Preparation, characterizations and antibacterial activity of different nanoemulsions incorporating monoterpenes:in vitroandin vivostudies

Bio-based oil in water nanoemulsions incorporating (R)-carvone, cinnamaldehyde, citral, geraniol and pulegone were prepared, characterized and evaluated against two plant pathogenic bacteria. Nanoemulsions were prepared at 5% monoterpene into an aqueous solution containing a surfactant (tween 80, 10%) with stirring and ultra-sonication. The antibacterial activities were significantly affected by the formulation and nanoemulsion of cinnamaldehyde was the most active against Pectobacterium carotovorum and Ralstonia solanacearum (MIC = 60 and 100 mg/L, respectively). To explore the potential mechanism underlying the induced systemic resistance mediated by emulsified cinnamaldehyde, peroxidase (POD), polyphenol oxidase (PPO) and total soluble phenolic content were monitored in spunta potato (Solanum tubersum, L.) in tubers and leaves. The results showed that the activity PPO, POD and total phenolic content of tubers and leaves by cinnamaldehyde nanoemulsion at 1000 and 3000 mg/L were higher than control. Incorporation of such inexpensive treatments might reduce management costs and reduce the environmental pollution.