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Supplementary Materials and Methods. Figure S1: MALDI-TOF spectrum of the single-stranded oligonucleotide products of primer extension experiment with human DNA polymerase γ, AB61-TP, primer Prim248 and template (bio)-OligoAterm.

A regiospecific and enantiospecific synthesis of tritium-labeled 28-homocastasterone is reported. Appropriate chlorocarbonate, efficiently synthesized from the starting 28-homocastasterone in an overall yield of 46%, undergoes catalytic tritium dechlorination by the T2 /Pd[0]/Et3 N system, providing 28-[3β-3 H]homocastasterone, in a good yield, radiochemical purity (>97%), and with a high specific activity (5.8 Ci/mmol).

In our project, ghrelin analogs possessing enhanced stability and potential to significantly increase food intake were used. Three newly synthesized ghrelin analogs with fatty acid residues consisting of 8, 10, and 14 carbon atoms were studied. The main goal of this work was to develop a suitable analytical method for the determination of the stability of the novel ghrelin analogs in plasma. An appropriate liquid chromatography with mass spectrometry method was developed and optimized. The results obtained were compared with the data measured by using a commercial enzyme-linked immuno-sorbent assay kit, and a good correlation was found. A preparation strategy for plasma samples was optimized and consisted of simple dilution of the plasma samples followed by direct injection onto a very short monolithic column in combination with mass spectrometric detection. The developed analytical method was utilized for the determination of the stability of the prepared lipopeptides in plasma and for the quantification of the lipopeptides in a preliminary pharmacokinetic study. The feasibility of the developed separation method was clearly demonstrated. Accuracy and precision were within 80–120% and ±20% limits, respectively. Calibration curves were constructed in the range of 1–250 μg mL−1. This article is protected by copyright. All rights reserved

3-Hydroxycyclopent-1-ene-1-carboxylic acid (HOCPCA (1)) is a potent ligand for high-affinity γ-hydroxybutyric acid binding sites in the central nervous system. Various approaches to the introduction of a hydrogen label onto the HOCPCA skeleton are reported. The outcomes of the feasible C─H activation of olefin carbon (C-2) by iridium catalyst are compared with the reduction of the carbonyl group (C-3) by freshly prepared borodeuterides. The most efficient iridium catalysts proved to be Kerr bulky phosphine N-heterocyclic species providing outstanding deuterium enrichment (up to 91%) in a short period of time. The highest deuterium enrichment (>99%) was achieved through the reduction of ketone precursor 2 by lithium trimethoxyborodeuteride. Hence, analogical conditions were used for the tritiation experiment. [3 H]-HOCPCA selectively labeled on the position C-3 was synthetized with radiochemical purity >99%, an isolated yield of 637 mCi and specific activity = 28.9 Ci/mmol.

The radioactively labelled 6-amino-5-nitroso-uracil (1) and 5-acetyl-6-amino-1,3-dimethyl-uracil (2) were required for metabolic studies to assess their suitability as drug candidates. A common precursor for both compounds was [cyano-14 C]cyanoacetic acid (6), readily prepared from potassium [14 C]cyanide. ACS reagents, namely, diethyl ether, acetic acid and acetic anhydride, had to be rigorously repurified to achieve a successful synthesis of 14 C-labelled compounds on a tenth-of-a-milligramme scale. 6-Amino-5-nitroso-[6-14 C]uracil (1-14 C) (0.55 mCi) was prepared with radiochemical purity > 98% and specific activity (SA) = 55.6 mCi/mmol. 5-Acetyl-6-amino-1,3-dimethyl-[6-14 C]uracil (2-14 C) (8 mCi) was prepared with radiochemical purity > 97% and SA = 55.6 mCi/mmol. It has been shown that a SA assay can be made from standard 13 C NMR spectra, thus avoiding the need to perform lengthier inverse-gated 13 C NMR experiments.

