Counting the truxillines-11 or more, the question is now.

Truxillines are a group of tropane alkaloids present in coca leaves that are formed by photochemical dimerization of cinnamoylcocaine(s). Proportion of different truxilline forms present in cocaine serves as its geographical, manufacture, and storage "fingerprint"; thus, the quantitative determination of truxilline content represents one of the powerful methods of analysis and characterization of cocaine samples. Contrary to the statements repeatedly presented in the literature, namely, that there exist exactly 11 truxillines and that every single truxilline is diastereomer of any other, here we show that, in fact, a total of 15 truxillines exist, which can be divided in two structurally isomeric groups-five mutually diastereomeric truxillates and 10 mutually diastereomeric truxinates.

Development and validation of an analytical method based on QuEChERS followed by UHPLC-ToF-MS for the determination of tropane alkaloids in buckwheat (Fagopyrum esculentum L.) and buckwheat products.

A method was developed for the determination of tropane alkaloids (TAs), including atropine, scopolamine, anisodamine and homatropine in buckwheat and related products. This work presents an optimised methodology based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction procedure followed by ultra-high performance liquid chromatography combined with time-of-flight mass spectrometry for the determination of TAs (atropine, scopolamine, anisodamine and homatropine) in buckwheat samples. The analytical methodology was successfully validated, demonstrating good linearity, low limit of quantification, repeatability (RSDr < 15%), inter-day precision (RSDR < 19%) and recovery (74-113%). Finally, 13 commercial samples of buckwheat were analysed and the results demonstrated that they were in compliance with the current European regulations regarding TAs.

Occurrence and health risk assessment of tropane alkaloids in cereal foods consumed in Korea.

Tropane alkaloids (TA) are natural toxins found in certain plants, including cereals, of which atropine and scopolamine are the main species of concern due to their acute toxicity. This study aimed to determine the occurrence of TA in cereal foods and assess the potential health risks associated with their consumption in Korea. TA levels were analyzed in 80 raw and 71 processed cereal samples, which were distributed throughout Korea in 2021, using ultra-performance liquid chromatography-tandem mass spectrometry. At least one of the six TA species, namely atropine, scopolamine, pseudotropine, tropinone, scopine, and 6-hydroxytropinone, was detected in 10 out of the 151 samples at levels ranging from 0.12 to 88.10 µg kg-1. Dietary exposure (mean, 0.23 ng kg-1 bw day-1) to atropine and scopolamine in the Korean population was estimated to be low across all age groups. This is despite considering worst-case scenarios using the total concentrations of atropine and scopolamine in a millet sample, both of which were detected, and 95th percentile consumption for consumers of millet only. Both the hazard index and margin of exposure methods indicated that the current levels of TA exposure from millet consumption were unlikely to pose significant health risks to the Korean population.

Assessment of tropane alkaloid levels in Brazilian buckwheat flour products: A novel LC-UHPLC-MS/MS approach using solid-liquid extraction at low temperature.

In recent years, the monitoring of tropane alkaloids, specifically hyoscyamine and scopolamine, in food has become a pressing concern. This is due to increasing reports of food contamination with these compounds worldwide, raising awareness about the potential risks associated with their consumption. A novel method is proposed here for the determination of the sum of (+)-hyoscyamine, (-)-hyoscyamine, and (-)-scopolamine in buckwheat-based matrices, using solid-liquid extraction at low temperature and quantification by bidimensional chromatography coupled to tandem mass spectrometry. The validated method presented a linear response in the concentration range of 2.5-15 µg kg-1 (r > 0.99). The precision and accuracy were in the ranges from 0.8 to 11.0 % and from 96 to 103 %, respectively. The limit of quantification (LOQ) was 2.5 µg kg-1. No contamination was found at levels above the LOQ in any of the 18 samples analyzed (buckwheat flour, grains, and gluten-free mix).

Tropinone reductase: A comprehensive review on its role as the key enzyme in tropane alkaloids biosynthesis.

