Alekseeva N.S., Antypenko L.M.

Zaporizhzhya State Medical University, Ukraine

The ethyl (5-R-([1,2,4]triazolo[1,5-c]quinazolin-2-yl)acetates anticancer activity mechanism prediction via docking studies

to thymidine phosphorylase

The thymidine phosphorylase (TP) also known as platelet derived endothelial cell growth factor (PD-ECGF) is identified as a potential therapeutic target for cancer therapy, because it plays a crucial role in cancer angiogenesis via the release of its metabolic product, 2-deoxy-D-ribose, that stimulates the secretion and/or expression of many angiogenic factors, including MMP-9, MMP-2, VEGF, IL-8 as well as migration of endothelial cells and rapid formation of long-lasting functional neo-vessels, leading to increased metastasis and tumour growth [1,2].

Considering the presence of anticancer activity of the [1,2,4]triazolo[1,5-c]quinazoline derivatives [3], the prediction of the anti-TP activity by docking studies will detect their potential mechanism of action.

The virtual library of ethyl (5-R-([1,2,4]triazolo[1,5-c]quinazolin-2-yl)acetates on the basis of [1,2,4]triazolo[1,5-c]quinazoline skeleton was created in silico with introduction of the residues of thioalkyls, acids, esters, amides and amines (Pic.).

Investigation was conducted by flexible molecular docking, as an approach of finding molecules with affinity to a specific biological target using the software package OpenEye, including related utilities: Fred Receptor2.2.5, Vida4.1.1, Flipper, Babel3, Omega2.4.3 and Fred2.2.5 [4,5]. The crystal structure of the enzyme TP (2WK6.pdb) was obtained from the protein data bank [6]. The 1H-pyrrolo[2,3-d]pyrimidine-2,4-(3H,7H)-dione was used as the reference [7].

The methodology of research consisted of the following steps:

Ø generation of R-, S- and cis-, trans-isomers of ligands (the studied compounds and relevant drugs, program Flipper), which allowed the production isomer’s range of studied compounds;

Ø generation of 3D-structure of the obtained isomeric forms - molecular modelling (Hyper Chem 7.5) using the method of molecular mechanics (MM +) and semiempirical quantum mechanical method with Polak-Ribiere algorithm (PM3);

Ø generation of conformations of ligands (Omega2.4.3). The number of conformations obtained wasn’t significant due to the further selection by program Fred2.2.5 most optimal conformer;

Ø carrying out molecular docking (Fred2.2.5).

Pic. Investigated ethyl (5-R-([1,2,4]triazolo[1,5-c]quinazolin-2-yl)acetates.

A number of scoring functions (Shapegauss, PLP, Chemgauss2, Chemgauss3, Chemscore, OEChemscore, Screenscore, CGO, CGT, Zapbind, Consensus Score) was obtained as a result of studies, values of which assess specific characteristics of the ligand-protein complex, indicating the possibility of their matching.

The analysis of docking interactions between TP and investigated compounds has indicated that there is no possibility of their inlining into the ligand-protein complex.

Hence, in silico docking studies of the (5-R-([1,2,4]triazolo[1,5-c]quinazolin-2-yl)acetates into the thymidine phosphorylase binding site showed the absence of such activity of the designed structures.

Literature:

1. Thymidine phosphorylase in cancer cells stimulates human endothelial cell migration and invasion by the secretion of angiogenic factors. I.V. Bijnsdorp, F. Capriotti, F.A.E. Kruyt, N. Losekoot, M. Fukushima, A.W. Griffioen, V.L. Thijssen, G.J. Peters Br. J. Cancer 104 (2011) 1185–1192.

2. J. Folkman. What is the role of thymidine phosphorylase in tumor angiogenesis? J. Natl. Cancer Inst. 88 (1996) 1091–1092.

3. Synthesis and anticancer activity of 2-аlkyl(alkaryl-,aryl-,heteryl-)-[1,2,4]triazolo[1,5-c]quinazolines. S.I. Kovalenko, L.M. Antypenko, A.K. Bilyi, S.V. Kholodnyak, O.V. Karpenko, O.M. Antypenko, N.S. Mykhaylova, T.I. Los’, O. S. Kоlоmоеts’. Sci. Pharm., 81 (2013) 359-391.

4. Virtual Screening in Drug Discovery, (Eds.: J. Alvarez, B. Shoichet), CRC Press, Taylor & Francis, Boca Raton, FL, 2005, 451.

5. Protein Data Bank, pdb., [http://www.pdb.org].

6. Fred Receptor2.2.5, Vida4.1.1, Flipper, Babel3, Omega2.4.3 and Fred2.2.5: OpenEye Sci. Soft. Inc. [http://www.eyesopen.com], Santa Fe, NM, USA; 2011.

7. Synthesis, anti-thymidine phosphorylase activity and molecular docking of 5-thioxo-[1,2,4]triazolo[1,5-a][1,3,5]triazin-7-ones H. Bera, M.H. Lee, L.Sun, A.V. Dolzhenko, W.K. Chui Bioorg. Chem. 50 (2013) 34–40.