[Pyrido[2,3-b]pyrazines inhibiting both erlotinib-sensitive and erlotinib-resistant cell lines, and their preparation via regioselective condensation reaction]. / Erlotinib-érzékeny és erlotinib-rezisztens sejtvonalakat gátló pirido[2,3-b] pirazinok, és eloállításuk régiószelektív kondenzációs reakcióval.

The EGFR inhibitor erlotinib possesses high anti-tumor effect but despite the good clinical responses in most of the cases recrudescence occures. This can be attributed to a secondary, acquired mutation causing resistance to tyrosine kinase inhibitors. In our work we were looking for small-molecule inhibitors, which simultaneously affect on the proliferation of erlotinib-sensitive PC9 cells and PC9-ER erlotinib-resistant cells. A set of molecules were selected from Vichem Chemie Research Ltd.'s kinase inhibitor compound library (Nested Chemical Library™). According to the results of medium throughput screening (MTS) of this set of compounds, novel structures with pyrido[2,3-b]pyrazine core were designed. These compounds were proved to be effective inhibitors of resistant cells in phenotypic screening. Based on these results structure-activity relationships were set up. The pyrido[2,3-b]pyrazine core was synthesized by a condensation reaction, which resulting two asymmetric products. In the reaction two regioisomer intermediates formed, and one of the products is the intermediate of the effective compounds. This condensation reaction was optimized, the regioisomers were identified by NMR analysis and X-ray crystallography. As a result of optimization we found that lower reaction temperature and replacement of dimethylformamide solvent with trifluoroacetic acid provided the undesired isomer in less than 2 % ratio.

[Development and study of structure-activity relationship of drugs against Mycobacterium tuberculosis]. / Mycobacterium tuberculosis ellenes hatóanyagok fejlesztése és szerkezet-hatás összefüggéseinek vizsgálata.

Tuberculosis is considered to be one of the major health problem not only in the less developed countries but in the economically developed countries as well. Roughly one third of the world's population are infected with Mycobacterium tuberculosis and a significant part of them are carriers of latent tuberculosis. From ten percent of these latent infections are developing the active TB disease and fifty percent of them die from the illness without appropriate treatment. The drug-resistant Mycobacterium tuberculosis (MDR-TB, XDR-TB) and TB-HIV co-infection attracted attention to the most serious infectious disease. Inhibition of alternative signaling pathways were an important part of the research strategies for cancer and inflammatory diseases in recent years. In case of Mycobacterium tuberculosis such pathways were also identified, for example, three serine-threonine kinases (PknA, PknB, PknG) which are necessary and essential for bacterial growth. In this paper we summarize our best anti-TB active compounds, their biological effects and structure-activity relationships using in silico modeling, biochemical measurements and tests on active bacteria.

[Application of Kohonen Self-Organizing Feature Maps in QSAR of human ADMET and kinase data sets]. / Kohonen-féle önszervezodo tulajdonságtérkép használata humán ADMET és kináz adatok QSAR predikciójában.

QSAR predictions have been proven very useful in a large number of studies for drug design, such as kinase inhibitor design as targets for cancer therapy, however the overall predictability often remains unsatisfactory. To improve predictability of ADMET features and kinase inhibitory data, we present a new method using Kohonen's Self-Organizing Feature Map (SOFM) to cluster molecules based on explanatory variables (X) and separate dissimilar ones. We calculated SOFM clusters for a large number of molecules with human ADMET and kinase inhibitory data, and we showed that chemically similar molecules were in the same SOFM cluster, and within such clusters the QSAR models had significantly better predictability. We used also target variables (Y, e.g. ADMET) jointly with X variables to create a novel type of clustering. With our method, cells of loosely coupled XY data could be identified and separated into different model building sets.

Tyrosine kinase inhibitors - small molecular weight compounds inhibiting EGFR.

