Assessment of Anticancer and Antibacterial Activities of Patchouli Essential Oil Nanoemulsion

Patchouli essential oil (PEO) obtained from Pogostemon cablin, acclaimed for its therapeutic properties and aroma, has gained increased attention for its potential applications in the food, pharmaceutical, and cosmeceutical industries. However, the application of PEO is modest due to its hydrophobicity, poor solubility in aqueous media, and high volatility. Nanoemulsions (NEs) rescue these inconsistencies with their proficiency in encapsulating PEO as nanosized droplets, thus providing a new dimension to the modern-day drug delivery of PEO. The present work reports the preparation of patchouli essential oil-based nanoemulsions (PNEs) by ultrasonication using Tween 80 as an emulsifier and water as the continuous medium. Twelve PNEs were prepared with 1:1, 1:2, and 1:3 oil-to-surfactant ratios (OSRs) and sonication times of 5, 10, 15, and 20 min. An increase in the sonication time and a decrease in the level of the OSR reduced the average droplet diameter (Z_avg) of the PNEs. PNE with 1:3 OSR and 20 min sonication was optimized for biological studies as it displayed the minimum Z_avg (∼14 nm), maximum stability upon centrifugation (5000 rpm), thermal treatment (30, 60, and 90 °C), and storage (4 weeks), where it showed a slowest Ostwald ripening rate (ω) of ∼6.7 × 10^-6 nm³ s^-1. The optimized PNE showed in vitro anticancer activity against A549 lung cancer cells by showing cell cytotoxicity and inducing apoptosis. The observation of a lower IC₅₀ of the optimized PNE (0.71 μL mL^-1) than that of PEO (1.13 μL mL^-1) confirmed improved anticancer activity. The first evidence of anticancer activity of PNE against the A549 lung cancer cell line is presented. Moreover, the optimized PNE also showed antibacterial activity against Vibrio cholerae, Bacillus cereus, Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium with minimum inhibitory concentration (MIC) values of 3.12, 3.12. 6.25, 6.25, and 3.12 μg mL^-1, respectively.