TAs, including hyoscyamine and scopolamine, were used to treat neuromuscular disorders ranging from nerve agent poisoning to Parkinson's disease. Tropinone reductase I (TR-I; EC 1.1.1.206) catalyzed the conversion of tropinone into tropine in the biosynthesis of TAs, directing the metabolic flow towards hyoscyamine and scopolamine. Tropinone reductase II (TR-II; EC 1.1.1.236) was responsible for the conversion of tropinone into pseudotropine, diverting the metabolic flux towards calystegine A3. The regulation of metabolite flow through both branches of the TAs pathway seemed to be influenced by the enzymatic activity of both enzymes and their accessibility to the precursor tropinone. The significant interest in the utilization of metabolic engineering for the efficient production of TAs has highlighted the importance of TRs as crucial enzymes that govern both the direction of metabolic flow and the yield of products. This review discussed recent advances for the TRs sources, properties, protein structure and biocatalytic mechanisms, and a detailed overview of its crucial role in the metabolism and synthesis of TAs was summarized. Furthermore, we conducted a detailed investigation into the evolutionary origins of these two TRs. A prospective analysis of potential challenges and applications of TRs was presented.

Development, validation, and application of a multimatrix UHPLC-MS/MS method for quantification of Datura-type alkaloids in food.

A quantitative ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for the determination of tropane alkaloids (TAs), atropine and scopolamine, in a variety of food products. The sample preparation of cereal-based food, oilseeds, honey, and pulses consisted of a solid-liquid extraction with an acidified mixture of methanol and water, while an additional step of solid-phase extraction on a cation-exchange sorbent was introduced in the treatment of teas and herbal infusions, aromatic herbs, spices and food supplements. The limits of quantification of the method varied from 0.5 to 2.5 µg kg-1. Apparent recovery was in the range of 70-120%, and repeatability and intermediate precision were below 20%. The method was successfully applied in a proficiency testing exercise as well as in the analysis of various commercial foods. Only 26% of the analysed food samples contained one or both TAs. The mean concentrations for atropine and scopolamine amounted to 21.9 and 6.5 µg kg-1, respectively, while the maximum concentrations were 523.3 and 131.4 µg kg-1, respectively. Overall, the highest levels of TA sum were found in an herbal infusion of fennel and a spice mix containing fennel and anise seeds.

The Evolutionary Pattern of Cocaine and Hyoscyamine Biosynthesis Provides Strategies To Produce Tropane Alkaloids.

Cocaine and hyoscyamine are two tropane alkaloids (TA) from Erythroxylaceae and Solanaceae, respectively. These famous compounds possess anticholinergic properties that can be used to treat neuromuscular disorders. While the hyoscyamine biosynthetic pathway has been fully elucidated allowing its de novo synthesis in yeast, the cocaine pathway remained only partially elucidated. Recently, the Huang research group has completed the cocaine biosynthetic route by characterizing its two missing enzymes. This allowed the whole pathway to be transferring into Nicotiana benthamiana to achieve cocaine production. Here, besides highlighting the impact of this discovery, we discuss how TA biosynthesis evolved via the recruitment of two distinct and convergent pathways in Erythroxylaceae and Solanaceae. Finally, while enriching our knowledge on TA biosynthesis, this diversification of the molecular actors involved in cocaine and hyoscyamine biosynthesis opens perspectives in metabolic engineering by exploring enzyme biochemical plasticity that can ease and shorten TA pathway reconstitution in heterologous organisms.

Deuterated [18F]fluoroethyl tropane analogs as dopamine transporter probes: Synthesis and biological evaluation.

