Antifungal effects of lycorine on Botrytis cinerea and possible mechanisms.

Botrytis cinerea cause postharvest diseases on fruit and lead economic losses. Application of environment-friendly natural compounds is an alternative for synthetic fungicides to control postharvest disease. Lycorine is an indolizidine alkaloid which is widely used for human drug design, however, application of lycorine in controlling postharvest disease and the underlying mechanisms have not been reported. In this study, the effects of lycorine on mycelium growth, spore germination, disease development in apple fruit, cell viability, cell membrane integrity, cell wall deposition, and expression of mitogen-activated protein kinase (MAPK) and GTPase of B. cinerea were investigated. Our results showed that lycorine was effective in controlling postharvest gray mold caused by B. cinerea on apple fruit. In the in vitro tests, lycorine strongly inhibited spore germination and mycelium spreading in culture medium. Investigation via fluorescein diacetate and propidium iodide staining suggested that lycorine could damage the membrane integrity and impair cell viability of B. cinerea. Furthermore, the expression levels of several MAPK and GTPase coding genes were reduced upon the lycorine treatment. Taken together, lycorine is an effective and promising way to control postharvest disease caused by B. cinerea.

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

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

Pseudolycorine N-oxide, a new N-oxide from Narcissus tazetta.

A new N-oxide, Pseudolycorine N-oxide (1) was characterised along with eleven known alkaloids homolycorine (2), O-methylmaritidine (3), 8-O-demethylhomolycorine (4), homolycorine N-oxide (5), lycorine (6), narciclasine (7), pseudolycorine (8), ungeremine (9), 8-O-demethylmaritidine (10), zefbetaine (11) and lycorine N-oxide (12), from Narcissus tazetta. Their structures were established on the basis of spectroscopic data analysis. The extract, fractions and isolated compounds were screened for in vitro cytotoxicity against two human cancer cell lines, human cervical cancer (SiHa) and human epidermoid carcinoma (KB) cells. The study demonstrated the cytotoxic potential of extract and its chloroform and n-butanol fractions. Further, the results revealed the bioactive potential of narciclasine, pseudolycorine and homolycorine alkaloids. However, new N-oxide (1) was not active against these cell lines.

Narciclasine-4-O-ß-D-xylopyranoside, a new narciclasine glycoside from Zephyranthes minuta.

A new narciclasine glycoside, narciclasine-4-O-ß-D-xylopyranoside (1) was characterised along with four known alkaloids pancratistatin (2), 1-O-(3-hydroxybutyryl) pancratistatin (3), vittatine (4), 9-O-demethylgalanthine (5) from Zephyranthes minuta. Their structures were established on the basis of spectroscopic data analysis. The in vitro cytotoxic study of extract, fractions and isolated compounds against two human cancer cell lines (KB and SiHa) indicated the potential activity of extract and n-butanol fraction due to presence of active alkaloids pancratistatin, 1-O-(3-hydroxybutyryl) pancratistatin, lycorine and haemanthamine.

Identification of narciclasine from Lycoris radiata (L'Her.) Herb. and its inhibitory effect on LPS-induced inflammatory responses in macrophages.

Lycoris radiata (L'Her.) Herb. (L. radiata) was traditionally used as a folk medicine in China for treatment of Alzheimer's disease. However, the specific component responsible for its considerable toxicity remained unclear thus restricting its clinical trials. Narciclasine (NCS) was isolated from L. radiata and treatment of NCS for 72 h exhibited significant antiproliferative effects against L02, Hep G2, HT-29 and RAW264.7 cells. However, what needs to be emphasized is that at safe working concentrations of 0.001-0.016 µM, administration of NCS for 24 h inhibited the mRNA expression of inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-ɑ), interleukin-1beta (IL-1ß) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-induced macrophages thereby suppressing production of nitric oxide (NO), IL-6, TNF-ɑ and IL-1ß. NCS supplementation also inhibited nuclear factor-kappa B (NF-κB) activation by suppressing NF-κB P65 phosphorylation and nuclear translocation, IκBɑ degradation and phosphorylation, and IκKɑ/ß phosphorylation. The phosphorylation of c-Jun N-terminal kinase (JNK) and P38, and expression of COX-2 was also attenuated by NCS. These results suggested that NCS might exert anti-inflammatory effects through inhibiting NF-κB and mitogen-activated protein kinase (MAPK) pathways even at very low doses.

Green techniques in comparison to conventional ones in the extraction of Amaryllidaceae alkaloids: Best solvents selection and parameters optimization.

