Furoxan derivatives demonstrated in vivo efficacy by reducing Mycobacterium tuberculosis to undetectable levels in a mouse model of infection.

OBJECTIVES: The most recent survey conducted by the World Health Organization described Tuberculosis (TB) as one of the top 10 causes of death and the leading cause of death from a single infectious agent. The increasing number of TB-resistant cases has contributed to this scenario. In light of this, new strategies to control and treat the disease are necessary. Our research group has previously described furoxan derivatives as promising scaffolds to be explored as new antitubercular drugs. RESULTS: Two of these furoxan derivatives, (14b) and (14c), demonstrated a high selectivity against Mycobacterium tuberculosis. The compounds (14b) and (14c) were also active against a latent M. tuberculosis strain, with MIC90 values of 6.67 µM and 9.84 µM, respectively; they were also active against monoresistant strains (MIC90 values ranging from 0.61 to 20.42 µM) and clinical MDR strains (MIC90 values ranging from 3.09 to 42.95 µM). Time-kill experiments with compound (14c) showed early bactericidal effects that were superior to those of the first- and second-line anti-tuberculosis drugs currently used in therapy. The safety of compounds (14b) and (14c) was demonstrated by the Ames test because these molecules were not mutagenic under the tested conditions. Finally, we confirmed the safety, and high efficacy of compounds (14b) and (14c), which reduced M. tuberculosis to undetectable levels in a mouse aerosol model of infection. CONCLUSION: Altogether, we have identified two advanced lead compounds, (14b) and (14c), as novel promising candidates for the treatment of TB infection.

Design, Synthesis, and Efficacy Testing of Nitroethylene- and 7-Nitrobenzoxadiazol-Based Flavodoxin Inhibitors against Helicobacter pylori Drug-Resistant Clinical Strains and in Helicobacter pylori-Infected Mice.

Helicobacter pylori (Hp) infection is the main cause of peptic ulcer and gastric cancer. Hp eradication rates have fallen due to increasing bacterial resistance to currently used broad-spectrum antimicrobials. We have designed, synthesized, and tested redox variants of nitroethylene- and 7-nitrobenzoxadiazole-based inhibitors of the essential Hp protein flavodoxin. Derivatives of the 7-nitrobenzoxadiazole lead, carrying reduced forms of the nitro group and/or oxidized forms of a sulfur atom, display high therapeutic indexes against several reference Hp strains. These inhibitors are effective against metronidazole-, clarithromycin-, and rifampicin-resistant Hp clinical isolates. Their toxicity for mice after oral administration is low, and, when administered individually at single daily doses for 8 days in a mice model of Hp infection, they decrease significantly Hp gastric colonization rates and are able to eradicate the infection in up to 60% of the mice. These flavodoxin inhibitors constitute a novel family of Hp-specific antimicrobials that may help fight the constant increase of Hp antimicrobial-resistant strains.

Nonclinical Safety Assessment of the γ-Secretase Inhibitor Avagacestat.

The toxicity of avagacestat, a sulfonamide-based gamma (γ)-secretase inhibitor that was in development as a treatment for Alzheimer's disease, was evaluated in a comprehensive nonclinical toxicology program that included 6-month and 1-year repeat-dose toxicity studies in rats and dogs, respectively. There was a spectrum of mechanism-based changes attributed to inhibition of Notch signaling that regulates the differentiation and proliferation of cells throughout development and in adult tissues. In both rats and dogs, ovarian follicular degeneration and atrophy and a low incidence of granulosa cell hyperplasia and benign granulosa-thecal cell tumors were observed. Gastrointestinal (GI) findings, including goblet cell metaplasia, dilatation of intestinal crypts/glands, mucosal epithelial necrosis and regeneration, and villous atrophy, were limited to dogs that had clinical evidence of GI toxicity. Other avagacestat-related findings attributed to interference with Notch signaling included decreases in peripheral lymphocytes (T and/or B cells) and lymphoid depletion in lymph nodes and the spleen in both species, as well as epiphyseal cartilage and trabecular bone changes in rats. Pharmacologically mediated decreases in brain and cerebrospinal fluid levels of ß-amyloid (Aß) peptides Aß40 and Aß42 and decreased expression of white blood cell mRNA levels of the Notch-regulated gene hairy and enhancer of split-1 confirmed target engagement at all doses. Reductions in brain Aß peptide levels (22 to 34%) in dogs after 1 year at exposures up to the no-observed-effect level for GI toxicity of 1.1× the human plasma exposure, and reversible GI changes at a 3.2× multiple, indicated that a sustained pharmacodynamic effect was attained at exposures without dose-limiting toxicity.

