Evernic and diffractaic acids: Novel regulators of intracellular redox homeostasis in the MCF-7 cell line

Oxidative stress plays a critical role in tumor development and cancer cell survival; however, the effects of lichen secondary metabolites on antioxidant defense systems are not yet fully understood. In our previous study, we demonstrated that the lichen secondary metabolites evernic acid (EA) and diffractaic acid (DA) exert significant cytotoxic and anti-migratory effects in MCF-7 breast cancer cells through inhibition of thioredoxin reductase 1 (TrxR1), a key oxidoreductase enzyme involved in maintaining cellular redox homeostasis and frequently upregulated in cancer cells. In this study, the effects of EA and DA on oxidative stress and the antioxidant system in MCF-7 cells were investigated comprehensively for the first time.

Intracellular glutathione (GSH), reactive oxygen species (ROS), and malondialdehyde (MDA) levels were measured in MCF-7 cells, together with antioxidant enzyme activities and gene/protein expression. Both EA and DA disrupted redox homeostasis by decreasing GSH and increasing ROS. EA also elevated MDA levels and caused a significant redox imbalance by suppressing the activity of SOD, CAT, GR, GPX, and GST. In contrast, DA selectively inhibited SOD, CAT, and GST activity, exhibiting more balanced redox modulation while promoting apoptosis.

EA triggered ferroptosis-associated molecular alterations by disrupting the GSH-GPX4 axis. Collectively, these findings demonstrate that EA and DA act as redox-modulating molecules that induce cytotoxicity in MCF-7 cells through distinct mechanisms, highlighting the therapeutic potential of lichen secondary metabolites in breast cancer.