Design, Synthesis, Structure-Activity Relationships, and Preliminary Anticancer Properties of Menthol-Modified...

Menthol-modified coumarin esters (1a-e) and 3-phosphorylated coumarins (2a, 2b, 3) were synthesized. The Michael addition of P-(O)H groups to the coumarin skeleton offered access to 3,4-dihydrocoumarin derivatives (4a-4d, 5a-5b). The addition reaction proceeded with high yields (89-98%) in a short time under mild temperature conditions and environmentally friendly solvents such as CH₃CN or water. The resulting compounds (1a-1f, 2a, 2b, 3, 4a-4d, 5a-5b) were subjected to in vitro cytotoxicity evaluation against human cancer cell lines: colorectal (SW480, SW620), prostate (PC3), breast (MDA-MB-231), and human keratinocytes (HaCaT) by MTT assay. Doxorubicin and cisplatin were used as reference compounds. Based on the findings, the three most promising compounds (2b, 4a, 4b) were selected for further biological studies, which included evaluation of their ability to induce apoptosis, inhibit IL-6 secretion, and antiproliferative activity. Compounds such as 4a and 4b were tested as diastereomeric mixtures due to the limited possibility of separating them into individual isomers at this stage. Nevertheless, promising activity and selectivity against selected cancer cell lines were observed. The in vivo toxicological evaluation performed on zebrafish larvae indicated that coumarin 2b did not present toxic effects. In addition, the prediction of physicochemical properties, ADME, and pharmacokinetic profiles was performed by in silico methods. The results indicate the significant potential of the selected compounds as candidates for further research toward the design of new bioactive compounds.