Bruceine D and Narclasine inhibit the proliferation of breast cancer cells and the prediction of potential drug targets

BACKGROUND

Breast cancer is one of the most common female malignancies. This study explored the underlying mechanism through which the two plant compounds (Brucaine D and Narclasine) inhibited the proliferation of breast cancer cells.

OBJECTIVE

The purpose of this study was to explore the effect of Brucaine D and Narclasine on breast cancer development and their potential drug targets.

METHODS

GSE85871 dataset containing 212 samples and the hallmark gene set "h.all.v2023.1.Hs.symbols.gmt" were downloaded from the Gene Expression Omnibus (GEO) database and the Molecular Signatures Database (MSigDB) database, respectively. Principal component analysis (PCA) was applied to classify clusters showing similar gene expression pattern. Single sample gene set enrichment analysis (ssGSEA) was used to calculate the hallmark score for different drug treatment groups. The expressions of genes related to angiogenesis, glycolysis and cell cycle were detected. Protein-protein interaction (PPI) network analysis was performed to study the interaction of the hub genes. Then, HERB database was employed to identify potential target genes for Narclasine and Bruceine D. Finally, in vitro experiments were conducted to validate partial drug-target pair.

RESULTS

PCA analysis showed that the significant changes in gene expression patterns took place in 6 drugs treatment groups (Narciclasine, Bruceine D, Japonicone A, 1beta-hydroxyalatolactone, Britanin, and four mixture drugs) in comparison to the remaining drug treatment groups. The ssGSEA pathway enrichment analysis demonstrated that Narciclasine and Bruceine treatments had similar enriched pathways, for instance, suppressed pathways related to angiogenesis, Glycolysis, and cell cycle, etc.. Further gene expression analysis confirmed that Narciclasine and Bruceine had a strong ability to inhibit these cell cycle genes, and that MYC, CHEK2, MELK, CDK4 and EZH2 were closely interacted with each other in the PPI analysis. Drug target prediction revealed that Androgen Receptor (AR) and Estrogen Receptor 1 (ESR1) were the targets for Bruceine D, and Cytochrome P450 3A4 enzyme (CYP3A4) was the target for Narciclasine. Cell experiments also confirmed the connections between Narciclasine and CYP3A4.

CONCLUSION

The present study uncovered that Narciclasine and Bruceine D could inhibit the growth of breast cancer and also predicted the potential targets for these two drugs, providing a new therapeutic direction for breast cancer patients.

Identification of haemanthamine as a phytotoxic alkaloid in Narcissus pseudonarcissus L. (Daffodil) emerging buds

Emerging buds of Narcissus pseudonarcissus were found to accumulate the alkaloid haemanthamine (1) at high concentrations, exceeding that of narciclasine (2), the most abundant constituent in bulbs of the plant. A phytoactivity screening assay demonstrated the novel phytotoxicity of haemanthamine against Raphanus sativus (radish), Lactuca sativus (lettuce), Triticum aestivum (red wheat), Solanum lycopersicum (tomato), Cucumis sativus (cucumber), Ipomoea (Morning glory), and Lens culinaris (lentil). Haemanthamine (1) phytotoxicity was found to exceed that of the commercial herbicide glyphosate and less toxic than narciclasine (2).

Pseudolycorine chloride ameliorates Th17 cell-mediated central nervous system autoimmunity by restraining myeloid-derived suppressor cell expansion

CONTEXT

The alkaloids of Narcissus tazetta L. var. Chinensis Roem (Amaryllidaceae) have antitumor and antiviral activities. However, the immunopharmacological effects of one of its constituents, pseudolycorine chloride (PLY), have not been reported yet.

OBJECTIVE

We evaluated the effect of PLY on myeloid-derived suppressor cells (MDSCs) expansion and differentiation into monocyte-like MDSCs (M-MDSCs) and examined whether PLY alleviates Th17 cell-mediated experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS).

MATERIALS AND METHODS

In vitro, MDSCs were treated with PLY (0.67, 2 and 6 μM) or solcitinib (10 μM, positive control) for 48 or 96 h, and their proliferation, expansion, and differentiation into M-MDSCs were examined by flow cytometry. Myelin oligodendrocyte glycoprotein (MOG_35-55) was used to induce EAE in female C57BL/6 mice, and the mice were treated with 40 mg/kg/d PLY or 1 mg/kg/d FK-506 (tacrolimus, positive control) for 21 days. Inflammatory infiltration, spinal cord demyelination, and MDSCs and Th17 cells infiltration into the spinal cord were examined using haematoxylin and eosin staining, Luxol fast blue staining, and immunofluorescence, respectively.

RESULTS

In vitro, PLY (IC50/24 h = 6.18 μM) significantly inhibited IL-6 and GM-CSF-induced MDSCs proliferation, expansion and differentiation into M-MDSCs at all concentrations used. However, these concentrations did not show cytotoxicity. In mice, PLY (40 mg/kg) treatment alleviated EAE and inhibited inflammatory infiltration, demyelination, and MDSCs and Th17 cells infiltration into the spinal cord.

DISCUSSION AND CONCLUSIONS

PLY may be an excellent candidate for the treatment of MS and other autoimmune diseases.

