Larvicidal activities of Piper kadsura (Choisy) Ohwi extract and its constituents against Aedes albopictus, toxicity to non-target organisms and development of cellulose nanocrystal-stabilized Pickering emulsion

Abstract

Among 15 plant methanol extracts, Piper kadsura stem extract (PkSE) showed the strongest larvicidal activity against Aedes albotictus. Larvicidal activities of P. kadsura stem extract were 100 % and 80 % at 0.01 and 0.005 mg/mL concentrations, respectively. Two isobutyl amides, pellitorine and chingchengenamide A, and one neolignan, piperenone, were isolated as active compounds from PkSE. Larvicidal activities of chingchengenamide A, piperenone, and pellitorine were 100 %, 100 %, and 87.5 % at 0.005 mg/mL concentration, respectively, and 100 %, 67.5 %, and 15.0 % at 0.0025 mg/mL. Cellulose nanocrystal (CNC)-stabilized Pickering emulsion of PkSE was developed, and its larvicidal activity was slightly higher than that of pure PkSE. Acute oral and dermal toxicity of PkSE toward rat, Rattus norvegicus, was >2000 mg/kg body weight. Acute contact toxicity of PkSE to honeybee was >100 μg/bee. The no observed effect concentration (NOEC) of PkSE to Oryzias latipes was 0.031 mg/mL.