An undisputed trend in sample preparation at present is to meet the requirements of green chemistry especially in the field of natural products. Green technology continuously pursues new solvents to replace common organic solvents that possess inherent toxicity. Over the past two decades, non-ionic surfactants have gained enormous attention from the scientific community. The micelle-mediated extraction and cloud-point preconcentration (CPE) methods offer a convenient alternative to the conventional extraction systems. Recently, natural deep eutectic solvents (NDESs) have emerged as green and sustainable solvents for efficient extraction of bioactive compounds or drugs. They are generally composed of neutral, acidic or basic compounds that form liquids of high viscosity when mixed in certain molar ratio. The presented work aimed to comprehensively compare and evaluate the potential and effectiveness of NDES as well as non-ionic surfactants (Genapol X-080, Triton X-100 and Triton X-114) for extraction of Amaryllidaceae alkaloids from Crinum powellii bulbs as representative example of plant material, in comparison to the conventional solvents (methanol, ethanol and water).A new validated high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous quantitation of three alkaloids markers, lycorine, crinine and crinamine, in the bulbs of C. powellii. Extraction efficiency of the targeted alkaloids from the bulb matrix with organic and ecofriendly (green) solvents were studied. Results revealed that NDES and surfactants were significantly more efficient in alkaloid extraction than previous methods requiring the consumption of organic solvents and water. Genapol X-80 demonstrated 138%, 149% and 145%, while choline chloride: fructose (5:2): H2O (35%) NDES mixture demonstrated 243%, 225% and 238% of the total alkaloidal extraction capacity of ethanol, methanol and water, respectively at 50 °C for extraction time 1 h using ultrasonication for all experiments. Furthermore, Box-Behnken response surface design combined with the overall desirability value were successfully employed to optimize and study the individual and interactive effect of process variables such as extraction temperature, time and surfactant %, for Genapol X-80, and sonication extraction temperature, time and water concentration, for choline chloride: fructose: H2O NDES mixture, on the alkaloidal yield from C. powellii. It was evident that parameters interacting together can act in synergism if adjusted properly according to the optimized conditions to obtain maximum alkaloids extractability. It is for the first time that the efficiency of micelle-mediated extraction has been compared to that of natural deep eutectic solvents for the extraction of alkaloids and the results thoroughly discussed.

Antibacterial activity and virtual screening by molecular docking of lycorine from Pancratium foetidum Pom (Moroccan endemic Amaryllidaceae).

Lycorine is an alkaloid isolated from bulbs of Pancratium foetidum Pom Amaryllidaceae of the genus Lycoris. It has very strong pharmacodynamics properties and biological effects, among others, antimalarial, antiviral, antitumor, and anti-inflammatory. Lycorine has been identified and characterized by thin layer chromatography, IR and NMR (1H and 13C NMR, COZY, HMBC, HSQC and NOESY). The antibacterial activity of lycorine has been evaluated. Lycorine has a moderate antibacterial activity on the majority of strains studied, nevertheless it is more effective than Streptomycin and Ampicillin against bacteria: P. aeruginosa, En. cloacae. To confirm these results, it is necessary to use qualitative techniques and methods, etc… We performed a virtual docking ligand-lycorine protein screening study to predict and characterize their mode of interaction with the LpxC receptor. Docking results have shown that lycorine can interact with target amino residues studied by hydrogen and metal-ion bonds. In addition, the ADME-Tox profile study has shown that lycorine is all in agreement, either with Lipinski's critics or with the toxicity standards.

Metabolite profiling and isolation of biologically active compounds from Scadoxus puniceus, a highly traded South African medicinal plant.

Scadoxus puniceus (Amaryllidaceae), a medicinal plant of high value in South Africa, is used as a component of a traditional herbal tonic prescribed to treat several ailments. Ultra-high performance liquid chromatography-tandem mass spectrometry quantified the phenolic compounds in different organs of S. puniceus. Gravity column chromatography was used to separate fractions and active compounds. The structure of these compounds was determined using 1D and 2D nuclear magnetic resonance and mass spectroscopic techniques. A microplate technique was used to determine the acetylcholinesterase inhibitory activity of the pure compounds. Metabolite profiling revealed a greater profusion of hydroxycinnamic acids (69.5%), as opposed to hydroxybenzoic acids (30.5%). Chlorogenic acid was the most abundant (49.6% of hydroxycinnamic acids) compound. In addition to chlorogenic acid, the study is the first to report the presence of sinapic, gallic, and m-hydroxybenzoic acids in the Amaryllidaceae. Chromatographic separation of S. puniceus led to the isolation of haemanthamine (1), haemanthidine (2), and a rare chlorinated amide, metolachlor (3), the natural occurrence of which is described for the first time. Haemanthamine, haemanthidine, and metolachlor displayed strong acetylcholinesterase inhibitory activity (IC50 ; 23.1, 23.7, and 11.5 µM, respectively). These results substantiate the frequent use of S. puniceus as a medicinal plant and hold much promise for further pharmaceutical development.