INTRODUCTION: The dopamine transporter (DAT) is vitally correlated with Parkinson's disease (PD) and other neurodegenerative diseases. Non-invasive imaging of DAT contributes to early diagnosis and monitoring of related diseases. Recently, we reported a deuterated [18F]fluoroethyl tropane analogue [18F]FECNT-d4 as a potential DAT PET imaging agent. The objective of this work was to extend the investigation by comparing four deuterated [18F]fluoroethyl tropane derivatives ([18F]2a-d) to develop metabolically stable DAT radioligands. METHODS: Four fluoroethyl substituted phenyl-tropane compounds 1a-d and deuterated compounds 2a-d were synthesized and their IC50 values to DAT were evaluated. The [18F]fluoroethyl ligands [18F]1a-d and [18F]2a-d were obtained from corresponding labeling precursors by one-step radio-labeling reactions and investigated in terms of lipophilicity and in vitro binding affinity studies. [18F]1d and [18F]2d were then selected for further evaluations by in vivo metabolism study, biodistribution, ex vivo autoradiography, and microPET imaging studies. RESULTS: [18F]1a-d and [18F]2a-d were obtained in radiochemical yield of 11-32 % with molar activities of 28-54 GBq/µmol. The 1d and 2d exhibited relatively high affinity to DAT (IC50: 1.9-2.1 nM). Ex vivo autoradiography and microPET studies showed that [18F]2d selectively localized on DAT-rich striatal regions and the specific signal could be blocked by DAT inhibitor. Biodistribution results showed that [18F]2d consistently exhibited a higher ratio of the target to non-target (striatum/cerebellum) than [18F]1d. Furthermore, metabolism study indicated that the in vivo metabolic stability of [18F]2d was superior to that of [18F]1d. CONCLUSION: Our findings suggested that the deuterated compound [18F]2d might be a potential probe for DAT PET imaging in the brain.

Gastrointestinal bioaccessibility and fiber mitigation of tropane alkaloids assessed on tea and cookies by in vitro digestion.

BACKGROUND: Tropane alkaloids (TAs) are toxic compounds with a high anticholinergic effect. They have been widely analyzed in food samples, but their fate in the gastrointestinal tract has not been evaluated yet. RESULTS: In this study, static in vitro digestion was performed to assess gastrointestinal bioaccessibility of the most common TAs on tea and home-made cookies. Cookies enriched with dietary fiber (pectin, arabinogalactan, and κ-carrageenan) were also tested to evaluate their influence on TA bioaccessibility. Two extraction methods and a liquid chromatography-mass spectrometry method were optimized and validated. Bioaccessibility for tea (60-105%) was higher than for cookies (39-93%) (P = 0.001-0.002), which indicates TAs could be more easily absorbed when they are contaminating tea. Digestion of cookies enriched with 50 g kg-1 of different fibers showed that, although no significant changes were observed in the gastric phase (P = 0.084-0.920), duodenal bioaccessibility was significantly reduced (P = 0.008-0.039). Pectin was the fiber with a better mitigation effect for all the compounds. CONCLUSION: TAs bioaccessibility was determined after in vitro digestion of contaminated tea and cookies. Dietary fiber seems to be a promising mitigation strategy, significantly reducing TA bioaccessibility percentages. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Redirecting tropane alkaloid metabolism reveals pyrrolidine alkaloid diversity in Atropa belladonna.

Plant-specialized metabolism is complex, with frequent examples of highly branched biosynthetic pathways, and shared chemical intermediates. As such, many plant-specialized metabolic networks are poorly characterized. The N-methyl Δ1 -pyrrolinium cation is a simple pyrrolidine alkaloid and precursor of pharmacologically important tropane alkaloids. Silencing of pyrrolidine ketide synthase (AbPyKS) in the roots of Atropa belladonna (Deadly Nightshade) reduces tropane alkaloid abundance and causes high N-methyl Δ1 -pyrrolinium cation accumulation. The consequences of this metabolic shift on alkaloid metabolism are unknown. In this study, we utilized discovery metabolomics coupled with AbPyKS silencing to reveal major changes in the root alkaloid metabolome of A. belladonna. We discovered and annotated almost 40 pyrrolidine alkaloids that increase when AbPyKS activity is reduced. Suppression of phenyllactate biosynthesis, combined with metabolic engineering in planta, and chemical synthesis indicates several of these pyrrolidines share a core structure formed through the nonenzymatic Mannich-like decarboxylative condensation of the N-methyl Δ1 -pyrrolinium cation with 2-O-malonylphenyllactate. Decoration of this core scaffold through hydroxylation and glycosylation leads to mono- and dipyrrolidine alkaloid diversity. This study reveals the previously unknown complexity of the A. belladonna root metabolome and creates a foundation for future investigation into the biosynthesis, function, and potential utility of these novel alkaloids.

Scopolamine and atropine in feeds - determination with liquid chromatography mass spectrometry.

