The Anti-Cholinesterase Potential of Fifteen Different Species of Narcissus L. (Amaryllidaceae) Collected in Spain

Narcissus L. is a renowned plant genus with a notable center of diversity and is primarily located in the Mediterranean region. These plants are widely recognized for their ornamental value, owing to the beauty of their flowers; nonetheless, they also hold pharmacological importance. In Europe, pharmaceutical companies usually use the bulbs of Narcissus pseudonarcissus cv. Carlton to extract galanthamine, which is one of the few medications approved by the FDA for the palliative treatment of mild-to-moderate symptoms of Alzheimer's disease. The purpose of this study was to evaluate the potential of these plants in Alzheimer's disease. The alkaloid extract from the leaves of different species of Narcissus was obtained by an acid-base extraction work-up -procedure. The biological potential of the samples was carried out by evaluating their ability to inhibit the enzymes acetyl- and butyrylcholinesterase (AChE and BuChE, respectively). The species N. jacetanus exhibited the best inhibition values against AChE, with IC50 values of 0.75 ± 0.03 µg·mL-1, while N. jonquilla was the most active against BuChE, with IC50 values of 11.72 ± 1.15 µg·mL-1.

Chemical and Biological Aspects of Different Species of the Genus Clinanthus Herb. (Amaryllidaceae) from South America

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.

Gas chromatography-mass spectrometry of some homolycorine-type Amaryllidaceae alkaloids

RATIONALE

Gas chromatography-mass spectrometry (GC-MS) is the most frequently applied technique for analyzing Amaryllidaceae alkaloids in plant extracts. Having these compounds, known for their potent bioactivities, is a distinctive chemotaxonomic feature of the Amaryllidoideae subfamily (Amaryllidaceae). The Amaryllidaceae alkaloids of homolycorine type with a C3-C4 double bond generally show molecular and diagnostic ions at the high-mass region with low intensity in the EIMS mode, leading to problematic identification in complex plant extracts.

METHODS

Eleven standard homolycorine-type alkaloids (isolated and identified by 1D and 2D nuclear magnetic resonance) were subjected to separation with GC and studied with electron impact mass spectrometry (EIMS) including single quadrupole (GC-EIMS), tandem (GC-EIMS/MS), and high-resolution (GC-HR-EIMS) detectors, as well as with chemical ionization mass spectrometry (GC-CIMS). Alkaloid fractions from two Hippeastrum species and Clivia miniata were subjected to GC-EIMS and GC-CIMS for alkaloid identification.

RESULTS

GC-EIMS in combination with GC-CIMS provided significant structural information of homolycorine-type alkaloids with C3-C4 double bond, facilitating their unambiguous identification. Based on the obtained typical fragmentation, other 11 homolycorine-type compounds were identified in extracts from two Hippeastrum species by parallel GC-EIMS, GC-CIMS, and liquid chromatography-electrospray ionization time-of-flight mass spectrometry and in extracts from C. miniata by GC-EIMS.

CONCLUSIONS

GC-MS can be successfully applied for the identification of new and known homolycorine-type alkaloids, among others within the Amaryllidoideae subfamily, as well as for chemotaxonomical and chemoecological studies.

Chemical Survey of Three Species of the Genus Rauhia Traub (Amaryllidaceae)

Plant biodiversity is an important source of compounds with medicinal properties. The alkaloid galanthamine, first isolated from Galanthus woronowii (Amaryllidaceae), is approved by the FDA for the palliative treatment of mild to moderate Alzheimer's disease due to its acetylcholinesterase (AChE) inhibitory activity. Obtaining this active pharmaceutical ingredient, still sourced on an industrial scale from the Amaryllidaceae species, is a challenge for pharmaceutical companies due to its low natural yield and the high cost of its synthesis. The aim of this work was to determine the alkaloid profile of three different Rauhia (Amaryllidaceae) species collected in Peru, and to assess the potential application of their extracts for the treatment of Alzheimer's disease. The alkaloids were identified by gas chromatography coupled to mass spectrometry (GC-MS), and the AChE inhibitory activity of the extracts was analyzed. Thirty compounds were quantified from the Rauhia species, the R. multiflora extract being the most interesting due to its high diversity of galanthamine-type structures. The R. multiflora extract was also the most active against AChE, with the half maximal inhibitory concentration (IC₅₀) values of 0.17 ± 0.02 μg·mL^-1 in comparison with the IC₅₀ values of 0.53 ± 0.12 μg·mL^-1 for galanthamine, used as a reference. Computational experiments were carried out on the activity of the galanthamine-type alkaloids identified in R. multiflora toward five different human AChE structures. The simulation of the molecules 3-O-acetylgalanthamine, 3-O-acetylsanguinine, narwedine, and lycoraminone on the 4EY6 crystal structure theoretically showed a higher inhibition of hAChE and different interactions with the active site compared to galanthamine. In conclusion, the results of this first alkaloid profiling of the Rauhia species indicate that R. multiflora is an important natural source of galanthamine-type structures and could be used as a model for the development of biotechnological tools necessary to advance the sustainable production of galanthamine.

GC-MS of some lycorine-type Amaryllidaceae alkaloids

The search for novel bioactive compounds and the identification of known ones in the plant kingdom are a challenge for the scientists working in different fields of plant science. In the recent years, mass spectrometry is the most frequently applied method for analysis of complex mixtures of plant metabolites. Twenty-two alkaloids of different lycorine skeleton subtypes (with a Δ^3,4 double bond, with a Δ^4,11 double bond, with saturated rings C and D, and with aromatic ring C) were subjected to separation with gas chromatography and studied with electron impact mass spectrometry including single quadropole (GC-EIMS), tandem mass (GC-EIMS/MS) and high resolution mass (EI-HRMS) detectors in order to determine their fragmentation pattern. The compounds showed excellent separation and specific MS fragmentation allowing structural determination. The GC-MS can be successfully applied for searching new and identification of known bioactive molecules, chemotaxonomical and chemoecological studies, among others, within the Amaryllidoideae subfamily.