Protective effects and mechanisms of lycorine against adriamycin-induced cardiotoxicity

BACKGROUND

Adriamycin (ADR), a high-efficiency, broad-spectrum anthraquinone chemotherapeutic agent, is currently used to treat various malignant tumors and can lead to cumulative, dose-dependent, and irreversible cardiotoxicity. Lycorine (LYC) is a benzyl phenethylamine alkaloid that exerts remarkable therapeutic effects on cancers and sepsis.

PURPOSE

However, researchers have not yet elucidated whether LYC exerts protective effects against cardiotoxicity induced by ADR and the possible molecular mechanisms.

DESIGN

This study established ADR injury models in vitro and in vivo to explore the effects of LYC against cardiotoxicity induced by ADR. The effects of LYC on blood biochemical parameters, cardiac parameters and structure, ADR-related pathophysiological processes, and the SIRT1/PPARγ signal pathway in ADR-injured models, were analyzed using a series of experimental methods.

RESULTS

LYC significantly improved survival rate, blood biochemical parameters (LDH, CK, and BUN), cardiac parameters (SV and CO), mitochondrial dysfunction, and ameliorated oxidative stress, apoptosis, and myocardial fibrosis in ADR-injured mice (p<0.05). Moreover, LYC obviously increased cell viability and reduced oxidative stress, apoptosis, and mitochondrial dysfunction in ADR-injured cells (p<0.05). Furthermore, this study confirmed that the protective effect of LYC on ADR-induced cardiotoxicitymight be mediated by the SIRT1/PPARγ signaling pathway. These results revealed that the beneficial role of LYC on cardiotoxicity induced by ADR were mediated via regulating SIRT1/PPARγ signaling for the first time.

CONCLUSION

These discoveries may provide a theoretical basis for the exploitation of LYC as a potential cardioprotective drug candidate due to its multiple biological functions to reduce ADR-induced cardiotoxicity, but further preclinical and clinical studies are still needed.

Lycorine nanoparticles induce apoptosis through mitochondrial intrinsic pathway and inhibit migration and invasion in HepG2 cells

Lycorine-nanoparticles (LYC-NPs) were successfully synthesized using anti-solvent precipitation-freeze drying method, and characterized using transmission electron microscopy (TEM), particle size analysis and Fourier transform infrared spectroscopy (FTIR). Then, the antitumor effects of LYC-NPs against HepG2 cells were investigated, and the underlying molecular mechanisms were explored. Our results showed that LYC-NPs displayed potent antiproliferative against HepG2 cells concentration dependently. Flow cytometry analysis exhibited that LYC-NPs triggered apoptosis and impeded cell cycle in G0/G1 phase. Moreover, the up-regulated expression of cleaved caspases-3 and Bax, and decrease of mitochondrial membrane potential and the Bcl-2 expression were involved in LYC-NPs apoptosis, implying that LYC-NPs induced apoptosis via the mitochondrial-mediated apoptosis pathway. Furthermore, LYC-NPs distinctly impaired HepG2 cells migration and invasion with down-regulation of matrix metalloproteinase-2 (MMP-2) and MMP-9 expression. These results indicated that LYC-NPs could be an favorable agent for restraining the growth and metastasis of HepG2 cells.

Antimicrobial crinane-type alkaloids from the bulbs of Crinum latifolium

A phytochemical investigation on the 90% ethanol aqueous extract of the bulbs of Crinum latifolium led to the isolation of three new crinane-type alkaloids, designated as crinumlatines A-C (1-3). The structures of the new compounds were elucidated by spectroscopic analysis (NMR, IR, UV, and MS). The isolated alkaloids were tested in vitro for antimicrobial potentials against 5 pathogenic microorganisms. As a result, compounds 1-3 exhibited some antimicrobial activity against the tested Gram negative bacteria with minimum inhibitory concentration values less than 50 μg/ml.

Synthesis and antiviral activity of lycorine derivatives

There are no effective antiviral drugs to treat hand, foot, and mouth disease. In this study, a series of lycorine derivatives were synthesized and evaluated against enterovirus 71 and coxsackievirus A16 in vitro. Derivatives 7c-m with the phenoxyacyl group at the C-1 position showed higher efficacy and lower toxicity than lycorine. In addition, derivative 7e enhanced the survival rate to 40% in the mouse model of the lethal EV71 infection.

Gigantelline, gigantellinine and gigancrinine, cherylline- and crinine-type alkaloids isolated from Crinum jagus with anti-acetylcholinesterase activity

Three undescribed Amarylidaceae alkaloids, named gigantelline, gigantellinine and gigancrinine, were isolated from Crinum jagus (syn. = Crinum giganteum) collected in Senegal, together with the already known sanguinine, cherylline, lycorine, crinine, flexinine and the isoquinolinone derivative hippadine. Gigantelline, gigantellinine and gigancrinine were characterized as 4-(6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydro-isoquinolin-4-yl)-phenol, its 7-O-demethyl-5ꞌ-hydroxy-4ꞌ-methoxy derivative and 5,6a,7,7a,8a,9-hexahydro-6,9a-ethano[1,3]dioxolo[4,5-j]oxireno[2,3-b]phenanthridin-9-ol, respectively, by using spectroscopic (1D and 2D ¹H and ¹³C NMR and HRESIMS) and chemical methods. Their relative configuration was assigned by NOESY NMR spectra and NMR calculations, while the absolute configuration was assigned using electronic circular dichroism (ECD) experiments and calculations. Sanguinine, cherylline, crinine, flexinine, and the isoquinolinone hippadine, were isolated for the first time from C. jagus. Cherylline, gigantellinine, crinine, flexinine and sanguinine inhibited the activity of AChE in a dose-dependent manner, and inhibition by sanguinine was remarkably effective (IC₅₀ = 1.83 ± 0.01 μM). Cherylline and hippadine showed weak cytotoxicity at 100 μM.

