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Covering: 2015 to 2020Nitrogen heterocyclic natural products (NHNPs) are primary or secondary metabolites containing nitrogen heterocyclic (N-heterocyclic) skeletons. Due to the existence of the N-heterocyclic structure, NHNPs exhibit various bioactivities such as anticancer and antibacterial, which makes them widely used in medicines, pesticides, and food additives. However, the low content of these NHNPs in native organisms severely restricts their commercial application. Although a variety of NHNPs have been produced through extraction or chemical synthesis strategies, these methods suffer from several problems. The development of biotechnology provides new options for the production of NHNPs. This review introduces the recent progress of two strategies for the biosynthesis of NHNPs: enzymatic biosynthesis and microbial cell factory. In the enzymatic biosynthesis part, the recent progress in the mining of enzymes that synthesize N-heterocyclic skeletons (e.g., pyrrole, piperidine, diketopiperazine, and isoquinoline), the engineering of tailoring enzymes, and enzyme cascades constructed to synthesize NHNPs are discussed. In the microbial cell factory part, with tropane alkaloids (TAs) and tetrahydroisoquinoline (THIQ) alkaloids as the representative compounds, the strategies of unraveling unknown natural biosynthesis pathways of NHNPs in plants are summarized, and various metabolic engineering strategies to enhance their production in microbes are introduced. Ultimately, future perspectives for accelerating the biosynthesis of NHNPs are discussed.

Datura metel (Solanaceae) which is commonly known as thorn’s apple, Indian apple or devil’s trumpet isan annual herb of temperate zones which is distributed all over the world. D. metel belongs to the family solanaceae. From a longer period of time (37 A.D), species of this family had therapeutic uses. This article is based on the review of different scientific backgrounds and studies regarding the traditional uses, phytochemistry, biochemical constituents and pharmacological uses of D. metel. This review is based on the facts of the available literature review. Different researchers conducted researches and studies on D. metel and confirmed the presence of enormous chemical compounds like flavonoids, tropane alkaloids, tannins, saponins and withanolides. D. metel has been found to be pharmacologically important species because of its different pharmacological and traditional uses, such as hepatoprotective, antiviral effect, antibacterial effect, anti-asthmatic, analgesic, antipyretic and nephroprotective effect, anticancer and antifungal effect. However, further in vivo and in vitro advanced studies are required to carried out for the exact pharmacological mechanisms and for basis of clinical utility.

Seven new tropane alkaloids, including five monomeric (1-5), one dimeric (6), and one trimeric (7) 3α-nortropane ester, along with two known monomeric nortropane alkaloids (8 and 9), were isolated from the leaves and bark of Pellacalyx saccardianus. Their structures, including the absolute configuration of the enantiomeric pair of (±)-6, were elucidated by comprehensive spectroscopic analyses. Alkaloids 6 and 7 showed cytotoxicity toward human pancreatic cancer cell lines (AsPC-1, BxPC3, PANC-1, and SW1990). Alkaloids 1, 4, and 9 induced a smooth muscle relaxation effect comparable to that of atropine (Emax 106.1 ± 7.5%, 97.0 ± 5.2%, 100.9 ± 1.4%, 111.7 ± 1.7%, respectively) on isolated rat tracheal rings.

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 68Ga‐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, [68Ga]Ga‐HBED‐hexadiyne‐tropane, showed an IC50 value of 66 nM, together with a log D 7.4 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., Tracer metal: Tropanes are commonly used in radiopharmacy to assess the status of the dopaminergic system. However, no suitable radiometal‐labelled tracers are available for PET, primarily owing to the challenge of crossing the blood–brain barrier and loss of affinity through chelator attachment. We have developed 68Ga‐labelled phenyltropanes showing promising affinity and lipophilicity, and conducted a first PET study.

Made available in DSpace on 2021-06-25T19:56:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-11-11 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) INCT BioNat Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Tropane alkaloids are specialized plant metabolites mostly found in the Erythroxylaceae and Solanaceae families. Although tropane alkaloids have a high degree of structural similarity because of the tropane ring, their pharmacological actions are quite distinct. Brazil is one of the main hotspots of Erythroxylum spp. diversity with 123 species (almost 66% of the species catalogued in tropical America). Erythroxylum pungens occurs in the Caatinga, a promising biome that provides bioactive compounds, including tropane alkaloids. As part of our efforts to investigate this species, 15 alkaloids in specimens harvested under different environmental conditions are presented herein. The occurrence of 3-(2-methylbutyryloxy)tropan-6,7-diol in the stem bark of plants growing in their natural habitat, greenhouse controlled conditions, and after a period of water restriction, suggests that it is a potential chemical marker for the species. This alkaloid was evaluated for several parameters in zebrafish ( Danio rerio ) as a model organism. Regarding toxicity, teratogenic effects were observed at 19.5 mu M and the lethal dose for embryos was 18.4 mu M. No mortality was observed in adults, but a behavioral screen showed psychostimulatory action at 116.7 mu M. Overall, the alkaloid was able to cause zebrafish behavioral changes, prompting further investigation of its potential as a new molecule in the treatment of depression-like symptoms. In silico , targets involved in antidepressant pathways were identified by docking. Univ Fed Rio Grande do Norte, Dept Pharm, Gal Gustavo Cordeiro Farias St S-N, BR-59012570 Natal, RN, Brazil Univ Fed Rio Grande do Norte, Dept Physiol & Behav, Natal, RN, Brazil Univ Fed Mato Grosso do Sul, Fac Pharmaceut Sci Food & Nutr, Campo Grande, MS, Brazil Univ Fed Rio Grande do Sul, Fac Pharm, Porto Alegre, RS, Brazil Univ Fed Rio Grande do Sul, Ctr Biotechnol & Dept Bot, Porto Alegre, RS, Brazil Sao Paulo State Univ, Chem Inst, Araraquara, SP, Brazil Sao Paulo State Univ, Chem Inst, Araraquara, SP, Brazil CNPq: 445149/2014-0 INCT BioNat: 465637/2014-0 CAPES: 001 FAPESP: 2014/50926-0

