciclasine, haemanthamine- and montanine-type skeletons were cytotoxic and devoid of anti-SARS-CoV-2 activity. The lycorine-type scaffold was the most structurally diverse in this study and preliminary structure-activity relationships revealed the crucial role of ring C and substituents on rings A, C and D in its anti-SARS-CoV-2 activity. It also appears that two enantiomeric skeletons (haemanthamine- and crinine-types) displayed opposite activity/toxicity profiles regarding anti-SARS-CoV-2 activity. Pharmacophore-related moieties of the haemanthamine/crinine-type skeletons were the substituents on rings B, C and the dioxymethylene moiety. All galanthamine-type alkaloids in this study were devoid of cytotoxicity and it appears that varying substituents on rings C and D could enhance the anti-SARS-CoV-2 potency. Regarding MOAs, initial experimental results suggested Mpro and RdRp as possible viral targets. Dual functionality between anti-inflammatory activity on host cells and anti-SARS-CoV-2 activity on the SARS-CoV-2 virus of isoquinoline alkaloids, including AAs, were suggested as the possible MOAs to alleviate severe complications in COVID-19 patients. This dual functionality was proposed to be related to the p38 MAPK signaling pathway. Overall, Amaryllidaceae alkaloids appear to be promising for further investigation as anti-SARS-CoV-2 agents. The skeletal subclasses holding the premise for further investigation are lycorine-, crinine-, galanthamine- and homolycorine-types. [Display omitted] [ABSTRACT FROM AUTHOR]

The Amaryllidaceae species are well-known as a rich source of bioactive compounds in nature. Although Hymenocallis littoralis has been studied for decades, its polar components were rarely explored. The current phytochemical investigation of Amaryllidaceae alkaloids from H. littoralis led to the identification of three previously undescribed compounds: O-demethyl-norlycoramine (1), (−)-2-epi-pseudolycorine (2) and (+)-2-epi-pseudolycorine (3), together with eight known compounds: 6α-hydroxyhippeastidine (4), 6β-hydroxyhippeastidine (5), lycorine (6), 2-epi-lycorine (7), zephyranthine (8), ungeremine (9), pancratistatin (10) and 9-O-demethyl-7-O-methyllycorenine (11). Among the eight previously reported compounds, five were isolated from H. littoralis for the first time (compounds 4, 5, 7, 8, and 9). Compounds 1, 4, 5, 7, 8, and 11 exhibited weak anti-SARS-CoV-2 activity (EC50 = 40–77 µM) at non-cytotoxic concentrations. Assessment of cytotoxicity on the Vero-E6 cell line revealed lycorine and pancratistatin as cytotoxic substances with CC50 values of 1.2 µM and 0.13 µM, respectively. The preliminary structure-activity relationship for the lycorine-type alkaloids in this study was further investigated, and as a result ring C appears to play a crucial role in their anti-SARS-CoV-2 activity.

Since the ancient times, Amaryllidaceae genus Narcissus has been reported for the production of biologically important alkaloids, many of which are used as therapeutic tools for human diseases. Among them, galanthamine (Gal) has received a considerable attention for its acetylcholinesterase inhibitory activity for the treatment of early to mid-stage Alzheimer’s diseases. In this study, gas chromatography-mass spectrophotometry was used to determine the galanthamine content along with the detection of other biologically important alkaloids in dormant bulb and basal plate of two cultivated varieties of Narcissus pseudonarcissus, Carlton and Andrew’s Choice. The amount of galanthamine was higher in Carlton bulb (860 µg Gal/g) and basal plate (1254 µg Gal/g) than Andrew’s Choice bulb (674 µg Gal/g) and basal plate (1051 µg Gal/g). Non-dormant Carlton bulb was used as control, which represented the galanthamine content of 1117 µg Gal/g. Besides galanthamine, other biologically important alkaloids were detected in Carlton such as lycoramine, lycorine, lycorenine, crinamine, and pancracine; while tazettine, oxoassoanine, lycorine, and o-methyl-macronine were detected in Andrew’s Choice. Findings of this study suggest that both Narcissus cultivars could be the important sources for the isolation of naturally occurring bioactive alkaloids for their commercial availability and could be potentially used in pharmaceuticals. [ABSTRACT FROM AUTHOR]

