In Silico Based Approach to Investigate Plant Lignans as Inhibitor Candidates for Estrogen Receptor in Breast Cancer

Background: In the last decades, growing evidence demonstrates interest in phytoestrogen intake to modulate targets in different types of cancer. Plant lignans have proven efficacious in blocking estrogen receptors of breast cancer cells. Among them, four phytoestrogen lignans: pinoresinol, matairesinol, lariciresinol, and secoisolariciresinol have been most studied. However, available studies have mostly dealt with the anti-cancer effects of groups of lignans in certain foods or plants and the effects of specific lignans, especially from a molecular interaction viewpoint, have been rarely addressed in the literature. Objective: We aimed to in silico predict pharmacological properties, binding ability and binding strength of pinoresinol, matairesinol, lariciresinol and secoisolariciresinol as possible inhibitors of estrogen receptor alpha which is the most important biomarker in breast cancer. Methods: Firstly, we evaluated the pharmacological properties of four lignans using SwissADME. Then we investigated the ligand-receptor interactions of these molecules as positively appraised ligands for ER-positive breast cancer targeted therapy using docking method. We finally compared the inhibitory effect possibility of the lignans against endoxifen which is the active metabolite of tamoxifen. Results: The best binding affinity of endoxifen, matairesinol, pinoresinol, lariciresinol and secoisolariciresinol were respectively -9.2, -7.5, -6.7, -6.7, -5.8 kcal/mol. In the meantime, matairesinol showed a minimum binding energy than other studied lignans in addition to the most similar interactions to endoxifen with conserved domain residues of the active site pocket in Leu:391, Ala:350, Met:421, and Phe:404. Conclusion: Among the studied lignans, matairesinol showed favorable pharmacokinetics and drug-likeliness properties, the least binding energy as well as the most common interactions in conserved residues of the active site pocket with estrogens. This makes it a molecule with low number of nonspecific interactions, better target selectivity, and hence fewer side effects. Thus, our results introduce matairesinol as a possibly effective anti-estrogen receptor inhibitor candidate.