Nigella damascena L. Essential Oil-A Valuable Source of β-Elemene for Antimicrobial Testing

The most commonly used plant source of β-elemene is Y. H. Chen & C. Ling (syn. of Salisb.) with its content in supercritical CO₂ extract up to 27.83%. However, the other rich source of this compound is L. essential oil, in which β-elemene accounts for 47%. In this work, the effective protocol for preparative isolation of β-elemene from a new source- essential oil-using high performance counter-current chromatography HPCCC was elaborated. Furthermore, since sesquiterpens are known as potent antimicrobials, the need for finding new agents designed to combat multi-drug resistant strains was addressed and the purified target compound and the essential oil were tested for its activity against a panel of Gram-positive and Gram-negative bacteria, fungi, and mycobacterial strains. The application of the mixture of petroleum ether, acetonitrile, and acetone in the ratio 2:1.5:0.5 ( ) in the reversed phase mode yielded β-elemene with high purity in 70 min. The results obtained for antimicrobial assay clearly indicated that essential oil and isolated β-elemene exert action against strain H37Ra.