Tropane alkaloids (TAs) are naturally occurring plant toxins. Due to the fact that TA-producing plants can enter the food chain, they pose a risk for animals and human health. Therefore, sensitive analytical methods need to be developed to provide an adequate safety of feed and food. The presented method is based on liquid chromatography-mass spectrometry detection and enables the determination of scopolamine and atropine in compound feeds at a low level of contamination. Limits of quantification for scopolamine and atropine were 0.92 and 0.93 µg kg-1, respectively. Scopolamine-D3 and atropine-D3 were used for quantification. The method was successfully validated and applied to the analysis of 42 feed samples. Among investigated feeds, 67% contained at least one of the monitored alkaloids. Soybean meals were the feed materials contaminated most often, also with the highest determined concentrations of TAs, which reached 147.9 µg kg-1.

Tropane alkaloid biosynthesis: a centennial review.

Covering: 1917 to 2020Tropane alkaloids (TAs) are a remarkable class of plant secondary metabolites, which are characterized by an 8-azabicyclo[3.2.1]octane (nortropane) ring. Members of this class, such as hyoscyamine, scopolamine, and cocaine, are well known for their long history as poisons, hallucinogens, and anaesthetic agents. Since the structure of the tropane ring system was first elucidated in 1901, organic chemists and biochemists have been interested in how these mysterious tropane alkaloids are assembled in vitro and in vivo. However, it was only in 2020 that the complete biosynthetic route of hyoscyamine and scopolamine was clarified, and their de novo production in yeast was also achieved. The aim of this review is to present the innovative ideas and results in exploring the story of tropane alkaloid biosynthesis in plants from 1917 to 2020. This review also highlights that Robinson's classic synthesis of tropinone, which is one hundred years old, is biomimetic, and underscores the importance of total synthesis in the study of natural product biosynthesis.

68 Ga-Labelled Tropane Analogues for the Visualization of the Dopaminergic System.

The development of radiometal-labelled pharmaceuticals for neuroimaging could offer great potential due to easier handling during labelling and availability through radionuclide generator systems. Nonetheless, to date, no such tracers are available for positron emission tomography, primarily owing to the challenge of crossing the blood-brain barrier (BBB) and loss of affinity through chelator attachment. We have prepared a variety of 68 Ga-labelled phenyltropanes showing that, through a simple hydrocarbon-linker, it is possible to introduce a chelator onto the lead structure while maintaining its high affinity for hDAT (human dopamine transporter) and simultaneously achieving adequate lipophilicity. One of the candidates, [68 Ga]Ga-HBED-hexadiyne-tropane, showed an IC50 value of 66 nM, together with a log D7.4 of 0.96. A µPET study in a hemi-parkinsonian rat model showed a fast wash-out of the tracer, and no specific uptake in the brain, thus implying an inability to penetrate the BBB.

A Real-World Study of Cerebral 99mTc-TRODAT-1 Single-Photon Emission Computed Tomography (SPECT) Imaging of the Dopamine Transporter in Patients with Parkinson Disease from a Tertiary Hospital in Brazil.

BACKGROUND Studies on the routine clinical use of dopamine transporter (DAT) imaging have largely been conducted in Europe and the United States. In this real-world study, we investigated the use of cerebral 99mTc-TRODAT-1 SPECT imaging of DAT in patients with Parkinson disease (PD) at a tertiary hospital in Brazil. MATERIAL AND METHODS We included 119 patients with suspected PD or clinically unclear parkinsonism who underwent brain scintigraphy with 99mTc-TRODAT-1 during a 3-year period. Additionally, a brief interview was conducted with the physician who requested the scan to determine the usefulness of the method in clinical decision-making. RESULTS Regarding the scan requests, most were intended to evaluate or confirm dopaminergic denervation (69%), distinguish PD from essential tremor (10%), or distinguish degenerative parkinsonism from drug-induced parkinsonism (6%). Data analysis showed that scintigraphy with 99mTc-TRODAT-1 was useful in 85% of cases, changing the management of 75% of the patients who underwent a scan. The majority of physicians who requested the scan were neurologists, and 54% were self-reported movement disorder specialists. An inappropriate use of DAT imaging was seen in 5% of cases. CONCLUSIONS This study demonstrated that brain scintigraphy with the DAT ligand 99mTc-TRODAT-1 may influence diagnostic or therapeutic interventions, meaning that Brazilian physicians who requested the exam have taken in vivo DAT results into account at the time of clinical decision-making.

