GC-MS analysis of the volatile profile and the essential oil compositions of Tunisian Borago Officinalis L.: Regional locality and organ dependency

Seeking to explore new local natural resources, volatile profile as well as essential oil compositions of Tunisian Borago officinalis L. were analyzed. The current study aims at investigating the effects of the geographic origin and the plant part (flowers, leaves, and rosettes leaves) on the volatile profile of Borago officinalis L. The aerial parts were collected from three bioclimate zones in Tunisia namely Tunis, Bizerte, and Zaghouan. The essential oils were extracted by hydro distillation. The chemical composition of the latter was determined by gas chromatography coupled to mass spectrometry. Furthermore, an experimental procedure combining solid phase microextraction and gas chromatography coupled to mass spectrometry was implemented to study the volatile profile of Borago officinalis L. It was set up to assess the influence of different plant organs obtained from various sites on the aromatic profile. Essential oil yields ranged from 0.14 +/- 0.00% to 0.18 +/- 0.01%. Benzenacetaldehyde was the major compound of the essential oils (7.11-9.16%). Chromatographic analysis revealed that the chemical compositions vary considerably from one region to another. The ones extracted from Bizerte and Zaghouan collections were characterized by the predominance of aldehydes (27.02% and 35.16%), followed by oxygenated monoterpenes (20.64% and 20.58%). The essential oils obtained from the third collection (Tunis) showed the predominance of oxygenated monoterpenes (27.23%), followed by aldehydes (23.93%) and oxygenated sesquiterpenes (12.22%). The aldehydes were identified as the major chemical class in the flowers' volatile compounds dominated by octanal (13.32-16.42%) as well as in the leaves where nonanal was the major one (10.49-11.55%). In the rosettes aromatic profile, the oxygenated monoterpenes were the main chemical class with a percentage ranging from 39.45 to 46.64%. A relatively high content of acids (10.15%) was exclusively determined in Zaghouan flowers' volatile profile. Principal Component Analyses and Hierarchical Clustering Analyses were pertinent tools to differentiate the volatile fractions. The findings showed a remarkable difference and significant variations in quality and quantity of the secondary metabolites.