Bioassay guided isolation of mosquito biting deterrent compounds from Strumpfia maritima.

In our natural products screening program against mosquitoes, we screened ethanolic extract of Strumpfia maritima Jacq. which showed high biting deterrent activity in K & D bioassays against Aedes aegypti L. Through bioguided fractionation we isolated 6 compounds from the active fractions. The extract and pure compounds were evaluated for larvicidal and biting deterrent activity against Aedes aegypti.Ethanolic extract with proportion not biting (PNB) value of 0.8 ± 0.08 provided biting deterrent activity similar to DEET (PNB = 0.9 ± 0.05) against Ae. aegypti. Five out of eight fractions, prepared through bioassay-guided fractionation, showed biting deterrent activity similar to DEET. Six compounds were isolated from active fractions and characterize as squalene, ursolic acid, betulonic acid, cabraleone, ursolic acid acetate, and 27-p-E-Coumaroyloxyursolic acid. The biting deterrent activity of ursolic acid acetate (BDI = 0.85), cabraleone (BDI = 0.79), and ursolic acid (BDI = 0.78) was similar to DEET against Ae. aegypti. Strumpfia maritima extract did not show larvicidal activity at the highest screening dose of 125 ppm in the larvicidal bioassay.The ethanolic extract and pure compounds showed biting deterrent activity against Ae. aegypti. The high biting deterrent activity of ursolic acid acetate and cabraleone indicated a great potential for these natural compounds to be developed as mosquito repellents. This article is protected by copyright. All rights reserved.