Vol. 7, Issue 2, Part A (2025)

Background and objective: Argemone mexicana seed oil is a plant-derived bioactive known for its potent antimicrobial and anti-inflammatory properties. However, its clinical utility is hindered by poor water solubility, high viscosity, and chemical instability. Nano-emulsion technology provides a promising strategy to enhance the bioavailability and stability of such hydrophobic phytoconstituents. This study aimed to formulate and evaluate a stable nano-emulsion of Argemone mexicana oil using a low-energy method and assess its physicochemical properties and antimicrobial potential. 
Methods: A spontaneous emulsification technique was used for the development of oil-in-water nano-emulsions using Brij 30 as the primary surfactant. Pseudo-ternary phase diagrams were constructed to determine optimal composition ranges. The prepared formulations were characterized for droplet size, zeta potential, morphology (optical microscopy), viscosity, and physical stability. Antimicrobial activity was evaluated using agar well diffusion method against Escherichia coli.
Results: The optimized nano-emulsion (AB1) exhibited a mean droplet size of <100 nm and a zeta potential of -28.7 mV, indicating good colloidal stability. The system showed low viscosity (~4-8 cP) and remained stable without phase separation over a 3-month period at 4 °C and 25 °C. In vitro antimicrobial studies revealed a significant zone of inhibition (18 mm) with a MIC of 50 µg/mL for AB1, demonstrating enhanced activity compared to the crude oil.
Conclusion: The developed nano-emulsion of A. mexicana oil using low-energy emulsification significantly improved the oil’s physicochemical properties and antimicrobial efficacy, suggesting its potential application as a natural antimicrobial agent in pharmaceutical formulations.