Compound 1 is a selective and potent agonist of the G protein-coupled receptor GPR139 (EC50 = 39 nM). In this study, we describe the synthesis, radiolabelling and in vitro evaluation of [3H]-1 for the characterisation of GPR139 and its spatial expression in the brain using autoradiography. Two different synthesis routes for the radiolabelling of 1 based on a reductive debromination strategy were investigated using deuterium (D2, g). The route based on reductive debromination of the bromonaphthyl precursor 5 proved superior over arylbromide 4 and was employed for the radiolabelling experiments. Reductive debromination of precursor 5 was accomplished using 3H2, Pd/C and triethylamine in DMF at ambient temperature to give target molecule [3H]-1 with a specific activity of 19.3 Ci mmol-1 and a radiochemical purity of ≥95%. By application of autoradiography and binding studies, it was not possible to discriminate [3H]-1 binding to wildtype mice brains from GPR139 knockout mice brains and total binding from non-specific binding in CHO-k1 cells stably expressing human GPR139 receptor. Based on these experiments we conclude that [3H]-1 is not a suitable radioligand for the characterisation of GPR139.

A new catalytic enantiospecific approach to the synthesis of epibrassinosteroids (and other polyhydroxylated steroids) regiospecifically labeled by heavy isotopes of hydrogen is reported. Chlorocarbonate, efficiently synthesized from α-hydroxy ketone by a reaction with triphosgene, undergoes reductive tritium dechlorination catalyzed by the [Pd0]/Et3N system, providing 24-[3β-3H]epicastasterone and 24-[3β-3H]epibrassinolide, respectively, in good yield and with high specific activity (5.8 Ci/mmol; 20% tritium enrichment per molecule).

A detailed study of regiospecific silylation, oxidation, and reduction of sterols is reported. The different reactivity of 2α and 3α hydroxy groups is demonstrated on a 2α,3α-dihydroxy-5α-pregnane-6,20-dione as a model substrate. A regiospecific silylation of the 2α-alcohol occurred when silyl chloride was used under mild reaction conditions. The selective oxidation of one of the 2α,3α-diols by dimethyldioxirane or the Dess–Martin periodinane led to a mixture of α-hydroxyketones with high prevalence of 3,6,20-trione over 2,6,20-trione in the ratio 10:1. A regiospecific reduction of a model substrate by lithium tri-tert-butoxyaluminium hydride gives the C6 alcohol.

The brassinosteroids (BRs) are a class of native plant growth regulating substances with high biological activity even at very low concentration. These compounds have been rigorously explored and it has been found that they are not only growth regulators in plants but also promising antiviral agents. Recently, it has been reported that natural BRs exhibit relatively interesting anticancer activities. Up to now, the basic anticancer potential of BRs against several normal and human cancer cell lines has been determined. Natural BRs, at micromolar concentrations, impart cell growth-inhibitory responses in several human cancer cell lines without affecting the normal cells. To study the mechanism of action of BRs at the molecular level, the corresponding isotopically labelled compounds are essential. The latter BRs are essential for the investigation of biosynthesis, metabolism, transport and distribution in plants. This venture ultimately led us to explore the labeling of BRs by isotopes of hydrogen and carbon and the related technique to do this. The present review will shed light on the synthetic avenues in this field from the time of the discovery of labelled BRs up until their most recent advances.

A convenient method for the synthesis of tritium-labeled brassinosteroids with very high specific activity is reported. A 3H-labeled 24-epicastasterone was isolated in high yield (40 mCi), radiochemical purity (>97%) and a specific activity up to 99 Ci mmol−1. The labeling strategy was designed to employ a radiolabeling step at the late stage of the synthetic sequence.

The aim of this work was to synthesize deuterated and tritiated analogues of highly oxidized lupane derivatives known from our group. We selected compounds that previously showed very high cytotoxic activity on multiple cancer cell lines in order to further investigate the mechanism of their action. From starting material (compounds 1–4), we obtained benzyl platanate (5) and its reaction with deuteromethyltriphenylphosphonium iodide gave deuterated compound 6. Following benzyl deprotection gave free acid 7 and oxidation with SeO2 gave 30-oxo-[29-2H2]lup-20(29)-en-28-oic acid (8), which is one of the most active compounds synthesized in our group to date (IC50 6 μmol/L on CEM cell line). The alkylation of benzyl 2-hydroxy-3-oxolupa-1,20(29)-dien-28-oate (9) with methyliodide or deuteromethyliodide followed by a series of deprotection and hydrogenation steps gave compounds 10–14, where 2β-[31-2H3]methoxy-3-oxolupan-20(29)-en-28-oic acid (13) is especially interesting, it showed lower activity on CEM cell line (IC50 10 μmol/L) however, it was very active against Ph1—positive human leukemia BV-173 (IC50 0.91 μmol/L) and against human myelogenous leukemia K562 (IC50 0.52 μmol/L). Selectively labelled [3α-2H] and [3α-3H] methyl 3β-acetoxy-21,22-dioxolup-18-en-28-oates 24, 25 were prepared in three steps by reduction of corresponding 3-oxo derivatives and they showed moderate activity on CEM cell line (IC50 10 μmol/L). In total, 11 labelled compounds (6–8, 11, 14, 18, 19, 21, 22, 24 and 25) have not been reported before.

