This study evaluates the pediculicidal activity of nanoformulations containing different binary essential oil component mixtures (eugenol:linalool, 1,8 -cineole:linalool, and eugenol:thymol) using immersion bioassays. These have allowed us to evaluate the knockdown time affecting 50% of the individuals (KT). In addition, the type of interaction between the components in each mixture was established in terms of the combination index (IC). The KT values were 6.07; 8.83; 7.17 and 27.23 h for linalool, 1,8 -cineole, eugenol, and thymol, respectively. For the eugenol:linalool mixtures, the efficacy was lower or equal to that obtained for the nanoformulations of the pure compounds, with values of KT about 13.33, 8.16 and 6.71 h for mixtures with ratios 3:1, 1:1 and 1:3, respectively. These mixtures present IC > 1, evidencing antagonistic interaction, which is enhanced with eugenol content. In the case of the binary mixtures of 1,8 -cineole: linalool, KT values were similar to those obtained for eugenol:linalool mixtures with similar ratios. In this case, IC assumes values close to unity, suggesting additive interactions independently of the mixture composition. On the other side, mixtures of eugenol:thymol with 1:1 and 1:3 ratios showed values of 9.40 and 32.93 h, while the mixture with a 3:1 ratio showed the greatest effectiveness (KT of 4.42 h). Eugenol:thymol mixtures show synergistic interaction (IC < 1) for combinations 3:1 and 1:1, while no interaction was observed for 1:3 combination. This indicates that eugenol enhances thymol activity. These results must be considered an important step forward to the development of effective pediculicidal nanoformulations based on botanical compounds.

中文翻译：

---

有效性和化学见解：探索纳米胶束和单萜类化合物之间用于治疗头虱的相互作用

本研究使用浸没生物测定法评估了含有不同二元精油成分混合物（丁子香酚：芳樟醇、1,8-桉树脑：芳樟醇和丁子香酚：百里酚）的纳米制剂的杀虱活性。这些使我们能够评估影响 50% 个体的击倒时间 (KT)。此外，每种混合物中各组分之间的相互作用类型是根据组合指数（IC）确定的。 KT值为6.07； 8.83；芳樟醇、1,8-桉树脑、丁子香酚和百里酚分别为 7.17 和 27.23 小时。对于丁子香酚:芳樟醇混合物，功效低于或等于纯化合物纳米制剂所获得的功效，对于比例为3:1、1:1和1:3的混合物，KT值约为13.33、8.16和6.71小时， 分别。这些混合物的 IC > 1，证明拮抗相互作用，并且随着丁子香酚含量的增加而增强。在 1,8-桉树脑：芳樟醇的二元混合物的情况下，KT 值与具有相似比例的丁子香酚：芳樟醇混合物获得的值相似。在这种情况下，IC 假定值接近统一，表明加性相互作用与混合物组成无关。另一方面，1:1 和 1:3 比例的丁子香酚：百里酚混合物显示出 9.40 和 32.93 小时的值，而 3:1 比例的混合物显示出最大的有效性（KT 为 4.42 小时）。丁子香酚:百里酚混合物在 3:1 和 1:1 组合中表现出协同相互作用 (IC < 1)，而在 1:3 组合中未观察到相互作用。这表明丁子香酚增强了百里酚活性。这些结果必须被视为朝着开发基于植物化合物的有效杀虱纳米制剂迈出的重要一步。