Mosquito Larvicidal Activity and Cytotoxicity of the Extracts of Aromatic Plants from Malaysia

SIMPLE SUMMARY: Mosquitoes are not only a nuisance, but most of them pose a threat to human beings as they can transmit pathogens that are harmful and may turn fatal, such as dengue, chikungunya, and Zika. This study was carried out to evaluate the larvicidal properties of the solvent extracts from three aromatic plants, Curcuma longa (turmeric), Ocimum americanum (hoary basil), and Petroselinum crispum (parsley)—against the mosquito vector of dengue, Aedes albopictus. Thereafter, the phytochemical profiles and the cellular toxicity of the extracts were evaluated. The results indicate that the hexane extracts of O. americanum and P. crispum had the greatest larvicidal activity. Among these two, O. americanum was shown to be less toxic to African monkey kidney cells and possessed an abundant amount of methyl eugenol, which is a phytochemical with known larvicidal activities. Overall, our findings indicate that these aromatic plants, especially O. americanum, may prove to be highly promising alternatives as bioinsecticides. ABSTRACT: Despite ongoing control efforts, the mosquito population and diseases vectored by them continue to thrive worldwide, causing major health concerns. There has been growing interest in the use of botanicals as alternatives to insecticides due to their widespread insecticidal properties, biodegradability, and adaptability to ecological conditions. In this study, we investigated the larvicidal activity and cytotoxicity effects of solvent extracts from three aromatic plants—Curcuma longa (turmeric), Ocimum americanum (hoary basil), and Petroselinum crispum (parsley)—against Aedes albopictus. Subsequently, we examined the phytochemical composition of the extracts through gas chromatography–mass spectrometry (GC–MS) analysis. Results revealed that the hexane extracts of O. americanum and P. crispum exhibited the greatest larvicidal activity with the lowest median lethal concentration (LC(50)) values (<30 µg/mL) at 24 h post-treatment, with the former found to be significantly less toxic towards African monkey kidney (Vero) cells. The GC–MS analysis of the said extract indicated the presence of different classes of metabolites, including phenylpropanoids, very long-chain alkanes, fatty acids and their derivatives, and terpenes, with the most abundant component being methyl eugenol (55.28%), most of which, have been documented for their larvicidal activities. These findings provide valuable insights into the potential use and development of bioinsecticides, particularly from O. americanum.