Chemodiversity, chemotaxonomy and chemoecology of Amaryllidaceae alkaloids

The Amaryllidaceae alkaloids are a distinctive chemotaxonomic feature of the subfamily Amaryllidoideae of the family Amaryllidaceae, which consists of 59 genera and >800 species distributed primarily in tropical and subtropical areas. Since the first isolation, ca. 140 ago, >600 structurally diverse Amaryllidaceae alkaloids have been reported from ca. 350 species (44% of all species in the subfamily). A few have been found in other plant families, but the majority are unique to the Amaryllidoideae. These alkaloids have attracted considerable research interest due to their wide range of biological and pharmacological activities, which have been extensively reviewed. In this chapter we provide a review of the 636 structures of isolated or tentatively identified alkaloids from plants of the Amaryllidoideae and their classification into 42 skeleton types, as well as a discussion on their distribution, and chemotaxonomical and chemoecological aspects.

Analysis of Polyamines Conjugated with Hydroxycinnamoyl Acids by High-Performance Liquid Chromatography Coupled to Electrospray Ionization Tandem Mass Spectrometry

Polyamines conjugated with hydroxycinnamic acids are phenolic compounds, which are widespread in the plant kingdom playing important roles in development and defence responses. This chapter describes the methodology employed to analyze these phenolamides in plant material by liquid chromatography coupled to electrospray ionization tandem mass spectrometry (LC-MS-MS). These compounds are not always in sufficient concentration in plant tissues for analysis by more conventional methods such as UV detection of HPLC. Owing to their particular molecular structure, they cannot be analyzed as free polyamines. Thus, described herein is an extraction method for hydroxycinnamic acid amides in plant tissues such as leaves, and their analysis by LC-MS-MS, including identification and quantification protocols.

Hippeastrum reticulatum (Amaryllidaceae): Alkaloid Profiling, Biological Activities and Molecular Docking

The Amaryllidaceae family has proven to be a rich source of active compounds, which are characterized by unique skeleton arrangements and a broad spectrum of biological activities. The aim of this work was to perform the first detailed study of the alkaloid constituents of Hippeastrum reticulatum (Amaryllidaceae) and to determine the anti-parasitological and cholinesterase (AChE and BuChE) inhibitory activities of the epimers (6α-hydroxymaritidine and 6β-hydroxymaritidine). Twelve alkaloids were identified in H. reticulatum: eight known alkaloids by GC-MS and four unknown (6α-hydroxymaritidine, 6β-hydroxymaritidine, reticulinine and isoreticulinine) by NMR. The epimer mixture (6α-hydroxymaritidine and 6β-hydroxymaritidine) showed low activity against all protozoan parasites tested and weak AChE-inhibitory activity. Finally, a molecular docking analysis of AChE and BuChE proteins showed that isoreticulinine may be classified as a potential inhibitory molecule since it can be stabilized in the active site through hydrogen bonds, π-π stacking and hydrophobic interactions.

Alkaloid Constituents of the Amaryllidaceae Plant Amaryllis belladonna L

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

Analysis of Bioactive Amaryllidaceae Alkaloid Profiles in Lycoris Species by GC-MS

The genus Lycoris, a group of Amaryllidaceae plants distributed in temperate regions of Eastern Asia, is already known for containing representative alkaloids typical of this botanical family with a wide range of biological activities (for example, lycorine and galanthamine). In the present work, the alkaloid profiles of nine species, L. albiflora, L. aurea, L. chinensis, L. haywardii, L. incarnata, L. longituba, L. radiata, L. sprengeri, and L. squamigera, and one variety ( L. radiata var. pumila) have been evaluated by GC-MS. Structures belonging to the lycorine-, homolycorine-, haemanthamine-, narciclasine-, tazettine-, montanine- and galanthamine-series were identified and quantified, with galanthamine- and lycorine-type alkaloids predominating and usually showing a high relative abundance in comparison with other alkaloids of the extracts. Interestingly, L. longituba revealed itself to be a potential commercial source of bioactive alkaloids. In general terms, our results are consistent with the alkaloid profiles reported in the literature for previously studied species.

Crinine-type alkaloids from Hippeastrum aulicum and H. calyptratum

An ongoing search for alkaloids in the Amaryllidaceae species using GC-MS resulted in the identification of two crinine-type alkaloids, aulicine (1) and 3-O-methyl-epimacowine, (2) from the indigenous Brazilian species Hippeastrum aulicum and Hippeastrum calyptratum, respectively. In addition, two alkaloids, 11-oxohaemanthamine (3) and 7-methoxy-O-methyllycorenine (4) were both isolated from H. aulicum. Furthermore, we provide here complete NMR spectroscopic data for the homolycorine analogues nerinine (5) and albomaculine (6). The absolute stereochemistry of the 5,10b-ethano bridge in the crinine variants was determined by circular dichroism and X-ray crystallographic analysis, thus presenting the first direct evidence for the presence of crinine-type alkaloids in the genus Hippeastrum.

