Planta Med 2008; 74 - PE25
DOI: 10.1055/s-0028-1084724

High quality bergamot oil from Cephallonia (Greece): chemical analysis using enantiomeric GC-MS and larvicidal activity against mosquitoes

E Melliou 1, P Magiatis 1, A Michaelakis 2, G Koliopoulos 2, AL Skaltsounis 1
  • 1Department of Pharmacognosy and Natural Products Chemistry, Faculty of Pharmacy, University of Athens, Panepistimiopolis-Zografou, Athens 15771, Greece
  • 2Benaki Phytopathological Institute, 8 S. Delta Str. 14561 Kifissia Athens, Greece

The essential oil contained in the rind of the bergamot fruit (Citrus aurantium subsp. bergamia, syn. Citrus bergamia) is a high value product with many applications in perfume industry, beverage industry and cosmetology.

The bergamot trees were cultivated in Cephallonia island (region Vlachata) in a total area of 200.000m2. The plant material (leaves and fruits in different stages of maturity) were collected between December and February for a two years period. The rind of the fruit was separated manually and the essential oil was obtained either by cold pressing or by hydrodistillation. The total yield calculated on wet weight of fresh rinds was 0.8%. The leaves were submitted to hydrodistillation using a semi-industrial distiller. The obtained essential oils were analyzed using gas chromatography-mass spectrometry first with a DB-5 column and then with an enantiomeric column b-Dex sm. It was found that the main constituent of the cold press essential oil of the fruit rind was (-)-linalyl acetate with optical purity >99% which is responsible for the characteristic odour of the bergamot fruit. Other important constituents were (-)-linalool, (+)-limonene and γ-terpinene. One important index for the characterization of the high quality bergamot oil is the ratio linalool/linalyl acetate which must be 0.3. The performed analysis showed that the value of this specific index in the last stage of the fruit maturity was 0.32. Another characteristic index is the sum of linalool+linalyl acetate which was found to be >56%.

The obtained essential oils were tested for their larvicidal activity against the mosquito larvae of Culex pipiens (Diptera: Culicidae). The essential oil obtained by cold pressing showed an LC50 value of 58mg/L while the LD50 value of the corresponding essential oil obtained by hydrostillation was 106mg/L. The activity was found to be correlated with the percentage of linalyl acetate, since the samples obtained by the second method had lower concentration of linalyl acetate and showed reduced larvicidal toxicity. Finally, the essential oil obtained from the leaves presented similar larvicidal toxicity with the oil obtained by cold pressing of the rind (LC50=68mg/L).

Acknowledgement: The project was funded by the Hellenic export organization (HEPO)