The essential oil from basil contains high concentrations of linalool and methyl chavicol (estragole), in a ratio of about 3:1.Other constituents include: 1,8-cineole, eugenol, and myrcene, among others. The clove scent of sweet basil is derived from eugenol. The aroma profile of basil includes 1,8-cineole and methyl eugenol.
Insecticide and insect repellent
Studies of the essential oil have shown insecticidal and insect-repelling properties, including potential toxicity to mosquitos. The essential oil is found by Huignard et al. 2008 to inhibit electrical activity by decreasing action potential amplitude, by shortening the post hyperpolarization phase, and reducing the action frequency of action potentials. In Huignard’s opinion this is due to the linalool and estagole, the amplitude reduction due to linalool, and the phase shortening due to both.
Callosobruchus maculatus, a pest which affects cowpea, is repelled by the essential oil. The essential oil mixed with kaolin is both an adulticide and an ovicide, effective for three months in against C. maculatus in cowpea. The thrips Frankliniella occidentalis and Thrips tabaci are repelled by O. basilicum, making this useful as an insect repellent in other crops. The pests Sitophilus oryzae, Stegobium paniceum, Tribolium castaneum, and Bruchus chinensis are evaluated by Deshpande et al. 1974 and ’77.
The essential oil is found by Malik et al. 1987 and Sangwan et al. 1990 to be nematicidal against Tylenchulus semipenetrans, Meloidogyne javanica, Anguina tritici, and Heterodera cajani.
Bacterial and fungal inhibition
The essential oil of the leaf and/or terminal shoot is effective against a large number of bacterial species including Lactiplantibacillus plantarum and Pseudomonas spp. The essential oil of leaf and/or terminal shoot is also effective against a large number of fungal species including Aspergillus spp., Candida spp., Mucor spp., and Geotrichum candidum.