Alkaloid Variability in Leucojum aestivum from Wild Populations

Leucojum aestivum (summer snowflake) is a plant species used for the extraction of galanthamine, an acetylcholinesterase inhibitor for the treatment of Alzheimer’s disease. Extracts from bulbs collected from 18 Bulgarian populations and from shoot-clumps obtained in vitro from 8 different populations showed variations in their alkaloid composition. Nineteen alkaloids were detected in the studied samples by GC-MS. Typically, the alkaloid fractions of L. aestivum bulbs were dominated by galanthamine type compounds, but lycorine, haemanthamine and homolycorine type alkaloids were also found as dominant compounds in some of the samples. Extracts from the shoot-clumps obtained in vitro were found to contain galanthamine or lycorine as main alkaloids. The galanthamine content ranged from 28 to 2104 μg/g dry weight in the bulbs, and from traces to 454 μg/g dry weight in the shoot-clumps.

Alkaloids from Sternbergia colchiciflora

Twenty-one alkaloids and related compounds were found in Sternbergia colchiciflora (Amaryllidaceae), a hitherto not studied plant species. Twenty of them were detected by GC-MS in the crude extracts of this plant species. Ten alkaloids were isolated and their structures confirmed by NMR, MS and CD measurements. Many of the compounds found in this species, such as lycorine, tazettine, haemanthidine, are known to possess strong bioactivity. Variations in the alkaloid pattern were found during the phenological cycle of the plant. Lycorine-type compounds were dominant in the plant organs during both the fl owering period and dormancy. The alkaloid pattern during both periods of leaf development and fructification was dominated by haemanthamine-type in the leaves and lycorine-type compounds in the bulbs, respectively

Wild daffodils of the section Ganymedes from the Iberian Peninsula as a source of mesembrane alkaloids

The aim of this work was to perform a detailed study of the alkaloid content of Narcissus triandrus, as well as a complete analysis of the alkaloid profile of 18 wild populations, comprising all the taxa of the section Ganymedes. Through the application of a combination of spectroscopic and chromatographic methods, the isolation and structural elucidation of 3 compounds are reported for the first time from a natural source (2-oxomesembrenone, 7,7a-dehydromesembrenone and 2-oxoepimesembranol), together with the identification of 5 major common mesembrane alkaloids. Additionally, the GC-MS analysis of the alkaloid profile demonstrated the regular presence of mesembranes in all the studied plants, showing mesembrenone as the predominant compound without any typical Amaryllidaceae alkaloid being detected.

Alkaloids of the South African Amaryllidaceae: A Review

The plant family Amaryllidaceae is known for its horticultural and ornamental appeal as well as its medicinal value. In relation to these characteristics, trade in Amaryllid flower varieties (especially daffodils) is a multi-million dollar revenue generator for the floriculture industry. Of greater significance are the medicinal attributes of the family, which has already spawned the Alzheimer's prescription drug galanthamine, a potent and selective inhibitor of the enzyme acetylcholinesterase, of significance in the progression of neurodegeneration associated with motor neuron diseases, with annual global sales of around $150 million. Furthermore, it is anticipated that an anticancer drug target related to the Amaryllidaceae alkaloid pancratistatin, presently under advanced clinical evaluation, will enter commercial circulation within the next decade. Members of the Amaryllidaceae are distributed through both tropical and subtropical regions of the globe, but are of prominence within three distinct geographical locations, including Andean South America, the Mediterranean basin, and southern Africa. The southern African zone is known to harbor at least a third of the worldwide complement of around 1000 species, many of which are widely utilized in the traditional medicinal practices of the indigenous people of the region. Given its therapeutic and economic value, its natural abundance in the southern African region, coupled to its widespread usage in ethnic medicine, the family Amaryllidaceae provides a diverse and accessible platform for phytochemical based drug discovery. A consolidation of its traditional usage as well as its chemical and pharmacological profiles will thus guide efforts aimed at maximizing this potential. In undertaking this survey of the Amaryllidaceae of southern African, we aimed to achieve these goals.

Alkaloids of the South African Amaryllidaceae: a review

The plant family Amaryllidaceae is known for its horticultural and ornamental appeal as well as its medicinal value. In relation to these characteristics, trade in Amaryllid flower varieties (especially daffodils) is a multi-million dollar revenue generator for the floriculture industry. Of greater significance are the medicinal attributes of the family, which has already spawned the Alzheimer's prescription drug galanthamine, a potent and selective inhibitor of the enzyme acetylcholinesterase, of significance in the progression of neurodegeneration associated with motor neuron diseases, with annual global sales of around $150 million. Furthermore, it is anticipated that an anticancer drug target related to the Amaryllidaceae alkaloid pancratistatin, presently under advanced clinical evaluation, will enter commercial circulation within the next decade. Members of the Amaryllidaceae are distributed through both tropical and subtropical regions of the globe, but are of prominence within three distinct geographical locations, including Andean South America, the Mediterranean basin, and southern Africa. The southern African zone is known to harbor at least a third of the worldwide complement of around 1000 species, many of which are widely utilized in the traditional medicinal practices of the indigenous people of the region. Given its therapeutic and economic value, its natural abundance in the southern African region, coupled to its widespread usage in ethnic medicine, the family Amaryllidaceae provides a diverse and accessible platform for phytochemical based drug discovery. A consolidation of its traditional usage as well as its chemical and pharmacological profiles will thus guide efforts aimed at maximizing this potential. In undertaking this survey of the Amaryllidaceae of southern African, we aimed to achieve these goals.

