Novel alkylpolyaminoguanidines and alkylpolyaminobiguanides with potent antitrypanosomal activity

A series of polyaminoguanidines and polyaminobiguanides were synthesized and evaluated as potential antitrypanosomal agents. These analogues inhibit trypanothione reductase (TR) with IC50 values as low as 0.95 microM, but do not inhibit the closely related human enzyme glutathione reductase (GR). The most effective analogues, 7a, 7b and 8d, inhibited parasitic growth in vitro with IC50 values of 0.18, 0.09 and 0.18 microM, respectively. These agents represent a promising new class of potential antitrypanosomal agents.     

Thienopyridines: nitric oxide synthase inhibitors with potent in vivo activity

5-Substituted 7-amino-4,5-tetrahydrothieno[2,3-c]pyridines and 6-substituted 4-amino-6,7-dihydrothieno[3,2-c]pyridines were shown to be exceptionally potent inhibitors of inducible and neuronal nitric oxide synthase. Selectivity and potency could be modulated by variation of the 5- or 6-substituent. Compound 3e showed potent in vivo inhibition of iNOS.     

Pyrrolo-pyrimidones: a novel class of MK2 inhibitors with potent cellular activity

Pyrrolo-pyrimidones of the general structure 1 were synthesized and evaluated for their potential as MK2 inhibitors. Potent derivatives were discovered which inhibit MK2 in the nanomolar range and show potent inhibition of cytokine release from LPS-stimulated monocytes. These derivatives were shown to inhibit phosphorylation of hsp27, a downstream target of MK2 and are modestly selective in a panel of 28 kinases.     

Endogenous inhibitors of HIV: potent anti-HIV activity of leukemia inhibitory factor

The correlates of protective immunity in HIV-1 infection include the endogenous production of compounds with anti-HIV-1 activity. These compounds can be produced independently of specific humoral or cellular immune responses. A model of compartmental inhibition of HIV-1 infection is the placenta, an organ that prevents transmission of HIV-1 to the fetus in the majority of HIV-1 pregnancies. Studies of this organ elucidated new compounds and mechanisms for prevention and treatment of HIV including the potent inhibitor of HIV-1, leukemia inhibitory factor (LIF). Besides coordinating the humoral and cellular immune responses, cytokines such as IFN-gamma exhibit intrinsic antiviral activity that represents the first line of defense against pathogens prior to the development of a specific immune response. The study of antiviral factors is particularly important in HIV/AIDS because of the direct destruction of the immune system by HIV-1. In this report, we focus on the identification and mechanism of endogenously produced anti-HIV factors and the overall function of these factors in the prevention and treatment of HIV/AIDS.     

Vinyl sulfone-based inhibitors of trypanosomal cysteine protease rhodesain with improved antitrypanosomal activities

The number of reported cases of Human African Trypanosmiasis (HAT), caused by kinetoplastid protozoan parasite Trypanosoma brucei, is declining in sub-Saharan Africa. Historically, such declines are generally followed by periods of higher incidence, and one of the lingering public health challenges of HAT is that its drug development pipeline is historically sparse. As a continuation of our work on new antitrypanosomal agents, we found that partially saturated quinoline-based vinyl sulfone compounds selectively inhibit the growth of T. brucei but displayed relatively weak inhibitory activity towards T. brucei’s cysteine protease rhodesain. While two nitroaromatic analogues of the quinoline-based vinyl sulfone compounds displayed potent inhibition of T. brucei and rhodesain. The quinoline derivatives and the nitroaromatic-based compounds discovered in this work can serve as leads for ADME-based optimization and pre-clinical investigations.     

Peptidomimetic inhibitors of protein farnesyltransferase show potent antimalarial activity

Malaria continues to represent a very serious health problem in the tropics. The current methods of clinical treatment are showing deficiencies due to the increased incidence of resistance in the parasite. In the present paper we report the design, synthesis, and evaluation of potential antimalarial agents against a novel target, protein farnesyltransferase. We show that the most potent compounds are active against Plasmodium falciparum in vitro at submicromolar concentrations.     

Pyridyl aminothiazoles as potent Chk1 inhibitors: optimization of cellular activity

Translation of significant biochemical activity of pyridyl aminothiazole class of Chk1 inhibitors into functional CEA potency required analysis and adjustment of both physical properties and kinase selectivity profile of the series. The steps toward optimization of cellular potency included elimination of CDK7 activity, reduction of molecular weight and polar surface area and increase in lipophilicity of the molecules in the series.     

