Antitumor agents. 174. 2',3',4',5,6,7-Substituted 2-phenyl-1,8-naphthyridin-4-ones: their synthesis, cytotoxicity, and inhibition of tubulin polymerization

Synthesis and biological relationships of 3′,6-substituted 2-phenyl-4-quinolone-3-carboxylic acid derivatives as antimitotic agents

As part of a continuing search for potential anticancer drug candidates in the 2-phenyl-4-quinolone series, 3',6-substituted 2-phenyl-4-quinolone-3-carboxylic acid derivatives and their salts were synthesized and evaluated. Preliminary screening showed that carboxylic acid analogs containing a m-fluoro substituted 2-phenyl group displayed the highest in vitro anticancer activity. Activity decreased significantly if a chlorine or methoxy group replaced the fluorine atom. 3'-Fluoro-6-methoxy-2-phenyl-4-quinolone-3-carboxylic acid (68) had the highest in vitro cytotoxic activity among all tested carboxylic acid derivatives and their salts. The mechanism of action may be similar, but not identical, to that of tubulin binding drugs, such as navelbine and taxol. Compound 68 merits further investigation as a novel hydrophilic antimitotic agent.

Transcription profiling of gene expression in drug discovery and development: the NCI experience

Transcript profiling, using microarray or other analogous technologies, to query on a large-scale the expression of genes in tumours or their derivative cell lines has numerous potential uses in oncology drug discovery and development. Characterisation of genes expressed in tumours may allow tumours to be separated into subsets defining subtypes that have a distinctive pathway utilisation. The molecular entities comprising the pathways which distinguish one disease subset from another then become potential candidate drug targets. Alternatively, gene expression patterns may be correlated with the degree of antiproliferative effect of candidate drug leads. This can reveal aspects of the drug's action that could serve to provide a further basis for benchmarking the generation of analogues or provide important information about pathways potentially modulated by the drug in achieving cytotoxicity. New information is emerging that the expression of drug transport-related molecules is a major variable that can be usefully explored using gene expression data, and the features promoting successful drug handling by the tumour cell may be an additional variable which can be illuminated by gene expression studies.

A convenient one-pot synthesis of 1,8-naphthyridones

In this paper, we disclose an efficient one-pot procedure for the preparation of substituted 1,8-naphthyridin-4-one analogues. Previous efforts to effect this type of transformation were complicated by the formation of benzene tricarboxylate. Via the use of excess base, the impurity formation was completely inhibited. This allowed for the clean preparation of the desired intermediate and subsequent formation of naphthyridone analogues in a single flask, which could then be crystallized directly from the reaction mixture in good yield and high purity.

A fluorescence-based high-throughput assay for antimicrotubule drugs

With the advent of combinatorial chemistry and the extensive libraries of potential drugs produced from it, there is a growing need for rapid sensitive, high-throughput screening for drug potency. Microtubules are important targets for anticancer agents, and new antimicrotubule compounds are of continued interest in drug development. The in vitro potency of antimicrotubule drugs may be evaluated by measuring the extent of tubulin assembly. The extent of polymerization is proportional to the turbidity of the solution, which usually has been measured as apparent absorption. The turbidity method has inherent problems that hinder its adaptation to a high-throughput format, such as a requirement for high protein concentrations and a high coefficient of variation. We present here a high-throughput assay for antimicrotubule activity in which fluorescence is used to monitor microtubule assembly. Both assembly-inhibiting and assembly-promoting compounds can be evaluated. The assay is rapid and easy to perform, and the data are reliable, with good accuracy and reproducibility.

