Gas chromatography–mass spectrometry profile and antimicrobial activities of Ballota bullata Pomel and B. nigra L. subsp. uncinata (Fiori & Bég.): A comparative analysis

Abstract

This study was carried out to compare for the first time, the chemical composition and antimicrobial activities of essential oils from two Ballota species growing wild in different regions of Tunisia. The volatile oils obtained by hydro-distillation of Ballota bullata Pomel and Ballota nigra L. subsp. uncinata (Fiori & Bég.) Patzak were analyzed by gas chromatography (GC) and gas chromatography mass spectrometry (GC/MS) to investigate the variations in chemical profiles. The results showed a significant difference in terms of essential oil yields and characteristic aroma. Valerianol (18.3%), α-muurolol (7.9%) and spathulenol (7.1%) were identified as the major odorants in B. bullata, while B. nigra subsp. uncinata oil was mainly composed of hexadecanoic acid (31.8%) and linoleic acid (17.9%). In addition, oxygenated sesquiterpenes were found to be the principal constituents of B. bullata essential oil (42.1%), whereas long chain oxygenated hydrocarbons form the main class in B. nigra (49.7%). Moreover, the antimicrobial activities were tested in vitro against five bacteria: Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, Staphylococcus aureus and Bacillus subtilis and the yeast Candida albicans. B. bullata essential oil showed stronger antibacterial effects comparing to B. nigra oil. Consequently, B. bullata essential oil holds promising antimicrobial potential, confirming its traditional medical use.