Construction of Fluorescein Isothiocyanate-Labeled MSNs/PEG/Lycorine/Antibody as Drug Carrier for Targeting Prostate Cancer Cells

Lycorine possesses various pharmacological effects, including anti-tumor, antiviral, anti-malarial and anti-inflammatory properties, as well as a potential therapeutic against prostate cancer cells. Therefore, a drug carrier of lycorine with good biocompatibility, high drug loading capacity and good release ability is required to develop to gain maximum benefit from lycorine to target cancer cells. In this study, MSNs labeled with FITC and PEG were synthesized. These FITC-labeled MSNs/PEG/Lycorine/Antibody were loaded with lycorine and anti-EpCAM antibody, and analyzed for endocytosis, biocompatibility, drug loading and release ability. Furthermore, the effects of FITC-labeled MSNs/PEG/Lycorine/Antibody on PC-3M cell line were also investigated. The results revealed that the FITC-labeled MSNs/PEG/Lycorine/Antibody contained excellent biocompatibility, as well as efficiently penetrated into cancer cells. Moreover, the FITC-labeled MSNs/PEG/Lycorine/Antibody nano-composites exhibited excellent drug release ability and induced PC-3M cell death more quickly, as compared to the free lycorine, even at relatively lower concentrations. In conclusion, the FITC-labeled MSNs/PEG/Lycorine/Antibody developed in this study could be used as promising candidates of drug carriers of lycorine for cancer chemotherapy with maximization of anticancer efficacy and reduction of the undesirable side effects to normal cells.

Antineoplastic agents. 454. Synthesis of the strong cancer cell growth inhibitors trans-dihydronarciclasine and 7-deoxy-trans-dihydronarciclasine (1a)

To further pursue the antineoplastic leads offered by our isolation of trans-dihydronarciclasine (1a) and 7-deoxy-trans-dihydronarciclasine (1c) from two medicinal plant species of the Amaryllidaceae family, a practical palladium-catalyzed hydrogenation procedure was developed for the synthesis of these isocarbostyrils from narciclasine (2a) and 7-deoxynarciclasine (2c).

Isolation and structural modification of 7-deoxynarciclasine and 7-deoxy-trans-dihydronarciclasine

As an extension of structure-activity relationship studies of pancratistatin (1), various techniques were first evaluated for separating the mixtures of 7-deoxynarciclasine (2b) and 7-deoxy-trans-dihydronarciclasine (3a) isolated from Hymenocallis littoralis. An efficient solution for that otherwise difficult separation then allowed the lactam carbonyl group of protected (4c and 5c) alcohols 2b and 3a to be reduced employing lithium aluminum hydride. Cleavage (TBAF followed by H2SO4) of the silyl ester/acetonide protected 6a gave amine 8. X-ray crystal structure determinations were employed to confirm the structures of 3,4-acetonide-5-aza-6-deoxynarciclasine (6b), 5-aza-6-deoxynarciclasine (8a), and 5-aza-6-deoxy-trans-dihydronarciclasine (9a, 9b). Against the murine P388 lymphocytic leukemia and a panel of human cancer cell lines, the parent natural products, 7-deoxynarciclasine (2b) and 7-deoxy-trans-dihydronarciclasine (3a), were found to generally be more cancer cell growth inhibitory (GI50 0.1 to <0.01 microg/mL) than the compounds with structural modifications such as amine 8 by a factor of 10 or more. The trans ring juncture of isocarbostyril 3a proved to be an important modification of narciclasine (2a) for improving cancer cell growth inhibition in this series.

Antineoplastic agents. 553. The Texas grasshopper Brachystola magna

Bioassay (P388 lymphocytic leukemia cell line and human cancer cell lines) guided separation of an extract prepared from the previously chemically uninvestigated Texas grasshopper Brachystola magna led to isolation of the cancer cell growth inhibitory pancratistatin (1), narciclasine (2), and ungeremine (3). Pancratistatin (1) was first isolated from the bulbs of Hymenocallis littoralis), and the original crystal structure was deduced by X-ray analysis of a monomethyl ether derivative. In the present study pancratistatin (1) was isolated from an extract of B. magna, which led to the X-ray crystal structure of this anticancer drug. Since isoquinoline derivatives 1-3 are previously known only as constituents of amaryllidaceous plants, some of the interesting implications of their rediscovery in the grasshopper B. magna that does not appear to utilize amaryllis family plants were discussed.

New crinine-type alkaloids with inhibitory effect on induction of inducible nitric oxide synthase from Crinum yemense

The 80% aqueous methanolic extract from the bulbs of Crinum yemense showed a potent inhibitory effect on nitric oxide production in lipopolysaccharide-activated macrophages. Three new crinine-type alkaloids, yemenines A (1), B (2), and C (3), were isolated from the herbal extract together with six known alkaloids. The absolute configurations of 1-3 were determined on the basis of chemical and physicochemical evidence. The effects of the isolated alkaloids on nitric oxide production in lipopolysaccharide-activated macrophages were examined, and several alkaloids, e.g. 1, (+)-bulbispermine (6), (+)-crinamine (7), (+)-6-hydroxycrinamine (8), and (-)-lycorine (9), showed inhibitory effects on nitric oxide production and induction of inducible nitric oxide synthase.

