## 2 Materials and Methods
Briefly, in the MTS cytotoxicity assay, Caco-2 cells were exposed to the test/control sample series (1, 2, 3) at the time when about approximately 70% \"semi-confluent\" cell culture had occurred, and in the antiproliferative MTS assay, Caco-2 cells were exposed to three-test series at the time when about approximately 30% \"sub-confluent\" cell culture had occurred. After one or two division cell cycles (24 and/or 48 h) in the presence of test/control sample series, the culture medium is removed and Caco-2 cells are further incubated with MTS solution for another 2 h. In the end, the viability of the adherent cells is determined using CellTitter 96 AQueous One Solution Cell Proliferation Assay (Promega Corporation, Madison, WI, USA) [38]. The absorbance of the treated and control series samples is therefore measured at 490 nm with a Microplate Reader (Chameleon V Plate Reader, LKB Instruments) and the recorded values are used for cell viability estimation in vitro (see formula below). Results are presented as punctual DO\({}_{490}\) nm (mean \(\pm\) SD, \(n\) = 3), and not as viability percent, to better emphasize the influence of ethanol solvent in samples. **Molecular docking study:** Molecular docking simulations were conducted using CLC Drug Discovery Workbench (QIAGEN) in order to evaluate the reference compounds series (luteolin-7-O-glucoside, luteolin-8-C-glucoside, caffeic acid, gentisic acid and p-aminobenzic acid) potential inhibitory activity on the human tankyrase 1 (TNKS1) and human tankarase 2 (TNKS2) enzymes, involved in cancer development in humans; the catalitic domain of human tankyrase is involved in oncogenesis, through the Wnt signaling pathway responsible for the regeneration of intestinal epithelial cells [39]. Therefore, testing new molecules with satisfactory physical-chemical properties by in silico methods against human tankyrases to block the Wnt pathway constitutes a reliable approach to hit-to-lead stage of rational drug development for intestinal cancer treatment. The PDB entree 4W6E, corresponding to human tankyrase 1 (TNKS1) in complex to the native inhibitor (encoded Co-crystallized 3 JSA) [40], has been retrieved from Protein Data Bank ([[https://www.rcsb.org](https://www.rcsb.org)]([https://www.rcsb.org](https://www.rcsb.org)) (accessed on 8 October 2021)). The tankyrase 1's preparation was realized by: removing the co-factor (Zn ion) and the water molecules; protonation; setup binding site and binding pocket at 140.29 A\({}^{2}\). Likewise, 2-phenyl-4h-chromen-4-one, PDB entree 4 HKI (encoded Co-crystallized FLN) is the native molecule inhibitor of human tankyrase 2 (TNKS2), as resulted from the systematic study on different flavonoid subclasses, reported by [PERSON] Et. At [41]; the hit compounds discovered upon their previous screening of 500 natural or naturally derived flavonoid structures, revealed that interactions within nicotinamide binding site of tankyrase 2 is responsible for inhibiting activity. The tankyrase-2's preparation was achieved by: water and other molecules (zinc ion, sulfate ion, glycerol, di(hydroxyethyl)ether) removal, protonation, ligand optimization, setup binding site and binding pocket at 121.34 A\({}^{2}\). In both cases, the ligand's preparation was achieved by energy minimization using Spartan'14 software program from Wavefunction, Inc., Irvine, CA, USA [42]. Validation was made by re-docking the native ligands. Interactions of ligands in complex with the catalytic domain of human tankyrases were identified.