Synthesis and in vivo influenza virus-inhibitory effect of ester prodrug of 4-guanidino-7-O-methyl-Neu5Ac2en

A series of ester prodrugs of 7-O-methyl derivative of Zanamivir (compound 3) was synthesized and their efficacy was evaluated in an influenza infected mice model by intranasal administration. Compound 7c (CS-8958), octanoyl ester prodrug of the C-9 alcohol of compound 3, was found to be much longer-acting than Zanamivir. Furthermore, the in vivo efficacies of compounds 12a, 12b, and 12c, the linear alkyl ester prodrug of the carboxylic acid, were comparable to that exerted by compound 7c.     

Synthesis,cleavage, and antifungal activity of a number of novel,water-soluble ester prodrugs of antifungal triazole CS-758

In this study, the synthesis and evaluation of a number of esters of CS-758 as injectable prodrugs are described. Phosphoryl ester 1a was soluble in water (>30 mg/mL) and was converted to CS-758 in human liver microsome. It was also converted to CS-758 in rats after iv administration, wherein the bioavailability of CS-758 was 53%. Compound 1a (iv) reduced the viable cell counts in kidneys in a murine systemic Candida albicans infection model, wherein the effect was comparable to or slightly superior to that of CS-758 (po). The prodrug 1a proved to be a promising injectable antifungal agent whose further evaluation is warranted.     

Design,synthesis, in vitro and in vivo evaluation,and structure-activity relationship (SAR) discussion of novel dipeptidyl boronic acid proteasome inhibitors as orally available anti-cancer agents for the treatment of multiple myeloma and mechanism studies

A series of novel dipeptidyl boronic acid inhibitors of 20S proteasome were designed and synthesized. Aliphatic groups at R¹ position were designed for the first time to fully understand the SAR (structure–activity relationship). Among the screened compounds, novel inhibitor 5c inhibited the CT-L (chymotrypsin-like) activity with IC₅₀ of 8.21?nM and the MM (multiple myeloma) cells RPMI8226, U266B and ARH77 proliferations with the IC₅₀ of 8.99, 6.75 and 9.10?nM, respectively, which showed similar in vitro activities compared with the compound MLN2238 (biologically active form of marketed MLN9708). To investigate the oral availability, compound 5c was esterified to its prodrug 6a with the enzymatic IC₅₀ of 6.74?nM and RPMI8226, U266B and ARH77 cell proliferations IC₅₀ of 2.59, 4.32 and 3.68?nM, respectively. Furthermore, prodrug 6a exhibited good pharmacokinetic properties with oral bioavailability of 24.9%, similar with MLN9708 (27.8%). Moreover, compound 6a showed good microsomal stabilities and displayed stronger in vivo anticancer efficacy than MLN9708 in the human ARH77 xenograft mouse model. Finally, cell cycle results showed that compound 6a had a significant inhibitory effect on CT-L and inhibited cell cycle progression at the G2M stage.     

Synthesis of novel [1,2]-diamines with antituberculosis activity

Guided by the metabolism information of SQ109, derivatives with substituted geranylamine moiety or substituted admantane ring of SQ109 were synthesized and evaluated as antituberculosis agents. Among all tested compounds, compound 11c showed the most potent antituberculosis activity with MIC value of 0.3 μM against Mycobacterium tuberculosis H37Rv.     

Discovery of a novel bicyclic compound,DS54360155, as an orally potent analgesic without mu-opioid receptor agonist activity

We synthesized derivatives of a natural alkaloid, conolidine, and evaluated these derivatives in the acetic acid-induced writhing test and formalin test in ddY mice after oral administration. As a result, we identified (5S)-6-methyl-1,3,4,5,6,8-hexahydro-7H-2,5-methano[1,5]diazonino[7,8-b]indol-7-one sulfate salt, 15a (DS54360155), with a unique and original bicyclic skeleton, as an analgesic more potent than conolidine. Moreover, 15a did not exhibit mu-opioid receptor agonist activity.     