Palladium-catalyzed asymmetric allylic substitution of 2-arylcyclohexenol derivatives: asymmetric total syntheses of (+)-crinamine, (-)-haemanthidine, and (+)-pretazettine

Much interest has been shown in Amaryllidaceae alkaloids as synthetic targets due to their wide range of biological activities. Over 100 alkaloids have been isolated from members of the Amaryllidaceae family; most of them can be classified into eight skeletally homogeneous groups. We have succeeded in the first asymmetric total syntheses of the crinane-type alkaloids (+)-crinamine (1), (-)-haemanthidine (2), and (+)-pretazettine (3). The starting cyclohexenylamine 14 was obtained from allyl phosphonate 11c by palladium-catalyzed asymmetric amination in 82% yield and with 74% ee. The product was recrystallized from MeOH. Interestingly, (-)-14 with 99% ee was obtained from the mother liquor (74% recovery). Intramolecular carbonyl-ene reaction of (-)-10 proceeds in a highly stereoselective manner to give hexahydroindole derivative 9 as the sole product. In the Lewis-acid-catalyzed carbonyl-ene reaction, an interesting rearrangement product, 20, was isolated in high yield. From 9, (+)-crinamine was synthesized. Thus, the asymmetric total synthesis of (+)-crinamine was achieved in 10 steps from 11c, and the overall yield is 19%. The total synthesis of (-)-haemanthidine was also achieved from 9 by a short sequence of steps.

Antineoplastic agents. 511. Direct phosphorylation of phenpanstatin and pancratistatin

Selective phosphorylation of phenpanstatin (3a) with tetrabutylammonium dihydrogen phosphate and dicyclohexylcarbodiimide in pyridine followed by cation-exchange chromatographic procedures was found to provide an efficient route to a new series (3b-3d) of promising 3,4-O-cyclic phosphate prodrugs designated phenpanstatin phosphates. Application of analogous reaction conditions to pancratistatin (1a) led to a mixture of monophosphate derivatives where sodium pancratistatin 4-O-phosphate (4a) was isolated and the structure confirmed by X-ray crystallography. Modification of the reaction conditions allowed direct phosphorylation of pancratistatin followed by cation-exchange chromatography to afford sodium pancratistatin 3,4-O-cyclic phosphate (5a), which was selected for preclinical development.

Daffodil flowers delay senescence in cut Iris flowers

Visible symptoms of tepal senescence in cut Iris x hollandica (cv. Blue Magic) flowers were delayed by placing one cut daffodil flower (Narcissus pseudonarcissus, cv. Carlton) in the same vase. Addition of mucilage, exuded by daffodil stems, to the vase water had the same effect as the flowering daffodil stem. The active compound in the mucilage was identified as narciclasine (using LC/MS, GC/MS, 1H and 13C-NMR, and comparison with an authentic sample of narciclasine). The delay of senescence, either by mucilage or purified narciclasine, was correlated with a delayed increase in protease activity, and with a considerable reduction of maximum protease activity. Narciclasine did not affect in vitro protease activity, but is known to inhibit protein synthesis at the ribosomal level. Its effects on senescence and protease activity were similar to those of cycloheximide (CHX), another inhibitor of protein synthesis, but the effective narciclasine concentration was about 100 times lower than that of CHX. It is concluded that the delay of Iris tepal senescence by daffodil stems is due to narciclasine in daffodil mucilage, which apparently inhibits the synthesis of proteins involved in senescence.

Development of an Efficient Procedure for Indole Ring Synthesis from 2-Ethynylaniline Derivatives Catalyzed by Cu(II) Salts and Its Application to Natural Product Synthesis

The development of efficient methods for the indole synthesis catalyzed by Cu(II) salts and its applications were investigated. Cu(OAc)(2) has been proved to be the best catalyst for the synthesis of various 1-p-tolylsulfonyl or 1-methylsulfonylindoles, which have both electron-withdrawing and electron-donating groups on the aromatic ring and C2 position of indoles. For the primary aniline derivatives, Cu(OCOCF(3))(2) showed good activities, while Cu(OAc)(2) was a good catalyst for the cyclization of secondary anilines. This methodology could be applied to the sequential cyclization reaction for the compounds which have the electrophilic part in the same molecule. By prior treatment with KH, the sequential cyclization was realized to provide the tricyclic ring systems, but it was limited to five- and six-membered rings for the second cyclization. Finally, formal and total synthesis of hippadine with the Cu(II)-promoted indole synthesis as the key step was accomplished.