Neuropeptide FF (NPFF) belongs to the RF-amide family of peptides bearing the identical C-terminal amino acid sequence (R-F-NH2). In addition to NPFF, prolactin-releasing peptide (PrRP), another RF-amide, binds to NPFF receptors with high affinity. A selective antagonist of PrRP has not yet been identified, but a selective antagonist of NPFF, 1-adamantanecarbonyl-RF-NH2 (RF9), was recently reported to antagonize the hyperalgesic effect of NPFF after central administration to mice. In the present study, RF9 competed with NPFF analog D-Y-L-(N-Me)-F-Q-P-Q-R-F-NH2 (1DMe) in binding to CHO-K1 cell membranes transfected with the human NPFF2 receptor. In rat pituitary RC-4B/C cells, where the expression of the NPFF2 receptor was proved by immunodetection, RF9 did not reverse the phosphorylation of MAPK/ERK1/2 induced by [Tyr1]NPFF. In vivo experiments with fasted mice confirmed that centrally injected [Tyr1]NPFF significantly lowered food intake. However, RF9, a putative NPFF2 antagonist, did not reverse the anorectic effect of [Tyr1]NPFF. Paradoxically, RF9 itself exhibited an anorectic effect in fasted mice not only after intracerebroventricular but also after subcutaneous administration. This finding casts doubt on claims that RF9 is an NPFF antagonist.

Brassinosteroids (BRs) are plant-specific steroid hormones that play essential roles in the regulation of many important physiological processes in plant life. Their extremely low concentrations (~pmoles/g FW) in plant tissue and huge differences in polarity of individual members within the BR family hamper their detection and quantification. To address this problem, an immunoaffinity sorbent with broad specificity and high capacity for different BR metabolites containing a monoclonal antibody (mAb) against a BR spacer (20S)-2α,3α-dihydroxy-7-oxa-7α-homo-5α-pregnane-6-one-20 carboxylic acid (BR4812) was used for the rapid and highly selective isolation of endogenous BRs containing a 2α,3α-diol in ring A from minute plant samples. This enrichment procedure was successfully applied as a sample preparation method prior to quantitative analysis of BRs in real plant tissues by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Use of immunoaffinity chromatography (IAC) increased the sensitivity of the UHPLC-MS/MS analysis owing to improvements in the BR signal-to-noise ratio (S/N) and matrix factor (MF). Although MF values of BRs analyzed in classical samples ranged from 8.9% to 47.4%, MF values for the IAC purified samples reached 44.5-96.6%. Thus, the developed IAC-UHPLC-MS/MS approach was shown to be a simple, robust, effective and extremely fast procedure requiring minute amounts of plant samples suitable for the quantitative profiling of many BR metabolites, helping to overcome the major problems associated with their determination in very complex plant matrices.

3-Hydroxycyclopent-1-ene-1-carboxylic acid (HOCPCA (1)) is a potent ligand for high-affinity γ-hydroxybutyric acid binding sites in the central nervous system. Various approaches to the introduction of a hydrogen label onto the HOCPCA skeleton are reported. The outcomes of the feasible C─H activation of olefin carbon (C-2) by iridium catalyst are compared with the reduction of the carbonyl group (C-3) by freshly prepared borodeuterides. The most efficient iridium catalysts proved to be Kerr bulky phosphine N-heterocyclic species providing outstanding deuterium enrichment (up to 91%) in a short period of time. The highest deuterium enrichment (99%) was achieved through the reduction of ketone precursor 2 by lithium trimethoxyborodeuteride. Hence, analogical conditions were used for the tritiation experiment. [

The radioactively labelled 6-amino-5-nitroso-uracil (1) and 5-acetyl-6-amino-1,3-dimethyl-uracil (2) were required for metabolic studies to assess their suitability as drug candidates. A common precursor for both compounds was [cyano

