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Leech attachment is a common nuisance to outdoor recreationists and farmers in aquatic environments. Consequences include bleeding, infection, and, rarely, death. Methods to prevent leech attachment are anecdotal and individual; effective repellent formulations with universal applicability are needed. In this study, icaridin is demonstrated to be repellent and toxic to aquatic leech, and formulation of icaridin loading nitrocellulose (Icar-Nitr) is proposed as a new leech repellent. The nitrocellulose provided sustained drug release and waterproof properties. One optimal formulation, 10-Icar-Nitr, proved effective for leech repelling in aquatic environment. Using a rat model, the same formulation also showed removal and killing after leech attachment. The nitrocellulose reduced percutaneous absorption of icaridin, and 10-Icar-Nitr showed good biocompatibility. This study provides a potential new and practicable strategy for prevention and removal against leech attachment and bites. [ABSTRACT FROM AUTHOR]

Arctigenin (ARG) has potent antifatigue activity, but its clinical application has been restricted for its poor water solubility. In this study, seven ARG derivatives containing different amino acids coupled via an ethoxy linker were synthesized, and tested for their solubility, as well as activities to improve exercise performance in mice. All of the derivatives showed improved solubility compared to that of ARG. Derivative Z-A-6 exhibited the highest activity, showing that the mice ran a 4.88-fold greater distance in the running wheel test and swam a 2.86-fold greater time in the swimming test than those in the blank control group. Z-A-6 treatment increased the plasma superoxide dismutase and catalase concentrations as well as reduced lactic acid and blood urea nitrogen accumulation during exercise. Z-A-6 treatment enhanced the phosphorylation of adenosine monophosphate-activated protein kinase, and no acute toxicity was observed. The results will contribute to the development of potential antifatigue agents., (© The Author(s) 2023. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.)