An Approach to Pancratistatins via Ring-Closing Metathesis: Efficient Synthesis of Novel 1-Aryl-1-deoxyconduritols F

Structurally novel cyclitols, 1-aryl-1-deoxyconduritols F, were efficiently prepared from d-xylose, utilizing RCM as a key step. Various aromatic residues were incorporated in the cyclitol skeleton with total stereochemical control, utilizing a diastereoselective aryl cuprate addition to a gamma-alkoxy enoate. The synthetic route establishes a firm foundation for a practical synthesis of the antitumor alkaloid pancratistatin and its aryl analogues. [structure: see text]

Total Synthesis of Pancratistatin Relying on the [3,3]-Sigmatropic Rearrangement

A new total synthesis of the antitumor alkaloid, pancratistatin (1), has been accomplished from readily available starting materials. Claisen rearrangement of the racemic dihydropyranethylene 17 was employed to construct the A and C rings with the appropriate stereochemistry. In addition, the Ireland-Claisen rearrangement of the enantiomerically pure 9 followed by ring-closing metathesis provided the important intermediate 24, thus implying that our approach could yield the enantioselective synthesis of (+)-pancratistatin. With the appropriately functionalized cyclohexene 24, stereo- and regiocontrolled functional group interchanges, such as iodolactonization, dihydroxylations, and a cyclic sulfate elimination reaction, facilitated the production of the target natural product.

Alkaloid production in Crinum moorei cultures

The alkaloids cherylline (1), crinamidine (2), crinine (3), epibuphanisine (4), lycorine (5), powelline (6), undulatine (7), 1-epideacetylbowdensine (8), and 3-O-acetylhamayne (9) were identified in the in vitro propagated bulblets of Crinum moorei. In addition, crinine, powelline, and undulatine were detected in the solidified Murashige and Skoog (MS) medium. The identity of the alkaloids was confirmed by comparing retention times and mass spectra with known samples. Light, as well as benzyladenine (BA) and charcoal supplementation of the tissue culture medium, influenced the levels of specific alkaloids in both the bulblets and media.

Disposable electrochemical biosensor for the detection of the interaction between DNA and lycorine based on guanine and adenine signals

The interaction of lycorine (LYC) with calf thymus double stranded DNA (dsDNA) and calf thymus single stranded DNA (ssDNA) was studied electrochemically based on the oxidation signals of guanine and adenine by using differential pulse voltammetry (DPV) at carbon paste electrode (CPE) and pencil graphite electrode (PGE). As a result of the interaction of LYC with DNA, the voltammetric signal of guanine and adenine greatly decreased. The changes in the experimental parameters such as the concentration of LYC, and the accumulation time of LYC were studied by using DPV with PGE. The interaction of LYC with synthetic polynucleotides, such as poly[G] was also observed. The interaction of LYC with dsDNA was also observed at PGE in solution phase. In addition, the detection limit and the reproducibility was determined by using both electrochemical transducers. The application of electrochemical methods on the interactions between DNA and DNA targeted agent were explored.

Changes in some enzymes of microbodies and plastid development in excised radish cotyledons: effect of narciclasine

Narciclasine (NCS), isolated from mucilage of Narcissus bulb, showed inhibitory effects on growth and plastid development of excised radish cotyledons. NCS (0.1 mumol/L) started to show inhibitory effects on isocitrate lyase and hydroxypyruvate reductase activities after 24 h incubation in light. When NCS concentration was increased to 10 mumol/L, the activities of both enzymes are completely inhibited. From ultrastructural studies, NCS markedly prevented the degradation of protein bodies and lipid bodies, as well as chloroplast formation of excised radish cotyledons. There was only little degradation of protein and lipid bodies, and almost no chloroplast formation in the excised radish cotyledon treated with 1 mumol/L NCS. Therefore, our results provide clear evidence that NCS inhibited the transition of glyoxysomes and peroxisomes, and chloroplast development.

Galanthindole: a new indole alkaloid from Galanthus plicatus ssp. byzantinus

A new indole alkaloid, galanthindole, was isolated from Galanthus plicatus ssp. byzantinus (Amaryllidaceae), a plant native to northwestern Turkey. Incorporating a non-fused indole ring, galanthindole may represent the prototype of a new subgroup of the Amaryllidaceae alkaloids. Two other bases, (+)-11-hydroxyvittatine and hordenine, are also reported from the same plant.

Effects of lycorine on growth and effects of L-galactonic acid-gamma-lactone on ascorbic acid biosynthesis in strains of Cryptococcus laurentii isolated from Narcissus pseudonarcissus roots and bulbs

The alkaloid lycorine, which is considered to inhibit the last step in ascorbic acid biosynthesis, is produced by Narcissus pseudonarcissus. The growth of two strains (C1 and C3) of Cryptococcus laurentii isolated from root tips of N. pseudonarcissus is inhibited by lycorine, as is the in vivo production of ascorbic acid from L-galactonic acid-gamma-lactone. In contrast, C. laurentii strain C4, isolated from the lycorine-containing bracts of the bulb, was not inhibited by lycorine and did not contain ascorbic acid when cultivated with or without L-galactonic acid-gamma-lactone.

A new synthesis of (+)- and (-)-cherylline

A new and concise synthesis of enantiopure antipodes of alkaloid cherylline has been devised. The synthetic strategy relies upon the reduction of a diversely and polyprotected diarylenamine bearing a chiral auxiliary. Separation of diastereopure intermediates, concomitant deprotections and intramolecular reductive amination complete the synthesis of the natural (S)-enantiomer and of the unnatural (R)-configured antipode.

Total synthesis of (+/-)-alpha- and beta-lycoranes by sequential chemoselective conjugate addition-stereoselective nitro-Michael cyclization of an omega-nitro-alpha,beta,psi,omega-unsaturated ester

[reaction: see text] An omega-nitro-alpha,beta,psi,omega-unsaturated ester underwent a chemoselective conjugate addition of a nitroolefin moiety with aryllithium to produce a psi-aryl-omega-nitro-alpha,beta-unsaturated ester, which was then stereoselectively cyclized by intramolecular nitro-Michael reaction giving a functionalized cyclohexane applicable to the total synthesis of (+/-)-alpha- and beta-lycoranes.