Discovery of Novel and Potent Stearoyl Coenzyme A Desaturase 1 (SCD1) Inhibitors as Anticancer Agents.

A lead compound A was identified previously as an stearoyl coenzyme A desaturase (SCD) inhibitor during research on potential treatments for obesity. This compound showed high SCD1 binding affinity, but a poor pharmacokinetic (PK) profile and limited chemical accessibility, making it suboptimal for use in anticancer research. To identify potent SCD1 inhibitors with more promising PK profiles, we newly designed a series of 'non-spiro' 4, 4-disubstituted piperidine derivatives based on molecular modeling studies. As a result, we discovered compound 1a, which retained moderate SCD1 binding affinity. Optimization around 1a was accelerated by analyzing Hansch-Fujita and Hammett constants to obtain 4-phenyl-4-(trifluoromethyl)piperidine derivative 1n. Fine-tuning of the azole moiety of 1n led to compound 1o (T-3764518), which retained nanomolar affinity and exhibited an excellent PK profile. Reflecting the good potency and PK profile, orally administrated compound 1o showed significant pharmacodynamic (PD) marker reduction (at 0.3mg/kg, bid) in HCT116 mouse xenograft model and tumor growth suppression (at 1mg/kg, bid) in 786-O mouse xenograft model. In conclusion, we identified a new series of SCD1 inhibitors, represented by compound 1o, which represents a promising new chemical tool suitable for the study of SCD1 biology as well as the potential development of novel anticancer therapies.

Identification of sperm mRNA biomarkers associated with testis injury during preclinical testing of pharmaceutical compounds.

The human testis is sensitive to toxicant-induced injury but current methods for detecting adverse effects are limited, insensitive and unreliable. Animal studies use sensitive histopathological endpoints to assess toxicity, but require testicular tissue that is not available during human clinical trials. More sensitive and reliable molecular biomarkers of testicular injury are needed to better monitor testicular toxicity in both clinical and preclinical. Adult male Wistar Han rats were exposed for 4weeks to compounds previously associated with testicular injury, including cisplatin (0, 0.2, 0.3, or 0.4mg/kg/day), BI665915 (0, 20, 70, 100mg/kg/d), BI665636 (0, 20, 100mg/kg/d) or BI163538 (0, 70, 150, 300mg/kg/d) to evaluate reproductive toxicity and assess changes in sperm mRNA levels. None of the compounds resulted in any significant changes in body, testis or epididymis weights, nor were there decreases in testicular homogenization resistant spermatid head counts. Histopathological evaluation found that only BI665915 treatment caused any testicular effects, including minor germ cell loss and disorganization of the seminiferous tubule epithelium, and an increase in the number of retained spermatid heads. A custom PCR-array panel was used to assess induced changes in sperm mRNA. BI665915 treatment resulted in a significant increase in clusterin (Clu) levels and decreases in GTPase, IMAP family member 4 (Gimap4), prostaglandin D2 synthase (Ptgds) and transmembrane protein with EGF like and two follistatin like domains 1 (Tmeff1) levels. Correlation analysis between transcript levels and quantitative histopathological endpoints found a modest association between Clu with retained spermatid heads. These results demonstrate that sperm mRNA levels are sensitive molecular indicators of testicular injury that can potentially be translated into a clinical setting.

[3, 4- dinitro-furazan-based oxidation furazan acute and subchronic toxicity studies].

