Chemical Composition of Endemic Tragopogon oligolepis and Studies on the Antimicrobial Activity against Multi-Antibiotic Resistant Bacteria

Abstract

The antimicrobial activity of the n-hexane, chloroform, ethyl acetate and ethyl alcohol extracts from the aerial parts of T. oligolepis, endemic to Turkey collected from Mugla area, was evaluated against microorganisms including multi-antibiotic resistant bacteria. These activities were determined using the disc diffusion method, with 25 mu l of each extract containing 25 mg/ml crude extract per disc. For this study; 3 Gram-negative standart test bacteria (Enterobacter aerogenes RSKK 720, Pseudomonas aeruginosa ATCC 27853 and Escherichia coli ATCC 25922), 4 Gram-positive standart test bacteria (Micrococcus luteus NRRL B-4375, Bacillus subtilis ATCC 6633, Streptococcus mutans CNCTC 8/77 and Staphylococcus aureus ATCC 25923), 2 yeasts (Candida albicans ATCC 10239 and Candida tropicalis RSKK 665) and multi-antibiotic resistant strains of Stenotrophomonas maltophilia and various species of Staphylococcus were used. The chemical composition of the hexane extract of this plant was determined by Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS). The ethyl alcohol extract inhibited the growth of all Gram-negative bacteria and the inhibition zones ranged between 11-21 mm. This extract also inhibited the growth of all multi-antibiotic resistant strains of various species of Staphylococcus used, except Staphylococcus capitis MU 27 and Staphylococcus sp. MU 28. The chloroform extract exhibited the weakest antibacterial activity. The ethyl acetate extract had no effect on microorganisms tested. The hexane extract inhibited most of the Gram-negative bacteria including multi-antibiotic resistant strains of S. maltophilia. All of the extracts had no effect on yeasts. Total 20 compounds were determined in the hexane extract. The major compounds of the hexane extract of the plant were caryophyllene oxide (18.5%), beta-caryophyllene (16.3%), delta-cadinene (10.8%), manool (8.6%) and alpha-cadinene (4.8%), respectively.