Przewalskia tangutica is a traditional medicinal plant from Tibet used for the analgesic effect from the tropane alkaloids (TAs) produced by the plant. Its roots have the highest yield of hyoscyamine in all plant species and so have been overharvested becoming an endangered medicinal plant species. Metabolic engineering is a good way to improve the yield of TAs in plants. In our study, two functionally distinct tropinone reductases genes, PtTRI and PtTRII, were cloned from P. tangutica and the functional divergence were characterized. The enzyme kinetics of PtTRI and PtTRII were investigated. The phylogenetic analysis classified them into different clades: PtTRI and PtTRII were in the clade of tropine-forming reductase and pseudotropine-forming reductase, respectively. We found PtTRI to be expressed in the roots but less in leaves, whereas PtTRII was expressed in the roots at higher levels than in the leaves. The kinetic parameters (Km , Vmax , and Kcat ) were analyzed using purified recombinant enzymes at their optimum pH. Enzymatic analysis results showed that tropinone is a better substrate for PtTRII compared with PtTRI, suggesting that PtTRII might be a potential gene target for TA biosynthesis engineering. Compared with the reported TRIs, PtTRI exhibited a higher affinity for tropinone.

Several lines of evidence suggest that selective sigma-2 (σ2) ligands might be useful for the treatment of solid tumors. However, very few selective σ2 ligands have been identified. This study was aimed at identifying new selective σ2 receptor ligands using a previously identified agent, SYA 013 as a lead. Four groups, homopiperazine, piperazine, tropane and selected oxime analogs of the homopiperazines were identified, synthesized and subsequently screened at the σ1 and σ2 receptors. The results demonstrate that these scaffolds can be modified to obtain selective σ2 receptor ligands. 1-(5-Chloropyridin-2-yl)-4-(3-((4-fluorophenyl)thio)propyl)-1,4-diazepane, 7 and 3-(4-chlorophenyl)-8-(3-((2-fluorophenyl)thio)propyl)-8-azabicyclo[3.2.1]octan-3-ol, 21 were identified as the highest binding affinity ligands (σ2Ki = 2.2 nM) and (4-(4-(5-chloropyridin-2-yl)-1,4-diazepan-1-yl)-1-(4-fluorophenyl)-butan-1-one oxime, 22 as a high affinity and the most selective ligand for the σ2 receptor (σ1Ki/σ2Ki = 41.8).

A fast method for the determination of tropane alkaloids, using a portable CE instrument with a capacitively coupled contactless conductivity detector (CE-C4D) was developed and validated for determination of atropine and scopolamine in seeds from Solanaceae family plants. Separation was obtained within 5 min, using an optimized background electrolyte consisting of 0.5 M acetic acid with 0.25% (w/v) β-CD. The limit of detection and quantification was 0.5 µg/mL and 1.5 µg/mL, respectively, for both atropine and scopolamine. The developed method was validated with the following parameters—precision (CV): 1.07–2.08%, accuracy of the assay (recovery, RE): 101.0–102.7% and matrix effect (ME): 92.99–94.23%. Moreover, the optimized CE-C4D method was applied to the analysis of plant extracts and pharmaceuticals, proving its applicability and accuracy.

Shiou-Shiow Farn,1,2 Kang-Wei Chang,3 Wan-Chi Lin,1 Hung-Man Yu,1 Kun-Liang Lin,1 Yu-Chin Tseng,1 Yu Chang,1 Chung-Shan Yu,2,4 Wuu-Jyh Lin1 1Isotope Application Division, Institute of Nuclear Energy Research, Taoyuan, 32546, Taiwan; 2Department of Biomedical Engineering and Environmental Sciences, National Tsing-Hua University, Hsinchu, 300, Taiwan; 3Laboratory Animal Center, Office of Research and Development, Taipei Medical University, Taipei, 11031, Taiwan; 4Institute of Nuclear Engineering and Science, College of Nuclear Science, National Tsing-Hua University, Hsinchu, 300, TaiwanCorrespondence: Wuu-Jyh Lin; Chung-Shan Yu Email WJLin@seecurellc.com; csyu@mx.nthu.edu.twIntroduction: Novel radiotracer development for imaging dopamine transporters is a subject of interest because although [99mTc]TRODAT-1, [123I]β-CIT, and [123I]FP-CIT are commercially available; 99Mo/99mTc generator is in short supply and 123I production is highly dependent on compact cyclotron. Therefore, we designed a novel positron emission tomography (PET) tracer based on a tropane derivative through C-2 modification to conjugate NOTA for chelating 68Ga, a radioisotope derived from a 68Ge/68Ga generator.Methods: IPCAT-NOTA 22 was synthesized and labeled with [68Ga]GaCl4− at room temperature. Biological studies on serum stability, LogP, and in vitro autoradiography (binding assay and competitive assay) were performed. Furthermore, ex vivo autoradiography, biodistribution, and dynamic PET imaging studies were performed in Sprague Dawley rats.Results: [68Ga]IPCAT-NOTA 24 obtained had a radiochemical yield of ≥ 90% and a specific activity of 4.25 MBq/nmol. [68Ga]IPCAT-NOTA 24 of 85% radiochemical purity (RCP%) was stable at 37°C for up to 60 minutes in serum with a lipophilicity of 0.88. The specific binding ratio (SBR%) reached 15.8 ± 6.7 at 60 minutes, and the 85% specific uptake could be blocked through co-injection at 100- and 1000-fold of the cold precursor in in vitro binding studies. Tissue regional distribution studies in rats with [68Ga]IPCAT-NOTA 24 showed striatal uptake (0.02% at 5 minutes and 0.007% at 60 minutes) with SBR% of 6%, 25%, and 62% at 5– 15, 30– 40, and 60– 70 minutes, respectively, in NanoPET studies. The RCP% of [68Ga]IPCAT-NOTA 24 at 30 minutes in vivo remained 67.65%.Conclusion: Data described here provide new information on the design of PET probe of conjugate/pendent approach for DAT imaging. Another chelator or another direct method of intracranial injection must be used to prove the relation between [68Ga]IPCAT-NOTA 24 uptake and transporter localization.Keywords: Parkinson disease, dopamine transporter, Ga-68

