Michele Francesco Luigi Palomba

Design of Novel Bioisosteres of β-Diketo Acid Inhibitors of HIV-1 Integrase

HIV-1 integrase (IN) is an attractive and validated target for the development of novel therapeutics against AIDS. Significant efforts have been devoted to the identification of IN inhibitors using various methods. In this context, through virtual screening of the NCI database and structure-based drug design strategies, we identified several pharmacophoric fragments and incorporated them on various aromatic or heteroaromatic rings. In addition, we designed and synthesized a series of 5-aryl(heteroaryl)-isoxazole-3-carboxylic acids as biological isosteric analogues of β-diketo acid containing inhibitors of HIV-1 IN and their derivatives. Further computational docking studies were performed to investigate the mode of interactions of the most active ligands with the IN active site. Results suggested that some of the tested compounds could be considered as lead compounds and suitable for further optimization.

Synthesis and antiproliferative activity of 3-aryl-2-(1H-benzotriazol-1-yl)acrylonitriles. Part III

A new series of 30 3-aryl-2-(1H-benzotriazol-1-yl)acrylonitriles were synthesized and tested for biological activity as part of our research in the antimicrobial and antitumor fields. In particular, title compounds were evaluated in vitro against representative strains of Gram-positive and Gram-negative bacteria (S. aureus, Salmonella spp), mycobacteria (M. fortuitum, M. smegmatis ATCC 19420 and M. tuberculosis ATCC 27294), yeast and mould (C. albicans ATCC 10231 and A. fumigatus). Furthermore, their antiretroviral activity against HIV-1 was determined in MT-4 cells together with cytotoxicity. In these assays title compounds and 47 additional derivatives described previously (P. Sanna, A. Carta, M.E. Rahbar Nikookar, Eur. J. Med. Chem. 35 (2000) 535-543; P. Sanna, A. Carta, L. Gherardini, M.E. Rahbar Nikookar, Farmaco 57 (2002) 79-87) were tested for their capability to prevent MT-4 cell growth. All compounds resulted devoid of antibacterial, antifungal and anti-HIV-1 activity. In anti-mycobacterial assays several compounds resulted active (MIC(50)=6.0-70 microM) against M. tuberculosis. However, since they showed cytotoxicity against MT-4 cells at lower concentrations (CC(50)=0.05-25 microM), their anti-mycobacterial activity was not selective. For this reason, the most cytotoxic compounds were also evaluated for antiproliferative activity against a panel of human cell lines derived from both hematological and solid tumors. Compound 34 resulted the most potent compound against the above human tumor-derived cell lines.

Design and discovery of novel quinazolinedione-based redox modulators as therapies for pancreatic cancer

BACKGROUND Altered cellular bioenergetics and oxidative stress are emerging hallmarks of most cancers including pancreatic cancer. Elevated levels of intrinsic reactive oxygen species (ROS) in tumors make them more susceptible to exogenously induced oxidative stress. Excessive oxidative insults overwhelm their adaptive antioxidant capacity and trigger ROS-mediated cell death. Recently, we have discovered a novel class of quinazolinediones that exert their cytotoxic effects by modulating ROS-mediated signaling. METHODS Cytotoxic potential was determined by colorimetric and colony formation assays. An XF24 Extracellular Flux Analyzer, and colorimetric and fluorescent techniques were used to assess the bioenergetics and oxidative stress effects, respectively. Mechanism was determined by Western blots. RESULTS Compound 3a (6-[(2-acetylphenyl)amino]quinazoline-5,8-dione) was identified through a medium throughput screen of ~1000 highly diverse in-house compounds and chemotherapeutic agents for their ability to alter cellular bioenergetics. Further structural optimizations led to the discovery of a more potent analog, 3b (6-[(3-acetylphenyl)amino]quinazoline-5,8-dione) that displayed anti-proliferative activities in low micromolar range in both drug-sensitive and drug-resistant cancer cells. Treatment with 3b causes Akt activation resulting in increased cellular oxygen consumption and oxidative stress in pancreatic cancer cells. Moreover, oxidative stress induced by 3b promoted activation of stress kinases (p38/JNK) resulting in cancer cell death. Treatment with antioxidants was able to reduce cell death confirming ROS-mediated cytotoxicity. CONCLUSION In conclusion, our novel quinazolinediones are promising lead compounds that selectively induce ROS-mediated cell death in cancer cells and warrant further preclinical studies. GENERAL SIGNIFICANCE Since 3b (6-[(3-acetylphenyl)amino]quinazoline-5,8-dione) exerts Akt-dependent ROS-mediated cell death, it might provide potential therapeutic options for chemoresistant and Akt-overexpressing cancers.

