Preparation and Evaluation of Nanoemulsion of Citronella Essential Oil with Improved Antimicrobial and Anti-Cancer Properties

The development of new pharmaceutical solutions for treating various diseases results from a growing understanding of the benefits of using essential oils. One of the most often used volatile materials among essential oils is the oil of the citronella plant, termed citronella essential oil (CITEO), which has potential for use in food and medicine. Its wide use is limited due to lipophilicity, high volatility and poor physicochemical stability. With this background, the present study aims to evaluate the properties of CITEO-nanoemulsion (CITEO-NE) by analyzing its antimicrobial activities against Staphylococcus aureus (S. aureus) and Candida albicans (C. albicans) and its anticancer activity against, human skin adenocarcinoma cell line (A431). The CITEO-NE was prepared and evaluated for the size range of 130 ± 5 nm, polydispersity index (PDI) of 0.127 and zeta potential −12.6 mV. The percentage % of entrapment efficiency (%EE) of nanoemulsions loaded with CIT was very high at the beginning of the study, at 95.5 ± 4.775%. The MIC was observed to be 500 µg/mL for CITEO and 250 µg/mL for CITEO-NE against S. aureus and 250 µg/mL for CITEO and 125 µg/mL for CITEO-NE against C. albicans. The time-kill assay also suggests the effectiveness of CITEO-NE against the test pathogens as a novel alternative therapy. The IC₅₀ values of CITEO and CITEO-NE exhibited significant cytotoxic properties against the A431 cell line, with 41.20 μg/mL and 37.71 μg/mL, respectively. Hence, our findings revealed that encapsulation of CITEO increased the pharmacological properties.