We recently reported a convergent strategy to access the polycyclic guanidinium alkaloid (+)-batzelladine B via an aldol addition–retro-aldol–aza-Michael addition cascade. Here we describe the application of this approach toward the total syntheses of (+)-batzelladine E, (−)-dehydrobatzelladine C, and (+)-batzelladine K. The identification of suitable methods to functionalize a common tropane core by electrophilic alkynylation and nucleophilic 1,2-addition were essential to generalizing this approach. We provide evidence for the intermediacy of an acylallene species in the cascade reaction.

The genus Datura (Solanaceae) contains nine species of medicinal plants that have held both curative utility and cultural significance throughout history. This genus’ particular bioactivity results from the enormous diversity of alkaloids it contains, making it a valuable study organism for many disciplines. Although Datura contains mostly tropane alkaloids (such as hyoscyamine and scopolamine), indole, beta-carboline, and pyrrolidine alkaloids have also been identified. The tools available to explore specialized metabolism in plants have undergone remarkable advances over the past couple of decades and provide renewed opportunities for discoveries of new compounds and the genetic basis for their biosynthesis. This review provides a comprehensive overview of studies on the alkaloids of Datura that focuses on three questions: How do we find and identify alkaloids? Where do alkaloids come from? What factors affect their presence and abundance? We also address pitfalls and relevant questions applicable to natural products and metabolomics researchers. With both careful perspectives and new advances in instrumentation, the pace of alkaloid discovery—from not just Datura—has the potential to accelerate dramatically in the near future.

The aminocarbonylation of various alkenyl and (hetero)aryl iodides was carried out using tropane-based amines of biological importance, such as 8-azabicyclo[3.2.1]octan-3-one (nortropinone) and 3α-hydroxy-8-azabicyclo[3.2.1]octane (nortropine) as N-nucleophile. Using iodoalkenes, the two nucleophiles were selectively converted to the corresponding amide in the presence of Pd(OAc)2/2 PPh3 catalysts. In the presence of several iodo(hetero)arenes, the application of the bidentate Xantphos was necessary to produce the target compounds selectively. The new carboxamides of varied structure, formed in palladium-catalyzed aminocarbonylation reactions, were isolated and fully characterized. In this way, a novel synthetic method has been developed for the producing of N-acylnortropane derivatives of biological importance.

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.

INTRODUCTION Blocking Human Immunodeficiency Virus type 1 (HIV-1) entry via C-C chemokine receptor 5 (CCR5) inhibition has remained an essential strategy in HIV drug discovery. This underlies the development of CCR5 blockers, such as Maraviroc, which, however, elicits undesirable side effects despite its potency. BACKGROUND Recent lead optimization efforts led to the discovery of novel 1-heteroaryl-1,3-propanediamine derivatives; Compd-21 and -34, which were ~3 times more potent than Maraviroc, with improved pharmacokinetics. However, atomistic molecular interaction mechanism of how slight structural variance between these inhibitors significantly affects their binding profiles have not been elucidated. METHOD This study employed explicit lipid bilayer molecular dynamics (MD) simulations, and advance analyses to explore these inhibitory discrepancies. RESULTS Findings revealed that the thiophene moiety substitution common to Compd-21 and -34 enhanced their CCR5- inhibitory activities due to complementary high-affinity interactions with Trp862.60, Tyr1083.32, Tyr2516.51, Glu2837.39. These cumulatively accounted for their ΔGbind which were higher than Maraviroc. Binding dynamics further revealed that the compounds mediated direct competitive inhibition at CCR5 by blocking the gp120 V3 loop. Furthermore, constituent tropane and triazole moieties in the compounds commonly engaged in interactions with Glu2837.39 and Trp862.60, respectively. Structural analyses also revealed that both Compd-21 and -34 elicited distinct internal dynamic effect on CCR5 relative to Maraviroc. CONCLUSION Structural modifications at the thiophene substituent and the addition of new functional groups to the triazole ring may enhance inhibitor competition with gp120 V3-loop. Findings herein highlighted would contribute to future structure-based design of inhibitors of HIV-1 CCR5 with improved potencies.

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.

Erythroxylaceae is a family composed of four genera, with Erythroxylum being the only one represented in the Neotropical region. Chemical studies indicate the presence of alkaloids, terpenes, flavonoids, and phenolic compounds as main compounds. The incorporation of cytotoxic activity assays of natural products using cell cultures assists in the selection of potential chemotherapeutic agents. In this work, we describe a revision of the cytotoxicity evaluation studies performed with extracts or pure substances obtained from Erythroxylum species through an integrative review. We found studies that evaluated the cytotoxic activity of 21 species of Erythroxylum against 45 different cell lines. The analysis of the chemical composition of these species shows that the metabolites present in each species influence their cytotoxic potential, especially the presence of disubstituted tropane alkaloid species with the highest cytotoxic potential. MTT and Sulforrodamine B assays were the main in vitro tests used for the evaluation of the cytotoxic activities. From the total species, less than 10% of the Erythroxylum species have already been evaluated for cytotoxic activity. Four of them showed high cytotoxic activity according to the criteria of the NCI plant screening program. Thus, this genus represents a potential source of natural products with antitumor activity.

