Constituents of leaves and flowers essential oils of Helichrysum pallasii (Spreng.) Ledeb. growing wild in Lebanon.

The chemical compositions of the essential oils obtained from leaves and flowers of Helichrysum pallasii were analyzed by gas chromatography and gas chromatography-mass spectrometry. Among the 102 identified constituents, hexadecanoic acid (16.2%), (Z,Z)-9,12-octadecadienoic acid (6.8%), tetradecanoic acid (2.6%), and (Z)-caryophyllene (4.2%) were the main constituent of the oil from leaves, while in the oil from flowers hexadecanoic acid (14.7%), (Z,Z)-9,12-octadecadienoic acid (14.2%), (Z)-caryophyllene (3.6%), and delta-cadinene (3.1%) predominated. The oils were both characterized by sesquiterpenes (33.4% for leaves and 33.7% for flowers, respectively) and fatty acids and esters (30.3% in leaves and 35% in flowers, respectively). The in vitro activity of the essential oils of the plant against some microorganisms in comparison with chloramphenicol by the broth dilution method was determined. The oils exhibited a weak activity as inhibitors of growth of Staphylococcus epidermidis in vitro (minimum inhibitory concentration = 100 microg/mL).