Enhancing Pediculicidal Activity Against <i>Pediculus humanus capitis</i> Using Iron Oxide Nanoparticle-Based Formulations of some Plant Extracts and Acetic Acid Solution

Abstract

Infestations of head lice (Pediculus humanus capitis) continue to be a major public health concern. There have been instances of lice developing resistance to traditional chemical pediculicides. Therefore, there is a critical need to identify new and effective alternatives. The purpose of this study was to use a filter paper contact bioassay to determine the toxicity of three plant extracts (Azadirachta indica, Nigella sativa, and Sesamum indicum) on head lice, both alone and in combination with iron oxide nanoparticles (Fe3O4 Nps), at a concentration of 202mg L-1. The pediculicidal activity of A. indica oil was 88% at 3 μl/cm , whereas that of acetic acid solution (white vinegar) was 81% within 12 h, both without nanoparticles. With the addition of iron oxide nanoparticles, the toxicity was significantly amplified, and within 6-12 hours, A. indica and acetic acid killed all lice. When exposed to Fe3O4 nanoparticles, N. sativa died after 12 h. When exposed to Fe3O4 nanoparticles, S. indicum exhibited moderate toxicity (35% mortality) compared with its harmless effects. Within 12 h, A. indica eradicated all lice at a concentration of 6 μl/cm2, whereas an acetic acid solution resulted in 82% mortality. A. indica mixed with Fe3O4 nanoparticles, caused complete death within 1h and with acetic acid within 6h. N. sativa exhibited a death rate of 72% when exposed to Fe3O4 nanoparticles at 12 h. These results show that formulations based on iron oxide nanoparticles, combined with A. indica and acetic acid, have great promise as pediculicidal agents to fight head lice infestations.