Enhancing Pediculicidal Activity Against Pediculus humanus capitis 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 20 mg 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 3 4 exposed to Fe₃O₄ nanoparticles, S. indicum exhibited moderate toxicity (35% 3 4 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.