Water-soluble phosphate prodrugs of pleuromutilin analogues with potent in vivo antibacterial activity against Gram-positive pathogens

A phosphate prodrug strategy was investigated to address the problem of poor aqueous solubility of pleuromutilin analogues. Water-soluble phosphate prodrugs 6a, 6b and 6c of pleuromutilin analogues were designed and synthesized. Three compounds all exhibited excellent aqueous solubility (>50 mg/mL) at near-neutral pH and sufficient stability in buffer solution. In particular, the phenol pleuromutilin prodrug 6c displayed favourable pharmacokinetic profiles and comparable potency with vancomycin against MSSA and MRSA strains in vivo.     

Discovery of a novel chimeric ubenimex–gemcitabine with potent oral antitumor activity

Herein, a novel mutual prodrug BC-A1 was discovered by integrating ubenimex and gemcitabine into one molecule. Biological characterization revealed that compound BC-A1 could maintain both the anti-CD13 activity of ubenimex and the cytotoxic activity of gemcitabine in vitro. Further characterization also demonstrated that compound BC-A1 exhibited significant anti-invasion and anti-angiogenesis effects in vitro. The preliminary stability test of BC-A1 revealed that it could release gemcitabine in vitro. The in vivo anti-tumor results in liver cancer showed that at the same dosage, oral administration of BC-A1 was as potent as intraperitoneal administration of gemcitabine. This warranted the further research and development of the orally active prodrug BC-A1 because gemcitabine can not be orally administrated in clinic.     

In Vitro Characterization of the Anti-Bacterial Activity of SQ109 against Helicobacter pylori

The most evident challenge to treatment of Helicobacter pylori, a bacterium responsible for gastritis, peptic ulcers and gastric cancer, is the increasing rate of resistance to all currently used therapeutic antibiotics. Thus, the development of novel therapies is urgently required. N-geranyl-N''-(2-adamantyl) ethane-1, 2-diamine (SQ109) is an ethylene diamine-based antitubercular drug that is currently in clinical trials for the treatment of tuberculosis (TB). Previous pharmacokinetic studies of SQ109 revealed that persistently high concentrations of SQ109 remain in the stomach 4 hours post oral administration in rats. This finding, combined with the need for new anti- Helicobacter therapies, prompted us to define the in vitro efficacy of SQ109 against H. pylori. Liquid broth micro-dilution was used for susceptibility studies to determine the antimicrobial activity of SQ109 against a total of 6 laboratory strains and 20 clinical isolates of H. pylori; the clinical isolates included a multi-drug resistant strain. All strains tested were susceptible to SQ109 with MIC and MBC ranges of 6-10 µM and 50-60 µM, respectively. SQ109 killing kinetics were concentration- and time-dependent. SQ109 killed H. pylori in 8-10 h at 140 µM (2MBCs) or 4-6 h at 200 µM (~3MBCs). Importantly, though the kinetics of killing were altered, SQ109 retained potent bactericidal activity against H. pylori at low pH. Additionally, SQ109 demonstrated robust thermal stability and was effective at killing slow growing or static bacteria. In fact, pretreatment of cultures with a bacteriostatic concentration of chloramphenicol (Cm) synergized the effects of typically bacteriostatic concentrations of SQ109 to the level of five-logs of bacterial killing. A molar-to-molar comparison of the efficacy of SQ109 as compared to metronidazole (MTZ), amoxicillin (AMX), rifampicin (RIF) and clarithromycin (CLR), revealed that SQ109 was superior to MTZ, AMX and RIF but not to CLR. Finally, the frequency of resistance to SQ109 was low and electron microscopy studies revealed that SQ109 interacted with bacterial inner membrane and cytoplasmic content(s). Collectively, our in vitro data demonstrate that SQ109 is an effective monotherapy against susceptible and multi-drug resistant strains of H. pylori and may be useful alone or in combination with other antibiotics for development as a new class of anti- Helicobacter drugs.     