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.

Aim: Colon cancer is the third leading cause of death worldwide; therefore, there is a need for an effective therapy with lower side effects. Methods: A series of 8-alkyl-2,4-bisbenzylidene-3-nortropinones 3 & 14-39 was prepared via Claisen-Schmidt condensation of 8-alkyl-3-nortropinones 11-13 with different aromatic aldehydes. The target compounds were screened for their antiproliferative activity. Results: Most of the prepared compounds showed promising antiproliferative activity against many of 60 National Cancer Institute cell lines at 10 μM. Furthermore, 8-ethyl-2,4-bis(3,4-dimethoxybenzylidene)-8-nortropin-3-one 29 and its 3,4,5-trimethoxy analog 30 were the most active compounds against HCT116 cell line with IC50values 0.01 and 0.46 μM, respectively. Using CODESSA-Pro software, a significant 2D-quantitative structure–activity relationship (QSAR) model was obtained. Conclusion: The 8-Alkyl-2,4-bisbenzylidene-8-azabicyclo[3.2.1]octan-3-one represents an interesting core for further structural optimization to obtain more promising hits.

The genus Erythroxylum contains species used by indigenous people of South America long before the domestication of plants. Two species, E. coca and E. novogranatense, have been utilized for thousands of years specifically for their tropane alkaloid content. While abuse of the narcotic cocaine has impacted society on many levels, these species and their wild relatives contain untapped resources for the benefit of mankind in the form of foods, pharmaceuticals, phytotherapeutic products, and other high-value plant-derived metabolites. In this review, we describe the current state of knowledge of members within the genus and the recent advances in the realm of molecular biology and biochemistry.

In this research, tropane alkaloids in Radix physochlainae were extracted by tropine-type ionic liquid (IL) aqueous solutions under ultrasound assistance, and N-propyltropine hexafluorophosphate ([C3Tr][PF6]) was found to be the most ideal IL in this extraction mode after comprehensive screening. When 0.03 mol/L [C3Tr][PF6] aqueous solution was chosen as the extraction solvent, the solid-liquid ratio of raw material powders and ionic liquid aqueous solution was 1:20 (g/mL), ultrasonic power was 90 W and extraction time was 30 min, the extraction efficiency of tropane alkaloids has reached 121.3%. Compared with common heating extraction, it can further shorten the extraction time, improve extraction efficiency and decrease IL consumption. Furthermore, extraction mechanism together with potential toxicity of IL have been explored and discussed.

Tropane alkaloids (TA) are valuable secondary plant metabolites which are mostly found in high concentrations in the Solanaceae and Erythroxylaceae families. The TAs, which are characterized by their unique bicyclic tropane ring system, can be divided into three major groups: hyoscyamine and scopolamine, cocaine and calystegines. Although all TAs have the same basic structure, they differ immensely in their biological, chemical and pharmacological properties. Scopolamine, also known as hyoscine, has the largest legitimate market as a pharmacological agent due to its treatment of nausea, vomiting, motion sickness, as well as smooth muscle spasms while cocaine is the 2nd most frequently consumed illicit drug globally. This review provides a comprehensive overview of TAs, highlighting their structural diversity, use in pharmaceutical therapy from both historical and modern perspectives, natural biosynthesis in planta and emerging production possibilities using tissue culture and microbial biosynthesis of these compounds.

Parkinson&rsquo, s disease (PD) is a neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, leading to alteration of the integrity of dopaminergic transporters (DATs). In recent years, some radiopharmaceuticals have been used in the clinic to evaluate the integrity of DATs. These include tropane derivatives such as radiolabeled &beta, CIT and FP-CIT with iodine-123 (123I), and TRODAT-1 with metastable technetium-99 (99mTc). Radiolabeling of &beta, CIT with radioactive iodine is based on electrophilic radioiodination using oxidizing agents, such as Chloramine T or Iodo-Gen&reg, For the first time, the present work performed a comparative study of the radiolabeling of &beta, CIT with iodine-131 (131I), using either Chloramine T or Iodo-Gen&reg, as oxidizing agents, in order to improve the radiolabeling process of &beta, CIT and to choose the most advantageous oxidizing agent to be used in nuclear medicine. Both radiolabeling methods were similar and resulted in high radiochemical yield (&gt, 95%), with suitable 131I-&beta, CIT stability up to 72 h. Although Chloramine T is a strong oxidizing agent, it was as effective as Iodo-Gen&reg, for &beta, CIT radiolabeling with 131I, with the advantage of briefer reaction time and solubility in aqueous medium.

ATAD2 is a cancer-associated protein whose bromodomain has been described as among the least druggable of its class. In our recent disclosure of the first chemical probe against this bromodomain, GSK8814 (6), we described the use of a conformationally constrained methoxy piperidine to gain selectivity over the BET bromodomains. Here we describe an orthogonal conformational restriction strategy of the piperidine ring to give potent and selective tropane inhibitors and show structural insights into why this was more challenging than expected. Greater understanding of why different rational approaches succeeded or failed should help in the future design of selectivity in the bromodomain family.

Cell suspensions initiated from Duboisia myoporoides–a shrub belonging to the Solanaceae family and being a rich source of tropane alkaloids–previously showed their ability to glycosylate scopoletin into scopolin, which represent coumarins showing health benefits. To investigate the time course of this glycosylation reaction, an in vivo NMR approach was developed using a perfusion system in an 8-mm NMR tube and 1H NMR with 1D and 2D (TOCSY and NOESY) experiments. The time course of metabolic changes could therefore be followed without any labeling.