Cytotoxic Agents of the Crinane Series of Amaryllidaceae Alkaloids

In the alkaloid galanthamine, the plant family Amaryllidaceae has endowed the pharmaceutical community with a potent and selective inhibitor of the enzyme acetylcholinestersae (AChE), of prominence in the chemotherapeutic approach towards motor neuron diseases. Following on the commercial success of this prescription drug in the treatment of Alzheimer's disease, it is anticipated that other drug candidates will in future emerge from the family. In this regard, the phenanthridones, exemplified by narciclasine and pancratistatin, of the lycorine series of Amaryllidaceae alkaloids have shown much promise as remarkably potent and selective anticancer agents, with a drug target of the series destined for the clinical market within the next decade. Given these interesting biological properties and their natural abundance, plants of the Amaryllidaceae have provided a diverse and accessible platform for phytochemical-based drug discovery. The crinane series of Amaryllidaceae alkaloids are also enriched with a significant array of biological properties. As a consequence of their close structural similarity to the anticancer agents of the lycorine series, the cytotoxic potential of crinane alkaloids has been realized through structure-activity relationship (SAR) studies involving targets of both semi-synthetic and natural origin, which has identified several members as leads with promising antiproliferative profiles. As the first of its kind, this review seeks to collate such information from the past few decades in advancing the crinane group as a viable platform for anticancer drug discovery.

Cytotoxic Agents of the Crinane Series of Amaryllidaceae Alkaloids

In the alkaloid galanthamine, the plant family Amaryllidaceae has endowed the pharmaceutical community with a potent and selective inhibitor of the enzyme acetylcholinestersae (AChE), of prominence in the chemotherapeutic approach towards motor neuron diseases. Following on the commercial success of this prescription drug in the treatment of Alzheimer's disease, it is anticipated that other drug candidates will in future emerge from the family. In this regard, the phenanthridones, exemplified by narciclasine and pancratistatin, of the lycorine series of Amaryllidaceae alkaloids have shown much promise as remarkably potent and selective anticancer agents, with a drug target of the series destined for the clinical market within the next decade. Given these interesting biological properties and their natural abundance, plants of the Amaryllidaceae have provided a diverse and accessible platform for phytochemical-based drug discovery. The crinane series of Amaryllidaceae alkaloids are also enriched with a significant array of biological properties. As a consequence of their close structural similarity to the anticancer agents of the lycorine series, the cytotoxic potential of crinane alkaloids has been realized through structure-activity relationship (SAR) studies involving targets of both semi-synthetic and natural origin, which has identified several members as leads with promising antiproliferative profiles. As the first of its kind, this review seeks to collate such information from the past few decades in advancing the crinane group as a viable platform for anticancer drug discovery.

Alkaloids from Narcissus serotinus

Narcissus serotinus belongs to the Amaryllidaceae family, a group well known for an exclusive variety of alkaloids with interesting biological activities. This study was aimed at identifying the alkaloid constituents of N. serotinus collected in the Spanish region of Valencia, using a combination of chromatographic, spectroscopic, and spectrometric methods, including GC-MS and 2D NMR techniques. GC-MS analysis allowed for the direct identification of five known compounds. In addition, the isolation and structure elucidation of six new Amaryllidaceae alkaloids are described.

GC-MS of amaryllidaceous galanthamine-type alkaloids

Galanthamine-type alkaloids produced by plants of the Amaryllidaceae family are potent acetylcholinesterase inhibitors. One of them, galanthamine, has been marketed as a hydrobromide salt for the treatment of Alzheimer's disease. In the present work, gas chromatography with electron impact mass spectrometry (GC-EIMS) fragmentation of 12 reference compounds isolated from various amaryllidaceous plants and identified by spectroscopic methods (1D and 2D nuclear magnetic resonance, circular dichroism, high-resolution MS (HRMS) and EIMS) was studied by tandem mass spectrometry (GC-MS/MS) and accurate mass measurements (GC-HRMS). The studied compounds showed good peak shape and efficient GC separation with a GC-MS fragmentation pattern similar to that obtained by direct insertion probe. With the exception of galanthamine-N-oxide and N-formylnorgalanthamine, the galanthamine-type compounds showed abundant [M](+.) and [M-H](+) ions. A typical fragmentation pattern was also observed, depending on the substituents of the skeleton. Based on the fragmentation pathways of reference compounds, three other galanthamine-type alkaloids, including 3-O-(2'-butenoyl)sanguinine, which possesses a previously unelucidated structure, were identified in Leucojum aestivum ssp. pulchelum, a species endemic to the Balearic islands. GC-MS can be successfully applied to Amaryllidaceae plant samples in the routine screening for potentially new or known bioactive molecules, chemotaxonomy, biodiversity and identification of impurities in pharmaceutical substances.

Bioactive alkaloid extracts from Narcissus broussonetii: mass spectral studies

Plants of the Amaryllidaceae family are a well-known source of tetrahydroisoquinoline alkaloids with a wide range of biological activities, including antiviral, antitumoral, antiparasitic, psychopharmacological, and acetylcholinesterase inhibitory, among others. Recent advances in the use of GC or LC coupled to MS have allowed a chemically guided isolation of uncommon and bioactive alkaloids. In the present work, analytical methods were applied to study the alkaloid profile of Narcissus broussonetii, a plant endemic to North Africa. Using the GC-MS technique and an in-home mass fragmentation database, twenty-three alkaloids were identified, including the very rare dinitrogenous alkaloids obliquine, plicamine, and secoplicamine. Applying LC-ESI-LTQ-Orbitrap-MS, fragmentation profiles were found to be similar for obliquine and plicamine but different for secoplicamine. Pretazettine, a potent cytotoxic alkaloid, was also isolated from N. broussonetii, although its identification by GC-MS was only possible after a BSTFA-derivatization. The silylated crude methanolic extract only showed the presence of pretazettine-TMS, confirming that tazettine was formed after the alkaloid extraction. The same observation was made in Narcissus cultivars in which tazettine had been detected as the major alkaloid. As part of an ongoing project on MS of Amaryllidaceae alkaloids, the silylated tazettine and pretazettine were studied by GC-MS/MS, and found to differ in their fragmentation routes. Finally, the EtOAc extract of N. broussonetii showed notable in vitro activity against Trypanosoma cruzi, with an IC(50) value of 1.77 μg/ml.