Ghrelin, the only known peripherally produced and centrally acting peptide that stimulates food intake, is synthesized primarily in the stomach and acts through the growth hormone secretagogue receptor (GHS-R1a). In addition to its orexigenic effect, ghrelin stimulates the release of growth hormone (GH). In this study, we investigated the biological properties of full-length and shortened ghrelin analogs in which octanoylated Ser 3 is replaced with an octanoic acid moiety coupled to diaminopropionic acid (Dpr). Ghrelin analogs stabilized with Dpr( N -octanoyl) in position 3 and noncoded amino acids in position 1 (sarcosine) and/or position 4 (naphthylalanine or cyclohexylalanine) were found to possess affinities similar to those of ghrelin for cell membranes with transfected GHS-R1a. In vivo, the prolonged orexigenic effects of analogs containing Dpr( N -octanoyl) 3 compared with that of ghrelin in adult mice and a similar impact on GH secretion in young mice were found. Full-length [Dpr( N -octanoyl) 3 ]ghrelin and its analogs with a noncoded amino acid in position 1 and/or 4 showed significantly prolonged stability in blood plasma compared with that of ghrelin. Ghrelin analogs with a prolonged orexigenic effect are potential treatments for GH deficiency or cachexia that accompanies chronic diseases. Desoctanoylated ghrelin analogs and N-terminal penta- and octapeptides of ghrelin did not show any biological activity.

The hydrogen-to-deuterium isotope exchange reaction of hydrogen in position 5 of pyrimidine derivatives was studied using NMR techniques. The dependence of the reaction rate on the pH and on the solvent composition was explored. In tracer experiments using tritiated water, the application of this exchange reaction was tested for the preparation of pyrimidine derivatives labeled by tritium.

The ways of converting steroid vicinal diol into an unsaturated derivative were studied with the intention of preparing suitable precursors for the introduction of deuterium or tritium into the molecules of brassinosteroids. The model vicinal diol compound, 2α,3α-dihydroxy-5α-pregnane-6,20-dione (3), was converted with high regioselectivity to the α-hydroxy ketone derivative, 2α-hydroxy-5α-pregnane-3,6,20-trione (8), in a 75% yield. The attempts to convert α-hydroxy ketone 8 to the dioxolene derivative, 2α,3α-(isopropylidenedioxy)-5α-pregn-2-ene-6,20-dione (6), failed. The conditions for the conversion of ketone to the corresponding enol trialkylsilyl ether were optimized using cyclohexanone as a model compound. The best and reproducible results were obtained by using tert-butyldimethylsilyl trifluoromethansulfonate (TBDMSiOTf) as the silylating reagent and triethylamine as the base. Under these conditions, the 3,6,20-trione (8) was converted to 2,3-bis(tert-butyldimethylsilyloxy)-5α-pregn-2-ene-6,20-dione (14) with a 66% yield.

9-(2-Phosphonomethoxyethyl)-2,6-diamino-[8-3H]purine (4), 9-(2-phosphonomethoxyethyl)-[8-3H]guanine (6) and (R)-9-(2-phosphonomethoxypropyl)-[8-3H]adenine (11) with specific activities of 10.9, 7.9 and 16 Ci/mmol, respectively, were prepared by a catalytic dehalogenation of the corresponding 8-bromo derivatives 1, 2 and 9. The rate of the exchange of the tritium label on C-8 of the purine ring in title compounds with the hydrogen of water under physiological pH at 20 °C was studied using 3H NMR. The loss of 3H-label attained 7% in [8-3H]tenofovir (11), 10% in [8-3H]PMEDAP (4) and 12% in [8-3H]PMEG (6) after the period of 3 weeks. Storage at a temperature of –196 °C in liquid nitrogen ensured a better than 97% radiochemical purity of the prepared labeled compounds even after a six-month period.

Humanin (HN) and HN-derivatives are a family of peptides first reported in the last decade with potent in vitro and in vivo neuroprotective activity, which is mediated through a not completely elucidated mechanism. Recently, our group has evaluated the effect of various HN-derivatives on the 3-quinuclidinyl benzilate (QNB)-induced impairment of spatial orientation and memory in rats, by employing the T-maze test. In the present work four new, tyrosine containing HN-derivatives were synthesized (Y-PAGASRLLLTGEIDLP, peptide I; Y-PAGASRLLLLTGEIDLP, peptide II; Y-SALLRSIPAPAGASRLLLTGEIDLP, peptide III; Y-SALLRSIPAPAGASRLLLLTGEIDLP, peptide IV). The neuroprotective action of these peptides was evaluated in the T-maze test and the most active among them (peptides I and III) was radiolabeled with 125I. The pure monoradioiodinated peptides were used in: (i) in vitro binding studies with various neuronal cell lines and with brain and stomach membranes from rats and mice and (ii) in vivo biodistribution studies in rats and mice. Moreover, the metabolic stability of the above radiolabeled peptides was studied. Under the experimental conditions used, our data do not confirm the existence of specific binding sites for HN on the neuronal tissue. Nevertheless, they are setting the basis for further relevant studies aiming at the clarification of the mode of the neuroprotective action of HN-peptides.