Isomerisation of α-alkyl (Me, n-Pr, i-Pr, Bn) N,N-dimethylhydrazone derivatives of 8-methyl-8-azabicyclo-[3.2.1]octane (tropane) gave two isomers (E,exo Z,exo) while of 9-azabicyclo[3.3.1]nonane (granatane) three isomers (E,exo Z,exo and E,endo), excepting 2-isopropyl granatane. Relative free energies of isomeric hydrazones, at B3LYP/6-31G(d), provided satisfactory reproduction of isomer distributions for granatanes only. The thermodynamically preferred configuration for the 2-alkyl substituent was exo. The granatanone N,N-dimethylhydrazone was deuterated in D2O significantly faster than the tropinone analogue. The differences in two hydrazone series were rationalised using calculated ΔG's of tautomeric enhydrazines. Deuteration (Li-azaenolate or in D2O) led to exo (axial) α-deutero hydrazones of tropinone and granatanone. Crystal structures of tropane derived hydrazones, tropinone, 2-benzyltropinone and 3-granatanone salts were reported and used for assignment of configurations. Crystallization provided E,endo configured α-methyl, α-benzyl tropane hydrazones contrary to 2-isopropyltropane (remained E,exo). Crystallographic analysis, NMR and DFT calculations allowed configurational assignment to all experimentally accessible diastereomers of α-alkylated tropinone and granatanone hydrazones.

The 1,3-dipolar cycloaddition of a chiral nitrone with α,β-unsaturated lactones was carried out to give the corresponding isoxazolidines. Tetrahydro-1,3-oxazines with an oxa-tropane skeleton were obtained in one step by alkylation. The structures of several of these compounds were corroborated by X-ray diffraction and molecular modelling studies confirmed the results and proposed a mechanism for their formation.

Plant species of the Solanaceae family (nightshades) contain pharmacologically active anticholinergic tropane alkaloids, e.g., scopolamine and hyoscyamine. Tropane alkaloids are of special interest, either as active principles or as starting materials for semisynthetic production of other substances. For genetic evaluation, domestication, cultivation, harvest and post-harvest treatments, quantification of the individual active principles is necessary to monitor industrial processes and the resulting finished products. Up to now, frequently applied methods for quantification are based on high performance liquid chromatography and gas chromatography optionally combined with mass spectrometry. However, alternative analytical methods have the potential to replace the established standard methods partly. In this context, attenuated total reflection-Fourier transform infrared spectroscopy enabled chemotaxonomical classification of the Solanaceae Atropa belladonna, Datura stramonium, Hyoscyamus niger, Solanum dulcamara , and Duboisia in combination with cluster analysis. Also discrimination of genotypes within species was achieved to some extent. The most characteristic scopolamine bands could be identified in attenuated total reflection-Fourier transform infrared spectra of Solanaceae leaves, which allow a fast characterisation of plants with high scopolamine content. Applying a partial least square algorithm, very good calibration statistics were obtained for the prediction of the scopolamine content (residual prediction deviation = 7.67), and moderate prediction quality could be achieved for the hyoscyamine content (residual prediction deviation = 2.48).

Bivalent ligands of G protein-coupled receptors have been shown to simultaneously either bind to two adjacent receptors or to bridge different parts of one receptor protein. Recently, we found that bivalent agonists of muscarinic receptors can simultaneously occupy both the orthosteric transmitter binding site and the allosteric vestibule of the receptor protein. Such dualsteric agonists display a certain extent of subtype selectivity, generate pathway-specific signaling, and in addition may allow for designed partial agonism. Here, we want to extend the concept to bivalent antagonism. Using the phthal- and naphthalimide moieties, which bind to the allosteric, extracellular site, and atropine or scopolamine as orthosteric building blocks, both connected by a hexamethonium linker, we were able to prove a bitopic binding mode of antagonist hybrids for the first time. This is demonstrated by structure-activity relationships, site-directed mutagenesis, molecular docking studies, and molecular dynamics simulations. Findings revealed that a difference in spatial orientation of the orthosteric tropane moiety translates into a divergent M2/M5 subtype selectivity of the corresponding bitopic hybrids.

Annotations of protein or gene sequences from large scale sequencing projects are based on protein size, characteristic binding motifs, and conserved catalytic amino acids, but biochemical functions are often uncertain. In the large family of short-chain dehydrogenases/reductases (SDRs), functional predictions often fail. Putative tropinone reductases, named tropinone reductase-like (TRL), are SDRs annotated in many genomes of organisms that do not contain tropane alkaloids. SDRs in vitro often accept several substrates complicating functional assignments. Cochlearia officinalis, a Brassicaceae, contains tropane alkaloids, in contrast to the closely related Arabidopsis thaliana. TRLs from Arabidopsis and the tropinone reductase isolated from Cochlearia (CoTR) were investigated for their catalytic capacity. In contrast to CoTR, none of the Arabidopsis TRLs reduced tropinone in vitro. NAD(H) and NADP(H) preferences were relaxed in two TRLs, and protein homology models revealed flexibility of amino acid residues in the active site allowing binding of both cofactors. TRLs reduced various carbonyl compounds, among them terpene ketones. The reduction was stereospecific for most of TRLs investigated, and the corresponding terpene alcohol oxidation was stereoselective. Carbonyl compounds that were identified to serve as substrates were applied for modeling pharmacophores of each TRL. A database of commercially available compounds was screened using the pharmacophores. Compounds identified as potential substrates were confirmed by turnover in vitro. Thus pharmacophores may contribute to better predictability of biochemical functions of SDR enzymes.

