Chemical Composition and in-vitro Antimicrobial Activity of Leaf Essential Oils of Senecio pedunculatus Edgew. and Nepeta coerulescens Maxim

Abstract When talking of herbal medicines, one of the most important herbal families is the Lamiaceae family that includes a varied range of plants with biological and medicinal interests. Medicinal properties of the Lamiaceae species are mainly because of the high content of volatile components. Another family that possesses a good number of plants for our health care system is Compositae. Plant species in Compositae and Lamiaceae family are widely being used to cure various diseases. The present study aims to study the composition and in vitro antimicrobial activity of the leaf essential oil of Senecio pedunculatus Edgew.of the Compositae family and compare the results with Nepeta coerulescens Maxim. of Lamiaceae family, both having caryophyllene oxide as the major constituent in their leaf essential oil. The antifungal activity of the essential oil could be due to the presence of caryophyllene oxide since it is well known as a preservative in food, drugs, and cosmetics, had been tested in vitro as an antifungal against dermatophytes. Essential oils of the leaves of Senecio pedunculatus and Nepeta coerulescens contained 23.5 % and 29.3 % caryophyllene oxide, respectively, as the major constituent. The leaf essential oil of Senecio pedunculatus showed mild activity against one or more pathogens on Petri plate assay based on the zone of inhibition and MIC values. The essential oil was most effective against Bacillus subtilis and least effective against Staphylococus aureus. Among fungal strains, the essential oil was most effective against Aspergillus flavus. The Nepeta coerulescens leaf essential oil was most effective against Staphylococus aureus and least effective against Salmonella enterica. Among fungal strains, the essential oil was equally effective against Aspergillus flavus and Candida albicans.