Ligusticum sinense Nanoemulsion Gel as Potential Repellent against Aedes aegypti, Anopheles minimus, and Culex quinquefasciatus (Diptera: Culicidae).

Ligusticum sinense Oliv. cv. is a species of Umbelliferae (Apiaceae), a large plant family in the order Apiales. In this study, L. sinense hexane extract nanoemulsion gel (LHE-NEG) was investigated for mosquito repellency and compared to the standard chemical, N,N-diethyl-3-methylbenzamide (DEET), with the goal of developing a natural alternative to synthetic repellents in protecting against mosquito vectors. The results demonstrated that LHE-NEG afforded remarkable repellency against Aedes aegypti, Anopheles minimus, and Culex quinquefasciatus, with median protection times (MPTs) of 5.5 (4.5-6.0), 11.5 (8.5-12.5), and 11.25 (8.5-12.5) h, respectively, which was comparable to those of DEET-nanoemulsion gel (DEET-NEG: 8.5 (7.0-9.0), 12.0 (10.0-12.5), and 12.5 (10.0-13.5) h, respectively). Evaluation of skin irritation in 30 human volunteers revealed no potential irritant from LHE-NEG. The physical and biological stability of LHE-NEG were determined after being kept under heating/cooling cycle conditions. The stored samples of LHE-NEG exhibited some changes in appearance and differing degrees of repellency between those kept for 3 and 6 heating/cooling cycles, thus providing slightly shorter MPTs of 4.25 (4.0-4.5) and 3.25 (2.5-3.5) h, respectively, when compared to those of 5.0 (4.5-6.0) h in fresh preparation. These findings encourage commercially developed LHE-based products as an alternative to conventional synthetic repellents in preventing mosquito bites and helping to interrupt mosquito-borne disease transmission.