Antimicrobial activity of the crude extract, fractions and isolation of zerumbone from the rhizomes of Zingiber roseum

Abstract

The rhizome of Zingiber roseum has been used as traditional medicines for the treatment of gastric ulcer,skin diseases, and liver infections. Zerumbone is an essential sesquiterpenoid previously isolated from different speciesof Zingiberaceae and possesses numerous pharmacological properties. Based on previous reports, the aim of the currentstudy was to investigate the antimicrobial activity of extract, fractions, and isolation of zerumbone from Zingiber roseum.The antimicrobial activity was determined using disc diffusion method. The serial tube dilution technique was used todetermine Minimum Inhibitory Concentration (MIC) of the samples. Vacuum Liquid Chromatography (VLC) and opencolumn chromatography were used for separation. The methanol extract exhibited maximum antimicrobial activityagainst Escherichia coli, Saccharomyces cerevisiae, and Aspergillus niger in both methods. VLC of the extract yielded fivefractions (Fr. 1 to Fr. 5). Fr. 1 exhibited maximum antimicrobial activity compared to the other fractions. Columnchromatography of Fr.1 generated 47 fractions. Fraction 1 to 9 were combined and crystallized in n-hexane to isolatezerumbone as the most abundant source (yield 6.5 % from dried MeOH extract). Zerumbone showed good activityagainst all tested bacteria. The results of our study might validate the ethnobotanical use of Zingiber roseum rhizomes inthe treatment of infectious diseases. Moreover, Zingiber roseum could be one of the most abundant sources for theisolation of natural zerumbone to study different pharmacological studies in the field of new drug discovery.