Natural compounds as angiogenic enzyme thymidine phosphorylase inhibitors: In vitro biochemical inhibition, mechanistic, and in silico modeling studies

Abstract

Natural flora is the richest source of novel therapeutic agents due to their immense chemical diversity and novel biological properties. In this regard, eighteen natural products belonging to different chemical classes were evaluated for their thymidine phosphorylase (TP) inhibitory activity. TP shares identity with an angiogenic protein platelet derived endothelial cell growth factor (PD-ECGF). It assists tumor angiogenesis and is a key player in cancer progression, thus an ideal target to develop anti-angiogenic drugs. Eleven compounds 1–2, 5–10, 11, 15, and 18 showed a good to weak TP inhibitory activity (IC50 values between 44.0 to 420.3 μM), as compared to standards i.e. tipiracil (IC50 = 0.014 ± 0.002 μM) and 7-deazaxanthine (IC50 = 41.0 ± 1.63 μM). Kinetic studies were also performed on active compounds, in order to deduce the mechanism of ligand binding to enzyme. To get further insight into receptor protein (enzyme) and ligand interaction at atomic level, in- sillico studies were also performed. Active compounds were finally evaluated for cytotoxicity test against mouse fibroblast (3T3) cell line. Compound 18 (Masoprocol) showed a significant TP inhibitory activity (IC50 = 44.0 ± 0.5 μM). Kinetic studies showed that it inhibits the enzyme in a competitive manner (Ki = 25.6 ± 0.008 μM), while it adopts a binding pose different than the substrate thymidine. It is further found to be non-toxic in MTT cytotoxicity assay. This is the first report on TP inhibitory activity of several natural compounds, some of which may serve as leads for further research towards drug the development.

Recent Updates on Mechanisms of Resistance to 5-Fluorouracil and Reversal Strategies in Colon Cancer Treatment

“…The condition is due to the loss of function of TYMP gene following homozygous mutations c.1283 G > A, and c.1284 T > A, as well as mutations in DNA polymerase subunit gamma (POLG) and ribonucleotide reductase regulatory TP53 inducible subunit M2B (RRM2B) genes that lead to TYMP deficiency [ 252 , 253 , 254 ]. Interestingly, increased TYMP expression has been reported in cases of local inflammations such as rheumatoid arthritis and psoriasis, suggesting its plausible causal link with stress conditions such as hypoxia in the tumor microenvironment [ 255 , 256 ]. Indeed, TYMP overexpression may promote adaptive responses mediated by the hypoxia-inducible factor (HIF-1) pathway that prevents hypoxia-induced apoptosis that is triggered upon continuous chemotherapy [ 229 , 242 , 257 ].…”

Repurposing of US-FDA-approved drugs as negative modulators of ubiquitin specific protease-7 (USP7)

“…The degree of saturation of the individual protons of a ligand molecule reflects their proximity to the biomolecule surface. Moieties of ligands that are in close proximity to protein will receive more saturation, in comparison to distant ones (>5 Å) [ 11 , 25 , 26 ].…”

“…To get structural insights into ligand-protein complex, the co-crystal structure of USP7-CD with non-covalent inhibitor FT671 (PDB ID: 5NGE ) was used for the in silico studies [ 14 , 15 ] using the Glide 6.9 module of the Schrödinger suite of programs, version 2020-2 [ [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] ]. The protein preparation wizard tool and OPLS3 force field were employed for protein preparation, minimization, and optimization.…”

Antiangiogenic Activity and Ros-Mediated Lung Cancer Cell Line Injury of Zerumbone

“…Drugs to be used for the treatment for the condition should not only be efficacious but also not to cause significant adverse effects [27][28][29][30]. Recently, cancer researchers are focused on the natural sources, especially on traditional medicinal and edible types for the treatment of tumor and for controlling of angiogenesis and metastasis due to their safety issue [31]. In the present study, ZER exhibited TP inhibition with IC50 values of 50.3 ± 0.31 μg/ml or 230 ± 1.42 µM.…”