Comparative assessment of volatiles in juices and essential oils from minor Citrus fruits (Rutaceae)

Citrus Essential Oils (CEOs) from the peel of six minor Citrus fruits (C. bergamia ‘Castagnaro,’ ‘Fantastico,’ and ‘Femminello,’ C. × myrtifolia, C. mitis, and C. japonica) were obtained by hydrodistillation and cold hand pressing of the flavedo to investigate their volatile constituents and antimycotic activities. The volatile compounds present in the juices of the same fruits, obtained by manual squeezing of the endocarps, were evaluated by direct immersion and Solid Phase Micro Extraction. Monoterpenes were identified as the main class of components in all the six CEOs. Limonene was the most abundant compound, while BEOs (Bergamot Essential Oils) changed its composition according to the different extraction method and the fruit varieties. Non-metric Multidimensional Scaling (NMDS) of the matrix taxa x chemical compounds showed that five chemical compounds had a significant discriminative function among the samples: high amounts of limonene characterized the cluster of C japonica, C. × myrtifolia, and C mitis, while the group of three cultivars of C bergamia differed in its predominance of linalool and linalyl acetate. Furfural and 4-terpineol were identified in the highest amounts in the Citrus juices analyzed by direct immersion. BEO obtained by hydrodistillation of C bergamia ‘Fantastico’ was the most active in the antifungal tests. The antimycotic activity of C japonica EOs against dermatophytic species was also demonstrated. Based on our results, the use of these products would appear an interesting alternative in producing topical herbal products for the treatment of affected animals or for the purpose of environmental fungal control.