Studies toward the structural optimization of novel thiazolylhydrazone-based potent antitrypanosomal agents

In previous studies, we identified promising anti-Trypanosoma cruzi cruzain inhibitors based on thiazolylhydrazones. To optimize this series, a number of medicinal chemistry directions were explored and new thiazolylhydrazones and thiosemicarbazones were thus synthesized. Potent cruzain inhibitors were identified, such as thiazolylhydrazones 3b and 3j, which exhibited IC(50) of 200-400nM. Furthermore, molecular docking studies showed concordance with experimentally derived structure-activity relationships (SAR) data. In the course of this work, lead compounds exhibiting in vitro activity against both the epimastigote and trypomastigote forms of T. cruzi were identified and in vivo general toxicity analysis was subsequently performed. Novel SAR were documented, including the importance of the thiocarbonyl carbon attached to the thiazolyl ring and the direct comparison between thiosemicarbazones and thiazolylhydrazones.     

Enantiospecific antitrypanosomal in vitro activity of eflornithine

The polyamine synthesis inhibitor eflornithine is a recommended treatment for the neglected tropical disease Gambian human African trypanosomiasis in late stage. This parasitic disease, transmitted by the tsetse fly, is lethal unless treated. Eflornithine is administered by repeated intravenous infusions as a racemic mixture of L-eflornithine and D-eflornithine. The study compared the in vitro antitrypanosomal activity of the two enantiomers with the racemic mixture against three Trypanosoma brucei gambiense strains. Antitrypanosomal in vitro activity at varying drug concentrations was analysed by non-linear mixed effects modelling. For all three strains, L-eflornithine was more potent than D-eflornithine. Estimated 50% inhibitory concentrations of the three strains combined were 9.1 μM (95% confidence interval [8.1; 10]), 5.5 μM [4.5; 6.6], and 50 μM [42; 57] for racemic eflornithine, L-eflornithine and D-eflornithine, respectively. The higher in vitro potency of L-eflornithine warrants further studies to assess its potential for improving the treatment of late-stage Gambian human African trypanosomiasis.     

Design and synthesis of highly potent HIV protease inhibitors with activity against resistant virus

A series of highly potent HIV protease inhibitors have been designed and synthesized. These compounds are active against various clinical viral isolates as well as wild-type virus. The synthesis and biological activity of these HIV protease inhibitors are discussed.     

Discovery of pyrazolopyrimidine derivatives as potent BTK inhibitors with effective anticancer activity in MCL

Bruton’s tyrosine kinase (BTK) is a key regulator of B-cell receptor (BCR) signaling pathway and takes effect in the regulation of B-cell activation, survival, proliferation and differentiation. It has been proved that BTK is commonly overexpressed in mantle cell lymphoma (MCL), which makes it a focus of targeted therapy for MCL. Our studies yielded a novel series of pyrazolopyrimidine derivatives capable of potent inhibition of BTK. Notably, 12a showed higher selectivity against BTK and exhibited robust antiproliferative effects in both mantle cell lymphoma cell lines and primary patient tumor cells. Low micromolar doses of 12a induced strong cell apoptosis in Jeko-1 and Z138 cells.     

Synthesis and antibacterial activity of novel and potent DNA gyrase inhibitors with azole ring

The 4-piperidyl moiety and the pyrazole ring in 1-(3-chlorophenyl)-5-(4-phenoxyphenyl)-3-(4-piperidyl)pyrazole 2, which has previously shown improved DNA gyrase inhibition and target-related antibacterial activity, were transformed to other groups and the in vitro antibacterial activity of the synthesized compounds was evaluated. The selected pyrazole, oxazole and imidazole derivatives showed moderate inhibition against DNA gyrase and topoisomerase IV with similar IC(50) values (IC(50)=9.4-25 microg/mL). In addition, many of the pyrazole, oxazole and imidazole derivatives synthesized in this study exhibited potent antibacterial activity against quinolone-resistant clinical isolates and coumarin-resistant laboratory isolates of Gram-positive bacteria with minimal inhibitory concentration values equivalent to those against susceptible strains.     