Synthesis of some tropane-based compounds targeting colon cancer.

Background: In continuation of a previous work concerned with the anticancer activity of some 8-alkyl-2,4-bisarylidene-8-nortropan-3-ones, this work focuses on further modification to the tropane/pyran fused skeleton aiming to obtain improved anticancer activity. Methodology: Reaction of 8-alkyl-2,4-bisarylidene-8-nortropan-3-ones 1-21 with malononitrile under basic conditions afforded tropane/pyran hybrids 22-40 and tropane/pyridine hybrids 41, 42. X-ray crystallography for compounds 22 and 41 as representative examples confirmed their structures. They were tested for their anticancer activity in the HCT116 cell line. Results: Compounds 26 and 33 were the most active compounds with IC50 values of 3.39 and 0.01 µM against HCT116. Moreover, they revealed cyclin-dependent kinase-2 (CDK2) inhibition with IC50 = 104.91 and 49.13 nM, respectively. Furthermore, molecular docking of compounds 26 and 33 in the active site of CDK2 confirmed the obtained results. Conclusion: Tropane/pyran scaffold can be considered as a promising core for anticancer agents acting as CDK2 inhibitors.

Nicotinic Acetylcholine Receptor Accessory Subunits Determine the Activity Profile of Epibatidine Derivatives.

Epibatidine is a potent analgetic agent with very high affinity for brain nicotinic acetylcholine receptors (nAChR). We determined the activity profiles of three epibatidine derivatives, RTI-36, RTI-76, and RTI-102, which have affinity for brain nAChR equivalent to that of epibatidine but reduced analgetic activity. RNAs coding for nAChR monomeric subunits and/or concatamers were injected into Xenopus oocytes to obtain receptors of defined subunit composition and stoichiometry. The epibatidine analogs produced protracted activation of high sensitivity (HS) α4- and α2-containing receptors with the stoichiometry of 2alpha:3beta subunits but not low sensitivity (LS) receptors with the reverse ratio of alpha and beta subunits. Although not strongly activated by the epibatidine analogs, LS α4- and α2-containing receptors were potently desensitized by the epibatidine analogs. In general, the responses of α4(2)ß2(2)α5 and ß3α4ß2α6ß2 receptors were similar to those of the HS α4ß2 receptors. RTI-36, the analog closest in structure to epibatidine, was the most efficacious of the three compounds, also effectively activating α7 and α3ß4 receptors, albeit with lower potency and less desensitizing effect. Although not the most efficacious agonist, RTI-76 was the most potent desensitizer of α4- and α2-containing receptors. RTI-102, a strong partial agonist for HS α4ß2 receptors, was effectively an antagonist for LS α4ß2 receptors. Our results highlight the importance of subunit stoichiometry and the presence or absence of specific accessory subunits for determining the activity of these drugs on brain nAChR, affecting the interpretation of in vivo studies since in most cases these structural details are not known. SIGNIFICANCE STATEMENT: Epibatidine and related compounds are potent ligands for the high-affinity nicotine receptors of the brain, which are therapeutic targets and mediators of nicotine addiction. Far from being a homogeneous population, these receptors are diverse in subunit composition and vary in subunit stoichiometry. We show the importance of these structural details for drug activity profiles, which present a challenge for the interpretation of in vivo experiments since conventional methods, such as in situ hybridization and immunohistochemistry, cannot illuminate these details.

Determination of tropane alkaloids in cereals, tea and herbal infusions: Exploiting proficiency testing data as a basis to derive interlaboratory performance characteristics of an improved LC-MS/MS method.

Monitoring of tropane alkaloids is regulated in the European Union in cereal-based foods for infants and young children, tea and herbal infusions. The European Commission's Joint Research Centre (JRC) developed an improved LC-MS/MS analytical method using a pentafluorophenyl column, validated it and conducted two proficiency tests targeting these food categories. A subset of the data gathered from laboratories that used the JRC method was additionally exploited to derive interlaboratory performance characteristics. The method showed fit-for-purpose figures of merit. The LOQs for atropine and scopolamine were around 0.4 and 1.2 µg/kg in cereal products, and in tea and herbal infusions, respectively. Uncertainties varied from 15 to 25%. The reproducibility varied from 11 to 38% for scopolamine and from 17 to 44% for atropine at levels ranging from 0.18 to 18.8 and 1.2-54.0 µg/kg, respectively. Recoveries ranged from 71 to 96%. These performance parameters render the method a good candidate for standardisation.

