Enhancing the efficacy of monolaurin against SARS-CoV-2 and influenza A (H1N1) with a nanoemulsion formulation

Monolaurin was utilized to formulate temperature-driven phase inversion nanoemulsions containing lesser galangal essential oil, fixed oil, and Cremophor RH40, with aim for eradicating enveloped viruses. Results showed that the droplet size of the nanoemulsion depended on lesser galangal essential oil–fixed oil ratio, monolaurin concentration, and oil concentration. Nanoemulsions prepared from lesser galangal essential oil–perilla oil (60:40) exhibited approximately 50-nm nanosized droplets and high entrapment efficiency (98.68 % ± 2.45 %). After storage at 25 °C for 1 year, droplet size did not vary significantly from the initial size, and monolaurin content was >95 %, indicating good physical and chemical stability. The monolaurin was located at the oil–water interface as indicated by a two-dimensional nuclear Overhauser effect nuclear magnetic resonance spectroscope and computer simulation. The 0.2% w/v monolaurin nanoemulsion inhibited SARS-CoV-2 and influenza A (H1N1) viruses with efficacy more than 3 log reduction (99.90 %) and low cytotoxicity. Hence, the monolaurin nanoemulsion can successfully eradicate enveloped viruses, especially SARS-CoV-2 and influenza A (H1N1).