OBJECTIVE: To study the 3, 4- dinitro-furazan-based oxidation furazan (DNTF) of sub-acute toxicity and chronic toxicity, to determine the acute toxicity classification DNTF, the nature of toxic effects and major target organ for the development provide the basis for occupational exposure limits. METHODS: ( 1) Acute toxicity: The oral gavage method once infected, symptoms of poisoning of animals observed to calculate the LD50DNTF and 95% confidence limits. ( 2) sub-chronic experiment: selection of 96 healthy SD rats were randomly divided into four groups, doses of 25, 56.2, 125 mg/kg and the negative control group, Exposure for ninety days,five days a week, once a day, The rats were killed at end of Exposure, heart, liver, spleen, lung, kidney, brain,testis, uterus were taken to observe the pathological changes. RESULTS: ( 1) Acute oral toxicity test results indicate that DNTF rat oral LD50 greater than 5000 mg/kg, DNTF mice treated by oral LD50 4589 mg/kg, 95%confidence limit for the 4026-5230 mg/kg, Acute toxicity grade level is low toxicity compounds. (2) Sub-chronic toxicity experiment, the high-dose male rats, high, medium and low-dose group female rats weight gain than the negative control group, compared with the control group, the difference was statistically significant (P<0.05).125 mg/kg of serum alanine aminotransferase, aspartate aminotransferase was significantly higher. 125 mg/kg dose groups, liver, kidney, lung, testicular factor was significantly higher. Liver, kidney, lung histological examination showed obvious morphological changes. CONCLUSION: Acute toxicity grade DNTF low toxicity level compounds, target organ toxicity of liver, kidney and lung.

Identification of thioredoxin glutathione reductase inhibitors that kill cestode and trematode parasites.

Parasitic flatworms are responsible for serious infectious diseases that affect humans as well as livestock animals in vast regions of the world. Yet, the drug armamentarium available for treatment of these infections is limited: praziquantel is the single drug currently available for 200 million people infected with Schistosoma spp. and there is justified concern about emergence of drug resistance. Thioredoxin glutathione reductase (TGR) is an essential core enzyme for redox homeostasis in flatworm parasites. In this work, we searched for flatworm TGR inhibitors testing compounds belonging to various families known to inhibit thioredoxin reductase or TGR and also additional electrophilic compounds. Several furoxans and one thiadiazole potently inhibited TGRs from both classes of parasitic flatworms: cestoda (tapeworms) and trematoda (flukes), while several benzofuroxans and a quinoxaline moderately inhibited TGRs. Remarkably, five active compounds from diverse families possessed a phenylsulfonyl group, strongly suggesting that this moiety is a new pharmacophore. The most active inhibitors were further characterized and displayed slow and nearly irreversible binding to TGR. These compounds efficiently killed Echinococcus granulosus larval worms and Fasciola hepatica newly excysted juveniles in vitro at a 20 µM concentration. Our results support the concept that the redox metabolism of flatworm parasites is precarious and particularly susceptible to destabilization, show that furoxans can be used to target both flukes and tapeworms, and identified phenylsulfonyl as a new drug-hit moiety for both classes of flatworm parasites.

Identification and development of 2,5-disubstituted oxadiazole as potential candidate for treatment of XDR and MDR tuberculosis.

Tuberculosis, the infection on the verge of eradication once, is now a great threat to mankind. Emergence of MDR and XDR-TB synergised with HIV and other immune-compressive diseases have increased the life threatening capacities of the disease. A small molecule has been identified here, which showed potent anti-tubercular activity. The identified hit compound has also been proved active against nearly 25 clinical isolates comparable with isoniazid.

Metabolic, idiosyncratic toxicity of drugs: overview of the hepatic toxicity induced by the anxiolytic, panadiplon.