Analysis of phenolic compounds by high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry in senescent and water-stressed tobacco

Evaluation of a significant part of the phenylpropanoid pathway metabolites is facilitated by the fast high-performance liquid chromatography with electrospray ionization tandem mass spectrometry (LC-MS/MS) analytical method. The technology described was applied in tobacco plants (Nicotiana tabacum L. cv. Wisconsin) to identify 20 phenolic compounds and to detect differences in phenylpropanoid profiles in two types of experiments. In the first one, senescent and non-senescent parts of flowering plants were compared, while in the second, watered plants were compared with water-stressed young plants. The 20 identified phenolic compounds were: seven hydroxycinnamoylquinic acids, seven hydroxycinnamic acid glucosides, one salicylic acid glucoside, two conjugated flavonols with disaccharides, and three hydroxycinnamic acid amides (HCAA) of putrescine. In general, the levels of phenylpropanoid compounds increased under water stress or senescent conditions, with the exception of HCAA, which decreased in senescent samples, and 4-O-p-coumaroylquinic acid and trihydroxycinamic acid-O-glucoside, which did not change in both experiments. The main product in all the samples was 5-O-caffeoylquinic acid (neochlorogenic acid). Another compound, kaempferol-7-O-neohesperidoside, was tentatively identified for the first time in tobacco plants. This method, which can be applied in other plant species, allows a simple and efficient comparative study of metabolite profile variations (qualitative and quantitative) in response to different physiological and/or environmental plant situations.

Alkaloids from Hippeastrum papilio

Galanthamine, an acetylcholinesterase inhibitor marketed as a hydrobromide salt (Razadyne®, Reminyl®) for the treatment of Alzheimer's disease (AD), is obtained from Amaryllidaceae plants, especially those belonging to the genera Leucojum, Narcissus, Lycoris and Ungernia. The growing demand for galanthamine has prompted searches for new sources of this compound, as well as other bioactive alkaloids for the treatment of AD. In this paper we report the isolation of the new alkaloid 11β-hydroxygalanthamine, an epimer of the previously isolated alkaloid habranthine, which was identified using NMR techniques. It has been shown that 11β-hydroxygalanthamine has an important in vitro acetylcholinesterase inhibitory activity. Additionally, Hippeastrum papilio yielded substantial quantities of galanthamine.

Alkaloid diversity in Galanthus elwesii and Galanthus nivalis

Seventy alkaloids of galanthamine, lycorine, homolycorine, tazettine, haemanthamine, narciclasine, and tyramine types were detected by GC/MS in 25 Galanthus elwesii and seven Galanthus nivalis populations, collected from different locations in Bulgaria. Intraspecies diversity in the alkaloid profiles regarding the main alkaloid types (chemotypes) was observed. Tyramine-type protoalkaloids (namely, hordenine and its derivatives) were dominant in 19 populations of G. elwesii. In other populations of G. elwesii, the plants accumulated mainly homolycorine-, lycorine-, and galanthamine-type alkaloids. The alkaloid profiles of G. nivalis were dominated by narciclasine-, galanthamine-, lycorine-, haemanthamine-, or tazettine-type compounds. Geographical distribution of chemotypes indicated a relationship between populations, since adjacent populations often displayed similar alkaloid profiles. The results from year-to-year sampling and transplantation experiments imply genetic determination of alkaloid synthesis in the two studied species of Galanthus.

Antiproliferative alkaloids from Crinum zeylanicum

Crinum zeylanicum is used in folk medicine as a rubefacient in rheumatism, a treatment for malaria or as a poison. Complex alkaloid profiles in C. zeylanicum plant organs were revealed by GC-MS analysis, including several bioactive compounds. Crinine, lycorine, 11-O-acetoxyambelline, ambelline, 6-hydroxybuphanidrine and 6-ethoxybuphanidrine (an artefact of the isolation procedure) were isolated. Crinine, 6-hydroxybuphanidrine and 6-ethoxybuphanidrine showed antiproliferative effects against human tumor cell lines, crinine being the most active (IC₅₀ 14.04 μM against HL-60/Dox). The latter compound induced apoptosis in a dose-dependent manner in HL-60 and MDA-MB-231 cell lines. Structure-activity relationships in the studied molecules indicated that the hydrogenation of the double bond at C1-C2 leads to a loss of activity, whereas substitutions at C6, C8 and C11 affect their cytotoxicity.