α-5-Aza-2'-deoxy cytidine was labeled by tritium on the C-6 of the heterocyclic triazine ring. The structure of the α-5-aza-2'-deoxy-[6-3H]cytidine and the position of the label was proved by 3H and 1H NMR. The specific activity was 0.71 TBq mmol-1 (19.2 Ci mmol-1) and radiochemical purity was >99%. The long term stability of the product during the storage at -21 and -72 °C was followed by radio-HPLC.

CART (cocaine- and amphetamine-regulated transcript) peptides are neuropeptides abundant in the central nervous system and periphery found to be involved in the regulation of food intake behavior and other physiological processes. Recently, we reported specific binding of 125 I-CART(61–102) to the rat adrenal pheochromocytoma cell line PC12, both intact cells and cell membranes. In this study, several fragments of CART(61–102) corresponding to its structural loops were synthesized and tested for their potency in binding experiments using PC12 intact cells and cell membranes and in feeding test with fasted mice. From all shorter peptides tested, only CART(74–86) and CART(62–86) containing disulfide bridges kept partial binding potency of the original molecule with K i in 10 −5 and 10 −4 M range. However, these fragments were not able to inhibit food intake after their central administration up to a dose of 4 nmol/mouse. The results showed that a compact structure containing three disulfide bridges is necessary for preservation of full biological activity of CART peptides.

CART (cocaine- and amphetamine-regulated transcript) peptides have been studied for ten years. We report specific binding of 125I-CART(61-102) to the rat adrenal pheochromocytoma PC12 cell line, both intact cells and cell membranes. Saturation binding to intact plated cells resulted in Kd of 0.48 ± 0.16 nM and Bmax of 2228 ± 529 binding sites/cell. 125I-CART(61-102) was also bound to PC12 cells differentiated using nerve growth factor to the neuronal phenotype with non-specific binding below 20%, and Kd of 1.90 ± 0.27 nM and Bmax of 11194 ± 261 binding sites/cell. In competitive binding experiments, CART(61-102), CART(55-102) and di-iodinated CART(61-102) were bound to PC12 cell membranes with Ki in low nM range; their affinity to intact non-differentiated and differentiated cells was in low 10− 8 M range. In order to prove that iodination did not eliminate the pharmacological properties of CART, we tested the biological activity of di-iodinated CART(61-102). It decreased food intake in in vivo feeding experiment on fasted mice in a dose of 1 μg/mouse to the same extent as CART(61-102) in a dose of 0.5 μg/mouse.

6-Chloropurines substituted at the position 9 with variously modified bicyclic skeletons represent promising antiviral and anticancer agents. This work aimed to investigate the transport mechanisms of 9-[(1R*,2R*,4S*)-bicyclo[2.2.1]hept-2-yl]-6-chloro-9H-purine (9-norbornyl-6-chloropurine, NCP) and their relationship to the metabolism and biological activity of the compound. Transport experiments were conducted in CCRF-CEM cells using radiolabeled compound ([3H]NCP). The pattern of the intracellular uptake of [3H]NCP in CCRF-CEM cells pointed to a combination of passive and facilitated diffusion as prevailing transport mechanisms. NCP intracellular metabolism was found to enhance its uptake by modifying NCP concentration gradient. The transport kinetics reached steady state under the conditions of MRP and MDR proteins blockade, indicating that NCP is a substrate for these efflux pumps. Their inhibition also increased the cytotoxicity of NCP. Our findings suggest that the novel nucleoside analog NCP has potential to become a new orally available antileukemic agent due to its rapid membrane permeation.