Acetylcholinesterase Inhibitory Alkaloids from the Whole Plants of Zephyranthes carinata.

Eleven new alkaloids (1-11), classified as the 12-acetylplicamine (1), N-deformyl-seco-plicamine (2), plicamine (3-6), 4a-epi-plicamine (7), seco-plicamine (8), and lycorine (9-11) framework types, along with 15 known alkaloids (12-26) were isolated from the whole plants of Zephyranthes carinata. The structures of the new alkaloids 1-11 were established by extensive spectroscopic data interpretation. The absolute configurations of 9 and 10 were defined by single-crystal X-ray diffraction analysis. Zephycarinatines A (1), B (2), and G (7) represent the first examples of 12-acetylplicamine, N-deformyl-seco-plicamine, and 4a-epi-plicamine alkaloids, respectively. Alkaloids 6, 11, 17, and 20-23 exhibited AChE inhibitory activities with IC50 values ranging from 1.21 to 184.05 µM, and a preliminary structure-activity relationship is discussed.

Sarniensine, a mesembrine-type alkaloid isolated from Nerine sarniensis, an indigenous South African Amaryllidaceae, with larvicidal and adulticidal activities against Aedes aegypti.

A new mesembrine-type alkaloid, named sarniensine, was isolated together with tazettine, lycorine, the main alkaloid, and 3-epimacronine from Nerine sarniensis, with the last two produced for the first time by this plant. This Amaryllidaceae, which is indigenous of South Africa, was investigated for its alkaloid content, because the organic extract of its bulbs showed strong larvicidal activity with an LC50 value of 0.008µgµL-1 against first instar Aedes aegypti larvae and with an LD50 value 4.6µg/mosquito against adult female Ae. aegypti, which is the major vector for dengue, yellow fever and the Zika virus. The extract did not show repellency at MED value of 0.375mgcm2 against adult Ae. aegypti. Sarniensine was characterized using spectroscopic and chiroptical methods as (3aR,4Z,6S,7aS)-6-methoxy-3a-(2'-methoxymethyl-benzo [1,3]dioxol-1'-yl)-1-methyl-2,3,3a,6,7,7a-hexahydro-1H-indole. It was less effective against larva at the lowest concentration of 0.1µgµL-1, however it showed strong adulticidal activity with an LD50 value of 1.38±0.056µgmosquito-1.

Detailed protocol to assess in vivo and ex vivo myeloperoxidase activity in mouse models of vascular inflammation and disease using hydroethidine.

Myeloperoxidase (MPO) activity contributes to arterial inflammation, vascular dysfunction and disease, including atherosclerosis. Current assessment of MPO activity in biological systems in vivo utilizes 3-chlorotyrosine (3-Cl-Tyr) as a biomarker of hypochlorous acid (HOCl) and other chlorinating species. However, 3-Cl-Tyr is formed in low yield and is subject to further metabolism. Recently, we reported a method to selectively assess MPO-activity in vivo by measuring the conversion of hydroethidine to 2-chloroethidium (2-Cl-E(+)) by liquid chromatography with tandem mass spectrometry (LC-MS/MS) (J. Biol. Chem., 289, 2014, pp. 5580-5595). The hydroethidine-based method has greater sensitivity for MPO activity than measurement of 3-Cl-Tyr. The current methods paper provides a detailed protocol to determine in vivo and ex vivo MPO activity in arteries from mouse models of vascular inflammation and disease by utilizing the conversion of hydroethidine to 2-Cl-E(+). Procedures for the synthesis of standards, preparation of tissue homogenates and the generation of 2-Cl-E(+) are also provided in detail, as are the conditions for LC-MS/MS detection of 2-Cl-E(+).

Antibacterial activities of the methanol extracts, fractions and compounds from Fagara tessmannii.

