Abstract
BackgroundNorcantharidin (NCTD), a demethylated derivative of cantharidin (defensive toxin of blister beetles), has been reported to exhibit insecticidal activity against various types of agricultural pests. However, NCTD applications are limited by its poor water solubility and high dosage requirement. Nanoemulsions have attracted much attentions due to the transparent or translucence appearance, physical stability, high bioavailability and non-irritant in nature. In general, nanoemulsions with small droplet size can enhance the bioavailability of drugs, whereas this phenomenon is likely system dependent. In present study, NCTD nanoemulsions were developed and optimized to evaluate and improve the insecticidal activity of NCTD against Plutella xylostella (Lepidotera: Plutellidae) by a spontaneous emulsification method.ResultsTriacetin, Cremophor EL and butanol were selected as the constituents of NCTD nanoemulsions via solubility determination, emulsification efficiency and ternary phase diagram construction. Insecticidal activity of NCTD nanoemulsion was associated with the content of surfactant and cosurfactant: (1) Higher effective toxicity exhibited at Smix (surfactant to cosurfactant mass ratio) = 3:1 that may be associated with the changes in interfacial tension; (2) NCTD nanoemulsion at 3:7 < SOR (surfactant to oil mass ratio) < 6:4 was more effective at lower surfactant level, which was attributed to the relatively slow diffusion rate of NCTD hindering by excess surfactant. Interestingly, nanoemulsions with smaller droplets were not found to be more effective in our study.ConclusionsThe optimized NCTD nanoemulsion (triacetin/Cremophor EL/butanol (60/20/20, w/w)) exhibited effective insecticidal activity (LC50 60.414 mg/l, LC90 185.530 mg/l, 48 h) than the NCTD acetone solution (LC50 175.602 mg/L, LC90 303.050 mg/L, 48 h). Spontaneous emulsifying nanoemulsion employed to formulate this poor water-soluble pesticide is a potential system for agriculture application.
Highlights
Norcantharidin (NCTD), a demethylated derivative of cantharidin, has been reported to exhibit insecticidal activity against various types of agricultural pests
There is a focus on the potential for NCTD-nanoemulsions that were prepared by the spontaneous emulsification method, stabilized by nonionic surfactant with low content and approved for insecticide use
The highest solubility was observed in triacetin with 12.39 ± 0.21 mg/mL; the lower solubility was exhibited in tributyrin (3.06 ± 0.11 mg/mL)
Summary
Norcantharidin (NCTD), a demethylated derivative of cantharidin (defensive toxin of blister beetles), has been reported to exhibit insecticidal activity against various types of agricultural pests. Norcantharidin (NCTD), an available analogue of cantharidin, has been approved for the treatment of multiple types of cancer [8,9,10]. Nanoemulsions are a class of emulsions with droplet size ranging from 20 to 200 nm and are kinetically stable Due to their characteristic size, nanoemulsions have been used for improving the bioactivity/ bioavailability, stability and safety of some active substances [1, 20, 21]. There is a focus on the potential for NCTD-nanoemulsions that were prepared by the spontaneous emulsification method, stabilized by nonionic surfactant with low content and approved for insecticide use
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
