Functionalized para-substituted benzenes as 1,8-cineole production modulators in an endophytic Nodulisporium species

Abstract

A Nodulisporium species (designated Ti-13) was isolated as an endophyte from Cassia fistula. The fungus produces a spectrum of volatile organic compounds (VOCs) that includes ethanol, acetaldehyde and 1,8-cineole as major components. Initial observations of the fungal isolate suggested that reversible attenuation of the organism via removal from the host and successive transfers in pure culture resulted in a 50 % decrease in cineole production unrelated to an overall alteration in fungal growth. A compound (CPM1) was obtained from Betula pendula (silver birch) that increases the production of 1,8-cineole by an attenuated Ti-13 strain to its original level, as measured by a novel bioassay method employing a 1,8-cineole-sensitive fungus (Sclerotinia sclerotiorum). The host plant produces similar compounds possessing this activity. Bioactivity assays with structurally similar compounds such as ferulic acid and gallic acid suggested that the CPM1 does not act as a simple precursor to the biosynthesis of 1,8-cineole. NMR spectroscopy and HPLC-ES-MS indicated that the CPM1 is a para-substituted benzene with alkyl and carboxyl substituents. The VOCs of Ti-13, especially 1,8-cineole, have potential applications in the industrial, fuel and medical fields. ; We acknowledge the financial support of the NSF via a grant to Dr B. Peyton of the MSU Department of Chemical and Biological Engineering and the DoE to G. S. J. N. recognizes the support of the CBS-SURP, which is funded by the Howard Hughes Medical Institute. S. R-U-L. was supported in a 1 year stay (2010−2011) at MSU on a BOYSCAST fellowship from the Department of Science and Technology, Government of India. The camera lucida drawing was kindly done by Dr Jitra Kokaew of the Department of Plant Pathology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand. Financial support from Endophytics LLC is also acknowledged.