In this study, we aimed to elucidate some of the mechanisms of cell death induced by lobaric acid in A549 (human lung cancer) cells. For this purpose, the effects of cytotoxic concentrations on p53 and caspase-3 gene expressions were investigated. A549 cells were treated with varying concentrations of lobaric acid (12.5, 25, 50, and 100 µg/ml) for 48 hours and then their viability was evaluated and p53 and caspase-3 mRNA expressions were determined at statistically cytotoxic concentrations of 12.5, 50, and 100 µg/ml. According to beta-actin, it was determined that the increase in lobaric acid concentration revealed an upward trend in p53 and caspase-3 mRNA expressions. Furthermore, quantum chemical parameters such as frontier molecular orbitals, band gap energy and ionization potential, electronic affinity, chemical softness, chemical potential, electrophilicity index and chemical hardness were analyzed. Furthermore, molecular docking was performed to identify the binding sites and the binding behavior of lobaric acid to some target proteins (P53, Caspase-3 and Bcl-2).