Biological Activities of <i>Callistemon citrinus</i> and <i>Callistemon viminalis</i> Essential Oils: EMT‐Linked Antitumor, Antioxidant, and Antibacterial Effects

Essential oils, known for their medicinal properties, are rich in bioactive secondary metabolites with diverse biological activities. This study aimed to evaluate the antitumoral, antioxidant, and antimicrobial properties of essential oils derived from Callistemon viminalis and Callistemon citrinus. The oils exhibited dose-dependent cytotoxic effects against A549 lung cancer cells, with IC₅₀ values of 121 µg/mL for C. viminalis and 183 µg/mL for C. citrinus. Flow cytometry analysis confirmed apoptosis induction at both early and late stages. Antioxidant assays revealed a higher total phenolic content in C. viminalis (562.42 mg GAE/L) compared to C. citrinus (277.57 mg GAE/L), with corresponding 50% inhibitory concentration (IC₅₀) values of 169.77 and 198.45 g/L, respectively. Antimicrobial evaluations revealed that C. viminalis inhibited Acinetobacter baumannii (30 mm), Enterococcus faecalis (28 mm), and Escherichia coli (26 mm), whereas C. citrinus produced smaller inhibition zones (21, 20, and 16 mm, respectively). Neither oil showed activity against Pseudomonas aeruginosa or Staphylococcus aureus. These biological effects are attributed to the high terpene and phenolic content identified through GC/MS analysis, emphasizing the therapeutic potential of Callistemon essential oils as natural agents with promising properties.