Anticancer Property of Triacetylphloroglucinol and Its Molecular Interactions With Human Serum Albumin

Phloroglucinols, the phenolic compounds have been gaining importance as pharmacophores owing to the wide array of innate biological potentials such as antimicrobial, antioxidant, anticancer, antifungal, anticoagulant, anti-inflammatory and antimetastatic properties. In the present investigation, for the first time, we report the anticancer potential of 2,4,6-triacetylphloroglucinol (TAPG), a phloroglucinol derivative and its molecular interactions with human serum albumin (HSA). HSA is considered to be a good carrier to deliver anticancer drugs due to its accumulation in tumor cells. The preliminary anticancer potential was assessed through anti-proliferative assay and the inhibitory concentration (IC50) was determined., Cell cycle analysis, reactive oxygen species (ROS) generation and determination of mitochondrial membrane potential were done using IC50 value. TAPG showed potent cytotoxicity towards lung (A549), breast (MDA MB-231), colon (HCT-15) and cervical (HeLa) cancer cells in dose-dependent manner at 48 h without showing any toxic effect to normal cells such as human peripheral blood mononuclear cells (PBMCs) and human embryonic kidney (HEK-293) cells. Cell cycle analysis revealed G1 phase arrest in cancer cells upon TAPG treatment. Also, loss in mitochondrial membrane potential with increased ROS production was observed in TAPG-treated cancer cells. The drug-protein interactions were explored through steady-state fluorescence, time-resolved fluorescence (TRF), circular dichroism (CD), isothermal titration calorimetry (ITC) and computational studies. Fluorescence spectroscopy of HSA-TAPG interaction depicted strong static quenching of intrinsic fluorescence of HSA. Further, TRF study confirmed the ground-state complex formation. CD spectroscopy analysis depicted the secondary structural changes with decrease in α-helical content in protein upon interaction of TAPG with HSA. Both fluorescence and ITC studies exhibited the reversible and moderate affinity of TAPG towards HSA which favours the easy diffusion of molecule to target tissue. ITC study for TAPG-HSA interaction further demonstrated the spontaneity and exothermic reaction with involvement of electrostatic interactions. It was also confirmed through molecular docking and molecular dynamic simulation studies that TAPG showed stable interactions and strong affinity towards HSA in its site I than site II. Thus, present investigation demonstrates the anticancer potential of TAPG and its favourable binding with HSA.