Antineoplastic agents 500. Narcistatin

An efficient procedure was found for synthetic conversion of the sparingly soluble anticancer isocarbostyril narciclasine (1), a component of various Narcissus species, to a cyclic phosphate designated narcistatin (3b). The reaction between narciclasine, tetrabutylammonium dihydrogen phosphate, and p-toluenesulfonic acid in pyridine afforded pyridinium narcistatin (3a) in reasonable yields. Transformation of narcistatin (3a) to, for example, the water-soluble prodrug sodium narcistatin (3d) was easily achieved by cation exchange chromatography. Narcistatin (3b) and 15 salt derivatives were evaluated against a panel of human cancer cell lines, and the range (0.1-0.01) of GI(50) values in micro g/mL was found to parallel that shown by the parent narciclasine.

Total synthesis and biological evaluation of Amaryllidaceae alkaloids: narciclasine, ent-7-deoxypancratistatin, regioisomer of 7-deoxypancratistatin, 10b-epi-deoxypancratistatin, and truncated derivatives

Biocatalytic approaches have yielded efficient total syntheses of the major Amaryllidaceae alkaloids, all based on the key enzymatic dioxygenation of suitable aromatic precursors. This paper discusses the logic of general synthetic design for lycoricidine, narciclasine, pancratistatin, and 7-deoxypancratistatin. Experimental details are provided for the recently accomplished syntheses of narciclasine, ent-7-deoxypancratistatin, and 10b-epi-deoxypancratistatin via a new and selective opening of a cyclic sulfate over aziridines followed by aza-Payne rearrangement. The structural core of 7-deoxypancratistatin has also been degraded to a series of intermediates in which the amino inositol unit is cleaved and deoxygenated in a homologous fashion. These truncated derivatives and the compounds from the synthesis of the unnatural derivatives have been tested against six important human cancer cell lines in an effort to further develop the understanding of the mode of action for the most active congener in this group, pancratistatin. The results of the biological activity testing as well as experimental, spectral, and analytical data are provided in this manuscript for all relevant compounds.

Solid-phase extraction and reversed-phase high-performance liquid chromatography of the five major alkaloids in Narcissus confusus

A novel, fast and precise method, combining solid-phase extraction and reversed-phase high-performance liquid chromatography is described for the quantitative determination of five alkaloids (galanthamine, N-formylnorgalanthamine, haemanthamine, homolycorine and tazettine/pretazettine) from bulbs of wild Narcissus confusus, a high galanthamine-containing plant species growing in the Iberian Peninsula.

Total synthesis of anhydrolycorinone utilizing sequential intramolecular Diels-Alder reactions of a 1,3,4-oxadiazole

A convergent total synthesis of anhydrolycorinone is detailed, enlisting sequential intramolecular Diels-Alder reactions of a suitably substituted 2-amino-1,3,4-oxadiazole defining a novel oxadiazole --> furan --> benzene Diels-Alder strategy.

A short synthesis of (+)-narciclasine via a strategy derived from stereocontrolled epoxide formation and SnCl(4)-catalyzed arene-epoxide coupling

A facile construction of the typical framework of narcissus alkaloids has been realized by virtue of the development of a practical route involving stereocontrolled epoxide formation and SnCl(4)-catalyzed arene-epoxide coupling. To achieve this goal, it proved to be necessary to devise a strategy that would enable chemical transformations to install an epoxy moiety in a congested environment. The successful preparation of a hindered epoxide from O-isopropylidene-protected 4-aminocyclohexenol required three steps consisting principally of controlled bromohydration and base-promoted closure and N-alkylation. It was found that a catalytic amount of SnCl(4) not only maintained the catalytic cycle but also effected clean arylation to form a fused BC ring system. Several tactics that ultimately proved to be unsatisfactory are also discussed in an effort to set important boundary limits on arene-epoxide coupling. The requisite enantiopure 4-aminocyclohexenol was available via an asymmetric cycloaddition of diene to camphor-based chloronitroso. The total synthesis of (+)-narciclasine was realized in nine steps with an overall yield of 19%.

A dinitrogenous alkaloid from Cyrtanthus obliquus

The ethanolic extract of bulbs of Cyrtanthus obliquus (L.f.) Ait yielded the new dinitrogenous alkaloid obliquine (1), 3S, 4aS, 11S, 10bS-3,4,4a,13,11,5,6-heptahydro-5[2-(4-hydroxyphenyl)ethyl]-3-methoxy-13-methyl-[1,3-dioxolo[4,5-g]indolo[3,3a-c]-isoquinolin-12-one, together with the five known structures 11alpha-hydroxygalanthamine, 3-epimacronine, narcissidine, tazettine and trisphaeridine. All structures were established using 1D and 2D NMR techniques and HREIMS. The alkaloids were tested for cytotoxicity against two mammalian cell lines and did not show activity at concentrations up to 100 microg/ml.

Total Synthesis of Amaryllidaceae Alkaloid Buflavine

A concise synthesis of the amaryllidaceae alkaloid buflavine (1) and its regioisomer (2) involving sequential Meyers' biaryl coupling, enecarbamate formation, and hydrogenation followed by ultimate intramolecular reductive amination is presented.

