Abstract

Tulbaghia violacea Harv L.F. is one of the many medicinal plants used by Zulu traditional healers to treat respiratory tract diseases. Essential oil extracted from the rhizomes of T. violacea was evaluated for its chemical composition, antioxidant and antibacterial activities. The gas chromatography/mass spectrometry (GC/MS) analysis of the oils revealed the main constituents of the essential oils of T. violacea to be 2,4-dithiapentane (51.04%), ρ-xylene (20.59%), chloromethylmethyl sulfide (8.69%), σ-xylene (7.38%), thiodiglycol (6.43%) and ρ-xylol (5.88%). While the oil showed weak antioxidant activity, the antimicrobial activity of the essential oil carried out on both Gram positive and negative bacteria (using the agar disk diffusion method) showed that the oil of T. violacea was effective against 8 of the 16 microorganisms tested, with MIC values ranging from 2.5 to 5.0 mg/ml. The oil had low (1218 and 1641 µg/ml) cytotoxicity levels against HEK293 and HepG2 cell lines, respectively. It is apparent that the bioactivity of the essential oil of T. violacea contributes to the use of this plant in folk medicine.

Key words: Essential oil, antioxidant, antibacterial, Tulbaghia violacea.