Novel Adenine-Hydrazone Hybrids Against Human Lung Adenocarcinoma (A549): Design, Synthesis, Cellular Mechanistic...

Background/Objectives: Adenine derivatives are promising anticancer scaffolds, but their cellular mechanisms remain unclear. This study aimed to synthesize adenine-hydrazone hybrids and evaluate their cytotoxic effects in human lung adenocarcinoma (A549) cells. Methods: A series of adenine-hydrazone compounds (3a-r) was synthesized and tested for cytotoxicity in A549 and MRC-5 cells. Selected compounds were further analyzed for LDH release, oxidative stress markers, ROS production, mitochondrial membrane potential, cell-cycle distribution, apoptosis, and in silico docking against VEGFR2, ALK5, and EGFR. Results: Compounds with electron-withdrawing or donor-acceptor substituents showed the highest cytotoxicity, while halogenated and methoxy analogs were moderately active. Among the synthesized derivatives, 4F-substituted derivatives (3c) showed more activity than 2F- and 3F-substituted ones (3a and 3b). 4F- and 3Br-substituted derivatives (3f) showed more activity than only 4F-substituted ones (3c). 4-Nitro-substituted derivative (3i) showed more activity than 4F- (3c), 4Cl- (3d) and 4OMe- (3h) derivatives. Trimethoxy-substituted derivative (3l) showed more activity than di- and mono-substituted methoxy derivatives (3g, 3h, 3j and 3k). Among the salicyl aldehydederivatives (3m-r), 4-N(et)₂-substituted derivative (3r) showed more activity than non-substituted (3m), 5Br-(3n), 5Cl-(3o), 5Me (3p) and 3OCH₃ (3q) derivatives. Treatment induced oxidative stress, mitochondrial depolarization, Sub-G1 cell-cycle accumulation, and apoptosis. Docking studies indicated strong binding to VEGFR2 and ALK5, suggesting dual inhibition as a potential mechanism. Conclusions: Adenine-hydrazone derivatives exert substituent-dependent anticancer effects by inducing redox imbalance-associated mitochondrial dysfunction and regulated cell death. These results highlight their potential as lead structures for lung cancer therapy.