ARS | Publication request: Isolation and identification of mosquito (Aedes aegypti) biting deterrent fatty acids from male inflorescences of breadfruit (Artocarpus altilis (Parkinson)Fosberg)

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 13, 2012
Publication Date: April 3, 2012
Citation: Chauhan, K.R., Jones, M., Klun, J.A., Cantrell, C.L., Ragone, D., Brown, P., Murch, S. 2012. Isolation and identification of mosquito (Aedes aegypti) biting deterrent fatty acids from male inflorescences of breadfruit (Artocarpus altilis (Parkinson)Fosberg). Journal of Agricultural and Food Chemistry. 60:3867-3873.

Interpretive Summary: Breadfruit, Artocarpus altilis, is a tropical staple food crop traditionally cultivated throughout Oceania (Melanesia, Micronesia, and Polynesia). Dried male inflorescences of breadfruit are burned in communities throughout Oceania to repel flying insects, including mosquitoes. This study was conducted to identify chemicals responsible for mosquito deterrence. Chemical investigation led to the identification of capric, undecanoic, and lauric acid as the primary components responsible for the activity of the burning breadfruit. All three of these compounds were significantly more effective than DEET at repelling mosquitoes. This study suggests that this traditional practice is likely effective at deterring mosquitoes, and that the inflorescences could be developed into a valuable secondary product for local use or income generation. This information will be used by chemists and pharmacologists to direct development of novel natural mosquito repellents for protection of humans and animals.

Technical Abstract: Dried male inflorescences of breadfruit (Artocarpus altilis, Moraceae) are burned in communities throughout Oceania to repel flying insects, including mosquitoes. This study was conducted to identify chemicals responsible for mosquito deterrence. Various crude extracts were evaluated, and the most active, the hydrodistillate, was used for bioassay-guided fractionation. The hydrodistillate and all fractions displayed significant deterrent activity. Exploratory GC-MS analysis revealed more than 100 distinctive peaks, and more than 30 compounds were putatively identified, including a mixture of terpenes, aldehydes, fatty acids, and aromatics. A systematic bioassay-directed study using adult Aedes aegypti females identified capric, undecanoic, and lauric acid as primary deterrent constituents. A synthetic mixture of fatty acids present in the most active fraction and individual fatty acids were all significantly more active than N,N-diethyl-m-toluamide (DEET). These results provide support for this traditional practice and indicate the potential of male breadfruit flowers and fatty acids as mosquito repellents.