Chemical composition, antifungal and phytotoxic activities of Cistus ladanifer L. essential oil and hydrolate

Abstract

The use of synthetic chemical fungicides commonly applied in crop protection has been associated with environmental and human health risks. However, essential oils (EOs) and other bioproducts, such as hydrolates, are gaining more attention as eco-friendly alternative biofungicides. We analysed the chemical composition of essential oil (EO) and hydrolate obtained from hydrodistillation of air-dried plants of Cistus ladanifer L. by GC-MS. To assess their potential application as biofungicides, we evaluated the antifungal activity and phytotoxicity of EO and hydrolate. The oxygenated sesquiterpenes was the dominant group in the EO (28.36%), and the oxygenated monoterpenes in the hydrolate (43.62%). We tested the effect of EO and hydrolate on the mycelial growth of three phytopathogenic fungi (Fusarium oxysporum f.sp. radicis-lycopersici, Rhizoctonia solani and Cryphonectria parasitica) and one oomycete species (Phytophthora cinnamomi). The EO and hydrolate inhibited the mycelial growth of all four fungal species. The potential antifungal effect of the hydrolate was subsequently evaluated in situ with the experimental pathosystem P. cinnamomi - Lupinus luteus. The results showed that the hydrolate application significantly reduced seedling mortality in all three strains of P. cinnamomi tested (MYC-18, CA-9 and CA-4) (ED50 = 165.5 μl/ml, ED50 = 238.1 μl/ml and ED50 = 234.1 μl/ml, respectively). In phytotoxicity tests with Raphanus sativus and L. luteus seeds, the EO and hydrolate showed dose-dependent and species-dependent phytotoxic effects. These results show the high potential the C. ladanifer hydrolate to be used in the production of biofungicides to control phytopathogenic fungi.