Preclinical drug safety evaluation studies, typically conducted in two or more animal species, reveal and define dose-dependent toxicities and undesirable effects related to pharmacological mechanism of action. Idiosyncratic toxic responses are often not detected during this phase in development due to their relative rarity in incidence and differences in species sensitivity. This paper reviews and discusses the metabolic idiosyncratic toxicity and species differences observed for the experimental non-benzodiazepine anxiolytic, panadiplon. This compound produced evidence of hepatic toxicity in Phase 1 clinical trial volunteers that was not predicted by rat, dog or monkey preclinical studies. However, subsequent studies in Dutch-belted rabbits revealed a hepatic toxic syndrome consistent with a Reye's Syndrome-like idiosyncratic response. Investigations into the mechanism of toxicity using rabbits and cultured hepatocytes from several species, including human, provided a sketch of the complex pathway required to produce hepatic injury. This pathway includes drug metabolism to a carboxylic acid metabolite (cyclopropane carboxylic acid), inhibition of mitochondrial fatty acid beta-oxidation, and effects on intermediary metabolism including depletion of glycogen and disruption of glucose homeostasis. We also provide evidence suggesting that the carboxylic acid metabolite decreases the availability of liver CoA and carnitine secondary to the formation of unusual acyl derivatives. Hepatic toxicity could be ameliorated by administration of carnitine, and to a lesser extent by pantothenate. These hepatocellular pathway defects, though not directly resulting in cell death, rendered hepatocytes sensitive to secondary stress, which subsequently produced apoptosis and hepatocellular necrosis. Not all rabbits showed evidence of hepatic toxicity, suggesting that individual or species differences in any step along this pathway may account for idiosyncratic responses. These differences may be roughly applied to other metabolic idiosyncratic hepatotoxic responses and include variations in drug metabolism, effects on mitochondrial function, nutritional status, and health or underlying disease.

Herbicides and the microtubular apparatus of Nicotiana tabacum pollen tube: immunofluorescence and immunogold labelling studies.

Herbicides are chemical compounds widely used in agriculture. As their intensive application is becoming a cause of environmental pollution, detailed and more sophisticated investigations are needed to understand better their consequences at the biological level. After herbicides are dispersed in the fields, they establish chemical interactions with both target and non-target plants. In both cases, herbicides can interact with the plant reproductive apparatus; consequently they could play a role during the fertilisation process in higher plants. Using an antibody to the alpha-tubulin subunit in immunofluorescence and immunoelectron microscopy techniques, we investigated the distribution of microtubules in Nicotiana tabacum pollen tubes grown under in vitro conditions in the presence of five different herbicides selected among those used frequently in central Italy. Herbicides have a specific effect on the microtubular apparatus of both pollen tube and generative cell. In addition to other tests and assays, these results suggest that the microtubule cytoskeleton of pollen tubes can be used as a bioindicator for studying the toxicity effects induced by herbicides.

Pharmacological screening of few new 2-(substituted acetyl) amino-5-alkyl-1,3,4-oxadiazoles.

Nine new 2-(substituted acetyl) amino-5-alkyl-1,3,4-oxadiazoles were synthesised and confirmed on the basis of IR and nitrogen analysis. These were screened for spasmolytic, anti-inflammatory and their effects on blood pressure after determining ALD50. Compounds GK-4 i.e. 2-(diethylaminoacetyl)- amino-5-methyl-1,3,4-oxadiazole and GK-8 i.e. 2-(din-propylamino acetyl)-amino-5-ethyl-1,3,4-oxadiazole were found to be spasmolytic. Compound GK-6 i.e. 2-(diethylaminoacetyl)-amino-5-n-propyl-1,3,4-oxadiazole was found to be a potent hypotensive agent with the effect lasting for more than two hours.

[Some pharmacological actions of furazan hydrazides and of 2 correspondent furoxan derivatives]. / Alcune azioni farmacologiche dell'idrazide furazanica e dei due corrispondenti derivati furossanici

A study has been made of the acute toxicity, action on the guinea pig ileum, on the ventricle edge, on frog spinal reflex, and on the respiratory and cardiac activity and pulse of the following compounds: 3-methyl-4-furazancarbohydrazide (I); 3-methyl-4-furoxancarbohydrazide (II); 4-methyl-3-furoxancarbohydrazide (III). The compounds had no action on guinea pig ileum or ventricle edge. Compound (I) showed depressant activity on frog spinal reflex whereas compound (II) showed excitation and compound (III) had no direct spinal action. The compounds tested affected respiration and ECG only at the highest doses used. The pulse rate was raised by substance (I) in all cases whereas substances (II) and (III) raised pulse rate only at low doses.