Preparation and antitrypanosomal activity of secochiliolide acid derivatives

Secochiliolide acid (1) isolated from the Patagonian shrub Nardophyllum bryoides, was used as a scaffold for the preparation of a series of nine derivatives. Compound 1 and its derivatives were tested against Trypanosoma cruzi epimastigotes grown in liquid media. It was first observed that secochiliolide acid (1) inhibited the proliferation of the parasites, with an IC₅₀ of 2 μg/mL. Six of the synthesized derivatives were also active with IC₅₀’s between 2 and 7 μg/mL which are comparable to that of the commercial drug benznidazole (2.5 μg/mL). These results indicate that the carboxyl group is not essential for the bioactivity of 1, while the presence of the tetrasubstituted exocyclic double bond seems to be important. Moreover, the presence of the furan and spirolactone rings is not essential for the bioactivity per se, but is important in combination with other structural fragments present in the molecule.     

Synthesis and biological activity of novel potent endothelin-converting enzyme-1 inhibitors

Through directed screening of metalloprotease inhibitors, CGS 30084 (1) has been identified as a potent endothelin-converting enzyme-1 (ECE-1) inhibitor in vitro (IC50 = 77 nM). Herein we report the syntheses and biological activities of analogues derived from this lead, based on modifications of the biphenyl moiety. Compound 10, the thioacetate methyl ester prodrug derivative of compound 6m, was found to be an orally active and potent inhibitor of ECE-1 activity in rats.     

Imidazolinones: potent inhibitors of acetohydroxyacid synthase

The imidazolinones, a new chemical class of herbicides, were shown to be uncompetitive inhibitors of acetohydroxyacid synthase from corn. This is the first common enzyme in the biosynthetic pathway for valine, leucine, and isoleucine. The K_i for the imidazolinones tested ranged from 2 to 12 micromolar. These results may explain the mechanism of action of these new herbicides.     

Synthesis and biological evaluation of 1,4-benzodiazepin-2-ones with antitrypanosomal activity

A library of 1,4-benzodiazepines has been synthesized and evaluated against Trypanosoma brucei, a causative parasite of Human African trypanosomiasis. Benzodiazepines possessing a P2- transporter motif were found to have MIC values as low as 0.78 μM.     

Development of improved inhibitors of wall teichoic acid biosynthesis with potent activity against Staphylococcus aureus

A small molecule (1835F03) that inhibits Staphylococcus aureus wall teichoic acid biosynthesis, a proposed antibiotic target, has been discovered. Rapid, parallel, solution-phase synthesis was employed to generate a focused library of analogs, providing detailed information about structure–activity relationships and leading to the identification of targocil, a potent antibiotic.     

Design,synthesis, and biological activity of novel tetrahydropyrazolopyridone derivatives as FXa inhibitors with potent anticoagulant activity

A series of novel tetrahydropyrazolopyridone derivatives containing 1,3,4-triazole, triazolylmethyl, and partially saturated heterocyclic moieties as P2 binding element was designed, synthesized, and evaluated in vitro for anticoagulant activity in human and rabbit plasma. All compounds showed moderate to significant potency, and compounds 15b, 15c, 20b, 20c, and 22b were further examined for their inhibitory activity against human FXa in vitro. While compounds 15c and 22b were tested for rat venous thrombosis in vivo. The most promising compound 15c, with an IC₅₀ (FXa) value of 0.14 μM and 98% inhibition rate, warranted further investigation as an FXa inhibitor.     

Indirubin derivatives as potent FLT3 inhibitors with anti-proliferative activity of acute myeloid leukemic cells

Indirubin derivatives were identified as potent FLT3 tyrosine kinase inhibitors with anti-proliferative activity at acute myeloid leukemic cell lines, RS4;11 and MV4;11 which express FLT3-WT and FLT3-ITD mutation, respectively. Among several 5 and 5′-substituted indirubin derivatives, 5-fluoro analog, 13 exhibited potent inhibitory activity at FLT3 (IC₅₀ = 15 nM) with more than 100-fold selectivity versus 6 other kinases and potent anti-proliferative effect for MV4;11 cells (IC₅₀ = 72 nM) with 30-fold selectivity versus RS4;11 cells. Cell cycle analysis indicated that compound 13 induced cell cycle arrest at G₀/G₁ phase in MV4;11 cells.