The Ugi reaction has been successfully applied to the synthesis of novel arginase inhibitors. In an effort to decrease conformational flexibility of the previously reported series of 2-amino-6-boronohexanoic acid (ABH) analogs 1, we designed and synthesized a series of compounds, 2, in which a piperidine ring is linked directly to a quaternary amino acid center. Further improvement of in vitro activity was achieved by adding two carbon bridge in the piperidine ring, that is, tropane analogs 11. These improvements in activity are rationalized by X-ray crystallography analysis, which show that the tropane ring nitrogen atom moves into direct contact with Asp202 (arginase II numbering). The synthetic routes described here enabled the design of novel arginase inhibitors with improved potency and markedly different physico-chemical properties compared to ABH. Compound 11c represents the most in vitro active arginase inhibitor reported to date.

Introduction Hyoscyamine and scopolamine, anti-cholinergic agents widely used in medicine, are typically obtained from plants grown under natural conditions. Since field cultivation entails certain difficulties (changeable weather, pests, etc.), attempts have been made to develop a plant in vitro culture system as an alternative source for the production of these compounds. During experiments to locate the limiting steps in the biotechnological procedure, it is important to monitor not only the levels of the final products but also the changes in the concentration of their precursors. Objective To develop a HPTLC method for the separation and quantitation of the main tropane alkaloids hyoscyamine and scopolamine, their respective direct precursors littorine and anisodamine, and cuscohygrine, a product of a parallel biosynthetic pathway that shares a common precursor (N-methyl-∆1-pyrrolium cation) with tropane alkaloids. Methods Using alkaloid extracts from Atropa baetica hairy roots, different TLC chromatographic systems and developing procedures were investigated. Results Full separation of all compounds was obtained on HPTLC Si60 F254 plates preconditioned with mobile phase vapours (chloroform:methanol:acetone:25% ammonia ratios of 75:15:10:1.8, v/v/v/v). The chromatograms were developed twice (at distances of 4.0 and 3.0 cm) in a Camag twin trough chamber and visualised with Dragendorff's reagent. Densitometric detection (λ = 190 and 520 nm) was used for quantitative analyses of the different plant samples. Conclusion This method can be recommended for quantitation of hyoscyamine, scopolamine, anisodamine, littorine and cuscohygrine in different plant material (field grown vs. in vitro cultures). Copyright © 2013 John Wiley & Sons, Ltd.

The serotonin transporter (SERT) has been implicated in a variety of neuropsychiatric disorders including depression, anxiety, and suicide, and is the target of the selective serotonin reuptake inhibitor (SSRI) class of antidepressants. The availability of SERT-specific positron emission tomography (PET) radioligands will allow the SERT to be studied noninvasively in living subjects through PET imaging of the SERT and occupancy studies of SSRIs. Numerous diaryl sulfide and tropane derivatives have been developed and radiolabeled with (11) C or (18) F for imaging the SERT with PET.

Radiolabelling of cocaine-derived 3-phenyltropanes for dopamine transporter positron emission tomography with 18F and 11C is reviewed. Copyright © 2013 John Wiley & Sons, Ltd.

Molecules derived from plants make up a sizeable proportion of the drugs currently available on the market. These include a number of secondary metabolite compounds the monetary value of which is very high. New pharmaceuticals often originate in nature. Approximately 50% of new drug entities against cancer or microbial infections are derived from plants or micro-organisms. However, these compounds are structurally often too complex to be economically manufactured by chemical synthesis, and frequently isolation from naturally grown or cultivated plants is not a sustainable option. Therefore the biotechnological production of high-value plant secondary metabolites in cultivated cells is potentially an attractive alternative. Compared to microbial systems eukaryotic organisms such as plants are far more complex, and our understanding of the metabolic pathways in plants and their regulation at the systems level has been rather poor until recently. However, metabolic engineering including advanced multigene transformation techniques and state-of-art metabolomics platforms has given us entirely new tools to exploit plants as Green Factories. Single step engineering may be successful on occasion but in complex pathways, intermediate gene interventions most often do not affect the end product accumulation. In this review we discuss recent developments towards elucidation of complex plant biosynthetic pathways and the production of a number of highvalue pharmaceuticals including paclitaxel, tropane, morphine and terpenoid indole alkaloids in plants and cell cultures. VTT and UdL gratefully acknowledge support from European Union Framework 7 Program Integrated Project 222716 SmartCell; European Union Framework 7 European Research Council IDEAS Advanced Grant (to PC) Program-BIOFORCE; COST Actions FA0804 Molecular farming: plants as a production platform for high value proteins and FA1006 Plant Metabolic Engineering for High Value Products.

The tropane and granatane alkaloids belong to the larger pyrroline and piperidine classes of plant alkaloids, respectively. Their core structures share common moieties and their scattered distribution among angiosperms suggest that their biosynthesis may share common ancestry in some orders, while they may be independently derived in others. Tropane and granatane alkaloid diversity arises from the myriad modifications occurring to their core ring structures. Throughout much of human history, humans have cultivated tropane- and granatane-producing plants for their medicinal properties. This manuscript will discuss the diversity of their biological and ecological roles as well as what is known about the structural genes and enzymes responsible for their biosynthesis. In addition, modern approaches to producing some pharmaceutically important tropanes via metabolic engineering endeavors are discussed.