Orally active C-6 heteroaryl- and heterocyclyl-substituted imidazo[1,2-a]pyridine acid pump antagonists (APAs)

Acid pump antagonists (APAs) such as the imidazo[1,2-a]pyridine AZD-0865 2 have proven efficacious at low oral doses in acid related gastric disorders. Herein we describe some of the broader SAR in this class of molecule and detail the discovery of an imidazo[1,2-a]pyridine 15 which has excellent efficacy in animal models of gastric acid secretion following oral administration, as well as a good overall developability profile. The discovery strategy focuses on use of heteroaryl and heterocyclic substituents at the C-6 position and optimization of developability characteristics through modulation of global physico-chemical properties.     

Discovery of pyridone-containing imidazolines as potent and selective inhibitors of neuropeptide Y Y5 receptor

A series of 2-pyridone-containing imidazoline derivatives was synthesized and evaluated as neuropeptide Y Y5 receptor antagonists. Optimization of the 2-pyridone structure on the 2-position of the imidazoline ring led to identification of 1-(difluoromethyl)-5-[(4S,5S)-4-(4-fluorophenyl)-4-(6-fluoropyridin-3-yl)-5-methyl-4,5-dihydro-1H-imidazol-2-yl]pyridin-2(1H)-one (7m). Compound 7m displayed statistically significant inhibition of food intake in an agonist-induced food intake model in SD rats and no adverse cardiovascular effects in anesthetized dogs. In addition, markedly higher brain penetrability and a lower plasma Occ90 value were observed in P-gp-deficient mdr1a (?/?) mice compared to mdr1a (+/+) mice after oral administration of 7m.     

Optimization of spirocyclic proline tryptophan hydroxylase-1 inhibitors

As a follow-up to the discovery of our spirocyclic proline-based TPH1 inhibitor lead, we describe the optimization of this scaffold. Through a combination of X-ray co-crystal structure guided design and an in vivo screen, new substitutions in the lipophilic region of the inhibitors were identified. This effort led to new TPH1 inhibitors with in vivo efficacy when dosed as their corresponding ethyl ester prodrugs. In particular, 15b (KAR5585), the prodrug of the potent TPH1 inhibitor 15a (KAR5417), showed robust reduction of intestinal serotonin (5-HT) levels in mice. Furthermore, oral administration of 15b generated high and sustained systemic exposure of the active parent 15a in rats and dogs. KAR5585 was selected for further pharmacological evaluation in disease models associated with a dysfunctional peripheral 5-HT system.     

Discovery of 2-aminoisobutyric acid ethyl ester (AIBEE) phosphoramidate prodrugs for delivering nucleoside HCV NS5B polymerase inhibitors

Our HCV research program investigated novel 2′-dihalogenated nucleoside HCV polymerase inhibitors and identified compound 1, a 5′-phosphoramidate prodrug of 2′-deoxy-2′-α-bromo-β-chloro uridine. Although 1 had a favorable in vitro activity profile in HCV replicons, oral dosing in dog resulted in low levels of the active 5′-triphosphate (TP) in liver. Metabolism studies using human hepatocytes provided a simple assay for screening alternative phosphoramidate prodrug analogs. Compounds that produced high TP concentrations in hepatocytes were tested in dog liver biopsy studies. This method identified 2-aminoisobutyric acid ethyl ester (AIBEE) phosphoramidate prodrug 14, which provided 100-fold higher TP concentrations in dog liver in comparison to 1 (4 and 24 h after 5 mg/kg oral dose).     

