Screening of multi-enzyme modulation and in silico glutamate-gated chloride channel inhibition using Pogostemon benghalensis-mediated nano-insecticide against Periplaneta americana

Synanthropic urban insect pests, particularly American cockroaches ( Periplaneta americana ), pose significant health risks in urban areas due to their ability to carry harmful microbes and intestinal worms. The extensive use of synthetic insecticides has resulted in adverse effects on human health and the environment, prompting increased interest in safe, natural alternatives. Essential oil-based nanoformulation strategies have gained popularity in urban pest management. In this study, we provide the first integrated evaluation of Pogostemon benghalensis essential oil nanoemulsion (PBEONE) against late-instar nymphs of P. americana , using residual contact toxicity, enzyme response, morphological assessment, and in silico analyses to explore its mechanisms of action. GC-MS analysis identified key bioactive compounds in the essential oil, including Furanoeudesma 1,3-diene (16.20%), 6-epi-shyobunol (11.62%), β-caryophyllene (7.27%), and β-ocimene (4.91%). The residual contact toxicity bioassay revealed concentration- and time-dependent effects, with the median lethal concentration (LC 50 ) of 48.41 µl/mL after 30 minutes. Biochemical assessments indicated selective modulation of key physiological enzymes, with moderate protein depletion, significant inhibition of acetylcholinesterase (AChE) and alkaline phosphatase (ALP), and minimal changes in glutathione S-transferase (GST). Antennal, leg distortion, and abnormal posture confirmed PBEONE's anti-roach activity. Furthermore, in silico examinations showed that β-caryophyllene had the highest binding energy (-6.1 Kcal/mol), and fipronil (reference compound) had -7.6 Kcal/mol against the glutamate-gated chloride channel (GluCl) of P. americana . The hydrophobic interactions between β-caryophyllene and GluCl support modulation rather than strong receptor blockade. Collectively, the findings suggest that PBEONE induces physiological modulation via a multi-target mechanism, highlighting its potential as a sustainable alternative for urban pest management. Highlights 1 1 Essential oil nanoemulsion induced rapid mortality in late-instar cockroaches • Enzyme modulation confirms the neurophysiological disruption mechanism • Docking supports GluCl interaction via hydrophobic modulation • Morphological deformities validate residual contact bio-efficacy • Sustainable nano-biopesticide candidate for urban pest management