Chemical composition and repellent activity against Anopheles gambiae of essential oils from three plant taxa collected in the Democratic Republic of the Congo.

Abstract

Essential oils (EOs) derived from aromatic plants are currently being investigated as potential mosquito repellents that could be used to complement existing preventive measures. Anopheles gambiae is one of the major malaria vectors in sub-Saharan Africa. The aim of this study was to evaluate the repellent activity against Anopheles gambiae and the chemical composition of essential oils extracted from three plant taxa collected in the Democratic Republic of the Congo : Aframomum stipulatum, Lippia multiflora, and Leptonychiopsis sp. The essential oils were obtained by hydrodistillation and subsequently analyzed using gas chromatography-mass spectrometry (GC-MS). Repellent activity was assessed against adult female A. gambiae using a human-skin bioassay. Ethanol was used as the negative control, while a 13% DEET formulation served as the positive control. The protection rate and duration of protection were measured. The essential oils investigated exhibited different chemical profiles. 1,8-Cineole was the major compound identified in the essential oils of L. multiflora (59.01%) and Leptonychiopsis sp. (61.53%), whereas it accounted for only 3.10% of the essential oil of A. stipulatum. The reported protection rates were 68% for A. stipulatum, 77% for L. multiflora, 93% for Leptonychiopsis sp., and 86% for the DEET-based positive control. The longest protection duration was recorded for the essential oil of Leptonychiopsis sp., reaching 82.3 minutes. Under the experimental conditions described, the essential oil of Leptonychiopsis sp. exhibited the highest protection rate and the longest protection duration among the essential oils tested. These preliminary findings warrant further investigation, particularly through standardized efficacy and safety studies.