Design,synthesis, and preliminary pharmacological evaluation of new imidazolinones as l-DOPA prodrugs

l-DOPA, the immediate biological precursor of dopamine, is still considered the drug of choice in the treatment of Parkinson’s disease. However, therapy with l-DOPA is associated with a number of acute problems. With the aim to increase the bioavailability after oral administration, we designed a multi-protected l-DOPA prodrugs able to release the drug by both spontaneous chemical or enzyme catalyzed hydrolysis. The new compounds have been synthesized and preliminarily evaluated for their water solubility, log P, chemical stability, and enzymatic stability. The results indicate that the incorporation of the amino acidic moiety of l-DOPA into an imidazoline-4-one ring provides prodrugs sufficiently stable to potentially cross unchanged the acidic environment of the stomach, and to be absorbed from the intestine. They also might be able to release l-DOPA in human plasma after enzymatic hydrolysis. The ability of prodrugs 6a–b to increase basal levels of striatal DA, and influence brain neurochemistry associated with dopaminergic activity following oral administration, as well as the radical-scavenging activity against DPPH for compounds 6a–b and 15a are also reported.     

Prodrugs of the cancer cell selective anti-cancer agent (Z)-2-(1H-indol-3-yl)-3-(isoquinolin-5-yl)acrylonitrile (A131) are orally efficacious in a mouse model of resistant colon cancer

A131 (1) possesses a unique cancer cell selective dual mechanism of action where cancer cells are killed but normal cells only undergo growth arrest and are able to regrow after removal of 1. SAR studies of 1 indicate that only the specific structure of 1 elicits the full pharmacological effect. However, application of 1 in mouse models of cancer has been hampered by its low solubility and stability when given orally. In this work we describe the study of various prodrugs based on modification of the indole nitrogen. A range of acyl analogues were prepared as prodrugs which were shown to undergo degradation to the parent drug in plasma. A preferred prodrug fully elicited the pharmacological effects of 1 in cells and led to high aqueous solubility suitable for oral administration. In a mouse model of paclitaxel-resistant colon cancer, compound 10, as a TFA salt, showed 76% tumor growth inhibition when administered at an oral dose of 80?mg/kg twice a day.     

PEG-amino acid-przewaquinone a conjugations: Synthesis,physicochemical properties and protective effect in a rat model of brain ischemia-reperfusion

A total of 21 PEG-przewaquinone A conjugations with high drug loading ability, good water solubility and in vivo slow-release quality were obtained by conjugating przewaquinone A with PEG through amino acids and tripeptides spacers respectively. Notably, compound 3a can obviously reduce the brain ischemia-reperfusion damage dose-dependently in a rat model, which indicated the efficacy of our PEG prodrug strategy.     

Synthesis and evaluation of novel 7-azaindazolyl-indolyl-maleimide derivatives as antitumor agents and protein kinase C inhibitors

A series of novel 7-azaindazolyl-indolyl-maleimides were synthesized and evaluated for their antiproliferative activity in vitro against various human cancer cell lines and protein kinase C inhibitory activity. Compounds 8a–c, 8e and 14a were the most promising compounds against K562, A549, ECA-109, KB and SMMC-7721 cell lines in vitro. Compounds 9a–j showed moderate PKC inhibition. Further mechanism of action studies revealed that the antiproliferative activity of compound 8b in KB cells might involve the mitochondria-mediated apoptosis pathway.     

Synthesis and bioactive evaluation of a novel series of coumarinazoles

A series of novel coumarinazoles were designed, synthesized, and characterized by IR, NMR, MS and HRMS spectra. The bioactive assay for the newly prepared compounds against six bacteria and five fungi manifested that most new compounds exhibited good or even stronger antibacterial and antifungal activities in comparison with reference drugs Chloromycin, Norfloxacin and Fluconazole. Bis-azole alcohols 7a and 7d–e showed better anti-Candida utilis activity than mono-azole derivatives 4a and 4d–e at the tested concentrations, and they were more potent than the clinical Fluconazole. While triazole alcohol 7a gave comparable anti-Candida albicans and anti-Candida mycoderma activity to Fluconazole and better anti-MRSA activity than mono-triazole one 4a and clinical Norfloxacin. 1H-Benzoimidazol-2-ylthio coumarin derivatives 4e and 7e gave the strongest anti-Escherichia coli JM109 efficacy. Oxiran-2-ylmethoxy moiety was found to be a beneficial fragment to improve antibacterial and antifungal activity to some extent.     