A new and efficient procedure for the preparation of brassinosteroids labeled with hydrogen isotopes was developed. A four-step reaction sequence started with the selective oxidation of a 2,3-diol group to an α-hydroxy ketone, which was converted stereospecifically into a chlorocarbonate by reaction with triphosgene. A subsequent Pd-catalyzed reductive dechlorination with deuterium gas yielded deuterium-labeled brassinosteroid 2,3-carbonates. The reaction sequence was completed by base-catalyzed hydrolysis of the cyclic carbonate.

7-(2-Thienyl)-7-deazaadenosine (AB61) showed nanomolar cytotoxic activities against various cancer cell lines but only mild (micromolar) activities against normal fibroblasts. The selectivity of AB61 was found to be due to inefficient phosphorylation of AB61 in normal fibroblasts. The phosphorylation of AB61 in the leukemic CCRF-CEM cell line proceeds well and it was shown that AB61 is incorporated into both DNA and RNA, preferentially as a ribonucleotide. It was further confirmed that a triphosphate of AB61 is a substrate for both RNA and DNA polymerases in enzymatic assays. Gene expression analysis suggests that AB61 affects DNA damage pathways and protein translation/folding machinery. Indeed, the formation of large 53BP1 foci was observed in nuclei of AB61-treated U2OS-GFP-53BP1 cells indicating DNA damage. Random incorporation of AB61 into RNA blocked its translation in an in vitro assay and reduction of reporter protein expression was also observed in mice after 4-hour treatment with AB61. AB61 also significantly reduced tumor volume in mice bearing SK- OV-3, BT-549, HT-29 and MDA-MB231 xenografts. The results indicate that AB61 is a promising compound with the unique mechanism of action and deserves further development as an anticancer agent. This work was supported by the Ministry of Education of the Czech Republic (LO1304). Citation Format: Petr Dzubak, Marian Hajduch, Pavla Perlikova, Gabriela Rylová, Petr Naus, Tomas Elbert, Eva Tloustova, Aurelie Bourderioux, Lenka Slavetinska, Kamil Motyka, Dalibor Dolezal, Pawel Znojek, Alice Nova, Monika Harvanova, Michal Siler, Jan Hlavac, Michal Hocek. AB61, a new potent nucleoside cytostatic: Molecular mechanisms of action and preclinical activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5100. doi:10.1158/1538-7445.AM2017-5100

7-(2-Thienyl)-7-deazaadenosine (AB61) showed nanomolar cytotoxic activities against various cancer cell lines but only mild (micromolar) activities against normal fibroblasts. The selectivity of AB61 was found to be due to inefficient phosphorylation of AB61 in normal fibroblasts. The phosphorylation of AB61 in the leukemic CCRF-CEM cell line proceeds well and it was shown that AB61 is incorporated into both DNA and RNA, preferentially as a ribonucleotide. It was further confirmed that a triphosphate of AB61 is a substrate for both RNA and DNA polymerases in enzymatic assays. Gene expression analysis suggests that AB61 affects DNA damage pathways and protein translation/folding machinery. Indeed, formation of large 53BP1 foci was observed in nuclei of AB61-treated U2OS-GFP-53BP1 cells indicating DNA damage. Random incorporation of AB61 into RNA blocked its translation in an in vitro assay and reduction of reporter protein expression was also observed in mice after 4-hour treatment with AB61. AB61 also significantly reduced tumor volume in mice bearing SK-OV-3, BT-549, and HT-29 xenografts. The results indicate that AB61 is a promising compound with unique mechanism of action and deserves further development as an anticancer agent. Mol Cancer Ther; 15(5); 922–37. ©2016 AACR.

Seven esters of alpha-truxillic acid have been synthesized: bis-3-piperidylpropyl ester and its quaternary bis-N-ethyl derivative, bis-N-diethylaminopropyl ester and its quaternary bis-N-methyl derivative, and bis-4-piperidylbutyl ester and its quaternary bis-N-methyl and bis-N-ethyl derivatives. All esters inhibited the specific binding of muscarinic receptor antagonist [methyl-3H]-N-methylscopolamine ([3H]-NMS) to muscarinic receptors in membranes of CHO cell lines stably expressing the human gene for the M1, M2, M3 or M4 subtype of muscarinic receptors. All esters displayed the highest potency at the M2 and the lowest potency at the M3 receptor subtype. In experiments performed on the M2 muscarinic receptor subtype, the affinity between the receptors and the esters was greatly increased when the concentration of ions was diminished. The highest affinities were found for the tertiary bis-3-piperidylpropyl and bis-4-piperidylbutyl aminoesters (equilibrium dissociation constants of 52 and 179 pM, respectively, in the low ionic strength medium). All investigated esters slowed down the dissociation of [3H]-NMS from the M2 muscarinic receptor subtype. [3H]-NMS dissociation from the M1, M3 and M4 muscarinic receptor subtypes was investigated in experiments with the bis-4-piperidylbutyl aminoester and also found to be decelerated. It is concluded that the esters of alpha-truxillic acid act as M2-selective allosteric modulators of muscarinic receptors and that, by their potency, the tertiary bis-3-piperidylpropyl and bis-4-piperidylbutyl aminoesters surpass the other known allosteric modulators of these receptors.