Tropane alkaloids (TAs), rich in the plant of Physochlaina infundibularis Kuang, which is named Huashanshen (HSS) in China, showed good effects on types of spasms. However, no data were collected to explore the relationship between the specificity for muscarinic receptor subtypes and the structures of these TAs. To address this issue, an extracted ion chromatogram (EIC) strategy using ultra-high performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-Q/TOF-MS) based on the fragmentation behavior of the TA standards was established to rapidly capture the varied TAs from HSS. Based on the provided structural information of diagnostic ions or neutral loss, 29 TAs were efficiently profiled, especially some trace ingredients. In additional, via virtual validation combined with molecular dynamic simulation, approximately a dozen alkaloids were found with high selectivity for muscarinic receptors. In additional, N-acetyl convolicine was chosen for selectivity evaluation of M2 or M3 receptors through the use of a dual-luciferase reporter assay system at the cellular level and an ACh-induced constricted strip test in vitro. After summarizing the active fragments and the structure-activity relationship (SAR) information, a new modified TA that takes advantage of both the high affinity and high selectivity for M3 receptors was proposed and evaluated successfully. This study provided an effective approach for the discovery and design of natural products based on highly selective drugs by UPLC-Q/TOF-MS coupled with virtual calculation and biological evaluation. Graphical Abstract Active fragments-guided strategy for selective inhibitors from HSS.

With structural guidance, tropane-derived HTS hits were modified to optimize for HSP90 inhibition and a desirable in vivo profile. Through an iterative SAR development process 12i (XL888) was discovered and shown to reduce HSP90 client protein content in PD studies. Furthermore, efficacy experiments performed in a NCI-N87 mouse xenograft model demonstrated tumor regression in some dosing regimens.

Tropane (8-methyl-8-azabicyclo[3.2.1]octane) and granatane (9-methyl-9-azabicyclo[3.3.1]nonane) derivatives undergo fast N-methyl inversion. The distribution of axial and equatorial N-methyl invertomers of protonated and free amine forms in aqueous and methanol solutions was studied by room and low temperature NMR spectroscopy on tropinone, tropine, granatan-3-one (pseudopelletierine or pseudopelletrierin) and α-granatan-3-ol. Theoretical (DFT) distributions in both gas phase and solutions are also reported. Applicability of the computational model for the studied system was verified by comparison with invertomer distributions inferred from inverse-gated 13C NMR experiments. Among the tested functionals, the BH&HLYP/cc-pVDZ method yields the best agreement with experiment. Moreover, accounting for orbital relaxation upon immersion in the solution was found to be of importance in order to properly reproduce observed distributions.

(-)-Hyoscyamine, the enantiomerically pure form of atropine, and its derivative scopolamine are tropane alkaloids that are extensively used in medicine. Hyoscyamine 6β-hydroxylase (H6H, EC 1.14.11.11), a monomeric α-ketoglutarate dependent dioxygenase, converts (-)-hyoscyamine to its 6,7-epoxy derivative, scopolamine, in two sequential steps. In this study, H6H of Atropa belladonna (AbH6H) was cloned, heterologously expressed in Escherichia coli, purified and characterized. The catalytic efficiency of AbH6H, especially for the second oxidation, was found to be low, and this may be one of the reasons why Atropa belladonna produces less scopolamine than other species in the same family. 6,7-Dehydrohyoscyamine, a potential precursor for the last step of epoxidation, was shown not to be an obligatory intermediate in the biosynthesis of scopolamine using purified AbH6H with an in vitro (18)O labeling experiment. Moreover, the nitrogen atom in the tropane ring of (-)-hyoscyamine was found to play an important role in substrate recognition.

A novel series of N-substituted tropane derivatives was characterized as potent muscarinic acetylcholine receptor antagonists (mAChRs). Kinetic washout studies showed that the N-endosubstituted analog 24 displayed much slower reversibility at mAChRs than the methyl-substituted parent molecule darotropium. In addition, it was shown that this characteristic appeared to translate into enhanced which duration of action in a mouse model of bronchonstriction.

In the study, we have examined the antitumor and antimicrobial activities of the methanol extract, the fractions, a fraction of total alkaloids and two alkaloids isolated from the stem of Erythroxylum caatingae Plowman. All test fractions, except the hexane fractions, showed antimicrobial activity on gram-positive bacteria and fungi. The acetate: methanol (95:5), acetate, chloroform and hexane fractions show the highest cytotoxicity activity against the NCI-H292, HEp-2 and K562 cell lines using MTT. The absence of hemolysis in the erythrocytes of mice was observed in these fractions and 6β-Benzoyloxy-3α-(3,4,5- trimethoxybenzoyloxy) tropane (catuabine B). Staining with Annexin V-FITC and JC-1 was used to verify the mechanism of action of the compounds of E. caatingae that showed cytotoxicity less than 30 μg/mL in leukemic cells. After 48 h of incubation, we observed that the acetate: methanol (95:5), acetate, and chloroform fractions, as well as the catuabine B, increased in the number of cells in early apoptosis, from 53.0 to 74.8%. An analysis of the potential of the mitochondrial membrane by incorporation of JC-1 showed that most cells during incubation of the acetate: methanol (95:5) and acetate fractions (63.85 and 59.2%) were stained, suggesting the involvement of an intrinsic pathway of apoptosis.

The synthesis and structure-activity relationships of 8-substituted-3-[2-(diarylmethoxyethylidenyl)]-8-azabicyclo[3.2.1]octane derivatives were investigated at the dopamine transporter (DAT), the serotonin transporter (SERT) and norepinephrine transporter (NET). The rigid ethylidenyl-8-azabicyclic[3.2.1]octane skeleton imparted modestly stereoselective binding and uptake inhibition at the DAT. Additional structure-activity studies provided a transporter affinity profile that was reminiscent of the structure-activity of GBR 12909. From these studies, the 8-cyclopropylmethyl group has been identified as a unique moiety that imparts high SERT/DAT selectivity. In this study the 8-cyclopropylmethyl derivative 22e (DAT K(i) of 4.0 nM) was among the most potent compounds of the series at the DAT and was the most DAT selective ligand of the series (SERT/DAT: 1060). Similarly, the 8-chlorobenzyl derivative 22g (DAT K(i) of 3.9 nM) was found to be highly selective for the DAT over the NET (NET/DAT: 1358).

