Identification of compounds from Etonia rosemary (Conradina etonia)

Mosquitoes transmit pathogens that result in diseases harmful to human, livestock, and wildlife hosts. Numerous measures can be used to reduce insect-borne disease risk to humans, and one approach is the use of topical repellents to prevent host-seeking arthropods from taking a blood meal. A current emphasis in the development of new repellents is that they be safe. Therefore, natural products sources are increasingly being explored. Compounds from plants of the mint family (Lamiaceae) have been demonstrated to be insect repellents. This study examines compounds from Etonia rosemary (Conradina etonia) to identify compounds for examination as insect repellents. Samples of Etonia rosemary were passively extracted with hexane, dichloromethane, and methanol and analyzed by GC/MS. This extraction method was chosen to eliminate thermal degradation of plant components that can occur during the distillation procedure. Additional headspace volatile compounds from this plant were identified using microscale purge-and-trap GC/MS. A variety of terpenes, terpenic alcohols, ketones, and aldehydes were identified in the extracts with terpenes and short-chained aldehydes detected in greatest abundance.