Antiproliferative amaryllidaceae alkaloids isolated from the bulbs of Sprekelia formosissima and Hymenocallis x festalis

Seven alkaloids were isolated from Sprekelia formosissima, and five from Hymenocallis x festalis. Tazettine, lycorine, haemanthidine and haemanthamine were evaluated for antiproliferative and multidrug resistance (mdr) reversing activity on mouse lymphoma cells. Lycorine, haemanthidine and haemanthamine displayed pronounced cell growth inhibitory activities against both drug-sensitive and drug-resistant cell lines, but did not significantly inhibit mdr-1 p-glycoprotein. Thus, the tested alkaloids are apparently not substrates for the mdr efflux pump. Assays for interactions with DNA and RNA revealed that the antiproliferative effects of lycorine and haemanthamine result from their complex formation with RNA.

Stereocontrolled total synthesis of pancratistatin

A new total synthesis of the antitumor alkaloids, pancratistatin (1), has been accomplished from readily available staring materials. The Claisen rearrangement of dihydropyranethylene 5 was employed to construct the A and C rings. Stereo- and regiocontrolled functional group interchange, such as iodolactonization, dihydroxylations, and a cyclic sulfate elimination reaction, allows for the production of the target natural product. [reaction: see text]

Two new alkaloids of the crinane series from Pancratium sickenbergeri

Two new alkaloids; ent-6alpha/6beta-hydroxybuphanisine, (-)-8-demethylmaritidine and seven known alkaloids were isolated from Pancratium sickenbergeri grown in Egypt. Three of the known alkaloids were tested in the NCI cytotoxicity screen, but were found to be inactive.

A new strategy towards the total synthesis of phenanthridone alkaloids: synthesis of (+)-2,7-dideoxypancratistatin as a model study

A new strategy towards the synthesis of phenanthridone alkaloids has been reported through the synthesis of (+)-2,7-dideoxypancratistatin from D-(-)-quinic acid employing PET initiated carbocyclization of an electron rich aromatics by silylenol ether as a key step.

Inhibition of cell cycle progression through specific phase by pancratistatin derivatives

Pancratistatin derivatives, 1-O-(3-hydroxybutyryl)pancratistatin (HBP) and 1-O-(3-O-beta-D-glucopyranosylbutyryl)pancratistatin (GBP), showed strong cytostatic activity against rat embryo fibroblast 3Y1 at concentrations less than 1 microM. When the effect on cell cycle progression was examined in 3Y1 fibroblasts arrested at G0/G1 phase by serum deprivation, HBP, GBP, and pancratistatin inhibited the progression of 3Y1 fibroblasts from G0/G1 to S phase. In addition, when the effect on cell cycle progression was studied in 3Y1 fibroblasts synchronized at late G1/early S phases by treating with hydroxyurea, HBP blocked further progression through S phase, while GBP and pancratistatin did not affect the progression, but retarded it. On the other hand, when the effect of HBP and GBP on the progression was evaluated in promyelocytic leukemia HL-60RG cells synchronized at G0/G1 phase, the cells did not progress into S phase and accumulated in sub G0/G1 phase, which indicated apoptotic cells. These findings suggest that of Amaryllidaceae alkaloids, HBP blocks the progression of cell cycle at least at G0/G1 and S phases and GBP does at least at G0/G1 phase, resulting in apoptosis induction in tumor cells.

Total synthesis of epi-7-deoxypancratistatin via aza-Payne rearrangement and intramolecular cyclization

[reaction: see text] epi-7-Deoxypancratistatin containing the cis-fused phenanthridone core was synthesized in 12 steps from bromobenzene. Key features of this synthesis include the enzymatic oxidation of bromobenzene with toluene dioxygenase, selective opening of a cyclic sulfate over an aziridine with oxygen nucleophiles, and an intramolecular Lewis acid-catalyzed cyclization onto an epoxy conduramine derived via aza-Payne rearrangement.

In vitro activities of two antimitotic compounds, pancratistatin and 7-deoxynarciclasine, against Encephalitozoon intestinalis, a microsporidium causing infections in humans

The antiparasitic effect of a collection of compounds with antimitotic activity has been tested on a mammalian cell line infected with Encephalitozoon intestinalis, a microsporidian causing intestinal and systemic infection in immunocompromised patients. The antiparasitic effect was evaluated by counting the number of parasitophorous vacuoles detected by immunofluorescence. Out of 526 compounds tested, 2 (pancratistatin and 7-deoxynarciclasine) inhibited the infection without affecting the host cell. The 50% inhibitory concentrations (IC(50)s) of pancratistatin and 7-deoxynarciclasine for E. intestinalis were 0.18 microM and 0.2 microM, respectively, approximately eightfold lower than the IC(50)s of these same compounds against the host cells. Electron microscopy confirmed the gradual decrease in the number of parasitophorous vacuoles and showed that of the two life cycle phases, sporogony was more sensitive to the inhibitors than merogony. Furthermore, the persistence of meronts in some cells apparently devoid of sporonts and spores indicated that the inhibitors block development rather than entry of the parasite into the host cell. The occurrence of binucleate sporoblasts and spores suggests that these inhibitors blocked a specific phase of cell division.