ETHNOPHARMACOLOGICAL RELEVANCE: Fagara tessmannii is a shrub of the African rainforests used to treat bacterial infections, cancers, swellings and inflammation. In the present study, the methanol extract from the leaves (FTL), bark (FTB), and roots (FTR) of this plant as well as fractions (FTR1-5) and compounds isolated from FTR namely ß-sitosterol-3-O-ß-d-glucopyranoside (1), nitidine chloride (2) and buesgenine (3), were tested for their antimicrobial activities against a panel of Gram-negative bacteria including multidrug resistant (MDR) phenotypes. MATERIALS AND METHODS: The broth microdilution method was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the above samples; Column chromatography was used for the fractionation and purification of the roots extract whilst the chemical structures of compounds were determined using spectroscopic techniques. RESULTS: Results of the MIC determinations indicated that the crude extracts from the roots as well as fraction FTRa4 were active on all the 26 tested bacterial strains. MIC values below 100µg/mL were obtained with roots, leaves and bark extract respectively against 30.8%, 15.4% and 11.5% tested bacteria. The lowest MIC value below of 8µg/mL was obtained with extract from the roots against Escherichia coli MC100 strain. The lowest MIC value of 4µg/mL was also obtained with compound 3 against E. coli AG102 and Klebsiella pneumoniae ATCC11296 CONCLUSIONS: The present study demonstrates that F. tessmannii is a potential source of antimicrobial drugs to fight against MDR bacteria. Benzophenanthrine alkaloids 2 and 3 are the main antibacterial consituents of the roots of the plant.

Bioassay-guided isolation of Poliovirus-inhibiting constituents from Zephyranthes candida.

CONTEXT: Plants of the Zephyranthes genus are globally used in folk medicine. In a previous study, Zephyranthes candida Linn. (Amaryllidaceae) was identified as having antiviral properties; this led to anti-poliovirus assay-guided isolation of compounds from crude methanol extract of the plant. OBJECTIVE: Isolation of anti-poliovirus constituents from Z. candida. MATERIAL AND METHODS: Active chloroform fraction from crude methanol extract of Z. candida (whole plant) was subjected to bioassay-guided fractionation; repeated column and preparative thin layer chromatography led to isolation of active compounds. Chemical structures were identified using spectroscopic techniques. Using serial two-fold dilution of maximum non-toxic concentration (MNTC) of each compound (0.0625-1 µg/mL for lycorine and 0.625-10 µg/mL for trisphaeridine and 7-hydroxy-3',4'-methylenedioxyflavan), the ability of extracts to inhibit viral-induced cell death in tissue culture was evaluated 72 h post-infection by the colorimetric method using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) dye. Regression analysis was used to determine 50% inhibitory concentration (IC50) and 50% cytotoxicity concentration (CC50), from which selective index (SI) was calculated. RESULTS: From the chloroform fraction, three compounds were isolated and identified, namely lycorine (1), trisphaeridine (2), and 7-hydroxy-3',4'-methylenedioxyflavan (3) as the anti-polioviral components. Lycorine was the most active, with an IC50 value of 0.058 µg/mL followed by trisphaeridine (2) with an IC50 of 0.1427 µg/mL, and 7-hydroxy-3',4'-methylenedioxyflavan (3) with an IC50 of 0.2384 µg/mL. DISCUSSIONS AND CONCLUSIONS: The antipoliovirus activity of trisphaeridine (2) and 7-hydroxy-3',4'-methylenedioxyflavan (3) is established in this report; these compounds are of moderate toxicity and have very good SI. They could be a potential template for the development of a new antiviral agent.

In vitro and in vivo activity of benzo[c]phenanthridines against Leishmania amazonensis.

Seven benzo[c]phenanthridines, synthetic or isolated from Zanthoxylum rhoifolium root bark, were evaluated against Leishmania amazonensis axenic amastigotes. Five of them were considered leishmanicidal, with IC50 values ranging from 0.03 to 0.54 µM, and were evaluated on intramacrophagic amastigotes of L. amazonensis. Chelerythrine displayed the best activity (IC50=0.5 µM), which was in the same range as the reference compound amphotericin B (IC50=0.4 µM). In vivo studies with chelerythrine, avicine, and fagaridine on a model of mice cutaneous leishmaniasis resulted in the identification of fagaridine as the most active compound. Fagaridine decreased the parasitic burden more than 50% at the 3rd and 6th weeks after the end of treatment.

Angoline: a selective IL-6/STAT3 signaling pathway inhibitor isolated from Zanthoxylum nitidum.

