Bergamot orange: Phytochemical screening and antioxidant activity of fruit parts and hydrodistillation waste products of species cultivated in Western Greece and Southern Italy

Bergamot orange (Citrus bergamia Risso) is a species extensively used for its essential oil extracted from the peel. However, bergamot fruit contains also non-volatile components with high antioxidant activity, mainly flavanones and lesser amounts of flavones¹. In line with our research² we carried out a comparative study on the chemical content and the biological activity of bergamot oranges cultivated on Kefalonia Island (Lourdas) of Greece and in the Italian region of Calabria (Reggio Calabria). The different parts of the fruit (albedo, flavedo and juice) were extracted and analyzed by HPLC to compare relative concentrations and by UHPLC-HRMS to identify main phytochemicals. The same analysis was performed for the waste water and waste peel obtained after a hydrodistillation process for essential oil production. Finally, all extracts, have been assessed for their total phenolic (TPC) and total flavonoid (TFC) content and for their antioxidant activity against the DPPH radical. The phytochemical screening of both cultivars showed the presence of 5 main flavanones, highly accumulated in the albedo part. The rind and the juice of Kefalonian bergamots showed a 2.74 and 4.99-fold higher neoeriocitrin content than the respective Calabrian fruit parts while naringin content was found to be 1.22 and 1.66-fold higher in the Calabrian bergamots, respectively. On the other hand, flavanones neohesperidin, melitidin and brutieridin were only detected in Calabrian bergamots. Among the two cultivars, the methanolic extracts of the Kefalonian fruit rind and juice showed a higher antioxidant potential than the respective Calabrian bergamot extracts, probably due to the high TPC and TFC contents. Furthermore, our study showed that the vegetable material and the waste water after hydrodistillation can still be considered good sources of phenolic compounds with appreciable antioxidant potential.

Keywords: Bergamot orange, metabolic profiling, UHPLC-HRMS, antioxidant.

References:

[1] Gardana C, Nalin F, Simonetti P. Evaluation of flavonoids and furanocoumarins from Citrus bergamia (Bergamot) juice and identification of new compounds. Molecules 2008; 13: 2220 – 2228

[2] Melliou E, Michaelakis A, Koliopoulos G, Skaltsounis AL, Magiatis P. High quality bergamot oil from Greece: Chemical analysis using chiral gas chromatography and larvicidal activity against the West Nile virus vector. Molecules 2009; 14: 1948 – 1949