Effects of fungicides on galanthamine and metabolite profiles in Narcissus bulbs

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.

Do Fungicides Affect Alkaloid Production in Catharanthus roseus (L.) G. Don. Seedlings?

The presence of endophytes in plants is undeniable, but how significant their involvement is in the host plant biosynthetic pathways is still unclear. The results reported from fungicide treatments in plants varied. Fungicide treatment in Taxus was found to decrease the taxol content. In Ipomoea asarifolia, Pronto Plus and Folicur treatments coincided with the disappearance of ergot alkaloids from the plant. In Narcissus pseudonarcissus cv. Carlton, a mixture of fungicide applications decreased the alkaloids concentration and altered the carbohydrate metabolism. Jacobaea plants treated with Folicur reduced the pyrrolizidine alkaloids content. There have not been any studies into the involvement of endophytic fungi on alkaloids production of Catharanthus roseus until now. Though there is a report on the isolation of the endophytic fungi, Fusarium oxysporum from C. roseus, which was reported to produce vinblastine and vincristine in vitro. To detect possible collaborations between these two different organisms, fungicides were applied to suppress the endophytic fungi in seedlings and then measure the metabolomes by ¹HNMR and HPLC analysis. The results indicate that endophytic fungi were not directly involved in alkaloids biosynthesis. Treatment with fungicides influenced both the primary and secondary metabolism of C. roseus. The systemic fungicides Pronto Plus and Folicur caused an increase in loganin and secologanin levels. In contrast, control samples had higher level of catharanthine and vindoline. This means that fungicide treatments cause changes in plant secondary metabolism.

Impact of Geraniol and Geraniol Nanoemulsions on Botrytis cinerea and Effect of Geraniol on Cucumber Plants’ Metabolic Profile Analyzed by LC-QTOF-MS

In the present study, the bioactive substance geraniol was tested in vitro and in planta against B. cinerea on cucumber plants, and the changes in the metabolic profile of cucumber plants inoculated with the pathogen and/or treated with geraniol were monitored by a novel LC-QTOF-MS method employing target and suspect screening. The aforementioned treatments were also studied for their impact on membrane lipid peroxidation calculated as malondialdehyde (MDA) content. Additionally, geraniol-loaded nanoemulsions (GNEs) were synthesized and tested against B. cinerea as an integrated formulation mode of geraniol application. The EC₅₀ values calculated for geraniol and GNEs against B. cinerea were calculated at 235 μg/mL and 105 μg/mL, respectively. The in planta experiment on cucumber plants demonstrated the ability of geraniol and GNEs to significantly inhibit B. cinerea under greenhouse conditions. The LC-QTOF-MS analysis of the metabolic profile of the cucumber plants treated with geraniol demonstrated an increase in the concentration levels of myricetin, chlorogenic acid, and kaempferol rhamnoside, as compared to control plants and the presence of B. cinerea caused an increase in sinapic acid and genistein. These compounds are part of important biosynthetic pathways mostly related to responses against a pathogen attack.

Pressurized Natural Deep Eutectic Solvent Extraction of Galanthamine and Related Alkaloids from Narcissus pseudonarcissus

The isolation of a compound from a natural source involves many organic and mostly toxic solvents for extraction and purification. Natural deep eutectic solvents have been shown to be efficient options for the extraction of natural products. They have the advantage of being composed of abundantly available common primary metabolites, being nontoxic and environmentally safe solvents. The aim of this study was to develop a natural deep eutectic solvent-based extraction method for galanthamine, an important therapeutic agent for the treatment of Alzheimer's disease. This alkaloid can be produced by synthesis or by extraction from Narcissus bulbs. To develop an efficient extraction method, a number of different natural deep eutectic solvents was first tested for their solubilization capacity of galanthamine bromide salt. Promising results were obtained for ionic liquids, as well as some amphoteric and acidic natural deep eutectic solvents. In a two-cycle extraction process, the best solvents were tested for the extraction of galanthamine from bulbs. The ionic liquids produced poor yields, and the best results were obtained with some acid and sugar mixtures, among which malic acid-sucrose-water (1 : 1 : 5) proved to be the best, showing similar yields to that of the exhaustive Soxhlet extraction with methanol. Furthermore, the natural deep eutectic solvent was more selective for galanthamine.

