Larvicidal activity of 4-hydroxycoumarin derivatives against Aedes aegypti

Coumarins are natural substances found in a variety of plants. It is well known that plant-derived natural products are extensively used as biologically active compounds. Among them, coumarins were the first preservatives used by man, originally in their natural state within plant tissues and then as natural materials obtained by water distillation. During our search for new types of coumarin derivatives possessing a larvicidal activity, we investigated the synthesis of 4-hydroxycoumarin derivatives.

The coumarin derivatives were synthesized and the structure determination and larvicidal effects were studied.

The structure analyses were conducted by nuclear magnetic resonance (NMR), and mass (MS) spectroscopy revealed that the coumarin derivatives were obtained in good yields, and the eight coumarin derivatives were 3-{1,2,3,4-tetrahydro-3-[4-(4-trifluoromethylbenzyloxy)phenyl}-1-naphthalen-1-on (1), 3-{1,2,3,4-tetrahydro-3-[4-(4-trifluoro methylbenzyloxy)phenyl}-1-naphthalen-1-ol (2), brodifacoum (3), difethialone (4), bromadiolone (5), 4-hydroxy-3-(1,2,3,4-tetrahydronaphthalen-1-yl)-2H-chromen-2-one (coumatetralyl) (6), cis-flocoumafen (7) and trans-flocoumafen (8).

The compounds were tested against the F(21) laboratory strain of Aedes aegypti L. Brodifacoum and cis-flocoumafen mediated strong activity with an LC(50) values of 8.23 and 9.34 ppm, respectively.

The above indicates that brodifacoum may play a more important role in the toxicity of 4-hydroxycoumarin derivatives.