A rapid and facile method for the dereplication of purified natural products

A new approach to the use of commercial databases for the dereplication of purified natural products has been developed. This is based on searching a text file that links each structure with its molecular weight and an exact count of the number of methyl, methylene, and methine groups it contains. Analysis of such a text file, constructed from a database containing more than 126,000 natural product structures, revealed that these data, readily measured using MS and NMR spectroscopy, are highly discriminating. The identification of an alkaloid and a sesquiterpene using this new approach is described.

Lycobetaine acts as a selective topoisomerase II beta poison and inhibits the growth of human tumour cells

The phenanthridine alkaloid lycobetaine is a minor constituent of Amaryllidaceae. Inhibition of cell growth was studied in the clonogenic assay on 21 human tumour xenografts (mean IC(50) = 0.8 microM). The growth of human leukaemia cell lines was also potently inhibited (mean IC(50) = 1.3 microM). Athymic nude mice, carrying s.c. implanted human gastric tumour xenograft GXF251, were treated i.p. with lycobetaine for 4 weeks, resulting in a marked tumour growth delay. Lycobetaine was found to act as a specific topoisomerase II beta poison. In the presence of calf thymus DNA, pure recombinant human topoisomerase II beta protein was selectively depleted from SDS-gels, whereas no depletion of topoisomerase II alpha protein was observed. In A431 cells immunoband-depletion of topoisomerase II beta was induced, suggesting stabilization of the covalent catalytic DNA-intermediate in living cells. It is reasonable to assume that this mechanism will cause or at least contribute significantly to the antitumour activity.

Isolation and characterization of two new alkaloids, norpandamarilactonine-A and -B, from Pandanus amaryllifolius by spectroscopic and synthetic methods

Two new alkaloids, norpandamarilactonine-A (1) and -B (2), which have a pyrrolidinyl-alpha,beta-unsaturated gamma-lactone moiety as in the known pandamarilactonine alkaloids, were isolated from the leaves of Pandanus amaryllifolius. Their structures were determined by spectroscopic analysis and total synthesis.

Synthesis of aza bicyclic enones via anionic cyclization: application to the total synthesis of (-)-brunsvigine

[reaction: see text] A general approach to the synthesis of aza bicyclic enones was developed via a simple two-step annulation involving a Mitsunobu protocol and anionic cyclization. According to this strategy the total synthesis of (-)-brunsvigine was accomplished with 12% overall yield.

Antineoplastic agents. 450. Synthesis of (+)-pancratistatin from (+)-narciclasine as relay(1a)

(+)-Narciclasine (2) available in quantity from certain Amaryllidaceae species or by total synthesis was employed as a precursor for a 10-step synthetic conversion (3.6% overall yield) to natural (+)-pancratistatin (1a). The key procedures involved epoxidation of natural (+)-narciclasine (2) to epoxide 6, reduction to diol 8, and formation of cyclic sulfate 12 and its ring opening with cesium benzoate followed by saponification of the benzoate to afford (+)-pancratistatin (1a).

Formal total synthesis of (+/-)-gamma-lycorane and (+/-)-1-deoxylycorine using the [4+2]-cycloaddition/rearrangement cascade of furanyl carbamates

The total syntheses of gamma-lycorane and (+/-)-1-deoxylycorine were accomplished using an intramolecular Diels-Alder cycloaddition of a furanyl carbamate as the key step. The initially formed [4+2]-cycloadduct undergoes nitrogen-assisted ring opening followed by deprotonation/reprotonation of the resulting zwitterion to give a rearranged hexahydroindolinone. The stereochemical outcome of the IMDAF cycloaddition has the side arm of the tethered alkenyl group oriented syn with respect to the oxygen bridge. The key intermediate used in both syntheses corresponds to hexahydroindolinone 20. Removal of the t-Boc group in 20 followed by reaction with 6-iodobenzo[1,3]dioxole-5-carbonyl chloride afforded enamide 22. Treatment of this compound with Pd(OAc)(2) employing the Jeffrey modification of the Heck reaction provided the galanthan tetracycle 24 in good yield. Compound 24 was subsequently converted into (+/-)-gamma-lycorane using a four-step procedure to establish the cis-B,C-ring junction. A radical-based cyclization of the related enamide 33 was used for the synthesis of 1-deoxylycorine. Heating a benzene solution of 33 with AIBN and n-Bu(3)SnH at reflux gave the tetracyclic compound 38 possessing the requisite trans fusion between rings B and C in good yield. After hydrolysis and oxidation of 38 to 40, an oxidative decarboxylation reaction was used to provide the C(2)(-)C(3)(-)C(12) allylic alcohol unit characteristic of the lycorine alkaloids. The resulting enone was eventually transformed into (+/-)-1-deoxylycorine via known synthetic intermediates.

Crinane and lycorane type alkaloids from Zephyranthes citrina

Eight alkaloids have been isolated from Zephyranthes citrina (Amaryllidaceae). The alkaloid oxomaritidine is reported here for the first time from a natural source. The structure and stereochemistry of the alkaloids were determined by physical and spectroscopic methods.

Palladium-catalyzed intramolecular delta-lactam formation of aryl halides and amide-enolates: syntheses of cherylline and latifine

[reaction: see text] Palladium-catalyzed intramolecular carbon-carbon bond formation of aryl halides and amide-enolates gave 4-arylisoquinoline derivatives in good yields, which were further converted into the isoquinoline alkaloids cherylline and latifine.