N-(2,2-Dimethyl-2-(2-nitrophenyl)acetyl)-4-aminocyclophosphamide as a potential bioreductively activated prodrug of phosphoramide mustard

N-(2,2-Dimethyl-2-(2-nitrophenyl)acetyl)-4-aminocyclophosphamide isomers (DMNA-NH-CPA, 4) were synthesized stereospecifically from Boc-l-Hse(OBn)-OH and the degradation of the corresponding reduced amine 5a was investigated by UV/vis spectroscopy and LC/MS. The rate of cyclization of 5a was found to increase with decreasing pH, with half-lives ranging from 3.2 to 54 min at pH 4–7.4, suggesting that the cyclization is catalyzed by the hydronium ions. LC/MS analysis of the degradation products of 5a indicates that 4-aminocyclophosphamide is rapidly released from 4 upon reductive activation under acidic conditions and further decomposes into the cytotoxic phosphoramide mustard. These results validated 4-aminocyclophosphamide as a prodrug form of phosphoramide mustard and suggest that compound 4 can potentially be used as a prodrug of phosphoramide mustard for bioreductive activation.     

Design,synthesis and biological study of hybrid drug candidates of nitric oxide releasing cucurbitacin-inspired estrone analogs for treatment of hepatocellular carcinoma

Development of hybrid drug candidates is well known strategy for designing antitumor agents. Herein, a novel class of nitric oxide donating cucurbitacin inspired estrone analogs (NO-CIEAs) were designed and synthesized as multitarget agents. Synthesized analogs were initially evaluated for their anti-hepatocellular carcinoma activities. Among the tested analogs, NO-CIEAs 17 and 20a exhibited more potent activity against HepG2 cells (IC₅₀ = 4.69 and 12.5 µM, respectively) than the reference drug Erlotinib (IC₅₀ = 25 µM). Interestingly, NO-CIEA 17 exerted also a high potent activity against Erlotinib-resistant HepG2 cell line (HepG2-R) (IC₅₀ = 8.21 µM) giving insight about its importance in drug resistance therapy. Intracellular measurements of NO revealed that NO-CIEAs 17 and 20a showed a significant increase in NO production in tumor cells after 1 h of incubation comparable to the reference prodrug JS-K. Flow cytometric analysis showed that both NO-CIEAs 17 and 20a mainly arrested the HepG2 cells in the G0/G1 phase. Also, In-Cell Based ELISA screening showed that NO-CIEA 17 resulted in a potential inhibitory activity towards the EGFR and MAPK (25% and 29% inhibition compared to untreated control cells, respectively). This data suggests the binding ability of NO-CIEA 17 to the EGFR and ERK to be well correlated along with the docking and cellular studies. Also, treatment of HepG2-R cells with NO-CIEA 17 showed a potential reduction of MRP2 expression in a dose dependent manner providing a significant impact on the chemotherapeutic resistance. Overall, the current study provides a potential new approach for the discovery of a novel antitumor agent against HCC.     

Discovery of potent and orally active 3-alkoxy-5-phenoxy-N-thiazolyl benzamides as novel allosteric glucokinase activators

Identification and synthesis of novel 3-alkoxy-5-phenoxy-N-thiazolyl benzamides as glucokinase activators are described. Removal of an aniline structure of the prototype lead (2a) and incorporation of an alkoxy or phenoxy substituent led to the identification of 3-Isopropoxy-5-[4-(methylsulfonyl)phenoxy]-N-(4-methyl-1,3-thiazol-2-yl)benzamide (27e) as a novel, potent, and orally bioavailable GK activator. Rat oral glucose tolerance test indicated that 27e exhibited a glucose-lowering effect after 10 mg/kg oral administration.