• This is the first report of in vitro acetylcholinesterase inhibition, antioxidant activity and cytotoxicity on human neuroblastoma cell line by extracts and fractions from Crinum americanum. • Ten of seventeen compounds were identified for the first time in Crinum americanum. • The alkaloid-guided extraction step in the remaining plant material improved the chemical characterization of Crinum americanum leaves and bulbs. Two different alkaloid-guided extraction approaches were used to obtain extracts and fractions of leaves and bulbs from Crinum americanum L. (Amaryllidaceae). Samples were analyzed by gas chromatography-mass spectrometry (GC-MS) and acetylcholinesterase (AChE) inhibition activity, and evaluated for antioxidant capacity and cytotoxicity in human neuroblastoma cells (SH-SY5Y). Crinine ( 1 ), 1,2-didehydrocrinan-3-one ( 2 ), flexinine ( 3 ), lycorine ( 4 ), 1-O-acetyl-lycorine ( 5 ), caranine ( 6 ), acetyl-caranine ( 7 ), 11,12-didehydro-anhydrolycorine ( 8 ), hippadine ( 9 ), crinamine ( 10 ), 6-oxo-isocrinamine ( 11 ), macronine ( 12) , and epipowelline ( 13 ) were identified in different extracts and fractions. Additionally, four steroids were identified: stigmasterol ( 14 ), beta-sitosterol ( 15 ), cycloartenol acetate ( 16 ), and cycloeucalenol acetate ( 17 ). Lycorine and crinine were isolated, and their structures were confirmed by nuclear magnetic resonance (NMR) spectroscopy. All extracts and fractions inhibited AChE activity, but with IC 50 values ranging from 1–290 µg/mL. One fraction (L_EE2) from the ethanol extract of C. americanum leaves achieved the highest AChE inhibitory activity (IC 50 = 1.21 µg/mL), when compared to other extracts or fractions. The extracts did not exhibit significant antioxidant activity. After 24 h of treatment, ethanol extracts of leaves and bulbs showed cytotoxic effects on SH-SY5Y cells in a dose-dependent manner from 25 µg/mL. In this study, we highlighted that, after organic extraction, the remaining plant material still presented secondary metabolites, which is interesting for a better understanding of the chemical composition of C. americanum. To the best of our knowledge, this is the first report of in vitro AChE inhibition and cytotoxicity in SH-SY5Y cells using extracts and fractions from C. americanum. Furthermore, among the 17 compounds, ten were identified for the first time in this species. [ABSTRACT FROM AUTHOR]

In this study, a new series of aliphatic, cyclic, and heterocyclic derivatives of haemanthamine was designed and synthesized to enhance its inhibitory effect on the proliferation and viability of cancer cells. A library of haemanthamine derivatives was subjected to 10 μM single-dose cytotoxicity screening against a panel of human cell lines of various histotypes. Initial cytotoxicity evaluation of the parent haemanthamine (1) and a series of twenty-nine (2–30) semisynthetic analogues showed that for some of the newly formed derivatives, a certain cytotoxic effect was observed, in one case even higher than that of the parent compound. Specifically, 11-O-(4-chloro-3-nitrobenzoyl)haemanthamine (21) showed an enhanced antiproliferative effect, where the mean growth percent (GP) value was 5% compared to haemanthamine, leading to a decrease in the GP to 25%. Among ten cell lines tested, derivative 21, bearing a substituted aromatic ester bond via C-11 of haemanthamine, had excellent activity for inhibiting the growth of HeLa (IC50 = 0.2 ± 0.1 μM), A549 (IC50 = 1.7 ± 0.1 μM) and HT-29 (IC50 = 2.2 ± 0.1 μM) cells. When evaluating response kinetics, we found that 21 and haemanthamine dose- and time-dependently suppressed the proliferation of A549 cells. In contrast to haemanthamine (1), Trypan blue and lactate dehydrogenase (LDH) release assay revealed that 21 was capable of reducing the survival of A549 cells.

Multiple myeloma (MM) is largely incurable and drug-resistant. Novel therapeutic approaches such as inhibiting autophagy or rational drug combinations are aimed to overcome this issue. In this study, we found that lycorine exhibits a promising anti-proliferative activity against MM in vitro and in vivo by inhibiting autophagy. We identified High mobility group box 1 (HMGB1), an important regulator of autophagy, as the most aberrantly expressed protein after lycorine treatment and as a critical mediator of lycorine activity. Gene expression profiling (GEP) analysis showed that higher expression of HMGB1 is linked with the poor prognosis of MM. This correlation was further confirmed in human bone marrow CD138+ primary myeloma cells and MM cell lines. Mechanistically, proteasomal degradation of HMGB1 by lycorine inhibits the activation of MEK-ERK thereby decreases phosphorylation of Bcl-2 resulting in constitutive association of Bcl-2 with Beclin-1. In addition, we observed higher HMGB1 expression in bortezomib resistant cells and the combination of bortezomib plus lycorine was highly efficient in vitro and in vivo myeloma models as well as in re-sensitizing resistant cells to bortezomib. These observations indicate lycorine as an effective autophagy inhibitor and reveal that lycorine alone or in combination with bortezomib is a potential therapeutic strategy.

