Molluscicide Effects of Curcuma longa L. Essential Oil Nanoemulsions on Biomphalaria glabrata

Abstract Schistosomiasis is a neglected tropical disease associated with poor sanitation and caused by parasitic trematodes of the genus Schistosoma . Its transmission cycle involves freshwater snails of the Biomphalaria genus as intermediate hosts. Niclosamide is recommended by the World Health Organization (WHO) for controlling Biomphalaria spp. populations, and concerns about its environmental toxicity and resistance highlight the need for the development of new alternatives. Curcuma longa L. essential oil is reported to have antimicrobial and insecticidal properties, suggesting its potential for application in mollusk control strategies. However, its lipophilicity limits its application in aqueous environments. This study aimed to develop C. longa nanoemulsions and evaluate their molluscicidal activity toward Biomphalaria glabrata . The essential oil, obtained by hydrodistillation, was characterized by GC‒MS and GC‒FID, revealing ar-turmerone (38.72%), turmerone (27.94%), and curlone (25.38%) as major components. Nanoemulsions prepared via the low-energy method with polysorbate 80 as a surfactant presented a droplet size of 11.8 ± 0.25 nm and a polydispersity index (PdI) of 0.183 ± 0.028 and remained stable between 25 and 45 °C. The polysorbate 20 nanoemulsion had a droplet size of 115.9 ± 0.72 and a PdI of 0.209 ± 0.010 and remained stable up to 50 °C. Molluscicidal assays with the nanoformulations followed WHO protocols. The LC 90 values ranged from 44.84 to 89.72 µg/mL and from 33.86 to 126.42 µg/mL for the nanoformulations containing polysorbate 80 and polysorbate 20, respectively. The nanoemulsion formulated with polysorbate 80 showed promising molluscicidal activity against Biomphalaria glabrata , since its values remained within the efficacy criteria established by the World Health Organization (OMS), which recommends an LC 90 of less than or equal to 100 µg/mL. These results highlight the potential of nanoemulsions as environmentally friendly alternatives to assist in schistosomiasis control programs, especially through the control of intermediate hosts involved in disease transmission.