## 4 Discussion
Slae26 combinations with the five reference compounds (1:1 ratio between the active compounds in samples) in comparison with the control ethanol sample series (1:1 ratio between 40% ethanol solvent in Slae26 sample and 70% ethanol solvent in reference samples) indicated significant increases of inhibitory effects upon the viability of Caco-2 cells (IC\({}_{50}\) \(\sim\) 5 \(\mu\)g/mL sample), without interfering toxic effects of the ethanol solvent in samples. Puncutually, the IC\({}_{50}\) value of Skae26 was reduced from a 36 \(\mu\)g/mL sample to about a 5 \(\mu\)g/mL sample, signifying real therapeutic usefulness and antitumor potency on human colon cancer cell of Sla26 combinations with the five food-related bioactive compounds. Docking studies on the molecular target TNKS1 indicated the greatest inhibitory activity (score value: \(-\)104.15) for the native ligand, co-crystallized J5A, which establishedinteractions (hydrogen bonds) with three amino acid residues in the active binding site of chain A (SER1221, GLY1185, and GLY1196). In the series of test polyphenol compounds, luteolin-7-O-glucose showed the best docking score on TNKS1 (score value: \(-80.49\)) and established interactions with two of three amino acids (SER1221, GLY1185) in the binding site. The other scores were: luteolin-8-C-glucose (\(-68.88\)) > caffeic acid (\(-58.55\)) > gentisic acid (\(-51.02\)) > p-aminobenzoic acid (\(-49.16\)). In the case of molecular target TNKS2, luteolin-7-O-glucose emphasized the best docking score (\(-85.17\)), greater than that of the native ligand, Co-cristallized FLN (\(-76.97\)); luteolin-7-O-glucose interacted with two amino acids residues (SER1068 and GLY1032) on chain A, and one amino acid residue (GLU1138) on chain C. The other scores were: caffeic acid (\(-57.17\)) > gentisic acid (\(-51.66\)) > p-aminobenzoic acid (\(-50.42\)) > luteolin-8-C-glucose (\(-43.47\)). Overall, docking studies on the human tankyrase enzymes have confirmed antiproliferative potency of bioactive compounds from food products on human colon cancer cells, especially of luteolin-7-O-glucose. Other food-related bioactive compounds that have been proven to have antiproliferative activity against lung, colon, breast, and prostate cancer cells are terpenoids and volatile oils (EOs) from _Lamiaceae_ species [59]. Proving these, in vitro pharmacological studies on the volatile oils (EOs) extracted from the aerial part of lavender species (_Lavandula hybrid_ Rev., _Lavandula tafidia_ Medikus., _Lavandula vera_ D.C. and _Lavandula angustifolia_ Miller cultivated in Bulgaria), MTS test on Caco-2 cells and Caco-2 cell morphology analysis by electron microscopy before and after the treatment with EOs, respectively, both experiments have been confirmed to have augmented cytotoxic effects of EOs on the colon cancer, and at the same time better effectiveness of EOs in comparison with the separate constituents (e.g., linalool and 1,8-cineole), explained by their synergistic and more selective effect [60]. There were also revealed antimicrobial and antioxidant effects of EOs from lavender species, which are very usefully in managing intestinal diseases in humans [60,61]. Furthermore, studying the transport of caffeic and chlorogenic acids in Caco-2 cells, [PERSON] et al. [62] noticed a greater efficiency of absorption of caffeic acid, and the fact that polarized transport of caffeic acid has been inhibited by benzoic acid and acetic acid, two representative substrates of MCT (monocarboxylic acid transporter) in the intestine. They also revealed that the intestinal transport took place mainly by paracellular diffusion, and that m-comumaric acid and 3-(m-hydroxyphenyl) propionic acid, the main metabolites of chlorogenic and caffeic acid through the colonic microflora, competitively inhibited the transport of fluorescein, also known as a substrate of MCT. Together, these results proved the physiological importance of MCT-mediated absorption, both in the case of phenolic acids themselves and their colonic metabolites.