The global COVID-19 pandemic has claimed the lives of millions and disrupted nearly every aspect of human society. Currently, vaccines remain the only widely available medical means to address the cause of the pandemic, the SARS-CoV-2 virus. Unfortunately, current scientific consensus deems the emergence of vaccine-resistant SARS-CoV-2 variants highly likely. In this context, the design and development of broad-spectrum, small-molecule based antiviral drugs has been described as a potentially effective, alternative medical strategy to address circulating and reemerging CoVs. Small molecules are well-suited to target the least-rapidly evolving structures within CoVs such as highly conserved RNA replication enzymes, and this renders them less vulnerable to evolved drug resistance. Examination of the vast literature describing the inhibition of RNA viruses by Amaryllidaceae alkaloids suggests that future, broad-spectrum anti-CoV drugs may be derived from this family of natural products. [ABSTRACT FROM AUTHOR]

Cancer is a major cause of death and an impediment to increasing life expectancy worldwide. With the aim of finding new molecules for chemotherapeutic treatment of epidemiological relevance, ten alkaloid fractions from Amaryllidaceae species were tested against six cancer cell lines (AGS, BT-549, HEC-1B, MCF-7, MDA-MB 231, and PC3) with HaCat as a control cell line. Some species determined as critically endangered with minimal availability were propagated using in vitro plant tissue culture techniques. Molecular docking studies were carried out to illustrate binding orientations of the 30 Amaryllidaceae alkaloids identified in the active site of some molecular targets involved with anti-cancer activity for potential anti-cancer drugs. In gastric cancer cell line AGS, the best results (lower cell viability percentages) were obtained for Crinum jagus (48.06 ± 3.35%) and Eucharis bonplandii (45.79 ± 3.05%) at 30 µg/mL. The research focused on evaluating the identified alkaloids on the Bcl-2 protein family (Mcl-1 and Bcl-xL) and HK2, where the in vitro, in silico and statistical results suggest that powelline and buphanidrine alkaloids could present cytotoxic activity. Finally, combining experimental and theoretical assays allowed us to identify and characterize potentially useful alkaloids for cancer treatment.

Amaryllidaceae alkaloids are secondary metabolites with interesting medicinal properties. Almost every Narcissus species can synthesize them and constitute an excellent source for their isolation and study. Several Amaryllidaceae alkaloids have shown acetylcholinesterase inhibitory activities and are a promising tool for treating cholinergic disorders such as Alzheimer’s disease (AD). Indeed, three of the four palliative treatments approved for AD are acetylcholinesterase (AChE) inhibitors and one of them, galanthamine, is an Amaryllidaceae alkaloid itself. This molecule is currently isolated from natural sources. However, its production is insufficient to supply the increasing demand for the active principle. Our main aim is to discover tools to improve galanthamine production and to prospect for potential new and more efficient drugs for AD treatment. Furthermore, we seek to broaden the knowledge of plants of the genus Narcissus from a chemotaxonomic perspective. Hence, in this study, we evaluate the alkaloid content through GC–MS and the AChE inhibitory activity of ten autumn-flowering Narcissus, which have been less studied than their spring-flowering counterparts. A total of thirty Amaryllidaceae alkaloids have been found, twenty-eight properly identified. Two Narcissus contained galanthamine, and seven were able to inhibit AChE.

