Insecticidal activity of isolated phenylpropanoids from Alpinia galanga rhizomes against Spodoptera litura

Abstract

Botanical insecticides as a means of controlling insects present an alternative approach that is safer than the use of synthetic insecticides. The present study identified the insecticidal activity of extracts of the rhizomes of Alpinia galanga (L.) Willd. and seven isolated phenylpropanoids against the second instar of Spodoptera litura Fab. by topical application. The ethyl acetate extract had the highest toxicity on this insect with LD₅₀ values of 1.68 and 1.25 μg/larva after 24 and 48 h posttreatment, respectively. Among the seven phenylpropanoids separated from the ethyl acetate extract, 1′S-1′-acetoxychavicol acetate was identified as the most active compound with LD₅₀ values of 1.63 and 1.40 μg/larva after 24 and 48 h posttreatment, respectively, followed by p-coumaryl diacetate. In addition, the two active compounds decreased glutathione S-transferase activity and increased acetylcholinesterase activity. p-Coumaryl diacetate also decreased carboxylesterase activity.

Graphical Abstract

Keywords:

• Alpinia galanga
• detoxification enzymes
• insecticidal activity
• phenylpropanoids
• Spodoptera litura

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Center of Excellence for Innovation in Chemistry (PERCH-CIC), Ministry of Higher Education, Science, Research and Innovation; under the Strengthening and Developing New Researcher Plan, in conformance with the Research and Innovation of Graduate Study Strategy of the National Research Council of Thailand (NRCT) as of the fiscal year 2019; the Kasetsart University Research and Development Institute (KURDI); the Department of Chemistry, Faculty of Science, Graduate School, Kasetsart University.