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

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 mu g/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 mu g/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.

Automated summary

Botanical insecticides offer a safer alternative to synthetic insecticides for insect control. The study revealed that extracts of Alpinia galanga rhizomes and certain phenylpropanoids have insecticidal activity against Spodoptera litura Fab, with 1'S-1'-acetoxychavicol acetate being the most active compound.