Objectives: Given the success of galanthamine in treating Alzheimer's disease, this study aims to establish an effective method to find drugs from Amaryllidaceae alkaloids and to clarify its mechanism in treating Alzheimer's disease., Methods: The pharmacodynamic basis and mechanism of action between Amaryllidaceae alkaloids and Alzheimer's disease were explored by constructing a compound-target-disease network, targets protein-protein interaction, gene ontology, Kyoto Encyclopedia of Genes and Genomes pathway enrichment, and molecular docking verification., Key Findings: In total, a chemical library of 357 potential alkaloids was constructed. A total of 100 active alkaloid components were identified. Thirty-nine associated targets were yielded based on network construction, and the key targets were defined as HSP90AA1, ESR1, NOS3, PTGS2, and PPARG using protein-protein interaction network. Gene ontology items (490) and 68 Kyoto Encyclopedia of Genes and Genomes pathways were selected through the enrichment of target functions, including neuroactive ligand-receptor interaction, calcium signaling pathway, cAMP signaling pathway, Alzheimer disease, and serotonergic synapse that were related to Alzheimer's disease. Lastly, molecular docking demonstrated good stability in combining selected alkaloids with targets., Conclusions: This study explained the mechanisms of Amaryllidaceae alkaloids in preventing and treating Alzheimer's disease and established a novel strategy to discover new drugs from biological chemical sources., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Royal Pharmaceutical Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Amaryllidaceae alkaloids are a diverse group of alkaloids exclusively reported from the Amaryllidaceae plant family. In planta, their biosynthesis is still not fully characterized; however, a labeling study established 4'-O-methylnorbelladine as the key intermediate compound of the pathway. Previous reports have characterized O-methyltransferases from several Amaryllidaceae species. Nevertheless, the formation of the different O-methylnorbelladine derivatives (3'-O-methylnorbelladine, 4'-O-methylnorbelladine, and 3'4'-O-dimethylnorbelladine), the role, and the preferred substrates of O-methyltransferases are not clearly understood. In this study, we performed the biochemical characterization of an O-methyltransferase candidate from Narcissus papyraceus (NpOMT) in vitro and in vivo, following biotransformation of norbelladine in Nicotiana benthamiana having transient expression of NpOMT. Docking analysis was further used to investigate substrate preferences, as well as key interacting residues of NpOMT. Our study shows that NpOMT methylates norbelladine preferentially at the 4'-OH position in vitro and in planta. Interestingly, NpOMT also catalyzed the synthesis of 3',4'-O-dimethylnorbelladine from norbelladine and 4'-O-methylnorbelladine during in vitro enzymatic assay. Furthermore, we show that NpOMT methylates 3,4-dihydroxybenzylaldehyde and caffeic acid in a nonregiospecific manner to produce meta/para monomethylated products. This study reveals a novel catalytic potential of an Amaryllidaceae O-methyltransferase and its ability to regioselectively methylate norbelladine in the heterologous host N. benthamiana., Competing Interests: Conflicts of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Three previously undescribed and sixteen known alkaloids were bioguidedly isolated from the bulbs of Narcissus tazetta subsp. chinensis (M.Roem.) Masamura & Yanagih. The structures were elucidated by spectroscopic data, including HRESIMS, NMR, and ECD. Eleven of the isolated alkaloids exhibited immunosuppressive activity on the proliferation of human T cells. (+)-Narciclasine (18) showed the most significantly suppressive activity with an IC 50 value of 14 ± 5 nM. In vitro, (+)-narciclasine (18) blocked NF-κB signal transduction, but did not affect PI3K/AKT signal transduction. What was more, (+)-narciclasine significantly reduced ALT and AST levels and alleviated liver damage induced by ConA in AIH mouse model., Competing Interests: Declaration of competing interest The authors declare no competing financial interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Aiming to find Amaryllidaceae alkaloids against breast cancer, including the highly aggressive triple-negative breast cancer, the phytochemical study of Pancratium maritimum was carried out. Several Amaryllidaceae-type alkaloids, bearing scaffolds of the haemanthamine-, homolycorine-, lycorine-, galanthamine-, and tazettine-type were isolated (3–11), along with one alkamide (2) and a phenolic compound (1). The antiproliferative effect of compounds (1–11) was evaluated by the sulforhodamine B assay against triple-negative breast cancer cell lines MDA-MB-231 and MDA-MB-468, breast cancer cells MCF-7, and the non-malignant fibroblast (HFF-1) and breast (MCF12A) cell lines. The alkaloids 3, 5, 7, and 11 showed significant growth inhibitory effects against all breast cancer cell lines, with IC50 (half-maximal inhibitory concentration) values ranging from 0.73 to 16.3 µM. The homolycorine-type alkaloid 7 was selected for further investigation in MDA-MB-231 cells. In the annexin-V assay, compound 7 increased cell death by apoptosis, which was substantiated, in western blot analyses, by the increased expression of the pro-apoptotic protein Bax, and the decreased expression of the anti-apoptotic protein Bcl-xL. Consistently, it further stimulated mitochondrial reactive oxygen species (ROS) generation. The antiproliferative effect of compound 7 was also associated with G2/M cell cycle arrest, which was supported by an increase in the p21 protein expression levels. In MDA-MB-231 cells, compound 7 also exhibited synergistic effects with conventional chemotherapeutic drugs such as etoposide.