Preserved Extrastriatal 123I-FP-CIT Binding in Scans Without Evidence of Dopaminergic Deficit (SWEDD).

PURPOSE: Scans without evidence of dopaminergic deficit (SWEDD) have been initially described in a minority of subjects with suspected Parkinson's disease (PD). Although a highly controversial entity, longitudinal studies showed that SWEDD cases mostly involve non-degenerative conditions mimicking PD or misattribution of scan images to normal status. Using the Parkinson's Progression Markers Initiative (PPMI) cohort, we undertook a case-controlled analysis of [123I]N-ω-fluoropropyl-2ß-carbomethoxy-iodophenyl nortropane ([123I]FP-CIT) single photon emission computed tomography (SPECT) images to measure extrastriatal serotonergic transporter (SERT) density in SWEDD and PD. PROCEDURES: We included 37 SWEDD cases (mean age 60 years, 33 % female) with available [123I]FP-CIT SPECT imaging and high-resolution T1-weighted magnetic resonance imaging (MRI) for coregistration. Sixty-one controls and 62 similarly aged PD subjects were included for group comparisons. Regional [123I]FP-CIT was extracted with PETPVE12 using geometric transfer matrix and partial volume effect correction. RESULTS: PD subjects showed significantly lower [123I]FP-CIT binding in both striatal (caudate nucleus and putamen) and extrastriatal regions (pallidum and insula) compared with controls and SWEDD (all between-group p < 0.0001). PD group also showed lower binding in the thalamus relative to controls (p = 0.007). Receiver operating characteristics (ROC) area under the curve (AUC) did not show a significant difference when using extrastriatal region in addition to striatal ROIs for the separation of SWEDD and PD (95 % ROC-AUC for both methods, p = 0.52). In addition, striatal [123I]FP-CIT binding contralateral to the clinically more affected side was usually lower for PD (> 75 %) but not for SWEDD (< 49 %, p < 0.002). No significant difference regarding [123I]FP-CIT binding was observed between SWEDD and controls. CONCLUSION: These findings corroborate the view that SWEDD cases represent a heterogeneous group of conditions not involving dopaminergic and serotonergic terminals. Further studies are warranted to be assessed whether using extrastriatal [123I]FP-CIT evaluation can be of help in the assessment of degenerative parkinsonism.

Concise Synthesis of (+)-[13 C4 ]-Anatoxin-a by Dynamic Kinetic Resolution of a Cyclic Iminium Ion.

An asymmetric total synthesis of [13 C4 ]-anatoxin-a ([13 C4 ]-1) has been developed from commercially available ethyl [13 C4 ]-acetoacetate ([13 C4 ]-15). The unique requirements associated with isotope incorporation inspired a new, robust, and highly scalable route, providing access to 0.110 g of this internal standard for use in the detection and precise quantification of anatoxin-a in freshwater. A highlight of the synthesis is a method that leverages a cyclic iminium ion racemization to achieve dynamic kinetic resolution in an enantioselective Morita-Baylis-Hillman (MBH) cyclization.

Synthesis and evaluation of the performance of a small molecule library based on diverse tropane-related scaffolds.

A unified synthetic approach was developed that enabled the synthesis of diverse tropane-related scaffolds. The key intermediates that were exploited were cycloadducts formed by reaction between 3-hydroxy-pyridinium salts and vinyl sulfones or sulfonamides. The diverse tropane-related scaffolds were formed by addition of substituents to, cyclisation reactions of, and fusion of additional ring(s) to the key bicyclic intermediates. A set of 53 screening compounds was designed, synthesised and evaluated in order to determine the biological relevance of the scaffolds accessible using the synthetic approach. Two inhibitors of Hedgehog signalling, and four compounds with weak activity against the parasite P. falciparum, were discovered. Three of the active compounds may be considered to be indotropane or pyrrotropane pseudo natural products in which a tropane is fused with a fragment from another natural product class. It was concluded that the unified synthetic approach had yielded diverse scaffolds suitable for the design of performance-diverse screening libraries.