Transcriptome analysis of Leucojum aestivum and identification of genes involved in norbelladine biosynthesis

Transcriptome analysis of Leucojum aestivum led to the identification of 50 key genes associated with Amaryllidaceae alkaloid biosynthesis including norbelladine synthase which localized in the cytosol and catalyzed norbelladine formation. The Amaryllidaceae alkaloids (AAs) are a large group of plant specialized metabolites, which are known for their biological activities. Although the general chemical reactions in the AA biosynthetic pathway have been proposed, the genes and enzymes of the pathway remain largely unstudied. All AAs are synthesized from a common precursor, norbelladine, by the condensation of tyramine and 3,4-dihydroxybenzaldehyde. The enzyme norbelladine synthase (NBS) which catalyzes the condensation reaction has only been characterized at a molecular level from one species, and the subcellular localizations have not been explored. Hence, the intracellular compartments wherein the AAs are biosynthesized remain unknown. In this study, a first comprehensive transcriptomic analysis of summer snowflake (Leucojum aestivum) was done to identify key genes associated with AA biosynthesis. Fifty orthologous genes were identified and deposited into GenBank. In addition, we identified and further characterized NBS from the transcriptome of L. aestivum and previously reported Narcissus papyraceus. Phylogenetic analysis showed that LaNBS, NpNBS1 and NpNBS2 shared high amino acid identity. The heterologous expression of LaNBS produced a recombinant protein with NBS activity. Bioinformatic prediction and C-terminal GFP tagging in transiently transformed Nicotiana benthamiana showed that LaNBS, NpNBS1 and NpNBS2 were likely localized to the cytosol which suggests that the AA biosynthesis starts in the cytosol. This study provides an Amaryllidaceae transcriptome that will be very helpful to identify genes for characterization studies in AA metabolism in planta or using heterologous systems. In addition, our study will facilitate the bioengineering of AA biosynthetic pathway in plants or in microorganisms.

Multi-Omics Approach in the Identification of Potential Therapeutic Biomolecule for COVID-19

COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It has a disastrous effect on mankind due to the contagious and rapid nature of its spread. Although vaccines for SARS-CoV-2 have been successfully developed, the proven, effective, and specific therapeutic molecules are yet to be identified for the treatment. The repurposing of existing drugs and recognition of new medicines are continuously in progress. Efforts are being made to single out plant-based novel therapeutic compounds. As a result, some of these biomolecules are in their testing phase. During these efforts, the whole-genome sequencing of SARS-CoV-2 has given the direction to explore the omics systems and approaches to overcome this unprecedented health challenge globally. Genome, proteome, and metagenome sequence analyses have helped identify virus nature, thereby assisting in understanding the molecular mechanism, structural understanding, and disease propagation. The multi-omics approaches offer various tools and strategies for identifying potential therapeutic biomolecules for COVID-19 and exploring the plants producing biomolecules that can be used as biopharmaceutical products. This review explores the available multi-omics approaches and their scope to investigate the therapeutic promises of plant-based biomolecules in treating SARS-CoV-2 infection.

Plant metabolomics for studying the effect of two insecticides on comprehensive constituents of Lonicerae Japonicae Flos

Pesticides' overuse and misuse have been reported to induce ingredient variations in herbal medicine, which is now gaining attention in the medicinal field as a form of alternative medicine. To date, available studies on pesticide-induced ingredient variations of herbal medicine are limited only on a few compounds and remain most others unexamined. In this study, a plant metabolomics-based strategy was performed to systematically explore the effects of two frequently used insecticides on the comprehensive constituents of Lonicerae Japonicae Flos (LJF), the flower buds of Lonicera japonica Thunb. Field trials were designed on a cultivating plot of L. japonica with controls and treatments of imidacloprid (IMI) and compound flonicamid and acetamiprid (CFA). Unbiased metabolite profiling was conducted by ultra-high performance liquid chromatography/quadrupole-Orbitrap mass spectrometer. After data pretreatment by automatic extraction and screening, a data matrix of metabolite features was submitted for statistical analyses. Consequently, 29 metabolic markers, including chlorogenic acids, iridoids and organic acid-glucosides were obtained and characterized. The relative quantitative assay was subsequently performed to monitor their variations across flowering developments. This is the first study that systematically explored the insecticide-induced metabolite variations of LJF while taking into account the inherent variability of flowering development. The results were beneficial for holistic quality assessment of LJF and significant for guiding scientific use of pesticides in the large-scale cultivation.

