Review on the chemical composition of Litsea cubeba essential oils and the bioactivity of its major constituents citral and limonene
There are two chemotypes of Litsea cubeba (Lour.) Pers. (fam. Lauraceae) essential oils (EOs), either dominated by citral and limonene or by citronellal. L. cubeba EOs exhibits broad antimicrobial activity against bacteria and fungi with minimal inhibitory concentrations (MICs) from 0.5 to 2500 µg/mL. This antimicrobial activity is attributed to the monoterpene citral, exhibiting a broad antimicrobial spectrum against bacteria and fungi (MICs 50-1000 µg/mL). Pseudomonas aeruginosa were found most resistant, with MIC values above 1000 µg/mL. Citral's mode of action is not fully investigated. At biocidal concentrations, it affects membrane structure and cell respiration, leading to rapid energy depletion and cell death. Involvement of intracellular reactive oxygen species has not been verified. Limonene exhibits insignificant antimicrobial activity. MICs of d-limonene range from 1 to 20 mg/mL. Citral and L. cubeba EOs were also subjects of food application studies. Promising results have been reported for fresh produce or fruit-juice.