Synthesis and anti-mycobacterial activities of triazoloquinolones

A number of quinolone derivatives have been reported to possess anti-mycobacterial activity. Generally. Mycobacterium tuberculosis isolates expressing resistance to both isoniazid and rifampin are susceptible to fluoroquinolones. Benzotriazole is a hetero-bicyclic aromatic ring endowed with interesting chemical and biological properties and pharmacological activities. In a preliminary study we have recently reported the activity of triazolo[4,5-h]quinolone-carboxylic acids, a new class of benzotriazole derivatives active against multi-drug resistant M. tuberculosis (MDR-Mtb). In this study we confirm that this novel class of quinolones is endowed with a selective anti-mycobacterial activity, coupled with absence of cytotoxicity. The SAR analysis of the new derivatives in comparison with the previous series shows that the methyl group is the most effective substituent in both N-3 and N-9 positions of the ring system.

Anti-Mycobacterial Activity of Quinolones. Triazoloquinolones a New Class of Potent Anti-Mycobacterial Agents

A number of novel quinolone derivatives have been recentlyreported to posses in vitro and in vivo anti mycobacterial and DNA gyrase inhibition activities. It is known that mycobacteria expressing resistance to both isoniazid and rifampin (multi-drug resistant, MDR) is sensible to fluoroquinolones. Ciprofloxacin,oxfloxacin, moxifloxacin and levofloxacin are increasingly used for the treatment of tuberculosis, because they inhibit thetopoisomerases II (DNA gyrases) and IV, essential enzymes to maintain the supercoils in bacterial DNA. It has been demonstrated that complex mutations in DNA gyrase GyrA 2 GyrB 2 associated with quinolone resistance or hypersusceptibility take place in several MDR clinical isolates of M. tuberculosis . In this article we report the anti mycobacterial properties, mode of action and structure activity relationship (SAR) studies of the known quinolone derivatives. Furthermore, we report the synthesis and activity of 3,9 disubstituted-6-oxo-6,9-dihydro- 3H -[1,2,3]triazolo[4,5- h ]quinolone carboxylic acids and their esters as a new class of potent anti mycobacterial agents. The triazoloquinolone derivatives are particularly interesting for their activity against MDR M. tuberculosis .

Anti-inflammatory and analgesic amides: new developments.

A series of substituted N‐cycloalkyl benzamides, cinnamamides, and indole‐3‐carboxamides were synthesized and evaluated for their analgesic, antiinflammatory activities as well as for their gastrointestinal irritation liability. Indomethacin was used as reference drug in both tests. Compounds 1k, 1b, 1h, 1j, and 1g were the most active in the antiinflammatory paw edema inhibition test, with a sharply dose‐dependent effect. In terms of the analgesic activity (acetic acid writhing test), the most active compound was 5a followed by 3a, but many other compounds were found to have a non‐negligible potency. Even in this case, the effect was dose dependent.

Monitoring of benzylpenicillin in ovine milk by HPLC

A method for determination in vivo of the benzylpenicillin residues in ovine milk at low levels was described. Two groups of Sardinian breed sheep were treated with a dose of penicillin G sodium salt by intramammary infusion and intramuscular administration respectively. The residues were detected by isocratic HPLC method of the extract obtained from a previous cleanup procedure. Linear calibration plots were obtained over a large concentration range of 1 mg ml-1 -10 ng ml-1, with correlation coefficients greater than 0.998. Recoveries between 78.6 and 87.3% were obtained. Limit of detection (LOD) and limit of determination (LOQ) were 2.6 and 8.8 ng ml-1 respectively. This method would be useful for routine monitoring of penicillin G residues in ovine dairy milk.

Synthesis of N-[4-(alkyl)cyclohexyl]-substituted benzamides with anti-inflammatory and analgesic activities

Two series of N-[4-(alkyl)cyclohexyl]-substituted benzamides, i.e. a series of N-[4-(tert-butyl)cyclohexyl]-substituted benzamides and a series of N-[4-(ethyl)cyclohexyl]-substituted benzamides, were synthesised and evaluated for their anti-inflammatory and analgesic potencies, and gastrointestinal irritation liability.

Synthesis of Linear Azolo and Pyrido Quinolines from Quinoline Derivatives

Angular N-tricyclic systems as triazolo(4,5-f)quinolines, triazolo(4,5-h)quinolines, imidazo(4,5-f)quinolines, imidazo(4,5- h)quinolines were in the past obtained by connection of either f or h sides of the quinoline ring and both the adjacent carbon atoms of five-membered rings containing nitrogen atoms. Several attempts at obtaining the corresponding linear N-tricycles were made in the last century, but only the angular derivatives were obtained. Since 2000 a new simple pathway, involving suitable quinoline derivatives, which afforded the linear azolo and pyrido quinolines (imidazo(4,5-g)quinolines, triazolo(4,5-g)quinolines and pyrido(2,3- g)quinoxalines) has been developed. Several linear N-tricyclic derivatives have shown some interesting pharmaceutical activity.

Synthesis of N -[4-(propyl)cyclohexyl]-amides with anti-inflammatory and analgesic activities

Seventeen (un)substituted N-[4-(propyl)cyclohexyl]-amides (6a-h, 7a-h and 8) were synthesized and tested as anti-inflammatory and analgesic agents. The substituents on the aromatic ring were chosen in order to study the influence of electron-withdrawing or electron-donating residues, that change the electronic density on the aromatic moiety. The pharmacological results allow drawing some preliminary considerations on structure-activity relationships.