Halogenated benzoate derivatives of altholactone with improved anti-fungal activity

Abstract

Altholactone exhibited the anti-fungal activity with a high MIC value of 128 μg ml⁻¹ against Cryptococcus neoformans and Saccharomyces cerevisiae. Fifteen ester derivatives of altholactone 1–15 were modified by esterification and their structures were confirmed by spectroscopic methods. Most of the ester derivatives exhibited stronger anti-fungal activities than that of the precursor altholactone. 3-Bromo- and 2,4-dichlorobenzoates (7 and 15) exhibited the lowest minimal inhibitory concentration (MIC) values against C. neoformans at 16 μg ml⁻¹_, while the 4-bromo-, 4-iodo-, and 1-bromo-3-chlorobenzoates (11–13) displayed potent activity against S. cerevisiae with MIC values of 1 μg ml⁻¹. In conclusion, this analysis indicates that the anti-fungal activity of altholactone is enhanced by addition of halogenated benzoyl group to the 3-OH group.

Keywords:

• Altholactone
• anti-fungal activity
• ester derivative
• halogenated benzoate
• Polyalthia crassa

Acknowledgments

We are grateful to Dr Laran T. Jensen (Department of Biochemistry, Faculty of Science, Mahidol University) for critically proofreading of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.