STAT3 signaling pathway is an important target for human cancer therapy. Thus, the identification of small-molecules that target STAT3 signaling will be of great interests in the development of anticancer agents. The aim of this study was to identify novel inhibitors of STAT3 pathway from the roots of Zanthoxylum nitidum (Roxb.) DC. The bioassay-guided fractionation of MeOH extract of Z. nitidum using a STAT3-responsive gene reporter assay led to the isolation of angoline (1) as a potent and selective inhibitor of the STAT3 signaling pathway (IC50=11.56 µM). Angoline inhibited STAT3 phosphorylation and its target gene expression and consequently induced growth inhibition of human cancer cells with constitutively activated STAT3 (IC50=3.14-4.72 µM). This work provided a novel lead for the development of anti-cancer agents targeting the STAT3 signaling pathway.

New alkaloids from Pancratium maritimum.

As a part of ongoing search efforts for the discovery of anticancer lead entities from natural sources, bulbs and flowers of the amaryllidaceous plant Pancratium maritimum have been investigated. Fractionation of the extracts of the fresh flowers and bulbs of P. maritimum led to the isolation of four new alkaloids, namely pancrimatines A (1) and B (2), norismine (3), and pancrimatine C (4), together with the previously reported N-methyl-8,9-methylenedioxy-6-phenanthridone (5), trispheridine (6), and N-methyl-8,9-methylenedioxyphenanthridine (7). The structures of these alkaloids were established on the basis of extensive 1D and 2D NMR and high-resolution mass spectral analyses as well as comparison with the literature. Compounds 2 and 7 showed antiproliferative and antimigratory activity against the highly metastatic human prostate cancer cell line PC-3 cells without cytotoxicity. The phenanthridine alkaloid class was identified as having potential for use to control prostate cancer proliferation and migration.

Acetylcholineestarase-inhibiting alkaloids from Lycoris radiata delay paralysis of amyloid beta-expressing transgenic C. elegans CL4176.

The limited symptom relief and side effects of current Alzheimer's disease (AD) medications warrant urgent discovery and study of new anti-AD agents. The "cholinergic hypothesis" of AD prompts us to search for plant-derived acetylcholineesterase (AChE) inhibitors such as galanthamine that has been licensed in Europe for AD treatment. We used the unique amyloid ß-expressing transgenic C. elegans CL4176, which exhibits paralysis when human Aß1-42 is induced, to study two natural benzylphenethylamine alkaloids isolated from Lycoris radiata (L' Her.) Herb, galanthamine and haemanthidine, and their synthetic derivatives 1,2-Di-O-acetyllycorine and 1-O-acetyllycorine for their anti-paralysis effects. Our data indicate that these Lycoris compounds effectively delay the paralysis of CL4176 worms upon temperature up-shift, and prolong the lives of these transgenic worms. Lycoris compounds were shown to significantly inhibit the gene expression of ace-1 and ace-2. Additionally, the Lycoris compounds may modulate inflammatory and stress-related gene expressions to combat the Aß-toxicity in C. elegans.

Alkaloids from Boophone haemanthoides (Amaryllidaceae).

In this study, the South African Amaryllid Boophone haemanthoides was examined for its phytochemical composition and cytotoxicity. In the process eight alkaloid structures, including the new compound distichaminol, were identified in bulb ethanolic extracts. Of the isolates, lycorine and distichamine exhibited strong activities against human acute lymphoblastic leukemia (CEM), breast adenocarcinoma (MCF7) and cervical adenocarcinoma (HeLa) cells with IC50S ranging from 1.8 to 9.2 microM.

Narciclasine inhibits the responses of Arabidopsis roots to auxin.

The plant hormone auxin plays a central role in the regulation of plant growth and development, as well as in responses to environmental stimuli. Narciclasine (NCS, an Amaryllidaceae alkaloid) isolated from Narcissus tazetta bulbs has a broad range of inhibitory effects on plants. In this study, the role of NCS in responses to auxin in Arabidopsis thaliana roots was investigated. We demonstrated the inhibitory effects of NCS on auxin-inducible lateral root formation, root hair formation, primary root growth, and the expression of primary auxin-inducible genes in Arabidopsis roots using DR5::GUS reporter gene, native auxin promoters (IAA12::GUS, IAA13::GUS), and quantitative reverse transcription PCR analysis. Results also showed that NCS did not affect the expression of cytokinin-inducible ARR5::GUS reporter gene. NCS relieved the auxin-enhanced degradation of the Aux/IAA repressor modulated by the SCFTIR1 ubiquitin-proteasome pathway. In addition, NCS did not alter the auxin-stimulated interaction between IAA7/AXR2 (Aux/IAA proteins) and the F-box protein TIR1 activity of the proteasome. Taken together, these results suggest that NCS acts on the auxin signaling pathway upstream of TIR1, which modulates Aux/IAA protein degradation, and thereby affects the auxin-mediated responses in Arabidopsis roots.