Synthesis, photochemical synthesis and antitumor evaluation of novel derivatives of thieno[3',2':4,5]thieno[2,3-c]quinolones

The novel derivatives of thieno[3',2':4,5]thieno[2,3-c]quinolones 6a, 6b, 7, 10a and 10b were synthesized in multistep synthesis starting from thiophene-3-carboxaldehyde and malonic acid reacting in aldol condensation or from 3-bromothiophenes or methyl 4-bromothiophene-2-carboxylate reacting in Heck reaction. They resulted in corresponding substituted thienylacrylic acids 3a-c, which were cyclized into thieno[2,3-c]thiophene-2-carbonyl chlorides 4a-c and converted into thieno[2,3-c]thiophene-2-carboxamides 5a-d. Prepared carboxamides were photochemically dehydrohalogenated into corresponding substituted thieno[3',2':4,5]thieno[2,3-c]quinolones 6a-d. Compound 7 was prepared from 6d by alkylation with N-[3-(dimethylamino)propyl]chloride hydrochloride in the presence of NaH. Compounds 10a and 10b were prepared from 6c in the multistep synthesis over acid 8 and acid chloride 9. Compounds 6a, 6b, 7, 10a and 10b were found to exert cytostatic activities against malignant cell lines: pancreatic carcinoma (MiaPaCa2), breast carcinoma (MCF7), cervical carcinoma (HeLa), laryngeal carcinoma (Hep2), colon carcinoma (CaCo-2), melanoma (HBL), and human fibroblast cell lines (WI-38). The compound 6b, which bears the 3-dimethylaminopropyl substituent on quinolone nitrogen and methoxycarbonyl substituent on position 9, exhibited marked antitumor activity. On the contrary, compound 7, which also bears the 3-dimethylaminopropyl substituent on the quinolone nitrogen but anilido substituent on position 9, exhibited less antitumor activity than the others.

Antitumor Agents. Part 204: Synthesis and Biological Evaluation of Substituted 2-Aryl Quinazolinones

A series of 2',3',4',6,7-substituted 2-aryl quinazolinones were synthesized and evaluated for biological activity. Among them, 17 displayed significant growth inhibitory action against a panel of tumor cell lines. Compound 17 was also a potent inhibitor of tubulin polymerization. Compounds 8-10 displayed selective activity against P-gp-expressing epidermoid carcinoma of the asopharynx.

Novel antitumor agents from higher plants

This review article describes research on cytotoxic natural products isolated from plant sources, primarily preclinical lead identification and structural modification studies performed in the Natural Products Laboratory of Dr. K. H. Lee. As a result of this work, more than 100 new cytotoxic antitumor compounds and their synthetic analogs have shown confirmed activity in NCI's in vitro human tumor cell lines bioassay and are of current interest to NCI for further in vivo evaluation. A significant and ongoing project involves novel antitumor analogs related to podophyllotoxin and etoposide, and has led to a potent derivative designated GL331 (17). This compound is currently in Phase IIa clinical trials and shows promise as an anticancer drug, especially for drug-resistant cancers. Bioactivity-directed fractionation and isolation of medicinal herbs (primarily herbs of Chinese origin) have also led to many classes of cytotoxic compounds including polyphenolic compounds, sesquiterpene lactones, lignans, quassinoids, triterpene glucosides, flavonoids, colchicine derivatives, and quinone derivatives.

Anticancer drug design based on plant-derived natural products

This review article focuses on recent research in my laboratory on various classes of compounds that possess potent antitumor activity. These compounds were obtained by bioactivity- and mechanism of action-directed isolation and characterization coupled with rational drug design-based modification and analog synthesis. Structural modification, structure-activity relationship, and mechanism of action studies will be discussed.

Antitumor agents--CLXXV. Anti-tubulin action of (+)-thiocolchicine prepared by partial synthesis

(+)-Thiocolchicine (2b) was prepared from (+/-)-colchicine (1) in a five-step reaction sequence that included chromatographic separation of appropriate camphanylated diastereomers. Acid hydrolysis of the (+)-diastereomer, followed by acetylation, yielded the desired product 2b. (+)-Thiocolchicine has 15-fold lower inhibitory activity against tubulin polymerization than (-)-thiocolchicine, and is 29-fold less potent for inhibiting growth of human Burkitt lymphoma cells. The enantiomer 2a, prepared from the (-)-camphanylated diastereomer, had potent activity in all assays comparable to that of (-)-thiocolchicine prepared by other methods. These results support the hypothesis that the proper configuration of colchicine-related compounds is an important requirement for their anti-tubulin action.