Antifungal 5-n-alkylresorcinols from Pseudomonas rhizobacteria

5-n-alkylresorcinols (AR), a group of non-isoprenoid lipids, are long-chain homologues of orcinol [1]. This type of compounds exhibit biologically important properties [2]. These metabolites have been found in several organisms, being rhizobacteria an important source of AR, because of that Pseudomonas become a good source of chemical compounds as an alternative for the control of phytopathogenic microorganisms. As part of our research on antifungal compounds, the AR profiling and antifungal activity of AR-enriched extracts obtained from a set of liquid cultures of Pseudomonas rhizobacteria were investigated. Intra and extracellular-derived crude extracts were resulted by solvent extraction from PDB liquid cultures. The AR-enriched fractions were separately obtained by column chromatography from the crude extracts monitored by specific LC-DAD-controled diazonium coupling. Each AR-enriched fraction was evaluated in vitro against Fusarium oxysporum and Botrytis cinerea, exhibiting antifungal activity at different levels. In vitro results indicated that the hyphae are rolled as they grow by action of the test fractions. The mycelial inhibition was found to be in the 50 – 90% range at 1 – 100 µg/mL. Hence, from this fraction were isolated two antifungal AR-related compounds. Other seven AR compounds in the fraction were identified by azo-coupling derivatization and LC-MS analyses. Pseudomonas rhizobacteria-derived AR were found to affect the growth of phytopathogens reducing the growth area and deforming the hyphae, which can in turn affect the metabolism of the pathogen reducing the ability of colonizing host plants.

Acknowledgements: The present work is a product derived by the Project INV-CIAS-1471 financed by Vicerrectoría de Investigaciones at UMNG – Validity 2014.

Keywords: Pseudomonas, 5-n-alkylresorcinols, antifungal

References:

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[2] Kozubek A, Tyman J. Resorcinolic lipids, the natural non-isoprenoid phenolic amphiphiles and their biologycal activity. Chem. Rev. 1999, 99: 1 – 31.