Transcriptome and metabolome profiling of Narcissus pseudonarcissus 'King Alfred' reveal components of Amaryllidaceae alkaloid metabolism

Amaryllidaceae alkaloids (AAs) represent a diverse class of plant specialized metabolites and many display potent pharmacological activities. The AA metabolic pathway is poorly understood and resources are minimal. To enable AA pathway elucidation and novel biosynthetic enzymes discovery, we generated comprehensive metabolomic and corresponding transcriptomic datasets from different tissues of Narcissus pseudonarcissus ‘King Alfred’. In this study, we performed untargeted UPLC-QTOF-MS metabolite analysis from different tissues, which generated exhaustive list of compounds, including several AAs, most predominant and diverse in bulbs. RNA sequencing of N. pseudonarcissus ‘King Alfred’ bulbs yielded 195,347 transcripts, after assembly. Top expressed genes belong to process like metabolism, survival, and defense including alkaloid biosynthetic genes. The transcriptome contained complete sequences for all proposed genes encoding AA-biosynthetic enzymes such as tyrosine decarboxylase (TYDC1 and TYDC2), phenylalanine ammonia-lyase (PAL1 and PAL2) and phenolic acids hydroxylases (C4H and C3H) to name a few. Furthermore, transcriptome data were validated using RT-qPCR analysis and expression study in different tissues of N. pseudonarcissus ‘King Alfred’ was performed. Here, we present the first comprehensive metabolome and transcriptome study from N. pseudonarcissus ‘King Alfred’ providing invaluable resources for metabolic engineering and biotechnological applications.

Effect of organochlorine pesticides exposure on the maize root metabolome assessed using high-resolution magic-angle spinning (1)H NMR spectroscopy

(1)H-HRMAS NMR-based metabolomics was used to better understand the toxic effects on maize root tips of organochlorine pesticides (OCPs), namely lindane (γHCH) and chlordecone (CLD). Maize seedlings were exposed to 2.5 μM γHCH (mimicking basic environmental contaminations) for 7 days and compared to 2.5 μM CLD and 25 μM γHCH for 7 days (mimicking hot spot contaminations). The (1)H-HRMAS NMR-based metabolomic profiles provided details of the changes in carbohydrates, amino acids, tricarboxylic acid (TCA) cycle intermediates and fatty acids with a significant separation between the control and OCP-exposed root tips. First of all, alterations in the balance between glycolysis/gluconeogenesis were observed with sucrose depletion and with dose-dependent fluctuations in glucose content. Secondly, observations indicated that OCPs might inactivate the TCA cycle, with sizeable succinate and fumarate depletion. Thirdly, disturbances in the amino acid composition (GABA, glutamine/glutamate, asparagine, isoleucine) reflected a new distribution of internal nitrogen compounds under OCP stress. Finally, OCP exposure caused an increase in fatty acid content, concomitant with a marked rise in oxidized fatty acids which could indicate failures in cell integrity and vitality. Moreover, the accumulation of asparagine and oxidized fatty acids with the induction of LOX3 transcription levels under OCP exposure highlighted an induction of protein and lipid catabolism. The overall data indicated that the effect of OCPs on primary metabolism could have broader physiological consequences on root development. Therefore, (1)H-HRMAS NMR metabolomics is a sensitive tool for understanding molecular disturbances under OCP exposure and can be used to perform a rapid assessment of phytotoxicity.

Towards a molecular understanding of the biosynthesis of amaryllidaceae alkaloids in support of their expanding medical use

The alkaloids characteristically produced by the subfamily Amaryllidoideae of the Amaryllidaceae, bulbous plant species that include well know genera such as Narcissus (daffodils) and Galanthus (snowdrops), are a source of new pharmaceutical compounds. Presently, only the Amaryllidaceae alkaloid galanthamine, an acetylcholinesterase inhibitor used to treat symptoms of Alzheimer's disease, is produced commercially as a drug from cultivated plants. However, several Amaryllidaceae alkaloids have shown great promise as anti-cancer drugs, but their further clinical development is restricted by their limited commercial availability. Amaryllidaceae species have a long history of cultivation and breeding as ornamental bulbs, and phytochemical research has focussed on the diversity in alkaloid content and composition. In contrast to the available pharmacological and phytochemical data, ecological, physiological and molecular aspects of the Amaryllidaceae and their alkaloids are much less explored and the identity of the alkaloid biosynthetic genes is presently unknown. An improved molecular understanding of Amaryllidaceae alkaloid biosynthesis would greatly benefit the rational design of breeding programs to produce cultivars optimised for the production of pharmaceutical compounds and enable biotechnology based approaches.