Development and validation of a GC-MS method for rapid determination of galanthamine in Leucojum aestivum and Narcissus ssp.: a metabolomic approach

Galanthamine, an acetylcholinesterase inhibitor marketed as a hydrobromide salt for the treatment of Alzheimer's disease, is obtained from some Amaryllidaceae plants. A new method was developed and validated for its quantification by GC-MS in different plant sources: bulbs and leaves from Narcissus confusus; bulbs from N. pseudonarcissus cv. Carlton; and leaves and in vitro cultures from L. aestivum. Samples (50 mg) were extracted with methanol (1 mL) for 2 h, then aliquots of the extracts were silylated and analyzed by GC-MS. The calibration line was linear over a range of 15-800 μg galanthamine/sample, ensuring an analysis of samples with a content of 0.03-1.54% analyte referred to dry weight. The recovery was generally more than 95%. Good inter- and intra assay precision was observed (RSD<3%). Principal component analysis of GC-MS chromatograms allowed discrimination of the plant raw material with respect to species, organs and geographical regions. The analytical method developed in this study proved to be simple, sensitive and far more informative than the routine analytical methods (GC, HPLC, CE and NMR), so it may be useful for quality control of plant raw materials in the pharmaceutical industry.

Changes in apolar metabolites during in vitro organogenesis of Pancratium maritimum

Calli, shoot-clumps and regenerated plants were initiated from young fruits of Pancratium maritimum L. Their genetic stability was monitored by flow cytometry before chemical studies. Apolar metabolites (alkaloids extracted at pH > 7, free fatty acids and fatty alcohols, sterols etc.) were qualitatively and quantitatively analyzed by GC-MS. The results clearly demonstrated that alkaloid synthesis in P. maritimum is closely related with tissue differentiation. The highest amounts of alkaloids and presence of homolycorine and tazettine type compounds (end products of the biosynthetic pathway of the Amaryllidaceae alkaloids) were found in highly differentiated tissues. Galanthamine accumulated in the leaves of plantlets. The amount of hordenine, a protoalkaloid, is related with the ability of tissues to synthesize alkaloids. Saturated fatty acids were found in considerably higher levels in undifferentiated callus cultures and partially differentiated shoot-clumps than in regenerated plants. Mono- and dienoic fatty acids were found at higher levels in non-photosynthesizing tissues - calli, and in vitro and intact bulbs, while α-linolenic acid (trienoic acid) was found in higher amounts in the photosynthesizing leaves of shoot-clumps and regenerated plants than in bulbs and calli. Fatty alcohols were found mainly in leaves, while sterols tended to accumulate in photosynthesizing and undifferentiated tissues.

Metabolic profiling of bioactive Pancratium canariense extracts by GC-MS

INTRODUCTION

Pancratium canariense Ker Gawler is a plant species belonging to family Amaryllidaceae. Plants from this family are known to synthesise a particular type of bioactive compounds, named Amaryllidaceae alkaloids, which have shown AChE inhibitory activity.

OBJECTIVE

To perform the metabolite profiling of methanolic extracts from P. canariense in order to identify bioactive compounds.

METHODOLOGY

Methanolic extracts from bulbs, leaves and fruits were separated into alkaloid-free apolar and polar fractions, as well as alkaloid fractions, and subjected to AChE assay. Metabolite profiling of extracts and fractions of P. canariense was carried out by GC-EI-MS and LC-ESI-TOF-MS.

RESULTS

AChE inhibitory activities of the alkaloid fractions at a concentration of 10 microg/mL were 29.80 +/- 0.91, 40.93 +/- 4.60 and 58.06 +/- 1.18% for the bulbs, leaves and fruits, respectively. Seventy-six metabolites-mono-, di- and trisaccharides, fatty acids, amino acids, sterols as well as several Amaryllidaceae alkaloids-were detected. Further purification of the alkaloids from the methanolic extracts resulted in the detection of 31 compounds including several potent AChE inhibitors such as habranthine and galanthamine, and the structural elucidation of 3-O-acetylhabranthine, a new natural compound with potential AChE inhibitory activity.

CONCLUSION

The described method resulted in effective integration of both GC-EI-MS and LC-ESI-TOF-MS strategies, which permitted the identification of many metabolites, as well as the structural elucidation of new compounds with potential AChE inhibitory activity.

Three new alkaloids from Galanthus nivalis and Galanthus elwesii

Phytochemical studies on Galanthus species resulted in the isolation of three new compounds: 3,3'-O-(3',3''-dihydroxybutanoyl)hamayne and 11,3'-O-(3',3''-dihydroxybutanoyl)hamayne from G. nivalis and 2-O-(3'-hydroxybutanoyl)lycorine from G. elwesii. Additionally, 3,11-O-(3',3''-dihydroxybutanoyl)hamayne, 3,11,3'-O-(3',3'',3'''-trihydroxybutanoyl)hamayne, 8-O-demethylvasconine, tazettine, epimacronine, and ismine from G. nivalis; 2-O-(3'-acetoxybutanoyl)lycorine and incartine from G. elwesii; and hamayne, 11-O-(3'-hydroxybutanoyl)hamayne and lycorine from both species were isolated. Their structures were determined by EI-MS, HR-MS, CD, and 1D and 2D NMR (COSY, NOESY, HMQC, and HMBC) experiments.

Rapid TLC/GC-MS identification of acetylcholinesterase inhibitors in alkaloid extracts

Alkaloid extracts from 12 plant species of the families Amaryllidaceae, Fumariacae and Papaveraceae were studied with respect to their acetylcholinesterase inhibitory activity and alkaloid patterns. Fifty-three alkaloids were identified by GC-MS, including known acetylcholinesterase (AChE) inhibitors such as galanthamine, epigalanthamine, sanguinine and epinorgalanthamine in extracts of Amaryllidaceae plants and protopine in extracts of Fumariaceae and Papaveraceae plants. The galanthamine-containing extracts of the amaryllidaceous plants were found to be the most active while the extract of Corydalis bulbosa was the most active among the extracts of the tested plants from the Fumariaceae and Papaveraceae plants. TLC bioautographic assay, preparative TLC and GC-MS analysis were combined to identify the active compounds in the studied extracts. Galanthamine was isolated from the known AChE inhibitors in the extracts of Amaryllidaceae plants. Corydaline, bulbocapnine and stylopine were found to be active in the extracts of plant species of the families Fumariaceae and Papaveraceae. Available standards of deshydrocorydaline--a precursor of corydaline, corydaline and stylopine--were tested for AChE inhibitory activity. Deshydrocorydaline and corydaline showed potent inhibitory activity comparable with that of the positive control galanthamine.