We describe the synthesis and potency of a novel series of N-substituted 2-phenyl- and 2-methyl-2-phenyl-1,4-diaminobutane- based CCR5 antagonists. Compounds 7a and 12f were found to be potent in anti-HIV assays and bioavailable in the low-dose rat PK model.

Background: Tinospora cordifolia (TC) is a widely used shrub in Ayurveda system of medicine. The main chemical constituent reported from this shrub is alkaloid with nitrogen heterocycles such as tropane alkaloids, thiazole, piperidines, and pyridine derivatives; nonisoprene indole alkaloids; and pseudoalkaloids with antidiabetic effects. Materials and Methods: The nanoparticles (NPs) were synthesized via solvent evaporation method using a biodegradable poly(D,L-lactide) (PLA) polymer. The NPs were then characterized using spectroscopic methods, X-ray diffraction, and scanning electron microscopy. Release profile and entrapment efficiency of the NPs are studied. Further, the synthesized NPs were evaluated for the inhibitory activity to find the antidiabetic potential and compared with docking analysis. Results: In this study, the TC extract was loaded to PLA NPs by the solvent evaporation method. The synthesis of NPs is sonicated at 40% amplitude at 30 s to get 48% of yield. The loading efficiency was found to be 76.21% for 5 mg and 58.10% for 10 mg. Release profile was observed with controlled release up to 8 h and 70% of TC was released after 40 h. Release kinetic showed good correlation with Higuchi kinetics. The maximum inhibitory percentage of TC-loaded PLA NPs was found to be 92.59 ± 0.854 and shows potential activity for diabetes. The interaction of the compounds with the receptor, fentanyl, and cholic acid showed that the highest binding energies of −6.09 and −6.4 have the potential to activate the insulin receptor. Conclusion: The result proves that TC stem extract possesses a therapeutic effect on diabetes and it is noticeable that acarbose interaction with insulin receptor shows minimum binding affinity when compared to the compounds from mass spectrum shows the highest binding affinity which acts as an insulin activator and responsible for the inhibitory action of α-glucosidase.

Three tropane alkaloids, named schizanthines N, O, and P (1−3), have been isolated from the crude alkaloid extract of the endemic Chilean plant Schizanthus tricolor. On the basis of extensive NMR studies and MS fragmentation analysis, their structures were determined to be 3α-(E)-4-hydroxysenecioyloxy-6β-angeloyloxytropane (1), 3α-(E)-4-hydroxysenecioyloxy-6β-senecioyloxytropane (2), and 3α-mesaconyloxy-6β-senecioyloxytropane (3). Compounds 1 and 2 are the first isomeric alkaloids in the tropane series possessing a hydroxysenecioyl substituent as an esterifying moiety.

Tropane derivatives have been synthesized with the aim of finding serotonin antagonists with potential antimigraine activity. Aromatic and heteroaromatic esters of tropan-3-oxime were obtained. Their cerebrovascular activity as manifested by antiserotonin properties has been studied. On this basis the new antimigraine drug tropoxin has been discovered.

A series of 3-pyridinyl-tropane analogues based on previously reported compound 1 have been synthesized and shown to bind to the nociceptin receptor with high affinity. From the SAR study and our lead optimization efforts, compound 10 was found to possess potent oral antitussive activity in the capsaicin-induced guinea pig model. The rationale for compound selection and the biological profile of the optimized lead (10) are disclosed.

Baeyer–Villiger oxidations of several tropane derivatives have been investigated. Whereas tropenones 15a–c underwent exclusive epoxidation to 21a–c, the corresponding 6-oxotropane derivative 28 yielded the desired lactone 29. Baeyer–Villiger oxidation was also possible for the O-isopropylidene-protected diols 32a,b. The resulting lactones 33a,b were employed in the total synthesis of (±)-7a-epi-hyacinthacine A1 (7a-epi-7) via an intramolecular nucleophilic alkyllithium addition to a carbamate as the key lactamization step. The target compound was prepared from tropenone 15b in 10 steps and 14% overall yield. Enzymatic resolution of pyrrolidine (±)-36 provided a formal total synthesis to both enantiomers of 7.

Early studies led to the identification of 3β-(4-methoxyphenyl)tropane-2β-carboxylic acid methyl ester ( 5 ) with high affinity at the DAT (IC 50 = 6.5 nM) and 5-HTT ( K i = 4.3 nM), while having much less affinity at the NET ( K i = 1110 nM). In the present study, we replaced the 4′-methoxy group of the 3β-phenyl ring with a bioisosteric 4′-methylthio group to give 7a . We also synthesized a number of 3β-(4-alkylthiophenyl)tropanes 7b – e , 3β-(4-methylsulfinylphenyl) and 3β-(4-methylsulfonylphenyl)tropane analogues 7f – h as well as the 3β-(4-alkylthiophenyl)nortropane derivatives 8 – 11 to further characterize the structure–activity relationship of this type of compound for binding at monoamine transporters. With exception of the 4′-methylsulfonyl analogue 7h , all the tested compounds possessed high binding affinities at the 5-HTT. The K i values ranged from 0.19 nM to 49 nM. The 3β-(4-methylthiophenyl)tropane 7a and its N -(3-fluoropropyl) analogue 9a and N -allyl analogue 10a are the most selective compounds for the 5-HTT over the NET (NET/5-HTT = 314–364) in the series. However, none of the compounds showed selectivity similar to 5 for both the DAT and 5-HTT relative to the NET. This study provided useful SAR information for rational design of potent and selective monoamine transporter inhibitors.