• Biomolecules & Therapeutics
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• v.3 no.1
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• pp.34-37
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• 1995

Non-steroidal anti-inflammatory drugs (NSAIDs) have been known as inhibitors of the folate-requiring enzymes. In the present work, we have expanded on these observations and have investigated the inhibitory effects of NSAIDs on Lactobacillus casei thymidylate synthase expressed in E. coli. NSAIDs including sulphasalizine, salicylic acid, indomethacin and mefenamic acid were found to be competitive inhibitors with respect to folate of Lactobacillus casei thymidylate synthase. In contrast, aspirin and the antipyretic-analgesic drugs acetaminophen and antipyrine were weak inhibitors of the enzyme. Structure-activity correlation suggests that an aromatic ring with a side chain containing a carboxylic acid is a requirement for competitive inhibition of the thymidylate synthase. The results are consistent with the hypothesis that the antifolate activity of NSAIDs, and hence cytostatic consequences, are important factors in producing anti-inflammatory activity and aspirin exerts its anti-inflammatory effects after its conversion into salicylic acid, which possesses greater antifolate activity than its parent compound.

• Parasites, Hosts and Diseases
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• v.28 no.2
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• pp.79-84
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• 1990

Metabolic inhibitors which act in the process of pyrimidine salvage influenced on the uracil incorporation into nucleic acids of Toxoplasma. Inhibitors of dihydrofolate reductase, pyrimethamine and methotrexate, and inhibitors of thymidylate synthase, fluoro-uridine, fluoro·dUMP and fluoro-uracil, diminished isotopic uracil uptake in dose-dependent manners. Azauridine which suppresses do novo pyrimidine biosynthesis did not affect the salvage even in a relatively high dose. These results suggested that the activation of uracil salvage should be closely related with the function of TMP biosynthetic enzymes. The pattern of thymidine uptake had no differences between control HL-60 cells and Toxoplasma infected cells, which did not reject the specific proliferation of Texoplasma. It can be exploited to characterize the elects of various compounds related with the proliferation of Toxoplasma, especially its DNA synthesis. Key words: Toxoplasma gondii, uracil salvage, dihydrofolate reductase, thymidylate synthase TMP biosynthesis.

• Bulletin of the Korean Chemical Society
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• v.25 no.12
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• pp.1898-1906
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• 2004

Nonclassical quinazolinone analogs I, II, and III, in which the glutamic acid moiety of the classical antifolates is substituted by phenylglycine, phenylalanine or aminobenzoic acid and their methyl esters, were synthesized and evaluated as lipophilic inhibitors of thymidylate synthase (TS). The target compounds were generally potent inhibitors of L. casei and human TS with $IC_{50}$ values within the narrow range of 0.2-10 ${\mu}$M and 0.003-0.03 ${\mu}$M, respectively. Further, most of the target compounds showed cytotoxicity against tumor cell lines of murine and human origin with $IC_{50}$ values of as low as 0.050 ${\mu}$M. Substitution of another hydroxyl or carboxylic acid/ester group at the phenyl ring further increased the potency of TS inhibition and cell growth inhibition. Most effective were compounds If and Ic in which extra carboxylic acid/ester was present at the phenyl ring with nanomolar $IC_{50}$ values of 0.0044 and 0.0093 ${\mu}$M against human TS and submicromolar cytotoxic growth inhibition against all four tumor cell lines.

• Biomolecules & Therapeutics
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• v.20 no.1
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• pp.81-88
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• 2012

Histone deacetylases (HDACs) are enzymes involved in the remodelling of chromatin, and have a key role in the epigenetic regulation of gene expression. Histone deacetylase (HDAC) inhibitors are emerging as an exciting new class of potential anti-cancer agents. In recent years, a number of structurally diverse HDAC inhibitors have been identifi ed and these HDAC inhibitors induce growth arrest, differentiation and/or apoptosis of cancer cells in vitro and in vivo. However, the underlying molecular mechanisms remain unclear. This study aimed at investigating the anti-tumor activity of various HDAC inhibitors, IN-2001, using T47D human breast cancer cells. Moreover, the possible mechanism by which HDAC inhibitors exhibit anti-tumor activity was also explored. In estrogen receptor positive T47D cells, IN-2001, HDAC inhibitor showed anti-proliferative effects in dose-and time-dependent manner. In T47D human breast cancer cells showed anti-tumor activity of IN-2001 and the growth inhibitory effects of IN-2001 were related to the cell cycle arrest and induction of apoptosis. Flow cytometry studies revealed that IN-2001 showed accumulation of cells at $G_2$/M phase. At the same time, IN-2001 treatment time-dependently increased sub-$G_1$ population, representing apoptotic cells. IN-2001-mediated cell cycle arrest was associated with induction of cdk inhibitor expression. In T47D cells, IN-2001 as well as other HDAC inhibitors treatment significantly increased $p21^{WAF1}$ and $p27^{KIP1}$ expression. In addition, thymidylate synthase, an essential enzyme for DNA replication and repair, was down-regulated by IN-2001 and other HDAC inhibitors in the T47D human breast cancer cells. In summary, IN-2001 with a higher potency than other HDAC inhibitors induced growth inhibition, cell cycle arrest, and eventual apoptosis in human breast cancer possibly through modulation of cell cycle and apoptosis regulatory proteins, such as cdk inhibitors, cyclins, and thymidylate synthase.