Analysis of galanthamine-type alkaloids by capillary gas chromatography-mass spectrometry in plants

Galanthamine, an acetylcholinesterase inhibitor used for the treatment of Alzheimer's disease, and galanthamine-type alkaloids are synthesised in different plants of the family Amaryllidaceae. A capillary gas chromatographic-mass spectroscopic (CGC-MS) method for the separation of 7 galanthamine type alkaloids, including galanthamine and epigalanthamine, is described in the present paper. A simple method for the routine quantification of galanthamine in plants was developed using pre-packed columns with diatomaceous earth (Isolute HM-N), allowing simultaneous preparation of a large number of samples. Galanthamine showed excellent linearity in the range from 50 to 1000 microg/mL and the limit of quantification was 5 microg/mL in total ion current mode and 1.6 ng/mL in selected ion monitoring mode. The recovery of galanthamine was more than 90%. Interday reproducibility (RSD) of the extraction was 2.74%. A method to find and to microextract Amaryllidaceae alkaloids in low-mass plant samples is also described.

Antioxidant activity and phenolic composition of wild, edible, and medicinal fennel from different Mediterranean countries

Fennel (Foeniculum vulgare Mill.) is a typical aromatic plant of the Mediterranean area, long used as a medicinal and spice herb. Fennel is also well-known for its essential oil, which has been extensively studied for many years owing to its commercial importance. In this work, the antioxidant activity and the total phenolic and flavonoid contents, as well as the quantitative determination of individual flavonoids and phenolic acids of wild, edible, and medicinal fennel from different Mediterranean countries, have been determined. The antioxidant activity was measured as the free radical (DPPH), hydroxyl radical, and superoxide anion scavenging activities. Wild fennel was found to exhibit a radical scavenging activity, as well as a total phenolic and total flavonoid content, higher than those of both medicinal and edible fennels.

Antioxidant activity and phenolic composition of Lavandin (Lavandula x intermedia Emeric ex Loiseleur) waste

The phenolic content of lavandin waste obtained after the distillation of essential oils for the perfume industry was investigated to find an alternative use for this material. The antioxidant activity of different fractions as well as their total phenolic content were evaluated by different methods. Twenty-three phenolic compounds were identified by liquid chromatography coupled to ionspray mass spectrometry (LC/MS/MS), including phenolic acids, hydroxycinnamoylquinic acid derivatives, glucosides of hydroxycinnamic acids, and flavonoids, none of which have previously been reported in lavandin waste. Some structure-activity relationships were proposed by relating the type of scavenging activity of different fractions with the identified phenolic compounds. Contents of representative phenolic acids of Lamiaceae (chlorogenic and rosmarinic) were evaluated by high performance liquid chromatography-diode array detection (HPLC-DAD) and compared with those of other plant species.

Revised NMR data for incartine: an alkaloid from Galanthus elwesii

Phytochemical studies on Galanthus elwesii resulted in the isolation of five alkaloids: incartine, hordenine, hippeastrine, 8-O-demethylhomolycorine and lycorine. The NMR data given previously for incartine were revised and completed by two-dimensional 1H-1H and 1H-13C chemical shift correlation experiments. In vitro studies on the bioactivity of incartine were carried out.

Alkaloids from Galanthus nivalis

Phytochemical studies on Galanthus nivalis of Bulgarian origin resulted in the isolation of five compounds: 11-O-(3'-hydroxybutanoyl)hamayne, 3,11-O-(3',3''-dihydroxybutanoyl)hamayne, 3-O-(2''-butenoyl)-11-O-(3'-hydroxybutanoyl)hamayne, 3,11,3''-O-(3',3'',3'''-trihydroxybutanoyl)hamayne, and 2-O-(3'-acetoxybutanoyl)lycorine, together with five known alkaloids: ungeremine, lycorine, tazettine, hamayne, and ismine. Their structures were determined by (1)H and (13)C NMR spectroscopy and two-dimensional (1)H-(1)H and (1)H-(13)C chemical shift correlation experiments.

Chemical and biological aspects of Narcissus alkaloids

This chapter discusses the chemical and biological aspects of Narcissus alkaloids. Numerous alkaloids have been isolated from Narcissus speciesasaresult of the continuing search for novel alkaloids with pharmacological activity in the Amaryllidaceae family. The alkaloids isolated from this genus, classified in relation to the different skeleton types. The different Narcissus wild species and intersectional hybrids, grouped into subgenera and sections, with their corresponding alkaloids, arranged according to their ring system are listed. The biosynthetic pathways of Narcissus alkaloids includes: (1) enzymatic preparation of the precursors, (2) primary cyclization mechanisms, (3) enzymatic preparation of intermediates, (4) secondary cyclization, diversification, and restructuring. The chapter discusses proton nuclear magnetic resonance (1H NMR), carbon nuclear magnetic resonance (13C NMR), and mass spectrometry (MS) for Narcissus alkaloids. A list of the different Narcissus alkaloids, their spectroscopic properties, and literature with the most recent spectroscopic data is given. Several Narcissus extracts shows the following activities: antiviral, prophage induction, antibacterial, antifungal, antimalarial, insecticidal, cytotoxic, antitumor, antimitotic, antiplatelet, hypotensive, emetic, acetylcholine esterase inhibitory, antifertility, antinociceptive, chronotropic, pheromone, plant growth inhibitor, and allelopathic.