Abnormally elevated EGFR kinase activity can lead to various pathological states, including proliferative diseases such as cancer. The development of selective protein kinase inhibitors has become an important area of drug discovery for the potential treatment of a variety of solid tumors such as breast, ovarian and colorectal cancers, NSCLC, and carcinoma of the head and neck. There are three small molecule EGFR kinase inhibitor drugs in clinical use (gefitinib, erlotinib and lapatinib), and several others are currently undergoing clinical development. This review summarizes the development of EGFR kinase inhibitors, and includes descriptions of the binding modes, the importance of a multiple-targets strategy, the effects of sensitizing and resistance mutations in the EGFR, and molecular diagnostic approaches. In addition, the use of target fishing for selectivity profiling, off-target identification and quantitative structure-activity relationship modeling for the prediction of EGFR inhibition is discussed.

[Novel method for the synthesis of carboxamides from low reactivity esters: synthesis of 2-acylamino-1-benzothiophene-3-carboxamides]. / Uj eljárás savamidok eloállítására, alacsony reaktivitású eszterekbol: 2-acilamino-l-benzotiofén-3-karboxamid sz rmazékok eloállítása.

We planned and prepared a kinase inhibitor focused compound library around the 1-benzotiophene core structure, but the 2-acylamino-1-benzotiophene-3-carboxylic acid ethyl ester derivatives could not be converted to amides by the traditional methods like treatment with aqueous or alcoholic ammonia solution or ammonia gas. Under mild reaction conditions we have recovered the starting materials, higher temperature and pressure resulted the formation of pure ring-closed products. We have discovered a new method where the application of lithium amide in tetrahydrofurane resulted the desired compounds in acceptable yields (67-84%). The products were characterized thoroughly by spectral data, elementary analyses and melting points.

Synthesis and characterization of novel quinazoline type inhibitors for mutant and wild-type EGFR and RICK kinases.

The development of selective protein kinase inhibitors has become an important area of drug discovery for the treatment of different diseases. We report the synthesis and characterization of a series of novel quinazoline derivatives against three therapeutically important and pharmacologically related kinases: 1) epidermal growth factor receptor (EGFR; wild type and mutant) in the field of cancer, 2) receptor-interacting caspase-like apoptosis-regulatory kinase (RICK) in the field of inflammation, and 3) pUL97 of human cytomegalovirus (HCMV). For reference purpose we have synthesized the four clinically relevant quinazolines, including the lead compounds, which we previously identified for RICK and pUL97. A total of 52 quinazoline derivatives were synthesized and tested on the basis of these leads to specifically target the hydrophobic pocket of the ATP-binding site. Selected compounds were tested on wild-type and mutant forms of EGFR, RICK, and pUL97 kinases; their logP and logS values for assessing suitability as drugs were calculated and hit or lead compounds identified.

A novel drug discovery concept for tuberculosis: inhibition of bacterial and host cell signalling.

The Mycobacterium tuberculosis genome encodes for eleven eukaryotic-like Ser/Thr protein kinases. At least three of these (PknA, PknB and PknG) are essential for bacterial growth and survival. PknG is secreted by pathogenic mycobacteria, in macrophages to intervene with host cell signalling pathways and to block the fusion of the lysosomes with the phagosome by a still unknown mechanism. Based on our previously published results, we have initiated a drug discovery program, aiming to improve the potency against PknG and the physiochemical properties of the initially identified hit compound, AX20017, from the class of the tetrahydrobenzothiophenes. We have established a radioactive biochemical PknG kinase assay to test the novel analogues around AX20017. We have developed lead molecules with IC50 values in nanomolar range, and demonstrated their antituberculotic effects on human macrophages. Selected leads might ultimately serve the purpose of inducing phagosomal-lysosomal fusion and therefore destroy the residence of the intracellular mycobacteria. It is unclear at this time if these "homeless" mycobacteria are getting killed by the host, but they will be at least vulnerable to the activity of antimycobacterial agents. Released mycobacteria rely on the essential function of PknB for survival, which is our second molecular kinase target. PknB is a transmembrane protein, responsible for the cell growth and morphology. We have screened our library and synthesized novel compounds for the inhibition of PknB. A pharmacophore model was built and 70,000 molecules from our synthesizable virtual library have been screened to identify novel inhibitor scaffolds for the generation of templated compound libraries. Currently, we are using a radioactive kinase assay employing GarA as the putative, physiological substrate of PknB kinase. We have identified hits and generated optimised hit compounds with IC50 values for the inhibition of PknB in the nanomolar range. Yet those promising hits are not potent enough to yield meaningful "minimum inhibitory concentrations" in mycobacterial growth assays. In the course of our future work, we will increase the potency of the next generation of PknB inhibitors in order to improve their antibacterial activity.

