African trypanosomiasis is a disease caused by Trypanosoma brucei parasites with limited treatment options. Trypanosoma is unable to synthesize purines de novo and relies solely on their uptake and interconversion from the host, constituting purine nucleoside analogues a potential source of antitrypanosomal agents. Here we combine structural elements from known trypanocidal nucleoside analogues to develop a series of 3’-deoxy-7-deazaadenosine nucleosides, and investigate their effects against African trypanosomes. 3’-Deoxytubercidin is a highly potent trypanocide in vitro and displays curative activity in animal models of acute and CNS-stage disease, even at low doses and oral administration. Whole-genome RNAi screening reveals that the P2 nucleoside transporter and adenosine kinase are involved in the uptake and activation, respectively, of this analogue. This is confirmed by P1 and P2 transporter assays and nucleotide pool analysis. 3’-Deoxytubercidin is a promising lead to treat late-stage sleeping sickness.

Chagas disease, the leading cause of cardiac-related mortality in endemic Latin American countries.Trypanosoma cruzi, the disease-causing pathogen, is unable to synthesize purines de novo, necessitating salvage of pre-formed host purines. Therefore, purine and purine nucleoside analogs might constitute an attractive source to identify antitrypanosomal hits. In this study, structural elements of two purine nucleoside analogs, i.e. cordycepin and a recently discovered 7-substituted 7-deazaadenosine led to the identification of novel nucleoside analogs with potent in vitro activity. The structure-activity relationship of substituents at C7 was investigated, ultimately leading to the selection of compound 5 having a C7 para-chlorophenyl group for in vivo evaluation. This derivative showed complete suppression of T. cruzi Y-strain blood parasitemia when orally administered twice daily for 5 days at 25 mg/kg and was able to protect infected mice from parasite-induced mortality. However, sterile cure by immunosuppression could not be demonstrated. improved efficacy and safety profiles and preferentially with a new mode-of-action should be pursued. 4 Recently, several reports on new lead molecules have been published, marking a renewed hope in finding drugs to treat Chagas disease. [6][7][8][9][10] Trypanosoma cruzi, like their related T. brucei counterparts, are purine auxotrophs, i.e. they rely on the salvage of pre-formed purine analogs from the host as they are unable to synthesize the purine ring themselves. [11][12][13][14] Hence, focused purine (nucleoside) libraries are a promising source for discovering new antitrypanosomal agents. Natural antibiotics such as tubercidin, 15 Formycin A 16 and Formycin B, [17][18][19] cordycepin, [19][20][21][22][23] stylomycin aminonucleoside (also known as puromycin aminonucleoside) [24][25] as well as allopurinol [26][27] and certain other inosine analogs 20,[28][29] have been found to possess activity against T. cruzi (Figure 1). Allopurinol, although not a nucleoside analog sensu stricto (its active metabolite is generated by phosphoribosylation in the parasite 26 ), has been evaluated in clinical trials. 30 Figure 1: Examples of purine (nucleoside) analogs active against T. cruzi.Our group recently revisited the natural nucleoside antibiotic tubercidin and a series of 7-substituted analogs [in the body of the text, purine numbering will be used for nucleoside analogs; however, in the experimental section, IUPAC nomenclature and numbering of the pyrrolo[2,3-d]pyrimidine system will be applied] in search of novel hits active against T. brucei spp. parasites. 31 This study indicated that certain phenyl-substituted analogs (e.g. 2) also showed promising in vitro activity against intracellular T. cruzi amastigotes, which motivated us to explore related 7-substituted 7-deazapurine moieties with the carbohydrate group of cordycepin, i.e. a 3'-deoxy-D-ribofuranose for their activity against T. cruzi.Related sugar-modified 7-deazapurine nucleosides 32-34 have previously been assayed ...

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This paper reports on the identification and full chemical characterization of isotonitazene (N,N‐diethyl‐2‐[5‐nitro‐2‐({4‐[(propan‐2‐yl)oxy]phenyl}methyl)‐1H‐benzimidazol‐1‐yl]ethan‐1‐amine), a potent NPS opioid and the first member of the benzimidazole class of compounds to be available on online markets. Interestingly, this compound was sold under the name etonitazene, a structural analog. Identification of isotonitazene was performed by gas chromatography mass spectrometry (GC–MS) and liquid chromatography time‐of‐flight mass spectrometry (LC‐QTOF‐MS), the latter identifying an exact‐mass m/z value of 411.2398. All chromatographic data indicated the presence of a single, highly pure compound. Confirmation of the specific benzimidazole regio‐isomer was performed using 1H and 13C NMR spectroscopy, after which the chemical characterization was finalized by recording Fourier‐transform (FT‐IR) spectra. A live cell‐based reporter assay to assess the in vitro biological activity at the μ‐opioid receptor (MOR) revealed that isotonitazene has a high potency (EC50 of 11.1 nM) and efficacy (Emax 180% of that of hydromorphone), thus confirming that this substance is a strong opioid. Isotonitazene has not been previously detected, either in powder form, or in biological fluids. The high potency and efficacy of isotonitazene, combined with the fact that this compound was being sold undiluted, represents an imminent danger to anyone aiming to use this powder.

In recent years, thymidylate kinase (TMPK), an enzyme indispensable for bacterial DNA biosynthesis, has been pursued for the development of new antibacterial agents including against Mycobacterium tuberculosis, the causative agent for the widespread infectious disease tuberculosis (TB). In response to a growing need for more effective anti-TB drugs, we have built upon our previous efforts toward the exploration of novel and potent Mycobacterium tuberculosis TMPK ( MtTMPK) inhibitors, and reported here the design of a novel series of non-nucleoside inhibitors of MtTMPK. The inhibitors display hitherto unexplored interactions in the active site of MtTMPK, offering new insights into structure-activity relationships. To investigate the discrepancy between enzyme inhibitory activity and the whole-cell activity, experiments with efflux pump inhibitors and efflux pump knockout mutants were performed. The minimum inhibitory concentrations of particular inhibitors increased significantly when determined for the efflux pump mmr knockout mutant, which partly explains the observed dissonance.