Short communicationA tetracosatetraene as larvicidal compound isolated from Alpinia katsumadai

- The novel larvicidal compound was identified from Alpinia katsumadai.
- The active compound was isolated by bioassay-guidance with some chromatography.
- The active compound was elucidated by spectroscopic analysis with 1H NMR, 13C NMR, and ESI-MS.
- The active compound was screening by foam cell formation test with THP-1 cells.
- The active compound has larvicidal effect against Plutella xylostella L. and Mythimna separate.

Plutella xylostella and Mythimna separata are destructive insect pests causing damages to agricultural products. In this study, a larvicidal compound was identified by bioassay-guided isolation of methanol extracts of Alpinia katsumadai Hayata, a plant belonging to the Zingiberaceae, against P. xylostella and M. separata larvae. Because many insects, including P. xylostella and M. separate larvae, cannot synthesize sterols, they use phytosterols by converting them to the sterols necessary for hormonopoiesis, and resulting normal development, growth and reproduction. Results of our oil droplet formation test showed that compound 1 inhibited foam cell formation in ox-LDL treated THP-1 cells, suggesting that this compound may be inhibiting the sterol transport in insects. The compound 1 with larvicidal activity was elucidated by spectroscopic analysis (1H NMR, 13C NMR, and ESI-MS) as 2,3,22,23-tertrahydroxy-2,6,10,15,19,23-hexamethyl-6,10,14,18- tetracosatetraene. The 50% lethal concentration (LC50) values of compound 1 were 2 μg/mL and 16.9 μg/mL, respectively, against P. xylostella and M. separata larvae.