Drug discovery in the kinase inhibitory field using the Nested Chemical Library technology.

Kinase inhibitors are at the forefront of modern drug research, where mostly three technologies are used for hit-and-lead finding: high throughput screening of random libraries, three-dimensional structure-based drug design based on X-ray data, and focused libraries around limited number of new cores. Our novel Nested Chemical Library (NCL) (Vichem Chemie Research Ltd., Budapest, Hungary) technology is based on a knowledge base approach, where focused libraries around selected cores are used to generate pharmacophore models. NCL was designed on the platform of a diverse kinase inhibitory library organized around 97 core structures. We have established a unique, proprietary kinase inhibitory chemistry around these core structures with small focused sublibraries around each core. All the compounds in our NCL library are stored in a big unified Structured Query Language database along with their measured and calculated physicochemical and ADME/toxicity (ADMET) properties, together with thousands of molecular descriptors calculated for each compound. Biochemical kinase inhibitory assays on selected, cloned kinase enzymes for a few hundred NCL compound sets can provide sufficient biological data for rational computerized design of new analogues, based on our pharmacophore model-generating 3DNET4W QSPAR (quantitative structure-property/activity relationships) approach. Using this pharmacophore modeling approach and the ADMET filters, we can preselect synthesizable compounds for hit-and-lead optimization. Starting from this point and integrating the information from QSPAR, high-quality leads can be generated within a small number of optimization cycles. Applying NCL technology we have developed lead compounds for several validated kinase targets.

Synthesis of selective SRPK-1 inhibitors: novel tricyclic quinoxaline derivatives.

SR protein-specific kinase-1 (SRPK-1) has been identified as a validated target for hepatitis B virus (HBV). A series of novel tricyclic quinoxaline derivatives was designed and synthesised as potential kinase inhibitory antiviral agents and was found to be active and selective for SRPK-1 kinase. Most of these novel compounds have drug-like properties according to experimentally determined LogP and LogS values.

[Synthesis of thiophene and alpha-terthiophene derivatives with antiproliferative activity]. / Antiproliferatív hatású tiofén es alpha-tertiofénszármazékok eloállítása.

We have synthesised a series of known alpha-terthiophene lead molecules with PKC (protein kinase C) inhibitory activity and the compounds were tested in cell proliferation assay on EGF-RTK (epidermal growth factor receptor protein tyrosine kinase) over-expressing tumour cell line (A431). We found that two of them had excellent antiproliferative activity. We prepared a focused molecule library around the thiophene and the terthiophene scaffold and examined these compounds in cell proliferation assay on A431.

Improved, high yield synthesis of 3H-quinazolin-4-ones, the key intermediates of recently developed drugs.

Purine bases and their bioisosteric analogs are widely used as building blocks in combinatorial chemistry. Recently a great number of fused pyrimidine derivatives became known as potential drug molecules against various types of proliferative diseases, caused by over-expression of protein kinases. One of the most important compound families are quinazolines : e.g. the best inhibitor of EGFR tyrosine kinase is PD153035 (6,7-dimethoxy-4-(3'-bromophenyl)amino-quinazoline) and IRESSA (gefitinib, ZD1839), developed from this compound family, is presently the only one approved and granted drug by the FDA for the treatment of advanced non-small-cell lung cancer (NSCLC). KF31327 (3-ethyl-8-[2-(4-hydroxymethylpiperidino)benzylamino]-2,3-dihydro-1H-imidazo[4,5-g]-quinazoline-2-thione dihydrochloride) from this group, showed significantly higher inhibitory activity on cyclic GMP-specific phosphodiesterase compared with those of sildenafil (Viagra). The synthetic procedures of the example compounds are based on imidoyl chloride intermediates that were prepared from the appropriate 3H-quinazoline-4-ones. Although the key intermediates, quinazoline-4-ones, have been known since more than hundred years, their synthetic procedures have been improved much only in the past ten years. In this paper we reviewed the efficient synthetic methods of quinazolin-4-ones, and presented a novel, reliable method for their synthesis. There was no considerable effect of microwave-, or traditional thermal activation on the yield and compound purity.