A synthetic insect juvenile hormone analog (a juvenoid), ethyl N-[2-[4-[[2,2-(ethylenedioxy)cyclohexyl]methyl]phenox]ethyl]carbam ate, which has displayed high biological activity against different insect species and high stability under field conditions, was selected as a biologically active model compound for a study of a juvenile hormone analog degradation. The biologically active compound itself and its three diversely radiolabeled derivatives were applied to the flesh fly (Sarcophaga bullata) or the tsetse fly (Glossina palpalis), respectively. Monitoring of a fate of the applied juvenile hormone analog was carried out using a detection method of the radioactivity microdistribution within the whole insect body in combination with a radio high performance liquid chromatography (radio-HPLC), both of whole-body extracts made in different, but in advance scheduled, time intervals, and of extracts of insect excreta accumulated over an eight-day experiment.

The tritiated juvenoids ethyl N-{2-[4-(cis-2-hydroxy-1-cycloheptylmethyl)phenoxy]ethyl}carbamate (1), 2-[4-(trans-2-hydroxy-1-cyclohexylmethyl)phenoxy]ethyl N-ethylcarbamate (2) and ethyl N-{2-[4-(c-2-hydroxy-3-methyl-r-1-cyclohexylmethyl)phenoxy]ethyl}carbamate (3) were prepared by Catalyzed Exchange in Solution with Gas on PdO/BaSO4. The high degree of regio- and stereoselectivity observed in the products by 3H NMR is discussed in the terms of the stereoelectronic requirements of the exchange reaction.

Betaine-homocysteine S-methyltransferase 2 (BHMT-2) catalyzes the transfer of a methyl group from S-methylmethionine to l-homocysteine, yielding two molecules of l-methionine. It is one of three homocysteine methyltransferases in mammals, but its overall contribution to homocysteine remethylation and sulfur amino acid homeostasis is not known. Moreover, recombinant BHMT-2 is highly unstable, which has slowed research on its structural and catalytic properties. In this study, we have prepared the first series of BHMT-2 inhibitors to be described, and we have tested them with human recombinant BHMT-2 that has been stabilized by copurification with human recombinant BHMT. Among the compounds synthesized, (2S,8RS,11RS)-5-thia-2,11-diamino-8-methyldodecanedioic acid (11) was the most potent (K(i)(app) ∼77 nM) and selective inhibitor of BHMT-2. Compound 11 only weakly inhibited human BHMT (IC(50) about 77 μM). This compound (11) may be useful in future in vivo studies to probe the physiological significance of BHMT-2 in sulfur amino acid metabolism.

The labelled juvenoid 2-(4-(2-(ethoxycarbamatoethoxy)(benzene-U-14C)benzyl) -1-cyclohexanone ethylene acetal (8) (W 328) was prepared starting from p-hydroxy(ring-U-14C)benzoic acid (1) by a seven step synthesis in 11% overall yield. The reaction conditions previousiy reported for the „coid” synthesis of the W 328 (8) were modified to suit the small scale preparation.

Conditions for the transformation of a 2,3-diol group of common brassinosteroids to a 2,3-bis(silyloxy) enol group, a suitable precursor for regio- and stereoselective labelling reactions, are established.

The juvenoid analog 2-(4-(2-(ethoxycarbamato)ethoxy)benzyl)-1-cyclohexanone ethylene acetal (I) (W 328) was labelled by 3H in the benzyl position by the CESG method. 3H NMR revealed the stereoselectivity of the labelling. The results are compared with the data published in the literature and discussed in the terms of stereoelectronic requirements.

