Polymeric nanoemulsions enriched with Eucalyptus citriodora essential oil

Abstract Eucalyptus citriodora oil has a well-known antimicrobial activity, however, its volatility limits its therapeutic applicability. Oil-in-water chitosan-based nanoemulsions have been prepared using a high-energy method in variable conditions in order to produce a stable formulation with an effective antimicrobial action. Physical-chemical characterizations and antimicrobial activity were performed. Results showed that the nanoemulsions with stability over 60 days and encapsulation efficiency higher than 90% were the ones with higher surfactant content. An optimal formulation was produced with the longer chain surfactant, which impacted in a particle size of 489.2±0.25nm and encapsulation efficiency of 92.5±0.17%. This formulation showed sustained release over 72h according to zero order kinetics, where the drug diffusion is lower than the respective dissolution release rate. The bactericidal action of the tested formulations showed an expressive inhibition rate against S. typhimurium (73%), with potential for an effective release system for antimicrobial control.

摘要 柠檬桉叶油（Eucalyptus citriodora oil）具有公认的抗菌活性，但其挥发性限制了其治疗应用潜力。本研究采用高能乳化法在可变条件下制备了壳聚糖基水包油型纳米乳液，以获得兼具稳定性与高效抗菌活性的制剂。对所得制剂开展了理化表征与抗菌活性检测。结果表明，表面活性剂（surfactant）含量越高的纳米乳液，其稳定性可维持60天以上，包封率（encapsulation efficiency）亦高于90%。采用长链表面活性剂制备的最优制剂，粒径为489.2±0.25nm，包封率达92.5±0.17%。该制剂符合零级动力学（zero order kinetics）模型，可实现72小时以上的持续释药，其药物扩散速率低于对应溶解释放速率。受试制剂对鼠伤寒沙门氏菌（S. typhimurium）展现出73%的显著抑菌率，具备开发为高效抗菌控释体系的应用潜力。