In vitro photoinduced cytotoxic activity of Citrus bergamia and C. medica cv Diamante peel essential oils and identified active coumarins

Context. The search for innovative therapeutic approaches is gaining more interest inclinical oncology. Objective. In the present investigation we reported the chemical profile andthe photoinduced cytotoxic activity of two endemic Calabrian Citrus species (Rutaceae):Citrus bergamia Risso & Poit. and Citrus medica L. cv Diamante. Materials and Methods.Essential oils were obtained by hydrodistillation and analysed by GC and GC/MS. In order toevaluate the cytotoxic activity two melanoma models, such as amelanotic melanoma C32 andmalignant melanoma A375, were used. Results. The essential oil of C. bergamia wascharacterized by limonene, linalyl acetate, γ-terpinene, linalool and β-pinene as majorcomponents. The most abundant compounds of C. medica cv Diamante oil were limonene,γ-terpinene, citral, geranial, β-pinene and α-pinene. Two coumarins, bergapten and citropten,were also identified in C. bergamia and C. medica cv Diamante, respectively and tested forbiological activity. Both C. bergamia and C. medica cv Diamante oils exhibited a selectiveinteresting activity against the A375 cell line with IC50 values of 79.3 and 89.1 μg/mL,respectively, after 100 min of exposure with UV irradiation. The strong antiproliferativeactivity demonstrated with bergapten (IC50 value of 71.3 μg/mL after 20 min of irradiation)was not found with citropten. Discussion and conclusion. Our study suggested that UVirradiation is effective in activating essential oils and in particular bergapten. Thisphototoxicity may be considered as treatment option in some cases of lentigo maligna orlentigo maligna melanoma.