The published four step synthesis of N-{2-(2-heptyloxyphenyl-carbamoyloxy)-ethyl}-piperidinium chloride (5) and N-{2-(2-heptyl-oxyphenylcarbamoyloxy)-propyl}-diethylammonium chloride (6), which starts from o-acetamidophenol and 1-bromoheptane was scaled down and modified for radioisotope work. After chromatography 1064 MBq (28,7 mCi) of [heptyl-1-14C]heptacaine 5 and 840 MBq (22, 6 mCi) of [heptyl-1-14C]carbisocaine 6 were isolated. Radiochemical yields of 5 and 6 on starting 1-bromo [1-14C] heptane were 30% and 25%, respectively.

Nitrous acid deamination of 2-amino-1,6-anhydro-2-deoxy-β- D -glucopyranose ( 1 ) in the presence of weakly acidic, cation-exchange resin gave 1,6:2,3-dianhydro-β- D -mannopyranose ( 3 ) and 2,6-anhydro- D -mannose ( 6 ), characterized, respectively, as the 4-acetate of 3 and the per- O -acetylated reduction product of 6 , namely 2,3,4,6- tetra- O -acetyl-1,5-anhydro- D -mannitol, obtained in the ratio of 7:13. Comparative deaminatior of the 4- O -benzyl derivative of 1 led to similar qualitative results. Deamination of 3-amino-1,6-anhydro-3-deoxy-β- D -glucopyranose gave 1,6:2,3- and 1,6:3,4-dianhydro-β- D -allopyranose ( 13 and 16 ), characterized as the corresponding acetates, obtained in the ratio of 31:69, as well as the corresponding p -toluenesulfonates. Deamination of 4-amino-1,6-anhydro-4-deoxy-β- D -glucopyranose and of its 2- O -benzyl derivative gave the corresponding 1,6:3,4- D - galacto dianhydrides as the only detectable products. 2,5-Anhydro- D -glucose, characterized as the 1,3,4,6-tetra- O - acetyl derivative of the corresponding anhydropolyol, was obtained in 39% yield from the same deamination reaction performed on 2-amino-1,6-anhydro-2-deoxy-β- D - mannopyranose ( 24 ). In 90% acetic acid, the nitrous acid deamination of 24 , followed by per- O -acetylation, gave only 1,3-4-tri- O -acetyl-2,5-anhydro-α- D -glucoseptanose. In the case of 1,6-anhydro-3,4-dideoxy-3,4-epimino-β- D -altropyranose, only the corresponding glycosene was formed, namely, 1,6-anhydro-3,4-dideoxy-β- D - threo- -hex-3-enopyranose.

Conditions were found for almost quantitative carboxylation of n-hexyllithium with 14CO2 to afford lithium [1-14C] heptanoate. It was then possible to perform the reaction sequence lithium [1-14C] heptanoate[1-14C] heptan-1-ol 1-bromo [1-14C] heptane in one flask without isolation of intermediates. In the “hot” synthesis 12,8 GBq (346 mCi) of 1-bromo [1-14C] heptane with radiochemical purity better than 97 % were prepared from Ba14CO3 in 81 % yield.

1,6-Anhydro-4-O-benzyl-2-deoxy-2-isothiocyanato-β-D-glucopyranose (IV), prepared from 2-amino-1,6-anhydro-4-O-benzyl-2-deoxy-β-D-glucopyranose (I) by reaction with carbon disulfide followed by oxidation with iodine, was converted into the 3-O-p-toluenesulfonate VII. This was cyclized to give either the 2,3-epimino derivative X or the thiazoline XII. 2-Acetamido-3-S-acetyl-1,6-anhydro-4-O-benzyl-2-deoxy-3-thio-β-D-glucopyranose (XVI), obtained from compound XII, was desulfurized with Raney nickel to afford 2-acetamido-1,6-anhydro-2,3-dideoxy-β-D-ribo-hexopyranose (XVII). The isothiocyanato group was not affected upon acetylation of compound IV and acetolysis of the 1,6-anhydride bond with acetic anhydride and trifluoroacetic acid.

The modification of the reaction conditions of Hassner esterification - DCC/4-dimethylaminopyridine method - merely the gradual addition of DCC to the reaction mixture - eliminated the unwanted side reaction - N-acyl-N,N'-dicyclohexylurea formation - and thus improved the conversion of the acid to the desired ester. Glycerol tri[U-14C]palmitate, glycerol tri[U-14C]oleate and glycerol tri[9, 103H]stearate with molar activities greater than 1800 MBq.mmol−1 were prepared with preparative radiochemical yields about 86–92%.