Essential Oil from Flowering Tops of Lavandula dentata (L): Chemical Composition, Aantimicrobial, Antioxidant and Insecticidal Activities

Abstract

In this study, the chemical composition, antioxidant, antimicrobial, and insecticidal activities of essential oil (EO) from Lavandula dentata (L. dentata) flowering tops collected from northern Tunisia were assessed. Forty-three compounds were identified. β-eudesmol (21.178 %), myrtenol (13.023 %), and sabinol (11.021 %) were the main compounds. The antibacterial potential was evaluated against three Gram-positive bacteria and three Gram-negative bacteria. The diameter of inhibition varied between 20.83±0.47 mm and 24.16±0.47 mm. The largest one was found in Salmonella typhimurium, however, the smallest one was found in Bacillus cereus. The minimal inhibition concentration (MIC) varied between 0.1 and 0.6 μg/ml. Furthermore, the antifungal potential was carried out. The mycelial growth of all the treated fungi was significantly different from the control ones (p<0.05), except in the case of P. notatum when treated with a dose of 1.25 mg/ml. Moreover, L. dentata EO was screened for its antioxidant activity using three methods. IC50 values were 113.29± 0.012 mg/ml, 53.029± 0.02 mg/ml, 43.20± 0.004 mg/ml, respectively for the DPPH test, the ABTS test and the reducing power test. The insecticidal activity was tested against adults of two major insect pests namely Rhyzopertha dominica and Sitophilus oryzae using contact, fumigant toxicity, and repellent bioassays. Results revealed that the L. dentata EO exhibited strong fumigant, repellent, and contact properties. For all tests, R. dominica was more sensitive compared to S. oryzae. This study revealed that EO from L. dentata flowering tops could be potentially valorized as a new antibacterial, antifungal, and bioinsecticide product.