Acylated quercetagetin glycosides with antioxidant activity from Tagetes maxima

The fractionation of a methanolic extract of Tagetes maxima guided for antioxidant activity resulted in the isolation of three acylated quercetagetin glycosides, quercetagetin-7-O-(6-O-caffeoyl-beta-D-glucopyranoside), quercetagetin-7-O-(6-O-p-coumaroyl-beta-D-glucopyranoside) and quercetagetin-7-O-(6-O-galloyl-beta-D-glucopyranoside), as well as four known flavonoid glycosides. The structural elucidation was accomplished by spectroscopic methods (ESI-MS/MS and NMR). The antioxidant activity of fractions and isolated compounds was determined by checking the scavenging activity against three different radicals: 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH*), hydroxyl (*OH), and superoxide (O2*-). The three isolated compounds exhibited a high radical scavenging activity in comparison with reference compounds.

Alkaloids from Nerine filifolia

The novel compounds N-demethylbelladine, 6alpha-methoxybuphanidrine and filifoline, in addition to five known alkaloids, and phenol have been isolated from fresh bulbs of Nerine filifolia (Amaryllidaceae). The structure and stereochemistry of the compounds were determined by physical and spectroscopic methods, including 1D and 2D NMR and mass spectroscopic techniques. An unusual circular dichroism response from filifoline has required a semi-synthetic derivatisation strategy towards key C-11endo analogues of the beta-crinane representative ambelline in which the nature of substituents was observed to have a profound effect on molecular ellipticity. Filifoline was not cytotoxic to myoblast (L6) cells and exhibited no anti-protozoal activity in an in vitro screen against four different parasitic protozoa.

Improved production of galanthamine and related alkaloids by methyl jasmonate in Narcissus confusus shoot-clumps

Liquid-shake cultured shoot-clumps of Narcisus confussus were treated with the commonly used biotic elicitors methyl jasmonate, arachidonic acid, chitosan and salicylic acid. The effects of these compounds on the growth of the explants, as well as on the amount of the alkaloids released to the liquid culture medium and accumulated in the tissues at the end of the experiment were studied. The obtained results showed that, in general, high doses of these compounds had a negative effect on the growth of the explants, particularly the salicylic acid. On the contrary, the addition of methyl jasmonate, mainly at 25 microM, promoted the release of galanthamine and other related alkaloids to the liquid medium in proportions of up to 300% in relation to the control explants, and also their accumulation in tissues. The other elicitors studied did not have any interesting effects on the production of these Amaryllidaceae-type alkaloids.

Augustamine type alkaloids from Crinum kirkii

Sixteen more Amaryllidaceae alkaloids have been isolated from bulbs of Crinum kirkii Baker of which noraugustamine and 4a,N-dedihydronoraugustamine are hitherto unknown. Their structures and those of earlier known alkaloids have been established by physical and spectroscopic analysis. Application of 2D NMR techniques was used for complete characterization of the alkaloids as well as of 3-O-acetylsanguinine. 1,2-Diacetyllycorine and 3-O-acetylsanguinine showed activity against Trypanosoma brucci rhodesiense, the parasite associated with sleeping sickness. 3-O-acetylsanguinine also showed some activity against Trypanosoma cruzi.

Investigation of Lepechinia graveolens for its antioxidant activity and phenolic composition

A bioguided separation of Lepechinia graveolens (Reg.) Epling. (Lamiaceae) for antioxidant activity was carried out. The ethyl acetate fraction (EAF) from the methanolic extract was chromatographed on Sephadex LH-20 affording five active fractions. The radical scavenging activity of each fraction, as well as that of the isolated compounds, was tested using three different methods. The major isolated antioxidant compounds were identified as luteolin-7-O-glucuronide, rosmarinic acid, and rosmarinic acid methyl ester by means of 1H and 13C NMR and mass spectrometry. Twenty other minor phenolic compounds were determined by liquid chromatography-negative electrospray ionization tandem mass spectrometry. They included hydroxycinnamic acid derivatives, flavonoids and phenolic diterpenes. The major phenolic compound was found to be rosmarinic acid, which was quantitatively determined by high-performance liquid chromatography (HPLC)-diode array detector (DAD). The content of rosmarinic acid was 2.8% (referred to dry weight), this amount being around 30% of the total phenolic content (TPH) of the crude extract. It can be concluded that the antioxidant activity of Lepechinia graveolens was mainly due to rosmarinic acid, which allows this plant species to be considered as a potential new source of this well known natural antioxidant.

Separation and characterization of phenolic compounds in fennel (Foeniculum vulgare) using liquid chromatography-negative electrospray ionization tandem mass spectrometry

Liquid chromatography (LC) diode array detection (DAD) coupled to negative electrospray ionization (ESI) tandem mass spectrometry (MS/MS) was used for the rapid and sensitive identification of water-soluble phenolic compounds in fennel waste. The plant material was first extracted and then chromatographed on Sephadex LH-20 to afford seven fractions, each of them being subjected to LC-MS analysis. Identification of the compounds was carried out by interpretation of UV, MS, and MS/MS spectra. Forty-two phenolic substances were identified, 27 of which had not previously been reported in fennel, including hydroxycinnamic acid derivatives, flavonoid glycosides, and flavonoid aglycons.