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BioMed Research International
Volume 2014 (2014), Article ID 581985, 8 pages
Research Article

Antimicrobial Activity of Coronarin D and Its Synergistic Potential with Antibiotics

1Laboratory of Organic Synthesis, Chulabhorn Research Institute, Vibhavadi-Rangsit Highway, Laksi, Bangkok 10210, Thailand
2Laboratory of Natural Products, Chulabhorn Research Institute, Vibhavadi-Rangsit Highway, Laksi, Bangkok 10210, Thailand
3Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand

Received 4 February 2014; Accepted 29 April 2014; Published 15 May 2014

Academic Editor: Marc Léone

Copyright © 2014 Nanthawan Reuk-ngam et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Coronarin D is a labdane-type diterpene from the rhizomes of Hedychium coronarium. In the view of our ongoing effort to explore its novel biological activity, antimicrobial activity study of coronarin D was performed. The results showed that coronarin D was active against tested Gram-positive bacteria, inactive for tested Gram-negative bacteria, and weakly active against tested fungi. The antibacterial effect of the combination of coronarin D with nine classical antibiotics against four Gram-positive bacteria was also evaluated. The fractional inhibitory concentration indices (FICI) of coronarin D-antibiotics combinations, calculated from the checkerboard assay, were used as synergism indicator. Out of 36 combinations, 47% showed total synergism, 33% had partial synergistic interaction, 17% showed no effect, and 3% showed antagonism. By combination with coronarin D at concentration of 0.25 minimal inhibitory concentration (MIC), the activities of antibiotics were boosted to 4- to 128-fold. These finding suggested an attractive approach to combat the infectious diseases by using coronarin D-antibiotic drug combination.